Respiratory System - MCAT Biological and Biochemical Foundations of Living Systems
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In mammals, what muscles are involved in inhalation?
In mammals, what muscles are involved in inhalation?
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During inhalation, the external intercostal muscles and diaphragm both contract to help expand the thoracic cavity and draw in air. The internal intercostal muscles are involved in exhalation, and compress the thoracic cavity during contraction.
During inhalation, the external intercostal muscles and diaphragm both contract to help expand the thoracic cavity and draw in air. The internal intercostal muscles are involved in exhalation, and compress the thoracic cavity during contraction.
Which two muscles do humans use primarily for inhalation?
Which two muscles do humans use primarily for inhalation?
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The two muscles that help with breathing are the diaphragm and the external intercostal muscles. The diaphragm pulls the thoracic cavity downward and the external intercostal muscles expand the cavity outward. This expansion of the thoracic cavity leads to a decrease in pressure and allows air to be drawn into the lungs.
The two muscles that help with breathing are the diaphragm and the external intercostal muscles. The diaphragm pulls the thoracic cavity downward and the external intercostal muscles expand the cavity outward. This expansion of the thoracic cavity leads to a decrease in pressure and allows air to be drawn into the lungs.
Which of the following may signal a respiratory abnormality?
I. Low concentration of oxygen in the alveoli
II. High concentration of carbon dioxide in the alveoli
III. Contraction of intercostal muscles upon inhalation
Which of the following may signal a respiratory abnormality?
I. Low concentration of oxygen in the alveoli
II. High concentration of carbon dioxide in the alveoli
III. Contraction of intercostal muscles upon inhalation
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In a healthy individual, the concentration of oxygen in the alveoli is high and that of carbon dioxide is low. This allows oxygen to diffuse out of the alveoli into the blood stream while carbon dioxide diffuses into the alveoli to be eliminated via exhalation. Intercostal muscles and diaphragm contract, enlarging the thoracic cavity. Therefore, options I and II are both correct choices.
In a healthy individual, the concentration of oxygen in the alveoli is high and that of carbon dioxide is low. This allows oxygen to diffuse out of the alveoli into the blood stream while carbon dioxide diffuses into the alveoli to be eliminated via exhalation. Intercostal muscles and diaphragm contract, enlarging the thoracic cavity. Therefore, options I and II are both correct choices.
Gas exchange in the lungs is located in the .
Gas exchange in the lungs is located in the .
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Bronchioles end is clusters of small air sacs, the alveoli, where gas exchange occurs. Gases diffuse through the walls of the alveoli into the capillaries.
Bronchioles end is clusters of small air sacs, the alveoli, where gas exchange occurs. Gases diffuse through the walls of the alveoli into the capillaries.
Among the most important pH buffer systems in humans is the bicarbonate buffer, which keeps the blood at a remarkably precise 7.42 pH. The bicarbonate buffer system uses a series of important compounds and enzymes to make the system function. Figure 1 depicts the key reactions that take place.
The activity of this buffer system is mainly controlled by the renal and respiratory systems. The renal system excretes bicarbonate in the urine, while the respiratory system “blows off” carbon dioxide as needed. By balancing these two systems as needed, blood pH is maintained in such a narrow range.
When carbon dioxide is removed by the lungs, which of the following describes an accurate change in the system?
Among the most important pH buffer systems in humans is the bicarbonate buffer, which keeps the blood at a remarkably precise 7.42 pH. The bicarbonate buffer system uses a series of important compounds and enzymes to make the system function. Figure 1 depicts the key reactions that take place.
The activity of this buffer system is mainly controlled by the renal and respiratory systems. The renal system excretes bicarbonate in the urine, while the respiratory system “blows off” carbon dioxide as needed. By balancing these two systems as needed, blood pH is maintained in such a narrow range.
When carbon dioxide is removed by the lungs, which of the following describes an accurate change in the system?
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As CO2 is blown off by the lungs, the equilibrium is shifted away from carbonic acid via Le Chatelier's principle. The system is attempting to recapture the lost carbon dioxide by producing more, thus depleting the volume of free carbonic anhydrase. Ultimately, the same principle will shift the equilibrium away from bicarbonate.
As CO2 is blown off by the lungs, the equilibrium is shifted away from carbonic acid via Le Chatelier's principle. The system is attempting to recapture the lost carbon dioxide by producing more, thus depleting the volume of free carbonic anhydrase. Ultimately, the same principle will shift the equilibrium away from bicarbonate.
