Paramedic Exam Audio Crash Course™
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TABLE OF CONTENTS INTRODUCTION ................................................................................................................ ....... 1 CHAPTER 1: CELLULAR AND ACID BASE PHYSIOLOGY ............................................................... 5 Cell Physiology ............................................................................................................. ............. 5 Specialized Cells ........................................................................................................... ............. 5 Organization of the Cell .................................................................................................... ........ 7
Protein Types within the Cell Membrane ................................................................................. 7 Transport Across the Cell Membrane ....................................................................................... 8 Cell Cytoplasm .............................................................................................................. ........... 10 Organelles .................................................................................................................. ............. 11 Nucleus ..................................................................................................................... ............... 11 Centrioles .................................................................................................................. .............. 12 Ribosomes ................................................................................................................... ............ 12
Mitochondria ................................................................................................................ .......... 12 Endoplasmic Reticulum ....................................................................................................... .... 13
Golgi Apparatus.............................................................................................................. ......... 13 Vacuoles .................................................................................................................... .............. 13 Lysosomes ................................................................................................................... ............ 13 Peroxisomes ................................................................................................................. ........... 14
Cell Junctions .............................................................................................................. ............ 14 Cell Metabolism ............................................................................................................. ......... 14 Cellular Respiration ........................................................................................................ ......... 15 Building Blocks of the Cell ................................................................................................. ...... 16 Acid Base Physiology ........................................................................................................ ....... 17 Regulation of the Acid-Base System in the Body .................................................................... 19 Acid Base Disorders ......................................................................................................... ........ 20
Key Takeaways ............................................................................................................... ......... 23
Quiz ........................................................................................................................ ................. 24 CHAPTER 2: SHOCK ............................................................................................................ .... 28 Causes of Shock ............................................................................................................. .......... 28 Sepsis ...................................................................................................................... ................. 30 Sepsis-related Definitions ..................................................................................................... .. 32 Presentation ................................................................................................................ ............ 33 Diagnosing Sepsis ........................................................................................................... ......... 34
Treatment of Sepsis ......................................................................................................... ....... 34 Prognosis ................................................................................................................... .............. 35
Hypovolemic Shock ........................................................................................................... ...... 35 Evaluating the Shock Patient ................................................................................................ .. 37 Prehospital Care of Hypovolemic Shock ................................................................................. 38 Key Takeaways ............................................................................................................... ......... 40 Quiz ........................................................................................................................ ................. 41 CHAPTER 3: DRUGS USED IN EMS AND INTRAVENOUS MANAGEMENT ................................. 45 Medications used by a Paramedic .......................................................................................... 45 Starting an IV .............................................................................................................. ............. 49
Catheter Gauges ............................................................................................................. ........ 50 Intravenous Fluids .......................................................................................................... ......... 51 Intraosseous Lines .......................................................................................................... ......... 52
Key Takeaways ............................................................................................................... ......... 54 Quiz ........................................................................................................................ ................. 55 CHAPTER 4: AIRWAY MANAGEMENT ..................................................................................... 59 Evaluating the Airway ....................................................................................................... ...... 59 Evaluating Ventilation ...................................................................................................... ....... 63
Airway Adjuncts ............................................................................................................. ......... 64
Bag Valve Mask Procedure .................................................................................................... . 64 Intubation Procedure ........................................................................................................ ...... 66 Laryngeal Mask Airway ....................................................................................................... .... 68
Cricothyrotomy .............................................................................................................. ......... 69 Key Takeaways ............................................................................................................... ......... 72 Quiz ........................................................................................................................ ................. 73 CHAPTER 5: DYSPNEA MANAGEMENT ................................................................................... 77 Differentiating Dyspnea Causes .............................................................................................. 77 Respiratory Dyspnea ......................................................................................................... ...... 78
Dyspnea Treatment Strategies ............................................................................................... 83 Asthma ...................................................................................................................... .............. 84 Congestive Heart Failure .................................................................................................... ..... 85
Pneumonia ................................................................................................................... ........... 86 Pulmonary Embolism (PE) ..................................................................................................... .. 87 Pneumothorax ................................................................................................................ ........ 89 Key Takeaways ............................................................................................................... ......... 91 Quiz ........................................................................................................................ ................. 92 CHAPTER 6: CHEST PAIN AND ACUTE CORONARY SYNDROME ............................................... 96 Chest Pain Evaluation ....................................................................................................... ...... 96 Management of ACS ........................................................................................................... .. 101 Key Takeaways ............................................................................................................... ....... 103 Quiz ........................................................................................................................ ............... 104 CHAPTER 7: CARDIAC ARRHYTHMIA MANAGEMENT ........................................................... 109 Irregular Rhythms ........................................................................................................... ...... 109 Atrial Fibrillation ......................................................................................................... .......... 110 Premature Ventricular Contractions ..................................................................................... 111
