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Chapter 35 Respiration (Sections )

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1 Chapter 35 Respiration (Sections 35.6 - 35.8)

2 35.6 How You Breathe A respiratory cycle is one breath in (inhalation) and one breath out (exhalation) Changes in volume of lungs and thoracic cavity during a respiratory cycle alter pressure gradients between air inside and outside the respiratory tract respiratory cycle One inhalation and one exhalation Inhalation is always active, driven by muscle contractions

3 The Respiratory Cycle Inhalation: Diaphragm contracts, moves down
External intercostal muscles contract, lift rib cage upward and outward Lung volume expands Exhalation: Diaphragm and external intercostal muscles return to resting positions Rib cage moves down Lungs recoil passively

4 The Respiratory Cycle

5 The Respiratory Cycle Inward flow of air Outward flow of air
Figure Changes in the size of the thoracic cavity during a single respiratory cycle. The x-ray images reveal how inhalation and expiration change the lung volume. A Inhalation. Diaphragm contracts, moves down. External intercostal muscles contract, lift rib cage upward and outward. Lung volume expands. B Exhalation. Diaphragm, external intercostal muscles return to resting positions. Rib cage moves down. Lungs recoil passively. Fig , p. 586

6 The Heimlich Maneuver The Heimlich maneuver is used to rescue a person who is choking on something lodged in the trachea The rescuer presses forcefully on a person’s abdomen to force air out of the lungs and dislodge the object Heimlich maneuver Procedure designed to rescue a choking person

7 Heimlich Maneuver Instructions
Determine that the person is actually choking – a person who has an object lodged in their trachea cannot cough or speak Stand behind the person and place one fist below his or her rib cage, just above the navel, with your thumb facing inward Cover the fist with your other hand and thrust inward and upward; repeat until the object is expelled

8 The Heimlich Maneuver Figure How to perform the Heimlich maneuver on an adult who is choking. 1. Determine that the person is actually choking. A person who has an object lodged in their trachea cannot cough or speak. 2. Stand behind the person and place one fist below his or her rib cage, just above the navel, with your thumb facing inward as in A. 3. Cover the fist with your other hand as shown in B and thrust inward and upward. Repeat until the object is expelled.

9 ANIMATION: Heimlich maneuver
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10 Respiratory Volumes Total lung volume
Maximum volume of air that the lungs can hold ~5.7 liters in healthy adult males, 4.2 liters in females Tidal volume Volume that moves into and out of lungs during a respiratory cycle, about half a liter vital capacity Maximum volume that moves in and out with forced inhalation and exhalation

11 Respiratory Volumes Figure Respiratory volumes. In quiet breathing, the tidal volume of air entering and leaving the lungs is only 0.5 liter. Lungs never deflate completely. Even with a forced exhalation, a residual volume of air remains in them.

12 ANIMATION: Changes in lung volume and pressure
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13 Control of Breathing Neurons in the medulla oblongata of the brain stem act as the pacemaker for inhalation Nerves deliver signals calling for contraction to the diaphragm and intercostal muscles and you inhale Between signals, the muscles relax and you exhale Breathing patterns can also be altered voluntarily

14 Control of Breathing (cont.)
Breathing patterns change with activity level Activity increases CO2 production, which increases carbonic acid levels in blood Chemoreceptors in walls of carotid arteries and the aorta detect increased acidity and signal the brain, which responds by altering the breathing pattern

15 Respiratory Response to Increased Activity

16 Respiratory Response to Increased Activity
Stimulus Respiratory Response to Increased Activity CO2 concentration and acidity rise in the blood and cerebrospinal fluid. Response Chemoreceptors in wall of carotid arteries and aorta Respiratory center in brain stem Figure Respiratory response to increased activity levels. An increase in activity raises the CO2 level in interstitial tissue. It also makes the blood and cerebrospinal fluid more acidic. Chemoreceptors in blood vessels and the medulla sense the changes and signal the brain’s respiratory center, also in the brain stem. In response, the respiratory center sends signals along nerves to the diaphragm and intercostal muscles. These signals result in an increase in the rate and depth of breathing. Excess CO2 is expelled, which causes the level of this gas and acidity to decline. Chemoreceptors sense the decline and signal the respiratory center, which returns to its resting signaling pattern. CO2 concentration and acidity decline in the blood and cerebrospinal fluid. Diaphragm, Intercostal muscles Tidal volume and rate of breathing change. Fig , p. 587

