Chapt19 Respiratory System by Michael Walls

Chapter 19 Lecture PowerPoint

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Hole’s Human Anatomy and Physiology Twelfth Edition

Shier w Butler w Lewis

Chapter 19 Respiratory System

19.1: Introduction • The respiratory system consists of passages that filter incoming air and transport it into the body, into the lungs, and to the many microscopic air sacs where gases are exchanged • Respiration is the process of exchanging gases between the atmosphere and body cells • It consists of the following events: • Ventilation • External respiration • Transport of gases • Internal respiration • Cellular respiration 4

19.2: Why We Breathe • Respiration occurs on a macroscopic level at the organ system • Gas exchange, oxygen and carbon dioxide, occur at the cellular and molecular levels • Aerobic reactions of cellular respiration allow for: • ATP production • Carbon dioxide generation forming carbonic acid

• The organs of the respiratory system can be divided into two tracts: • Upper respiratory tract • The nose • Nasal cavity • Sinuses • Pharynx • Lower respiratory tract • Larynx • Trachea • Bronchial tree • Lungs

Frontal sinus Nasal cavity Hard palate

Soft palate Pharynx

Nostril Oral cavity Larynx

Epiglottis Esophagus Trachea

Bronchus

6 Right lung

Left lung

Nose Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Frontal sinus

Superior Middle Inferior

Nasal conchae

Sphenoidal sinus Nostril Hard palate Uvula Tongue

Hyoid bone

Pharyngeal tonsil Nasopharynx Opening of auditory tube Palatine tonsil Oropharynx Lingual tonsil Epiglottis Laryngopharynx

Larynx

Trachea

Esophagus

Nasal Cavity Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Nasal cavity

Mucus

Particle

Cilia Goblet cell Epithelial cell

(a)

(b) b: ÂŠ Biophoto Associates/Photo Researchers, Inc.

Sinuses â&#x20AC;˘ The sinuses are air-filled spaces in the maxillary, frontal, ethmoid, and sphenoid bones of the skull

19.1 Clinical Application The Effects of Cigarette Smoking on the Respiratory System

Pharynx â&#x20AC;˘ The pharynx is posterior to the oral cavity and between the nasal cavity and the larynx Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Superior Frontal sinus

Middle Inferior

Nasal conchae

Sphenoidal sinus Nostril Pharyngeal tonsil Hard palate

Uvula Tongue

Nasopharynx Opening of auditory tube Palatine tonsil Oropharynx Lingual tonsil Epiglottis

Hyoid bone

Laryngopharynx

Larynx

Trachea

Esophagus

Larynx • The larynx is an enlargement in the airway superior to the trachea and inferior to the pharynx • It is composed of a framework of muscles and cartilages bound by elastic tissue Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Epiglottic cartilage

Epiglottis Hyoid bone

False vocal cord

Thyroid cartilage

Glottis

Cricoid cartilage

True vocal cord (a)

Thyroid cartilage Cuneiform cartilage

Hyoid bone Epiglottis

Arytenoid cartilage

False vocal cord Thyroid cartilage

True vocal cord

Cricoid cartilage

Corniculate cartilage

Thyroid cartilage

Posterior portion of tongue

Cricoid cartilage

Glottis

False vocal cord True vocal cord Cuneiform cartilage

Corniculate cartilage (a) Trachea (a)

Epiglottis

Glottis Inner lining of trachea Hyoid bone (b) Epiglottic cartilage

Thyroid cartilage

Cricoid cartilage Trachea (b)

• The trachea (windpipe) is a flexible cylindrical tube about 2.5 centimeters in diameter and 12.5 centimeters in length • As it extends downward anterior to the esophagus and into the thoracic cavity, it splits into the right and left primary bronchi

Larynx

Thyroid cartilage Cricoid cartilage

Trachea Superior (upper) lobe bronchus

Cartilaginous ring Carina

Left primary bronchus Right primary bronchus

Middle lobe bronchus

Superior (upper) lobe bronchus Inferior (lower) lobe bronchi

Lumen of trachea

Hyaline cartilage Ciliated epithelium

Hyoid bone Smooth muscle

Connective tissue

Connective tissue Smooth muscle

Thyroid gland

Thyroid cartilage Cricoid cartilage

Incision Trachea

Jugular notch

Hyaline cartilage

Ciliated epithelium Lumen of trachea © Ed Reschke

Bronchial Tree â&#x20AC;˘ The bronchial tree consists of branched airways leading from the trachea to the microscopic air sacs in the lungs

Larynx

Trachea Right superior (upper) lobe Left superior (upper) lobe

Right primary bronchus

Secondary bronchus Tertiary bronchus Terminal bronchiole Right inferior (lower) lobe