Among the most important pH buffer systems in humans is the bicarbonate buffer, which keeps the blood at a remarkably precise 7.42 pH. The bicarbonate buffer system uses a series of important compounds and enzymes to make the system function. Figure 1 depicts the key reactions that take place.
The activity of this buffer system is mainly controlled by the renal and respiratory systems. The renal system excretes bicarbonate in the urine, while the respiratory system “blows off” carbon dioxide as needed. By balancing these two systems as needed, blood pH is maintained in such a narrow range.
A patient undergoes a procedure in a hospital, and begins to reabsorb large quantities of bicarbonate from the kidneys. In the above reaction .
Among the most important pH buffer systems in humans is the bicarbonate buffer, which keeps the blood at a remarkably precise 7.42 pH. The bicarbonate buffer system uses a series of important compounds and enzymes to make the system function. Figure 1 depicts the key reactions that take place.
The activity of this buffer system is mainly controlled by the renal and respiratory systems. The renal system excretes bicarbonate in the urine, while the respiratory system “blows off” carbon dioxide as needed. By balancing these two systems as needed, blood pH is maintained in such a narrow range.
A patient undergoes a procedure in a hospital, and begins to reabsorb large quantities of bicarbonate from the kidneys. In the above reaction .
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Via Le Chatelier's principle, the equilibrium is quickly shifted toward CO2, however, as the passage details, CO2 does not build up. Instead, it is blown off via the respiratory system.
Via Le Chatelier's principle, the equilibrium is quickly shifted toward CO2, however, as the passage details, CO2 does not build up. Instead, it is blown off via the respiratory system.
Which of the following is not one of the four processes that comprise external respiration?
Which of the following is not one of the four processes that comprise external respiration?
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The use of oxygen within the mitochondria to generate ATP via oxidative phosphorylation is a part of internal, or cellular, respiration.
The other four processes listed are all parts of external respiration, consisting of the mechanisms used to transport gases between the atmosphere and the body.
The use of oxygen within the mitochondria to generate ATP via oxidative phosphorylation is a part of internal, or cellular, respiration.
The other four processes listed are all parts of external respiration, consisting of the mechanisms used to transport gases between the atmosphere and the body.
There are two types of alvelolar cells that line the alveolar sacs in the lungs. Type I cells participate in gas exchange. What do type II cells do?
There are two types of alvelolar cells that line the alveolar sacs in the lungs. Type I cells participate in gas exchange. What do type II cells do?
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Type II alveolar cells have the ability to differentiate into type I cells if needed. However, they do not participate in gas exchange. They do secrete surfactant, a chemical that helps the alveoli stay open so that gas exchange can occur effectively.
Type II alveolar cells have the ability to differentiate into type I cells if needed. However, they do not participate in gas exchange. They do secrete surfactant, a chemical that helps the alveoli stay open so that gas exchange can occur effectively.
The brain is a very delicate structure with little room to move around. Surrounding the brain and the spinal cord are three protective layers in addition to the skull and the vertebral column. Directly surrounding the brain and spinal cord is the pia mater. Following the pia mater is the arachnoid mater. Between the pia mater and the arachnoid mater is the sub-arachnoid space where the cerebrospinal fluid circulates. Finally, the protective layer is the dura mater is loosely attached to the arachnoid mater but is strongly associated with the skull bone.
Depending on the type of injury, a certain type of vein and/or artery are more susceptible to injury. For example, the meningeal artery and vein run through the foramen spinosum and travel between the two layers making up the dura mater. As the artery and the vein are traveling in between the dura mater, there is a vulnerable region at the temple. A strike to the temple region could rupture these vessels and result in a epidural hematoma.
Traveling from the cerebral cortex to the venous dural sinus (located at certain regions between the two layers of the dura mater) is the cerebral vein. When an injury results in the dura mater shifting away from the arachnoid mater, the cerebral vein could rupture and lead to a subdural hematoma.
When the drainage system is compromised such as during an epidural hematoma, waste product in the blood concentrates. One of the waste products is carbon dioxide. What happens to the blood when the carbon dioxide is not properly removed?
The brain is a very delicate structure with little room to move around. Surrounding the brain and the spinal cord are three protective layers in addition to the skull and the vertebral column. Directly surrounding the brain and spinal cord is the pia mater. Following the pia mater is the arachnoid mater. Between the pia mater and the arachnoid mater is the sub-arachnoid space where the cerebrospinal fluid circulates. Finally, the protective layer is the dura mater is loosely attached to the arachnoid mater but is strongly associated with the skull bone.