Tachyarrhythmias ............................................................................................................ ..... 112 Atrial Flutter .............................................................................................................. ............ 113 Supraventricular Tachycardia (SVT) ...................................................................................... 114 Ventricular Tachycardia ..................................................................................................... ... 115 Ventricular Fibrillation .................................................................................................... ...... 116 Bradyarrhythmias and Asystole ............................................................................................ 11 7 Sinus Bradycardia ........................................................................................................... ....... 118 Heart Blocks ................................................................................................................ .......... 119 Asystole .................................................................................................................... ............. 120 Pulseless Electrical Activity ............................................................................................... .... 121
Key Takeaways ............................................................................................................... ....... 123 Quiz ........................................................................................................................ ............... 124 CHAPTER 8: MEDICAL EMERGENCIES ................................................................................... 128 Neurologic Emergencies ...................................................................................................... . 128 Stroke ...................................................................................................................... .............. 128 Seizures .................................................................................................................... ............. 130 Endocrine Emergencies ....................................................................................................... .. 131
Thyroid Storm ............................................................................................................... ........ 131 Myxedema Coma ............................................................................................................... ... 132 Diabetic Ketoacidosis (DKA) ................................................................................................. . 132 Adrenal Crisis .............................................................................................................. .......... 133 Immunologic Emergencies .................................................................................................... 134
Immune Deficiency ........................................................................................................... .... 134 Allergic Reactions .......................................................................................................... ........ 135 Infectious Disease Emergencies ............................................................................................ 1 36 Sepsis ...................................................................................................................... ............... 136
Meningitis .................................................................................................................. ........... 138 Necrotizing Fasciitis ....................................................................................................... ....... 139
Toxicologic Emergencies ..................................................................................................... .. 140 Opioid Emergencies .......................................................................................................... .... 140 Differential Diagnosis of Opioid Toxicity .............................................................................. 141 Gastrointestinal Emergencies ............................................................................................... 141 Gastrointestinal Bleeding ................................................................................................... ... 141 Peritonitis ................................................................................................................. ............. 142
Acute Mesenteric Ischemia .................................................................................................. 143 Bowel Obstruction ........................................................................................................... ..... 143 Pancreatitis ................................................................................................................ ........... 143 Hematologic Emergencies .................................................................................................... 144 Sickle Cell Disease ......................................................................................................... ........ 144 Hemophilia .................................................................................................................. .......... 145
Genitourinary Emergencies .................................................................................................. 145 Priapism .................................................................................................................... ............ 146 Paraphimosis ................................................................................................................ ......... 146 Testicular Torsion .......................................................................................................... ........ 147
Fournier’s Gangrene ......................................................................................................... .... 148 Behavioral/Psychiatric Emergencies ..................................................................................... 148
Violent/Agitated Patient .................................................................................................... ... 149 Suicidal Patient ............................................................................................................ .......... 150
Key Takeaways ............................................................................................................... ....... 151 CHAPTER 9: GYNECOLOGIC EMERGENCIES ........................................................................... 156 Ectopic pregnancy ........................................................................................................... ...... 156
Miscarriage or Spontaneous Abortion .................................................................................. 157 Vaginal Bleeding ............................................................................................................ ........ 159 Sexual Assault .............................................................................................................. ......... 161
Key Takeaways ............................................................................................................... ....... 164 Quiz ........................................................................................................................ ............... 165
CHAPTER 10: OBSTETRICAL AND NEWBORN CARE ............................................................... 169 Pre-Delivery Obstetrical Emergencies .................................................................................. 169
Hypertensive Emergencies ................................................................................................... 169 Placenta Previa ............................................................................................................. ......... 171
Placental Abruption ......................................................................................................... ..... 172 Normal Delivery ............................................................................................................. ....... 173 Basics of Pregnancy ......................................................................................................... ...... 173
Evaluation of Labor ......................................................................................................... ...... 174 Managing Delivery ........................................................................................................... ..... 175 Obstetrical Emergencies ..................................................................................................... .. 176 Newborn Resuscitation ....................................................................................................... .. 178
Key Takeaways ............................................................................................................... ....... 180 Quiz ........................................................................................................................ ............... 181 CHAPTER 11: MASS CASUALTY INCIDENTS, TRIAGE, AND INCIDENT MANAGEMENT ............ 186 Mass Casualty Incidents ..................................................................................................... ... 186
Declaring the MCI ........................................................................................................... ...... 187 Incident Command System ................................................................................................... 1 87 Scene Size Up ............................................................................................................... ......... 188 Trauma Centers .............................................................................................................. ....... 190 Flow of Care in MCIs ........................................................................................................ ..... 190 Mass Casualty Event ......................................................................................................... .... 192 Triage in EMS Settings ...................................................................................................... ..... 192 SALT Categories ............................................................................................................. ........ 194 START Adult Triage .......................................................................................................... ...... 194
