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Chapter 23 Respiratory System

Name the three basic processes of
respiration and explain each in terms of the
exchange of oxygen and carbon dioxide between two areas.
(1) Pulmonary Ventilation- The inhalation and exhalation of air and involves the exchange of air
between the atmosphere and the alveoli of the lungs.
(2) External (pulmonary) respiration- Exchange of gases between the alveoli of the lungs and the blood in pulmonary capillaries across the respiratory membrane. During this, pulmonary capillary blood gains O2 and loses CO2 .
(3) Internal (tissue) respiration- Exchange of gases between blood in systemic capillaries and tissue cells. Inthis step the blood loses O2 and gains CO2. Within cells, the metabolic reactions that consume O2 and give off CO2 during the production of ATP are termed cellular respiration
Define intrapleural and alveolar pressure.
Intrapleural pressure- The pressure between the two pleural layers in the pleural cavity during quiet
Alveolar (intrapulmonic) pressure- The pressure inside the lungs as the volume of the lungs increases during thoracic cavity expansion.
Define the term compliance and explain how lung elasticity and surface tension can affect Define the term compliance and explain how lung elasticity and surface tension can affect compliance.
Compliance- How much effort is required to stretch the lungs and chest wall. The lungs normally have high compliance and expand easily because elastic fibers in lung tissue are easily stretched and surfactant in alveolar fluid reduces surface tension
Explain the process of surface tension in the alveoli of the lung and discuss how this is Explain the process of surface tension in the alveoli of the lung and discuss how this is reduced by surfactant.
A thin layer of alveolar fluid coats the luminal surface of alveoli and exerts a force known as surface tension.
Surface tension arises at all air-water interfaces because the polar water molecules are more strongly attracted to each other than they are to gas molecules in the air. When liquid surrounds a sphere of air, as in an alveolus or a soap bubble, surface tension produces an inwardly directed force. Soap bubbles "burst" because they collapse inward due to surface tension. In the lungs, surface tension causes the alveoli to assume the smallest possible diameter. During breathing, surface tension must be overcome to expand the lungs during each inhalation. Surface tension also accounts for two-thirds of lung elastic recoil, which decreases the size of alveoli during exhalation. The surfactant (a mixture of phospholipids and lipoproteins) present in alveolar fluid reduces its surface tension below the surface tension of pure water.
Discuss four things that reduce compliance.
(1) scarring of lung tissue (for example, tuberculosis), (2) lung tissue filling with fluid (pulmonary edema), (3)
producing a deficiency in surfactant, or (4) impeding lung expansion in any way (for example, paralysis of the intercostal muscles).
Define pneumothorax and explain what
happens to the lung as a result of a
During pneumothorax, the pleural cavities may fill with air, blood or pus. Air in the pleural cavities, may cause the lungs to collapse.
Explain how bronchial tube diameter affects airway resistance.
The walls of the airways, especially the bronchioles, offer some resistance to the normal flow of air into and out of the lungs. As the lungs expand during inhalation, the bronchioles enlarge because their walls are pulled outward in all directions. Larger-diameter
airways have decreased resistance. Airway resistance then increases during exhalation as the diameter of bronchioles decreases. Airway diameter is also regulated by the degree of contraction or relaxation of smooth muscle in the walls of the airways. Signals from the sympathetic division of the autonomic nervous system cause relaxation of this smooth muscle, which results in bronchodilation and decreased resistance.
Explain the effect of norepinephrine on bronchial tube diameter.
Norepinephrine causes relaxation of smooth muscle in the bronchioles which increases (dialates) the bronchial tube diameter
Discuss the action of a beta blocker on airway resistance.
A beta blocker prevents relaxation of the smooth muscle of the airways and causes constriction of airways - vasoconstriction.
Give the formulas for Air flow in and Air flow out.
Air flow in= PAtm-PAlv / R
Air flow out= PAlv-PAtm/R
How does resistance affect air flow in and out of the lungs?
Any condition that narrows or obstructs the airways increases resistance, so that more pressure is required to maintain the same airflow.
normal pattern of quiet breathing.
temporary cessation of breathing.
Describe the difference between costal and diaphragmatic breathing.
Costal breathing- a pattern of shallow (chest) breathing consisting of an upward and outward movement of the chest due to contraction of the external intercostals muscles.
Diaphragmatic breathing- a pattern of deep (abdominal) breathings consisting of the outward movement of the abdomen due to the contraction and descent of the diaphragm.
State Boyle's law and explain its relationship to pulmonary ventilation.
Boyle's law states that the volume of gas varies inversely with pressure, assuming temperature stays the same. In pulmonary ventilation, the movement of air depends on pressure change.
During inhalation
the diaphragm contracts, chest expands, the lungs are pulled outward, and alveolar pressure decreases.
During exhalation
the diaphragm relaxes, the lungs recoil inward, and aveolar pressure increases forcing air out of the lungs

** Air moves into the lungs when alveolar pressure is less than atmospheric pressure, and out of the lungs when alveolar pressure is greater than atmospheric pressure.
Name the muscles involved in normal and labored inspiration and expiration.
Muscles involved in normal inspiration- diaphragm and external intercostals
Muscles involved in labored inspiration- sternocleidomastoid, scalenes, and pectoralis minor also contract.