Depending on the type of injury, a certain type of vein and/or artery are more susceptible to injury. For example, the meningeal artery and vein run through the foramen spinosum and travel between the two layers making up the dura mater. As the artery and the vein are traveling in between the dura mater, there is a vulnerable region at the temple. A strike to the temple region could rupture these vessels and result in a epidural hematoma.
Traveling from the cerebral cortex to the venous dural sinus (located at certain regions between the two layers of the dura mater) is the cerebral vein. When an injury results in the dura mater shifting away from the arachnoid mater, the cerebral vein could rupture and lead to a subdural hematoma.
When the drainage system is compromised such as during an epidural hematoma, waste product in the blood concentrates. One of the waste products is carbon dioxide. What happens to the blood when the carbon dioxide is not properly removed?
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Without proper venous drainage, carbon dioxide level increases in the blood. As the carbon dioxide concentration increases, it reacts with water to create protons. This reaction will lower the blood's pH. The equilibrium reaction is shown below:
Recall Le Chatelier's principle. When the carbon dioxide on the left side of the equation builds up, it drives the reaction to the right. As such, the hydrogen ion concentration will increase, leading to a more acidic solution (plasma) and a lower pH.
Without proper venous drainage, carbon dioxide level increases in the blood. As the carbon dioxide concentration increases, it reacts with water to create protons. This reaction will lower the blood's pH. The equilibrium reaction is shown below:
Recall Le Chatelier's principle. When the carbon dioxide on the left side of the equation builds up, it drives the reaction to the right. As such, the hydrogen ion concentration will increase, leading to a more acidic solution (plasma) and a lower pH.
The carbonic anhydrase reaction is shown below.
Which of the following outcomes seems the most reasonable for someone who has an increase in blood CO2 levels during exercise?
The carbonic anhydrase reaction is shown below.
Which of the following outcomes seems the most reasonable for someone who has an increase in blood CO2 levels during exercise?
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The individual's blood pH level will decrease (become more acidic). The increase in CO2 will cause the carbonic anhydrase reaction to shift to the right, increasing the concentration of protons (H+) in the blood. The individual can raise their pH level back to normal by breathing out all of the excess CO2. This accounts, in part, for increased respiration rates during exercise (along with the increased demand for oxygen).
The individual's blood pH level will decrease (become more acidic). The increase in CO2 will cause the carbonic anhydrase reaction to shift to the right, increasing the concentration of protons (H+) in the blood. The individual can raise their pH level back to normal by breathing out all of the excess CO2. This accounts, in part, for increased respiration rates during exercise (along with the increased demand for oxygen).
Whales are active at great, underwater depths for extended periods of time. Which of the following would LEAST contribute to such an ability?
Whales are active at great, underwater depths for extended periods of time. Which of the following would LEAST contribute to such an ability?
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When whales dive to great depths, they are unable to replenish oxygen from the water's surface. Several adaptive characteristics allow for the whales to maintain adequate oxygen supply to their tissues: large lung capacity (to absorb a greater amount of oxygen when breathing), selective arterial constriction (to restrict blood flow to non-essential tissues and thus prevent inefficient oxygen consumption), high cellular tolerance for carbon dioxide (CO₂ will build up over time without gas exchange), and large muscle myoglobin concentrations (to replenish oxygen supply to muscles as necessary).
A high basal metabolic rate, however, would increase the demand for oxygen and thus would not be an adaptive characteristic for whales in order to maintain themselves at great, watery depths without an external supply of oxygen.
When whales dive to great depths, they are unable to replenish oxygen from the water's surface. Several adaptive characteristics allow for the whales to maintain adequate oxygen supply to their tissues: large lung capacity (to absorb a greater amount of oxygen when breathing), selective arterial constriction (to restrict blood flow to non-essential tissues and thus prevent inefficient oxygen consumption), high cellular tolerance for carbon dioxide (CO₂ will build up over time without gas exchange), and large muscle myoglobin concentrations (to replenish oxygen supply to muscles as necessary).
A high basal metabolic rate, however, would increase the demand for oxygen and thus would not be an adaptive characteristic for whales in order to maintain themselves at great, watery depths without an external supply of oxygen.
Which of the following is a physiological consequence of breathing air with a slightly increased partial pressure of carbon dioxide?
Which of the following is a physiological consequence of breathing air with a slightly increased partial pressure of carbon dioxide?