Incident Management ......................................................................................................... . 195 Key Takeaways ............................................................................................................... ....... 197 Quiz ........................................................................................................................ ............... 198
CHAPTER 12: TRAUMA MANAGEMENT................................................................................ 202 Head Trauma ................................................................................................................. ........ 202
Chest Trauma ................................................................................................................ ........ 204 Abdominopelvic Trauma ....................................................................................................... 206 Extremity Trauma ............................................................................................................ ..... 209 Burns ....................................................................................................................... .............. 211 Burn Treatment .............................................................................................................. ....... 215 Key Takeaways ............................................................................................................... ....... 216 Quiz ........................................................................................................................ ............... 217 CHAPTER 13: SPECIAL POPULATIONS ................................................................................... 221 Pediatric Care .............................................................................................................. .......... 221 Pediatric Vital Signs ....................................................................................................... ........ 222 Normal Vital Signs by Age ................................................................................................... .. 224 Anatomy and Physiology Differences in the Child ................................................................ 225 Geriatric Care .............................................................................................................. .......... 227
Key Takeaways ............................................................................................................... ....... 229 Quiz ........................................................................................................................ ............... 230 SUMMARY ..................................................................................................................... ...... 234 COURSE QUESTIONS AND ANSWERS ................................................................................... 238
INTRODUCTION The purpose of this course is to prepare you for the National Registry of Emergency Medical Technicians (NREMT) Paramedic Examination—the test that must be taken as part of the
paramedic certification process. This course includes clinical and nonclinical information you must know in order to pass the test, with an emphasis on clinical care in the practice of EMS. The test is the most advanced examination taken by emergency medicine personnel, which is reflected in an increased complexity over other NREMT examinations. Chapter one focuses on normal cell physiology, normal acid-base physiology, and acid base disorders. Understanding cell physiology as an EMT-Paramedic is necessary because cells are
the building blocks of the body and make up every physiological response that happens in the body. An example of this is acid base disorders. This chapter discusses acid-base physiology
and disorders involving acids, bases, and the pH of the blood. Chapter two involves a discussion about shock. While shock is considered a situation of low blood pressure for various reasons, including sepsis and hypovolemia, it is actually a great deal
more than that. Shock decreases the tissue perfusion to major organs, leading to metabolic acidosis and acute end-organ failure. The treatment of shock must take place as soon as it is
identified in order to prevent tissue hypoxia, permanent end organ damage, and death from multiple organ failure. The subjects of chapter three are the drugs used by paramedics in the EMS system, which can be given by any number of routes, as well as intravenous and intraosseous lines. What’s unique to paramedics versus other EMS personnel is that the paramedic can give a wide variety of medications, including medications given intravenously. The paramedic must know the basics of starting an intravenous line, the different types of intravenous fluids given, and the purpose of an intraosseous line. These things are all covered in this chapter. 1
Chapter four is about airway management, which is one of the most important aspects of EMS. This is because the assessment and management of the patient’s airway is paramount to their survival. Without adequate evaluation and treatment of airway concerns, few other aspects of patient care will help the patient survive. The chapter discusses airway evaluation, ventilation concerns, airway adjuncts used by EMS, and procedures for intubating patients who require total airway support. Dyspnea or “shortness of breath” and its management is the topic of chapter five. This is a common complaint, affecting about eight percent of all patients seen in the emergency department. In half of these situations, dyspnea is the patient’s primary concern. For this reason, it is important to know the differential diagnosis of dyspnea as well as some common interventional strategies the paramedic needs to implement for those patients presenting with this symptom. The focus of chapter six is the evaluation of chest pain and the management of acute coronary syndrome. These are things that the paramedic commonly encounters in the EMS setting. The chapter covers the evaluation of chest pain in general (as not all chest pain is cardiac in nature)
as well as the management of acute coronary syndrome (ACS), which is a medical emergency for which the interventions begin in the field by the paramedic and EMS team. Chapter seven talks about the management of cardiac arrhythmias in EMS practice. Individuals will present with cardiac arrhythmias as the primary complaint with a variety of presentations. As a prehospital provider, the paramedic should be able to recognize the different arrhythmias and their presentations and should be able to initiate interventional strategies in keeping with current Advanced Cardiac Life Support (ACLS) protocols. The subject of chapter eight is medical emergencies. A paramedic handles emergencies from all areas of medicine on a daily basis. This chapter focuses mainly on internal medicine
emergencies, from neurological disorders that present emergently to things like endocrine, immunologic, infectious disease, and toxicologic emergencies, among others. Each of these is
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important to cover because of the numerous possible medical presentations that can await the paramedic as part of their everyday job. Chapter nine covers several different gynecological emergencies a paramedic might encounter. These include early pregnancy complications, such as ectopic pregnancy and miscarriage, as well as the general topic of vaginal bleeding. Sexual assault represents a special kind of gynecological emergency in which there are medical, psychosocial, and legal concerns. The paramedic who handles sensitive cases related to female gynecological emergencies needs to
manage these women on multiple levels of care. The focus of chapter ten is the emergency medical technician’s care of the pregnant patient, including pre-delivery obstetrical emergencies, the normal delivery process, and obstetrical emergencies. When caring for the pregnant patient, particularly one who delivers in the EMS setting, there are two patients to manage. For this reason, the process of newborn resuscitation is also covered in this chapter. Chapter eleven covers mass casualty incidents, triage, and incident management. All paramedics are likely to train for and be prepared for a mass casualty incident, in which the resources available cannot keep up with the number of casualties. In such a situation, triage is important in order to care for the greatest number of patients with the fewest resources, keeping in mind that the sickest or most injured patients often are not treated first. Incident management involves what the EMS system does in the aftermath of significant or traumatic incidents to help maintain the health and wellbeing of the EMS worker. Chapter twelve discusses the paramedic and trauma management. In a trauma situation, there may be a single area of the body affected, such as head or chest trauma; however, many times, the patient will have multiple body areas at the same time at risk for trauma. This chapter covers the different areas where trauma might be experienced as well as the management of burns that can affect any area of the body. The focus of chapter thirteen is the care of special populations. Not all patients a paramedic will care for are adults so the special needs of infants and children care are covered, including
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the important differences in vital signs and medical management of children versus adults. The geriatric population deserves special attention as well. Older adults have complex medical histories and some do not want aggressive care should they suffer medical decompensation.