17 Respiratory Response to Increased Activity
CO2 concentration and acidity rise in the blood and cerebrospinal fluid. STIMULUS Chemoreceptors in wall of carotid arteries and aorta Respiratory Response to Increased Activity RESPONSE CO2 concentration and acidity decline in the blood and cerebrospinal fluid. Respiratory center in brain stem Diaphragm, Intercostal muscles Tidal volume and rate of breathing change. Figure Respiratory response to increased activity levels. An increase in activity raises the CO2 level in interstitial tissue. It also makes the blood and cerebrospinal fluid more acidic. Chemoreceptors in blood vessels and the medulla sense the changes and signal the brain’s respiratory center, also in the brain stem. In response, the respiratory center sends signals along nerves to the diaphragm and intercostal muscles. These signals result in an increase in the rate and depth of breathing. Excess CO2 is expelled, which causes the level of this gas and acidity to decline. Chemoreceptors sense the decline and signal the respiratory center, which returns to its resting signaling pattern. Stepped Art Fig , p. 587

18 Key Concepts Respiratory Cycle
Inhalation is always an active process; it occurs when a part of the brain stem signals muscles to contract and increase the size of the thoracic cavity Exhalation is usually passive; muscles relax, the chest and lungs shrink, and air flows out of lungs

19 3D Animation: Respiratory Mechanics

20 ANIMATION: Pressure-Gradient Changes During Respiration
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21 35.7 Gas Exchange and Transport
Gases diffuse between air and fluid at alveoli, and are transported to and from alveoli in blood Oxygen diffuses from an alveolus into a pulmonary capillary at the lung’s respiratory membrane respiratory membrane Membrane consisting of alveolar epithelium, capillary endothelium, and their fused basement membranes; Site of gas exchange in the lungs

22 The Respiratory Membrane

23 The Respiratory Membrane
Figure Zooming in on the respiratory membrane in human lungs. Fig a, p. 588

24 The Respiratory Membrane
Figure Zooming in on the respiratory membrane in human lungs. A Surface view of the pulmonary capillaries associated with alveoli Fig a, p. 588

25 The Respiratory Membrane
Figure Zooming in on the respiratory membrane in human lungs. Fig b, p. 588

26 The Respiratory Membrane
red blood cell inside pulmonary capillary pore for air flow between adjoining alveoli air space inside alveolus Figure Zooming in on the respiratory membrane in human lungs. B Cutaway view of one of the alveoli and adjacent pulmonary capillaries Fig b, p. 588

27 The Respiratory Membrane
Figure Zooming in on the respiratory membrane in human lungs. Fig c, p. 588

28 The Respiratory Membrane
alveolar epithelium capillary endothelium fused basement membranes of both epithelial tissues Figure Zooming in on the respiratory membrane in human lungs. C Three components of the respiratory membrane Fig c, p. 588

29 Partial Pressure Gradient
Oxygen and carbon dioxide diffuse passively across the respiratory membrane The net direction of movement for these gases depends upon concentration gradients (partial pressure gradients) of each gas across the membrane partial pressure Pressure exerted by one gas in a mixture of gases

30 Oxygen Transport and Storage
O2 follows its partial pressure gradient across the respiratory membrane, into blood plasma, and finally into red blood cells Where O2 partial pressure is high, hemoglobin in red blood cells binds O2 and forms oxyhemoglobin Hemoglobin consists of four globin chains, each associated with an iron-containing heme group oxyhemoglobin Hemoglobin with oxygen bound to it

31 Hemoglobin

32 Hemoglobin alpha globin alpha globin beta globin beta globin
Figure Hemoglobin, the oxygen-transporting protein of red blood cells. It consists of four globin chains, each associated with an iron-containing heme group (shown in red). beta globin beta globin Fig , p. 588

33 Oxygen Transport and Storage (cont.)
Heme groups release O2 in places where the partial pressure of O2 is lower than that in the alveoli Metabolically active tissues have traits that encourage release of oxygen from heme, such as high temperature, low pH, and high CO2 partial pressure

34 Carbon Dioxide Transport
Carbon dioxide is transported to lungs in three forms: About 10% remains dissolved in plasma About 30% reversibly binds with hemoglobin and forms carbaminohemoglobin (HbCO2) Most CO2 (60%) is transported as bicarbonate (HCO3–)

35 Carbon Dioxide Transport (cont.)
CO2 follows its partial pressure gradient and diffuses from cells to interstitial fluid, to blood Most CO2 reacts with water in red blood cells forming bicarbonate – this reaction is reversed in the lungs In the lungs, CO2 diffuses out of blood into air inside alveoli, and exhaled

36 Bicarbonate Formation
Carbon dioxide combines with water, forming carbonic acid (H2CO3), which splits into bicarbonate and H+: CO2 + H2O ↔ H2CO3 (carbonic acid) H2CO3 (carbonic acid) ↔ HCO3– (bicarbonate) + H+ The enzyme carbonic anhydrase speeds this reaction carbonic anhydrase Enzyme in red blood cells that speeds the breakdown of carbonic acid into bicarbonate and H+