Muscles involved in normal expiration- diaphragm and external intercostals relax
Muscles involved in labored expiration - abdominal and internal intercostal muscles contract.
Describe the two factors that produce normal expiration
Factors that produce normal expiration (1) Elastic recoil of the chest walls and lungs.
(2) inward pull of surface tension due to film of alveolar fluid.
Give the name of the instrument that measures pulmonary volumes and the name
of the graph produced.
Spirometer or respirometer. The graph produced is called spirogram.
Tidal volume
the volume of 1 breath (inhalation/exhalation)
Inspiratory reserve volume (IRV)-
volume of air that can be moved into the
lungs between normal inhalation and maximum inhalation.
Expiratory reserve volume(ERV)-
volume of air that can be expelled from the
lungs between normal expiration and maximum exhalation
Residual volume (RV)-
The air that remains in the lungs to keep the alveoli slightly inflated.
Forced expiratory volume in one second (FEV)-
the volume of air that can be exhaled from the lungs in 1 second with maximal effort following a maximal inhalation
Given the appropriate values, be able to calculate the following: minute volume of respiration (MVR), alveolar ventilation rate (AVR), inspiratory capacity (IC), functional residual capacity (FRC), vital capacity (VC) and total lung capacity (TLC)
AVR= (TV x BR) then multiply answer by .70
State Dalton's law and given atmospheric pressure, be able to calculate the pO2, pCO2, and pN2.
Dalton's law states each gas in a mixture of gases exerts its own pressure as if all other gases were not present.

Atmospheric pressure is the sum of the pressures of all these gases
pO2= .209 x Atm
pCO2= .0004 x Atm
pN2= 0.786 x Atm
State Henry's law and explain how it relates to nitrogen narcosis and
decompression sickness.
Henry's law states that the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility.

Nitrogen Narcosis- a form of decompression sickness when partial pressure of nitrogen is higher in a mixture of compressed air than in air at sea level pressure. This has the same effect as alcohol intoxication. I believe this happens when the diver is descending.