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CHAPTER 1: CELLULAR AND ACID BASE PHYSIOLOGY This chapter focuses on normal cell physiology, normal acid-base physiology, and acid base disorders. The purpose of understanding cell physiology as an EMT-Paramedic is that cells are the building blocks of the body and make up every physiological response that happens in the body. An example of this is acid base disorders. The chapter discusses acid-base physiology and
disorders involving acids, bases, and the pH of the blood.
CELL PHYSIOLOGY The cell is both the structural and functional building block of the human body—and of life.
There are a hundred trillion cells in the human body that function differently, depending on the part of the body they are located. There are basic needs to all cells, namely oxygen, some type of energy source, and the removal of waste products. There are 200 subtypes of cells in the human body. Identical cells organized together are collectively called a “tissue.” Tissues organized for a common purpose are called and organ.
Organs do not have to have the same type of cell making them up. All physiological and biochemical processes, growth and development, and disease states can be attributed to abnormalities at the cellular level.
SPECIALIZED CELLS Cells of different tissues can be specialized in order to perform specific functions. These are some important specialized cells you should know about: A. Neurons—these are also referred to as nerve cells and are a part of the nervous system. Their purpose is to produce, process, and transmit information on a biochemical level.
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They make up the brain, spinal cord, and peripheral nerves. They are connected to one another via cell to cell connections called synapses. These chemical synapses can evoke
action potentials (electrical signals) that are sent to other neurons in the body. B. Epithelial cells—the functions of these cells include sensation detection, secretion, absorption, protection, transcellular transport, and selective permeability. These are considered “lining cells” because they line the inside of cavities and the lumen of the GI
tract. They also cover the outside of the body in the form of skin. C. Exocrine cells—these secrete products through ducts; the different products include sweat, mucus, and digestive enzymes. The products of these cells go to target organs by means of the ducts. An example of this is pancreatic enzymes that are secreted by pancreatic exocrine cells, travel through ducts, and act on the duodenum. D. Endocrine cells—these are similar to exocrine cells because they secrete products. The difference is that endocrine cells release their products (which are called hormones) into the bloodstream. An example of this is the hormone-secreting cells of the pituitary gland or the pancreatic islet cells. These travel to different parts of the body to act on distant target organs. E. Red blood cells (RBCs) —these are cells that lack a nucleus and that, as their function, collect oxygen from the lungs, delivering it to the body tissues. Gas exchange happens passively by leaving the RBCs and entering every cell of the body. F. White blood cells (WBCs)—these are also referred to as leukocytes. There are several types of leukocytes with varying functions. They are made in the bone marrow and help fight infectious diseases and foreign substances that enter the body. WBCs can be found in just about every tissue but predominate in the circulatory system, spleen, and lymphatic system.
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ORGANIZATION OF THE CELL The cell is bound by a cell membrane, contains liquid called “cytoplasm,” and contains organelles, which are different structures that perform various functions in the cell. The boundary of the cell is the plasma membrane or “cell membrane.” The membrane is semipermeable, meaning that it lets some molecules in and keeps other molecules out. Oxygen and nutrients are allowed in the cell, while toxins and waste products are kept out of the cell or extruded from the cell. There are specific pumps that keep a tight control over the concentration of certain solutes, such as potassium and sodium, within the cell itself. The plasma membrane is mostly a double phospholipid structure. A phospholipid is a molecule that has a polar (hydrophilic or water-loving) and a nonpolar (hydrophobic or water-hating) end. The polar ends are on either side of the membrane, while the middle of the membrane consists of the inner core of the cell membrane. Cholesterol and proteins make up the rest of the plasma membrane. There are several different types of proteins, including peripheral proteins, which are attached to the inner or outer surface of the membrane, and integral proteins, which are within the membrane itself. These float within the lipid bilayer in what’s called the “fluid mosaic model” of the cell membrane. Water, O2, CO2, and other small lipid soluble molecules (like hydrocarbons) pass through the membrane passively without assistance.