37 Partial Pressures for O2 and CO2

38 Partial Pressures for O2 and CO2
DRY INHALED AIR MOIST EXHALED AIR Partial Pressures for O2 and CO2 160 0.03 120 27 alveolar sacs pulmonary arteries pulmonary veins 104 40 40 45 100 40 start of systemic veins start of systemic capillaries Figure Partial pressures (in mm Hg) for oxygen (pink boxes) and carbon dioxide (blue boxes) in the atmosphere, blood, and tissues. 40 45 100 40 cells of body tissues less than 40 less than 45 Fig , p. 589

39 Partial Pressures for O2 and CO2
less than 45 cells of body tissues less than 40 DRY INHALED AIR 0.03 160 MOIST EXHALED AIR 120 27 Partial Pressures for O2 and CO2 alveolar sacs 40 104 start of systemic veins pulmonary arteries 45 40 start of systemic capillaries pulmonary veins 100 40 Figure Partial pressures (in mm Hg) for oxygen (pink boxes) and carbon dioxide (blue boxes) in the atmosphere, blood, and tissues. Stepped Art Fig , p. 589

40 Animation: Partial Pressure Gradients

41 The Carbon Monoxide Threat
Carbon monoxide (CO) is dangerous because hemoglobin has a higher affinity for CO than for O2 When CO builds up in air, it blocks O2 binding sites on hemoglobin, preventing O2 transport and causing carbon monoxide poisoning Symptoms: Nausea, headache, confusion, dizziness, and weakness

42 Effects of Altitude Oxygen in air decreases with altitude
People from a low altitude acclimatize to high altitude through altered breathing patterns, increased red blood cell production, and other changes Atmospheric pressure decreases with altitude When people from low altitudes suddenly ascend to high altitudes, cells get less oxygen – altitude sickness results Symptoms: Shortness of breath, headache, nausea

43 Key Concepts Gas Exchanges
Oxygen moves from air in the lungs into pulmonary capillaries, where it binds with hemoglobin Hemoglobin releases oxygen near active tissues Carbon dioxide is converted to bicarbonate in blood At the lungs, bicarbonate is converted back into carbon dioxide and water that can be exhaled

44 ANIMATION: Globin and hemoglobin structure
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45 Animation: Oxygen-Hemoglobin Saturation Curve

46 35.8 Respiratory Diseases and Disorders
Interrupted breathing, infectious organisms, and chronic inflammation can impair respiratory function Interrupted breathing disorders include apnea and sudden infant death syndrome (SIDS) Respiratory diseases include tuberculosis, pneumonia, bronchitis, and emphysema Smoking causes or worsens many respiratory problems

47 Interrupted Breathing
Sleep apnea Breathing repeatedly stops and restarts spontaneously, especially during sleep Sudden infant death syndrome (SIDS) Occurs when an infant does not awaken from an episode of apnea Infants are more at risk if their mother smoked or was exposed to smoke during pregnancy

48 Tuberculosis and Pneumonia
Tuberculosis (TB) About one in three people is infected by Mycobacterium tuberculosis but have no symptoms An active case of TB can be fatal Antibiotics can cure most cases of TB Pneumonia A general term for lung inflammation caused by an infection by bacteria, viruses, or fungi

49 Pneumonia X-ray shows infected tissues filled with fluid and white blood cells Figure X-ray showing pneumonia. Fluid and blood cells fill the lungs. Compare x-rays of clear, healthy lungs in Figure

50 Bronchitis and Asthma Bronchitis
An inflammation of the ciliated, mucus-producing epithelium of the bronchi Bacteria can colonize the mucus, leading to more inflammation, more mucus, and more coughing Asthma An inhaled allergen or irritant triggers inflammation and constriction of the airways, conditions that make breathing difficult

51 Emphysema Emphysema Tissue-destroying bacterial enzymes digest the thin, elastic alveolar wall, respiratory surface declines, and lungs become distended and inelastic, leaving the person constantly short of breath Some people inherit a genetic predisposition Tobacco smoking is by far the main risk factor

52 Key Concepts Respiratory Problems
Interrupted breathing (apnea), infectious diseases(such as tuberculosis), and inflammatory conditions (such as asthma and bronchitis) interfere with normal respiratory function

53 Up in Smoke (revisited)
Tobacco is the only legal consumer product that kills half of its regular users Globally, cigarette smoking kills 4 million people each year; about 70% of deaths occur in developing countries Nonsmokers also die of cancers and disease brought on by breathing secondhand smoke

54 Effects of Smoking Shortened life expectancy
Chronic bronchitis, emphysema Cancer of lungs, mouth, larynx, esophagus, pancreas, and bladder Heart attacks, strokes, and atherosclerosis Stillbirths and low birthweight Allergic responses, destruction of white blood cells (macrophages) in respiratory tract Slow bone healing

55 Lungs of Nonsmoker and Smoker
Figure Risks incurred by smokers and benefits of quitting. The photos show normal lung tissue and lungs of a smoker who had emphysema. lungs of a nonsmoker lungs of a smoker


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