Bends- (decompression sickness)- has to do with when a diver ascends too fast. All of the Nitrogen can't get out of the blood, so gas bubbles block small blood vessels causing joint pain, dizziness, shortness
of breath, fatigue, paralysis and unconsciousness.
Be able to rank oxygen, carbon dioxide and nitrogen from highest to lowest
solubility in blood plasma.
1.Carbon dioxide 2.Oxygen 3.Nitrogen
Given the number of feet below sea level a diver goes, be able to calculate the partial pressures of oxygen, carbon dioxide and nitrogen at that depth.
For every 33 ft. below sea level you increase atmospheric pressure by 1x
Example: 33' below is 760 x 2=1520 mmHG
66' below is 760 x 3=2280 mmHG
Discuss the characteristics of altitude sickness
Common signs and symptoms of altitude sickness; shortness of breath, headache, fatigue, insomnia, nausea and dizziness. These are all due to lower level of oxygen in the blood.
26. Discuss four factors that affect the rate of external respiration.
External respiration is the exchange of gases between alveoli and pulmonary blood capillaries. It depends on the the following factors;
partial pressure difference (as in the case of altitude sickness)-Alveolar Po2 must be higher than blood Po2. The rate of diffusion is faster when the difference between P02 in alveolar air and pulmonary capillary blood is larger; diffusion is slower when the difference is smaller.
surface area for gas exchange - any pulmonary disorder that decreases the functional surface area of
the respiratory membranes decreases the rate of external respiration.
diffusion distance - (requires small diffusion distance across respiratory membrane)
solubility and molecular weight of gases - (rate of airflow into and out of the lungs)
CO_2 diffuses 20 times faster than O_2 even though it weighs more because of its higher solubility.
Discuss how the following affect the dissociation of oxygen from hemoglobin:
pH, pCO2, temperature, and BPG level.
Acidity (pH)- As acidity increases (pH decreases), the affinity of hemoglobin for O2 decreases, and O2 dissociates more readily from hemoglobin (Figure 23-20a). In other words, increasing acidity enhances the unloading of oxygen from hemoglobin.
Discuss how the following affect the dissociation of oxygen from hemoglobin:
pH, pCO2, temperature, and BPG level.
pCO2- As pCO2 rises, hemoglobin releases O2 more readily (Figure 23-20b). pCO2 and pH are related factors because low blood pH (acidity) results from high pCO2. Increased pCO2 produces a more acidic environment, which helps release O2 from hemoglobin. During exercise, lactic acid—a byproduct of anaerobic metabolism within muscles—also decreases blood pH. Decreased pCO2 (and elevated pH) shifts the saturation curve to the left.
Discuss how the following affect the dissociation of oxygen from hemoglobin:
pH, pCO2, temperature, and BPG level.
Temperature- Within limits, as temperature increases, so does the amount of O2 released from hemoglobin (Figure 23-21). Heat is a byproduct of the metabolic reactions of all cells, and the heat released by contracting muscle fibers tends to raise body temperature. Metabolically active cells require more O2 and liberate more acids and heat. The acids and heat in turn promote release of O2 from oxyhemoglobin. Fever produces a similar result. In contrast, during hypothermia (lowered body temperature) cellular metabolism slows, the need for O2 is reduced, and more O2 remains bound to hemoglobin (a shift to the left in the saturation curve).
Discuss how the following affect the dissociation of oxygen from hemoglobin:
pH, pCO2, temperature, and BPG level.
BPG level- A substance found in red blood cells called 2, 3-bisphosphoglycerate (BPG), decreases the affinity of hemoglobin for O2 and thus helps unload O2 from hemoglobin. The greater the level of BPG, the more O2 is unloaded from hemoglobin.
Give the percent of carbon dioxide found dissolved in blood plasma, attached to hemoglobin on the red blood cell, and converted to bicarbonate and carried in the blood plasma.
Dissolved CO2- The smallest percentage—about 7%—is dissolved in blood plasma. Upon reaching the lungs, it diffuses into alveolar air and is exhaled.
Carbamino compounds- A somewhat higher percentage, about 23%, combines with the amino groups of amino acids and proteins in blood to form carbamino compounds. Because the most prevalent protein in blood is hemoglobin (inside red blood cells), most of the CO2 transported in this manner is bound to hemoglobin.
Bicarbonate ions- The greatest percentage of CO2—about 70%—is transported in blood plasma as bicarbonate ions (HCO3-).
Explain what happens at the tissues and in the lungs during internal respiration.
Include in this discussion what happens in the chloride shift and reverse chloride shift.
The left ventricle pumps oxygenated blood into the aorta and through the systemic arteries to systemic capillaries. The exchange of O2 and CO2 between systemic capillaries and tissue cells is called internal respiration or systemic gas exchange (Figure 23-17b). As O2 leaves the bloodstream, oxygenated blood is converted into deoxygenated blood. Unlike external respiration, which occurs only in the lungs, internal respiration occurs in tissues throughout the body.
As blood picks up CO2, HCO3- accumulates inside RBCs. Some HCO3- moves out into the blood plasma, down its concentration gradient. In exchange, chloride ions (Cl-) move from plasma into the RBCs. This exchange of negative ions, which maintains the electrical balance between blood plasma and RBC cytosol, is known as the chloride shift (Figure 23-23b). The net effect of these reactions is that CO2 is removed from tissue cells and transported in blood plasma as HCO3-. As blood passes through pulmonary capillaries in the lungs, all these reactions reverse and CO2 is exhaled.
Explain how the following equation relates to change in blood pH if CO2 levels rise or fall: CO2 + H2O -----_ H2CO3-----_ H+ + HCO3
pCO2 and pH are related factors because low blood pH (acidity) results from high pCO2. Increased pCO2 produces a more acidic environment, which helps release O2 from hemoglobin. During exercise, lactic acid—a byproduct of anaerobic metabolism within muscles—also decreases blood pH. Decreased pCO2 (and elevated pH) shifts the saturation curve to the left.
pH↓ ↑CO_2+H_2O→ ↑H_2CO_3→ ↑H^+ + ↑HCO_3-