PROTEIN TYPES WITHIN THE CELL MEMBRANE There are several different types of cell membrane proteins that form different functions. Some of these types of proteins are as follows: A. Channel proteins—these are integral proteins that provide entryways for certain watersoluble or hydrophilic substances, including polar molecules and charged ions. There is no energy expended in the transfer of these molecules. For this reason, the process is referred to as facilitated diffusion.
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B. Transport proteins—these will expend ATP (cellular energy) in order to transport molecules into or out of the cell. This is referred to as “active transport” because it requires energy in order to allow for the transport. C. Recognition proteins—these are cells that allow others to recognize the cell as being a self-cell and distinguish the cell as being of a certain type. They have short
polysaccharide (or sugar) chains extending from the surface of the cell. D. Adhesion proteins—these are proteins that attach to neighboring cells. They provide anchors for the internal filaments and tubules within the cells to provide stability and structure for the cell. E. Receptor proteins—these are located in and on the membrane and allow trigger molecules such as hormones to act on the interior of the cells. These are basically
binding proteins. F. Electron transfer proteins—these are involved from one molecule to another during various chemical reactions in the cell membrane.
TRANSPORT ACROSS THE CELL MEMBRANE There is passive and active transport across the cell membrane. Passive transport does not require the use of energy. Simple diffusion is the net movement of substances from an area of higher concentration to an area of lower concentration. There is random and constant movement of molecules that pass through the cell membrane to an area of lower concentration (also referred to as going down a gradient). Facilitated diffusion is the diffusion of solutes through the aid of proteins in the membrane. The biggest example of this is the facilitated diffusion of water with the help of aquaporins. This does not require ATP energy input but requires the aquaporin proteins. Osmosis refers to the diffusion of water molecules across a semipermeable membrane. When water moves into a cell by osmosis, hydrostatic pressure, also called osmotic pressure, can build up in the cell. On
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the other hand, dialysis is the term used to describe the diffusion of solutes (usually of a small size) across a selectively permeable membrane. Active transport involves the movement of solutes against a gradient. It requires the expenditure of ATP energy. There are two possible mechanisms by which this can occur. The first is through protein pumps. These are also known as ion pumps, which are membranebound transport pumps that transfer ions (potassium, sodium, hydrogen, and chloride, for example), amino acids, or monosaccharides across a membrane. In active transport, ATP changes the protein’s shape so that it will release the bound molecule on the opposite side of the membrane. The protein pumps are specific to the molecule being transported. The protein pumps are ATPases (ATP enzymes) that catalyze the reaction that takes ATP and turns it into ADP, releasing energy used to transport the molecule. The most well-known pump is the sodium-potassium pump or Na+/K+-ATPase enzyme, which actively transports sodium out of the cell and potassium into the cell. These are found on the membranes of every cell in the body. Vesicular transport involves the transport of large particles and large macromolecules across the plasma membrane. There are two major types of vesicular transport: endocytosis and exocytosis. Exocytosis involves the fusion of vesicles made inside the cell to the cell membrane. The vesicle opens up and extrudes the contents out of the cell. In endocytosis, vesicles are outside of the cell membrane and fuse with the cell membrane; the contents of the vesicle are discharged into the cell. There are three kinds of endocytosis, known as the following: A. Phagocytosis—this is referred to as “cell eating.” The dissolved materials enter the cell with the solid material forming a phagocytic vesicle in the cell. They fuse with
lysosomes inside the cell, allowing for the solid material to be broken down.
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B. Pinocytosis—this is referred to as “cell drinking.” The plasma membrane folds inward to form a channel in which the dissolved substances enter the cell and are enclosed in a pinocytic vesicle. C. Receptor-mediated endocytosis—this occurs when specific molecules in the extracellular space bind to a receptor site. The plasma membrane folds inward and forms a vesicle inside the cell that contains the molecules.
CELL CYTOPLASM The cytoplasm is the gel-like material that makes up the bulk of the inside of the cell. It consists of the cytosol (the liquid component), which is 89-90 percent water. It also contains salts, organic molecules, and numerous enzymes. Also dissolved in the cytosol are proteins and cell nutrients. In addition, the cytoplasm contains the organelles that serve functions inside the cell. There is a cell matrix that keeps the organelles and other compartments separated within the cell interior. The cytoskeleton consists of threadlike proteins that continually adapt to the cell’s needs, which are continually changing. The cytoskeleton helps to maintain their shape and allows the contents of the cell to move. The cytoskeletal network is made of three components: A. Microtubules—these function as the framework for organelles and vesicles to move within the interior of the cell. These are the thickest of the structures of the cytoskeleton. They are made from the tubulin protein subunit, forming the mitotic spindles that allow the cell to divide during mitosis. Along with the intermediate filaments and microfilaments, the microtubules will help give the cell its shape. B. Microfilaments—these provide mechanical support for the cell, enable cell movements, and determine cell shape. They have an arrow shape, with a barbed end and a pointed end. The protein subunit of microfilaments is actin. They predominate in muscle cells and in cells that need to change their shape quickly. Phagocytes also contain a lot of microfilaments.