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Slightly increased levels, or partial pressures, of carbon dioxide (CO2) would signal for an increase in breathing rate. As CO2 levels in the blood rise due to the breathing of such air as described in the passage, a breathing mechanism in the brain is triggered to increase ventilation (hyperventilation) to remove as much CO2 through the lungs as possible. A decrease in breathing rate would build up CO2 to even higher levels, causing respiratory acidosis. There would be no changes to blood pressure because slight increases of CO2 has no significant effect on this property.
Slightly increased levels, or partial pressures, of carbon dioxide (CO2) would signal for an increase in breathing rate. As CO2 levels in the blood rise due to the breathing of such air as described in the passage, a breathing mechanism in the brain is triggered to increase ventilation (hyperventilation) to remove as much CO2 through the lungs as possible. A decrease in breathing rate would build up CO2 to even higher levels, causing respiratory acidosis. There would be no changes to blood pressure because slight increases of CO2 has no significant effect on this property.
Where in the brain is respiration rate regulated?
Where in the brain is respiration rate regulated?
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It is important to know that the medulla oblongata in the brainstem is the site of breathing rate control. pH receptors at the medulla sense the hydrogen concentration in the blood, and increase or decrease the rate of breathing to alter bicarbonate levels in the blood, maintaining healthy pH levels.
The cerebellum is involved in balance and coordination, while the frontal cortex and occipital lobe are both regions of the cerebrum, involved in higher thinking, processing, and voluntary actions.
It is important to know that the medulla oblongata in the brainstem is the site of breathing rate control. pH receptors at the medulla sense the hydrogen concentration in the blood, and increase or decrease the rate of breathing to alter bicarbonate levels in the blood, maintaining healthy pH levels.
The cerebellum is involved in balance and coordination, while the frontal cortex and occipital lobe are both regions of the cerebrum, involved in higher thinking, processing, and voluntary actions.
Give the equation for total lung capacity.
Give the equation for total lung capacity.
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The total lung capacity is the maximum amount of air that can fill the lungs.
The vital capacity is the amount of air that can be exhaled after fully inhaling.
The tidal volume is the amount of air inhaled during normal, relaxed breathing.
The expiratory reserve volume is the amount of air that can be forcibly exhaled after a normal exhalation.
The inspiratory reserve volume is the amount of air that can be forcibly inhaled after a normal inhalation.
The residual volume is the amount of air still remaining in the lungs after the expiratory reserve volume is exhaled.
By adding the residual volume and vital capacity, you can obtain a value for the total lung capacity.
The total lung capacity is the maximum amount of air that can fill the lungs.
The vital capacity is the amount of air that can be exhaled after fully inhaling.
The tidal volume is the amount of air inhaled during normal, relaxed breathing.
The expiratory reserve volume is the amount of air that can be forcibly exhaled after a normal exhalation.
The inspiratory reserve volume is the amount of air that can be forcibly inhaled after a normal inhalation.
The residual volume is the amount of air still remaining in the lungs after the expiratory reserve volume is exhaled.
By adding the residual volume and vital capacity, you can obtain a value for the total lung capacity.
Both the sympathetic and the parasympathetic nervous systems are essential for homeostasis and for survival. For example, when we are trying to run away from a threat, the sympathetic nervous system is in full effect to allow us to escape from danger. However, when there is no obvious threat, the parasympathetic nervous system tends to be more in control.
There are similarities and differences between the sympathetic and the parasympathetic nervous systems. In preganglionic nerve fibers, both the sympathetic and the parasympathetic nervous system utilize the neurotransmitter acetylcholine. Closer to the target organ, the parasympathetic nervous system remains dependent on acetylcholine whereas norepinephrine and epinephrine are the predominant neurotransmitters utilized by the sympathetic nervous system.
When norepinephrine and epinephrine bind to their receptors, different effects are carried out based on the type of receptor, affinity, and location of the receptor. For example, epinephrine has a higher affinity for the beta-2 receptor. When epinephrine binds to the beta-2 receptor, common effects include vasodilation and bronchodilation. Norepinephrine has a stronger affinity for the alpha-1, alpha-2 and beta-1 receptors. When norepinephrine binds to its receptor, common effects on the body include vasoconstriction (alpha-1), increased heart rate (beta-1) and uterine contraction (alpha-1).
When a patient has a severe allergic reaction, a common prescribed drug is epinephrine. Which of the follow best explains the effects of epinephrine on a patient experiencing a severe allergic reaction?