pH↑ ↓CO_2+H_2O→ ↓ H_2CO_3 → ↓ H^+ + ↓HCO_3
. Name and explain the function of the three areas in the medulla and pons that control breathing.
(1) Medullary rhythmicity area in the medulla oblongata- controls the basic rhythm of respiration.
(2) Pneumotaxic area in the pons- Coordinates the transition between inhalation and exhalation by transmitting inhibitory impulses to the inspiratory area. The impulses shorten the duration of inhalation. When pheumotaxic area is more active, breathing rate is more rapid.
(3) Apneustic area in the pons- coordinates the transition between inhalation and exhalation by sending stimulatory impulses to the inspiratory area that activates it and prolongs inhalation. The result is a long, deep inhalation.
Explain how the medullary rhythmicity area controls normal and forceful
During normal, quiet breathing, the expiratory area is inactive; during forceful breathing, the inspiratory area activates the expiratory area. During quiet breathing, inhalation lasts for about 2 seconds and exhalation lasts for about 3 seconds. Nerve impulses generated in the inspiratory area establish the basic rhythm of breathing. While the inspiratory area is active, it generates nerve impulses for about 2 seconds (Figure 23-25a). The impulses propagate to the external intercostal muscles via intercostal nerves and to the diaphragm via the phrenic nerves. When the nerve impulses reach the diaphragm and external inter-costal muscles, the muscles contract and inhalation occurs. Even when all incoming nerve connections to the inspiratory area are cut or blocked, neurons in this area still rhythmically discharge impulses that cause inhalation. At the end of 2 seconds, the inspiratory area becomes inactive and nerve impulses cease. With no impulses arriving, the diaphragm and external intercostal muscles relax for about 3 seconds, allowing passive elastic recoil of the lungs and thoracic wall. Then, the cycle repeats.
The neurons of the expiratory area remain inactive during quiet breathing. However, during forceful breathing nerve impulses from the inspiratory area activate the expiratory area (Figure 23-25b). Impulses
from the expiratory area cause contraction of the internal intercostal and abdominal muscles, which decreases the size of the thoracic cavity and causes forceful exhalation.
Central chemoreceptors
are located in or near the medulla oblongata in the central nervous system.
Peripheral chemoreceptors
are located in the aortic bodies, clusters of chemoreceptors located in the wall of the arch of the aorta, and in the carotid bodies, which are oval nodules in the wall of the left and right common carotid arteries where they divide into the internal and external carotid arteries. These chemoreceptors are part of the peripheral nervous system.
Define the following terms: hypocapnia, hypercapnia, hypoxia, hypoventilation, and hyperventilation
Hypocapnia- state of reduced carbon dioxide in the blood. < 40 mmHg
Hypercapnia- a condition where there is too much carbon dioxide (CO2) in the blood
> 40 mmHg
Hypoxia- a deficiency of O2 at the tissue level.
Hypoventilation- occurs when ventilation is inadequate (hypo means "below") to perform needed gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis.
Hyperventilation- Rapid and deep breathing, which allows the inhalation of more O2 and exhalation of more CO2 until pCO2 and H+ are lowered to normal.
Discuss how hypoxia can lead to a positive feedback system which causes a
further reduction in the level of oxygen in the blood.
Severe deficiency of O2 depresses activity of the central chemoreceptors and inspiratory area, which then do not respond well to any inputs and send fewer impulses to the muscles of inhalation. As the breathing rate decreases or breathing ceases altogether, pO2 falls lower and lower, establishing a positive feedback cycle with a possibly fatal result.
a disorder characterized by chronic airway inflammation, airway hypersensitivity to a variety of stimuli, and airway obstruction.
a disorder characterized by destruction of the walls of the alveoli, producing abnormally large air spaces that remain filled with air during exhalation. With less surface area for gas exchange, O2 diffusion across the damaged respiratory membrane is reduced.
COPD (Chronic obstructive pulmonary disease)-
a type of respiratory disorder characterized by chronic and recurrent obstruction of airflow, which increases airway resistance.
Discuss the changes caused by exercise that lead to an increase in the rate and depth of breathing.
When muscles contract during exercise, they consume large amounts of O2 and produce large amounts of CO2. During vigorous exercise, O2 consumption and pulmonary ventilation both increase dramatically. At the onset of exercise, an abrupt increase in pulmonary ventilation is followed by a more gradual increase. With moderate exercise, the increase is due mostly to an increase in the depth of ventilation rather than to increased breathing rate. When exercise is more strenuous, the frequency of breathing also increases.
The abrupt increase in ventilation at the start of exercise is due to neural changes that send excitatory impulses to the inspiratory area in the medulla oblongata. These changes include (1) anticipation of the activity, which stimulates the limbic system; (2) sensory impulses from proprioceptors in muscles, tendons, and joints; and (3) motor impulses from the primary motor cortex (precentral gyrus). The more gradual increase in ventilation during moderate exercise is due to chemical and physical changes in the bloodstream, including (1) slightly decreased pCO2, due to increased O2 consumption; (2) slightly increased pCO2, due to increased CO2 production by contracting muscle fibers; and (3) increased temperature, due to liberation of more heat as more O2 is utilized. During strenuous exercise, HCO3- buffers H+ released by lactic acid in a reaction that liberates CO2, which further increases pCO2.
Explain the Hering-Breuer reflex (Inflation reflex).
A protective mechanism for preventing excessive inflation of the lungs rather than a key component in the normal regulation of respiration.