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C. Intermediate filaments—these are intermediate in diameter compared to microtubules and microfilaments. In contrast to microfilaments and microtubules, the intermediate filaments are not directly involved in cell movements. Instead, they appear to play a structural role by providing mechanical strength to cells and tissues.
ORGANELLES Organelles are the structures inside the cytoplasm that physically separate the different metabolic activities that occur within the cells. The organelles are each responsible for doing a
particular function within the cell. There are numerous types of organelles within the cell structure—from the nucleus, which is prominent within the cell, to the small lysosomes, which contain enzymes that break down particles and unwanted waste within the cell.
NUCLEUS The nucleus ultimately controls the cell and contains DNA, which is the genetic material inside the cell. It is the largest organelle in most cells, although some cells can have more than one nucleus or no nucleus at all. Skeletal muscle is an example of a cell type that has multiple
nuclei, while RBCs have lost their nucleus by the time they are mature. The nucleus has a phospholipid bilayer, which is similar to the plasma membrane. Most of the genetic information of the cell is contained within the nucleus. DNA is made into 22 matching pairs of chromosomes and a nonmatching “pair,” the X and Y chromosomes. Chromosomes are not actually visible until the time of cell division when the chromatin condenses and forms thicker chromosomes that can be pulled apart into two separate cells. Histone proteins bind and organize the DNA into bundles, known as nucleosomes. Nucleoli can be within the nucleus, which are made from DNA that is in the process of making ribosomes. These ribosomes are sent to the cytoplasm to manufacture proteins from amino acids.
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Chromosomes are located inside the nucleus as well. The substance of chromosomes is called
chromatin, which is made from deoxyribonucleic acid (DNA) strands and proteins. The DNA is arranged in a double helix.
CENTRIOLES Centrioles are structures made from nine bundles of three microtubules each. They are rodshaped and paired up to make the centrosome. Centrioles are crucial to cell division; they make the mitotic spindles that separate during act of cell division and pull the divided chromosomes to opposite sides of the cell. Centrioles are similar to basal bodies, which are at the base of each flagellum and cilium in those cells that have them.
RIBOSOMES Ribosomes are active in the process of making proteins. They act as the protein-making factories inside the cell. Each ribosome is made from a large and small subunit. Collectively, the
ribosomes are found on rough endoplasmic reticulum or together form polyribosomes within the cytoplasm. Some ribosomes are found free-floating in the cytoplasm unattached to anything. They make use of ribonucleic acid (RNA), which is sent from the nucleus to allow for protein synthesis in the ribosomes themselves.
MITOCHONDRIA Mitochondria are important organelles in that they generate the ATP, which is the universal form of energy used by all cells in the body. The fuel used to make ATP is primarily glucose, which goes through a series of reactions called glycolysis and the Krebs cycle in order to make ATP from ADP and phosphate. Mitochondria are roughly oval in shape and are membranebound with cristae that form small shelves or infoldings within the structure. It is within the mitochondrion that the Krebs cycle takes place. Cells that are highly metabolically active contain a lot of mitochondria. There is a small amount of genetic material within the mitochondria as well. 12
ENDOPLASMIC RETICULUM The endoplasmic reticulum is an extensive network of flattened sheets, tubes, and sacs that are involved with two different functions inside the cell. The basic structure is a membrane that either contains ribosomes or doesn’t contain ribosomes. The rough endoplasmic reticulum or RER is the part of the ER that contains ribosomes, which are important in making proteins. The RER collectively forms a protein-making factory located near the nucleus. The smooth endoplasmic reticulum or SER does not contain ribosomes but makes other materials and aids in synthesis of lipids and hormones. From there, they can be used within the cell or exported outside of the cell.
GOLGI APPARATUS This is the part of the cell that packages the different cellular products made by the cell into vesicles that ultimately will leave the cell. It is the “post office” of the cell or the cell’s central
delivery system. It looks like a bunch off flattened sacks that modify and package the different proteins and lipids into spherical vesicles that migrate to the plasma membrane in order to leave the cell.
VACUOLES These are empty spaces inside the cell that form when endocytosis has occurred and parts of the plasma membrane are pinched off in the process.
LYSOSOMES These are sac-like vesicles that contain very strong degradative enzymes. They are made in the Golgi apparatus and act to destroy toxins and unwanted waste products or debris by merging with vesicles, destroying their contents. There are many different “lysosomal storage diseases” that happen because of a malfunction in the lysosomes, resulting in a buildup of a waste product. 13
PEROXISOMES These are vesicular organelles that break down lipids and other chemicals through the act of oxidation. They can self-replicate and are heavily present in both the kidneys and the liver, where detoxification is important. They contain various oxidation molecules.