Right middle lobe

Left inferior (lower) lobe

Respiratory bronchiole Alveolar duct

Alveolus

Branches of the Bronchial Tree • The successive divisions of the branches from the trachea to the alveoli are: 1. Right and left primary bronchi 2. Secondary or lobar bronchi 3. Tertiary or segmental bronchi 4. Intralobular bronchioles 5. Terminal bronchioles 6. Respiratory bronchioles 7. Alveolar ducts 8. Alveolar sacs

Blood flow

Blood flow Intralobular bronchiole

Pulmonary venule

Pulmonary arteriole Blood flow

Smooth muscle Alveolus Pulmonary artery

Capillary network on surface of alveolus

Capillary

Simple squamous epithelial cells

Alveolus

The Respiratory Tubes • The structure of the bronchus is similar to that of the trachea, but the C-shaped cartilaginous rings are replaced with cartilaginous plates where the bronchus enters the lung • These respiratory tubes become thinner and thinner, and the cell layers thin and change until the alveoli is reached • It is the alveoli that provides surface area for gas exchange

Blood flow Blood flow

Venule

Arteriole Alveolar wall

Alveolus Air O2 CO2 CO2 O2

Capillary

Blood vessel

Capillary

Alveolus

Bronchiole Courtesy of the American Lung Association

Lungs • The right and left lungs are soft, spongy, cone-shaped organs in the thoracic cavity • The right lung has three lobes and the left lung two lobes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Right lung

Left lung

Thyroid cartilage Cricoid cartilage

Plane of section

Trachea

Clavicle Scapula

Superior (upper) lobe of right lung

Superior (upper) lobe of left lung

Middle lobe of right lung

Inferior (lower) lobe of left lung

Inferior (lower) lobe of right lung

Heart

Visceral pleura

Pericardial cavity

Parietal pleura

Pericardium Pleura

Right pleural cavity

Left pleural cavity

Rib cartilage

Sternum

19.2 Clinical Application Lung Irritants

19.4: Breathing Mechanism â&#x20AC;˘ Breathing or ventilation is the movement of air from outside of the body into the bronchial tree and the alveoli â&#x20AC;˘ The actions responsible for these air movements are inspiration, or inhalation, and expiration, or exhalation

Inspiration • Atmospheric pressure due to the weight of the air is the force that moves air into the lungs • At sea level, atmospheric pressure is 760 millimeters of mercury (mm Hg) • Moving the plunger of a syringe causes air to move in or out • Air movements in and out of the lungs occur in much the same way

Atmospheric pressure of 760 mm Hg on the outside Atmospheric pressure of 760 mm Hg on the inside

Diaphragm

24 (a)

(b)

Inspiration • Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges due to diaphragm downward movement caused by impulses carried by the phrenic nerves • Atmospheric pressure then forces air into the airways Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Atmospheric pressure (760 mm Hg)

Intra-alveolar pressure (760 mm Hg)

Intra-alveolar pressure (758 mm Hg)

Diaphragm (a)

(b)

Inspiration Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Sternocleidomastoid elevates sternum Sternum moves Up and out

Pectoralis minor elevates ribs

External intercostal muscles pull ribs up and out Diaphragm contracts

(a)

Diaphragm contracts more

(b)

Expiration â&#x20AC;˘ The forces responsible for normal resting expiration come from elastic recoil of lung tissues and from surface tension â&#x20AC;˘ These factors increase the intra-alveolar pressure about 1 mm Hg above atmospheric pressure forcing air out of the lungs

Expiration Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Posterior internal intercostal muscles pull ribs down and inward

Diaphragm

Diaphragm Abdominal organs recoil and press diaphragm upward

Abdominal organs force diaphragm higher

Abdominal wall muscles contract and compress abdominal organs (a)

(b)

Respiratory Air Volumes and Capacities • Different degrees of effort in breathing move different volumes of air in and out of the lungs • This measurement of volumes is called spirometry Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Lung volume in milliliters (mL)

6,000

5,000 Inspiratory reserve volume

Vital capacity

4,000

Inspiratory capacity Total lung capacity

3,000

2,000

1,000 0

Tidal volume Residual volume

Expiratory reserve volume

Functional residual capacity

Alveolar Ventilation • The volume of new atmospheric air moved into the respiratory passages each minute is minute ventilation • It equals the tidal volume multiplied by the breathing rate • Much of the new air remains in the physiologic dead space • The tidal volume minus the physiologic dead space then multiplied by breathing rate is the alveolar ventilation rate • This is the volume of air that reaches the alveoli • This impacts the concentrations of oxygen and carbon dioxide in the alveoli

