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.

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.