CELL JUNCTIONS These are the structures that connect cells to other cells so that tissues and organs can stay
together. There are three major kinds of cell junctions: A. Desmosomes—these are made from proteins and look like disks in the plasma membrane. There are protein fibers extending from the plasma membrane into the cytoplasm. These act as connection between cells that undergo a great deal of stress,
such as the heart muscle tissue and skin. B. Tight junctions—these are highly connective between cells, forming a bond that completely encircles the cells they connect. They do not allow material to filter between cells. Tight junctions are found in the digestive tract so that nothing goes past the cells other than the material that goes through the cells themselves. C. Gap junctions—these structures are actually slim tunnels that connect the cytoplasm of two cells next to each other. They consist of proteins known as connexons. The structures are so narrow that only small molecules and ions can pass from cell to cell. In addition, electrical impulses are allowed to go from one cell to another without interruption.
CELL METABOLISM Cell metabolism represents the sum of all of the chemical reactions that occur within the cell. There are two major cell reactions that take place that can be defined as part of the metabolism. Catabolic reactions or “catabolism” are responsible for breaking down or
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decomposing a molecule into its parts. Anabolism or anabolic reactions are the opposite of catabolism and represent the formation of a larger molecule from its component parts. As mentioned, the major energy molecule of the cell is ATP or adenosine triphosphate. Each ATP molecule is recycled about 2-3 thousand times a day to make enough energy for the cell. Because ATP cannot be stored, it must be consumed shortly after it is made. This allows for about ten million ATP molecules to be made and consumed every second in a single cell. Another important molecule in the process of cell metabolism is flavin adenine dinucleotide or FAD, which forms FADH2 after the addition of two hydrogen molecules. It participates in the Krebs cycle (which is the main metabolic process occurring in aerobic respiration). NAD or nicotinamide adenine dinucleotide reduces to NADH. NAD is use in glycolysis (anaerobic respiration) and the Krebs cycle (aerobic respiration) as well as in the electron transport chain, allowing for a lot of ATP to be made. NADP is use in fatty acid and nucleic acid synthesis, which
are anabolic reactions.
CELLULAR RESPIRATION This is the process of taking sugar molecules, turning them into glucose, and then metabolizing the glucose into CO2, water, and usable ATP. There are two major parts to cellular respiration. The first is glycolysis and the second is the citric acid cycle or Krebs cycle. These are called
cellular respiration because oxygen is used in the final step to take on the last electrons, forming the CO2 that leaves the cell and is ultimately expired from the body. Glycolysis takes place anaerobically and happens in the cytoplasm. It takes glucose and
converts it into two three-carbon molecules called pyruvate. It is pyruvate that is fed into the Krebs cycle in the mitochondria. Two molecules of ATP are necessary for this reaction to take place; however, four are created so there is a net gain of two ATP molecules. There are two NADH molecules made that participate in the electron transport chain (also located in the mitochondria). If glycolysis happens without the Krebs cycle, it is referred to as anaerobic
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respiration, producing lactic acid that ultimately accumulates and leads to muscle cramping or soreness. The Krebs cycle takes two molecules of pyruvate and breaks them down further. It is a cycle that participates in energy production in both animals and plants. It takes place inside the mitochondria and involves a series of reactions that generate ATP and creates CO2 and water. The Krebs cycle also makes NADH and FADH2, which go into the electron transport chain to make ATP. While the Krebs cycle makes energy itself, the most energy-producing aspect of cellular aerobic metabolism is the electron transport chain. The electron transport chain is extremely complicated. It is a series of oxidation-reduction reactions or redox reactions that transfer electrons from one molecule to another, making ATP in the process. The redox state of the cell describes the balance of both NAD+/NADH and NADP+/NADPH in the cell or organ. There are several diseases that cause an abnormal redox state in the cell, including sepsis, shock, and hypoxia.
BUILDING BLOCKS OF THE CELL There are three major classifications of molecules found within the cell. These include lipids, carbohydrates, and proteins. Lipids are considered fatty acids and the molecules that can be derived from fatty acids. These molecules will store energy and will become the structural components of the plasma membranes and other membranes within the cell. Lipids also act as signaling molecules in the cell. Carbohydrates consist mainly of carbon, oxygen, and hydrogen. There are monosaccharides, which consist of a single sugar molecule including glucose, fructose, and galactose. There are
disaccharides, which consist of two sugar molecules attached to one another (such as sucrose and lactose). There are numerous polysaccharides that are made from more than two sugar molecules. In humans, the main polysaccharide is glycogen, which is made from many molecules of glucose strung together. Other polysaccharides are starch and cellulose.
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Proteins are made from amino acids and composed mainly of nitrogen, carbon, hydrogen, and oxygen. The two other atoms found in some amino acids are phosphorus and sulfur. There are twenty different kinds of amino acids used by the human body. In various combinations, amino acids combine to make the basic protein structure. There are several structures associated with the protein molecule. There is the primary structure, which is just the polypeptide sequence in no particular shape. The secondary structure is formed by the hydrogen bonds between amino acids to create a semblance of a shape. The tertiary structure is the three-dimensional shape of the polypeptide. Most enzymes in the cell are proteins that catalyze a chemical reaction. Enzymes allow for reactions to occur that wouldn’t have otherwise occurred in nature. There are some enzymes, however, that are made from RNA, called ribozymes or RNA enzymes. Like other enzymes, they catalyze certain biochemical reactions.