Nonrespiratory Air Movements â&#x20AC;˘ Air movements other than breathing are called nonrespiratory movements â&#x20AC;˘ They clear air passages, as in coughing and sneezing, or express emotions, as in laughing and crying

19.3 Clinical Application Respiratory Disorders That Decrease Ventilation: Bronchial Asthma and Emphysema

19.5: Control of Breathing â&#x20AC;˘ Normal breathing is a rhythmic, involuntary act that continues when a person is unconscious â&#x20AC;˘ Respiratory muscles can be controlled as well voluntarily

• Groups of neurons in the brainstem comprise the respiratory areas that control breathing • Impulses travel on cranial nerves and spinal nerves, causing inspiration and expiration • Respiratory areas also adjust the rate and depth of breathing • The respiratory areas include: • Respiratory center of the medulla • Respiratory group of the pons

Midbrain Fourth ventricle

Pontine respiratory group Pons Medulla oblongata Ventral respiratory group Dorsal respiratory group

Medullary respiratory center Internal (expiratory) intercostal muscles External (inspiratory) intercostal muscles

Diaphragm

Respiratory areas Pontine respiratory group

Medullary respiratory center Ventral respiratory group

Dorsal respiratory group

Nerve impulses

Respiratory muscles

Basic rhythm of breathing

Forceful breathing 39

Factors Affecting Breathing • A number of factors affect breathing rate and depth including: • Partial pressure of oxygen (Po2) • Partial pressure of carbon dioxide (Pco2) • Degree of stretch of lung tissue • Emotional state • Level of physical activity • Receptors involved include mechanoreceptors and central and peripheral chemoreceptors

Medulla oblongata Sensory nerve (branch of glossopharyngeal nerve) Carotid bodies Sensory nerve (branch of vagus nerve)

Common carotid artery

Aorta

Aortic bodies

Heart

Factors Affecting Breathing • Changes in blood pH, O2 and CO2 concentration stimulates chemoreceptors Sensory pathway • Motor impulses can travel Vagus nerve from the respiratory center to the diaphragm and external Phrenic nerve intercostal muscles • Contraction of these muscles Stretch receptors Lung causes the lungs to expand stimulating mechanoreceptors in the lungs • Inhibitory impulses from the mechanoreceptors back to the respiratory center prevent overinflation of the lungs

Respiratory center Spinal cord –

– Motor pathways

External intercostal muscles Intercostal nerve

Rib Diaphragm

19.4 Clinical Application Exercise and Breathing

19.6: Alveolar Gas Exchanges â&#x20AC;˘ The alveoli are the sites of the vital process of gas exchange between the air and the blood

Alveoli Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

45 Courtesy of the American Lung Association

Copyright ÂŠ The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Type I (squamous epithelial) cell of alveolar wall

Type II (surfactantsecreting) cell

Fluid with surfactant

Macrophage

Alveolus

Respiratory membrane

Cell of capillary wall Capillary lumen

Alveolar fluid (with surfactant) Alveolar epithelium

Alveolus

Basement membrane of alveolar epithelium Interstitial space

Respiratory membrane

Basement membrane of capillary endothelium Capillary endothelium Diffusion of O2 Diffusion of CO2 Red blood cell Capillary

Respiratory Membrane • Part of the wall of an alveolus is made up of cells (type II cells) that secrete pulmonary surfactant • The bulk of the wall of an alveolus consists of a layer of simple squamous epithelium (type I cells) • Both of these layers make up the respiratory membrane through which gas exchange takes place

BM RBC AS IS

48 © Imagingbody.com

Alveolus

Diffusion of CO2

Alveolar wall

PCO = 40 mm Hg 2

PCO = 45 mm Hg 2

PO = 104 mm Hg 2

Diffusion of O2

PO = 40 mm Hg 2

Blood flow (from body tissues)

Blood flow (to body tissues)

Capillary

PCO = 40 mm Hg PO = 104 mm Hg 2

Diffusion Through the Respiratory Membrane • Molecules diffuse from regions where they are in higher concentration toward regions where they are in lower concentration • It is important to know the concentration gradient • In respiration, think in terms of gas partial pressures • Gases diffuse from areas of higher partial pressure to areas of lower partial pressure • The respiratory membrane is normally thin and gas exchange is rapid • Increased diffusion is favored with more surface area, shorter distance, greater solubility of gases and a steeper partial pressure gradient • Decreased diffusion occurs from decreased surface area 50

19.5 Clinical Application Effects of High Altitude

19.6 Clinical Application Disorders That Impair Gas Exchange: Pneumonia, Tuberculosis, and Adult Respiratory Distress Syndrome

19.7: Gas Transport â&#x20AC;˘ Blood transports O2 and CO2 between the lungs and the body cells â&#x20AC;˘ As the gases enter the blood, they dissolve in the plasma or chemically combine with other atoms or molecules

Oxygen Transport • Almost all oxygen carried in the blood is bound to the protein hemoglobin in the form of oxyhemoglobin • Chemical bonds between O2 and hemoglobin are relatively unstable • Oxyhemoglobin releases O2 into the body cells • About 75% of the O2 remains bound to hemoglobin in the venous blood ensuring safe CO2 levels and thereby pH

Alveolus

Blood PO = 95 mm Hg

Capillary

Hemoglobin molecules

Alveolar wall

Oxygen molecules

Diffusion of oxygen

(a)

Hemoglobin molecules

Blood flow (to lungs)

Oxyhemoglobin molecule

Blood flow (from body tissues)

Blood PO = 40 mm Hg

Tissue cells Tissue PO = 40 mm Hg

Diffusion of oxygen

(b)

100

% saturation of hemoglobin

90 80 70 60 50 40 30 20 10 0

60 70 80 PO2(mm Hg)

90 100 110 120 130 140

Oxyhemoglobin dissociation at 38Â°C

100

80 70 PCO =

20 mm Hg 40 mm Hg 80 mm Hg

50 40 30 20 10 10

60 70 80 PO (mm Hg)

100 110 120 130 140

100 90 80 70 pH =

7.6

7.4 7.2

40 30 20 10

60 70 80 90 100 PO2 (mm Hg) Oxyhemoglobin dissociation at 38°C

1 10

120

130

140

100 90

% saturation of hemoglobin

80 70 60 50 40 30 20 10 0

60 70 80 PO2 (mm Hg)

57 100 110

120

Oxyhemoglobin dissociation at various temperatures

130 140

Carbon Dioxide Transport • Blood flowing through capillaries gains CO2 because the tissues have a high Pco2 • The CO2 is transported to the lungs in one of three forms: • As CO2 dissolved in plasma • As part of a compound with hemoglobin • As part of a bicarbonate ion

Tissue cell

Tissue PCO2 = 45 mm Hg

Cellular CO2

CO2 dissolved in plasma PCO = 40 mm Hg 2

Blood flow from systemic arteriole

CO2 + H2O CO2 combined with hemoglobin to form carbaminohemoglobin

HCO3

H2CO3 PCO = 45 mm Hg

H+

H+combines with hemoglobin HCO3-

Plasma

Red blood cell

Blood flow to systemic venule

Capillary wall

Cl-

Red blood cell

HCO3-

Plasma

Cl-

HCO3HCO3Cl-

Alveolus PCO = 40 mm Hg 2

CO2

CO2dissolved in plasma

CO2 + H2O

PCO = 45 mm Hg 2

Blood flow from pulmonary arteriole

HCO3-

Plasma

CO2

Alveolar wall

H2CO3

CO2

Carbaminohemoglobin PCO = 40 mm Hg 2

HCO3-+ H+ H+ released from hemoglobin

Red blood cell

CO2 + hemoglobin

Blood flow to pulmonary venule

Capillary wall

19.8: Lifespan Changes • Lifespan changes reflect an accumulation of environmental influences and the effects of aging in other organ systems, and may include: • The cilia become less active • Mucous thickening • Swallowing, gagging, and coughing reflexes slowing • Macrophages in the lungs lose efficiency • An increased susceptibility to respiratory infections • A “barrel chest” may develop • Bronchial walls thin and collapse • Dead space increasing 63

Important Points in Chapter 19: Outcomes to be Assessed 19.1: Introduction  Identify the general functions of the respiratory system. 19.2: Why We Breathe  Explain why respiration is necessary for cellular survival. 19.3: Organs of the Respiratory System  Name and describe the locations of the organs of the respiratory system.  Describe the functions of each organ of the respiratory system. 19.4: Breathing Mechanism  Explain how inspiration and expiration are accomplished.  Name and define each of the respiratory air volumes and capacities.

Important Points in Chapter 19: Outcomes to be Assessed  Calculate the alveolar ventilation rate.  List several non-respiratory air movements and explain how each occurs. 19.5: Control of Breathing  Locate the respiratory areas and explain control of normal breathing.  Discuss how various factors affect breathing. 19.6: Alveolar Gas Exchanges  Define partial pressure and explain its importance in diffusion of gases.  Describe gas exchange in the pulmonary and systemic circuits. 65

Important Points in Chapter 19: Outcomes to be Assessed  Describe the structure and function of the respiratory membrane. 19.7: Gas Transport  Explain how the blood transports oxygen and carbon dioxide. 19.8: Lifespan Changes  Describe the effects of aging on the respiratory system.

Quiz 19 Complete Quiz 19 now! Read Chapter 20. 67