ACID BASE PHYSIOLOGY Acid base balance is extremely important to the body as it controls the pH of the blood and the cells, where many reactions take place. Because there is a very narrow range of pH in which reactions can occur, the body has several buffering systems that maintain the pH at what’s called the physiological pH. Buffers prevent radical changes in fluid pH by dampening the effect of hydrogen ions on the system. Weak acids and weak bases will make the best buffers by taking up hydrogen ions or hydroxyl ions. It takes just seconds for the body’s buffering systems to adjust the pH when necessary. The fastest buffering system is the respiratory tract. By exhaling CO2 from the body, the pH can rise in cases of acidosis. The kidneys can also combat acidosis by increasing hydrogen ion
excretion and by increasing the reabsorption of bicarbonate, which takes hours to days to have an effect but which will also serve to increase the pH in cases of acidosis. Plasma proteins,
phosphate, bicarbonate, and carbonic acid all act as buffer systems. Protein buffer systems are predominately intracellular, while the other buffering systems are extracellular.
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Almost any protein can function as a buffer. Amino acids contain positively charged amino groups and negatively charged carboxyl groups. In this way, a protein can be a weak acid or a weak base. Almost all of the buffering in the cell comes from protein buffering, while twothirds of the blood’s buffering comes from proteins. Hemoglobin is a protein that resides inside RBCs (red blood cells) and accounts for a full third of
the cell’s mass. During the conversion of CO2 into bicarbonate, hydrogen ions are liberated and must be buffered. Oxygen is dissociated and hemoglobin is reduced, leading to the maintenance of a normal pH. This happens at the tissue level. In the lungs, CO2 is reformed
and diffuses out into the alveoli. Hemoglobin acts as the buffer there. Hemoglobin accounts for a major buffering system in the bloodstream. The phosphate buffer also exists in the blood. Sodium dihydrogen phosphate is a weak acid, while sodium monohydrogen phosphate is a weak base. The two molecules move back and forth with each other, picking up a hydrogen ion (in the case of the weak basic form) or picking up a hydroxyl ion (in the case of the weak acid form). This buffers the blood from extremes in pH. The bicarbonate-carbonic acid buffer works similarly to the phosphate buffering system. Bicarbonate will pick up a hydrogen ion forming salt and carbonic acid (which is a weak acid). In the same way, carbonic acid will pick up a hydroxyl ion to form a weak base and water, leading to a weaker base than would be seen with the hydroxyl ion alone. The bicarbonate system protects primarily against acidic changes in the bloodstream versus an alkaline change (as there
is much more bicarbonate than carbonic acid in the bloodstream). Most of the waste products in the body, such as ketones and lactic acid, are acids, making it more important to protect the blood and the rest of the body from acidic changes. Carbonic acid levels are controlled by the amount of CO2 expired in the lungs, while the bicarbonate levels are controlled through the renal system. Bicarbonate can be more or less excreted by the kidneys, affecting its levels.
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REGULATION OF THE ACID-BASE SYSTEM IN THE BODY As mentioned, both the kidneys and the lungs contribute to the acid-base system of the body. The lungs regulate the blood levels of carbonic acid because CO2 plus water makes carbonic acid; CO2 and carbonic acid are in equilibrium in the bloodstream. When CO2 levels rise, the excess CO2 will react with water, forming carbonic acid to lower the pH. The individual will respond by increasing the rate or depth of the respirations to blow off CO2. This adjusts the pH to normal levels. Hyperventilation makes the blood too alkaline because CO2 is blown off and carbonic acid levels drop. Rebreathing air into a paper bag will increase the CO2/carbonic acid
levels in the bloodstream. Minor adjustments in the breathing rate and depth are usually sufficient to adjust the pH of the bloodstream in the pulmonary capillaries. If one doubled the respiratory rate, the CO2 difference would increase the blood pH by 0.2. This happens when a person exercises strenuously for a period of time. Exercise increases the lactic acid production and the production of CO2 at the cellular level and the breathing rate increases to counteract this and blow off the extra CO2 that is gained through the increase in cellular respiration. There are chemoreceptors in the walls of the aorta and in the carotid arteries. They regulate the respiratory rate by sensing the CO2 level changes in the blood. Other sensors are located in the brain so that changes in the pH of the CSF affect the respiratory center in the medulla oblongata, changing the respiratory rate to normalize the pH level. Hypercapnia happens with COPD, CHF, pneumonia (and anything else that impairs the release of CO2 in the lungs). Certain drugs and holding one’s breath can do this as well. Hypocapnia (low CO2 levels) will occur with hyperventilation. This drives off CO2 levels, leading to
respiratory alkalosis. The kidneys have a more complex buffering system that requires more time to normalize blood pH. Diarrhea and carbonic anhydrase inhibition will leach bicarbonate from the bloodstream or will otherwise decrease the bicarbonate level. Blood bicarbonate levels will also be decreased
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