Both the sympathetic and the parasympathetic nervous systems are essential for homeostasis and for survival. For example, when we are trying to run away from a threat, the sympathetic nervous system is in full effect to allow us to escape from danger. However, when there is no obvious threat, the parasympathetic nervous system tends to be more in control.
There are similarities and differences between the sympathetic and the parasympathetic nervous systems. In preganglionic nerve fibers, both the sympathetic and the parasympathetic nervous system utilize the neurotransmitter acetylcholine. Closer to the target organ, the parasympathetic nervous system remains dependent on acetylcholine whereas norepinephrine and epinephrine are the predominant neurotransmitters utilized by the sympathetic nervous system.
When norepinephrine and epinephrine bind to their receptors, different effects are carried out based on the type of receptor, affinity, and location of the receptor. For example, epinephrine has a higher affinity for the beta-2 receptor. When epinephrine binds to the beta-2 receptor, common effects include vasodilation and bronchodilation. Norepinephrine has a stronger affinity for the alpha-1, alpha-2 and beta-1 receptors. When norepinephrine binds to its receptor, common effects on the body include vasoconstriction (alpha-1), increased heart rate (beta-1) and uterine contraction (alpha-1).
When a patient has a severe allergic reaction, a common prescribed drug is epinephrine. Which of the follow best explains the effects of epinephrine on a patient experiencing a severe allergic reaction?
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Epinephrine binds to the beta-2 receptor. The binding of epinephrine to the beta-2 receptor causes bronchodilation by relaxing the smooth muscles surrounding the airway. The relaxation of the smooth muscles around the airway increases the airway diameter and therefore allows the patient to breathe easier.
Epinephrine binds to the beta-2 receptor. The binding of epinephrine to the beta-2 receptor causes bronchodilation by relaxing the smooth muscles surrounding the airway. The relaxation of the smooth muscles around the airway increases the airway diameter and therefore allows the patient to breathe easier.
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Duchenne Muscular Dystrophy is usually fatal by age 30. Which of the following is the most likely cause of death for these patients?
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Duchenne Muscular Dystrophy is usually fatal by age 30. Which of the following is the most likely cause of death for these patients?
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Duchenne Muscular Dystrophy is a muscular disorder, so cause of death will be related to muscle weakening. Two main muscles are essential to maintaining the body: the heart and the diaphragm. As the disease progresses to these muscles, causing weakening of the heart and diaphragm, the body begins to deteriorate and cause of death is usually heart failure or respiratory failure when these muscles give out.
Contraction of the diaphragm allows air to enter the lungs. A weaker contraction means less air flow, and eventually leads to respiratory failure.
Duchenne Muscular Dystrophy is a muscular disorder, so cause of death will be related to muscle weakening. Two main muscles are essential to maintaining the body: the heart and the diaphragm. As the disease progresses to these muscles, causing weakening of the heart and diaphragm, the body begins to deteriorate and cause of death is usually heart failure or respiratory failure when these muscles give out.
Contraction of the diaphragm allows air to enter the lungs. A weaker contraction means less air flow, and eventually leads to respiratory failure.
Which of the following is NOT a function of the upper respiratory system?
I. Inspired air is saturated with water.
II. Inspired air is filtered for particulates such as pollen.
III. Inspired air is brought to body temperature.
IV. Secretory immunoglobulins (IgA) bind certain antigens.
V. All of these are normal functions of the upper respiratory system.
Which of the following is NOT a function of the upper respiratory system?
I. Inspired air is saturated with water.
II. Inspired air is filtered for particulates such as pollen.
III. Inspired air is brought to body temperature.
IV. Secretory immunoglobulins (IgA) bind certain antigens.
V. All of these are normal functions of the upper respiratory system.
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By its argumentative phrasing, the question invites the respondent to "bite" on the least commonly discussed function of the respiratory system. Three possible responses are pretty obviously correct, but the statement about immunoglobulins is also true. Recall that IgA is present in secretions such as tears, saliva, and mucous fluids, and it indeed constitutes an important barrier to infectious agents. Some pathogens are capable of destroying this protein, facilitating their attachment to mucosal cells or biofilms.
By its argumentative phrasing, the question invites the respondent to "bite" on the least commonly discussed function of the respiratory system. Three possible responses are pretty obviously correct, but the statement about immunoglobulins is also true. Recall that IgA is present in secretions such as tears, saliva, and mucous fluids, and it indeed constitutes an important barrier to infectious agents. Some pathogens are capable of destroying this protein, facilitating their attachment to mucosal cells or biofilms.
Which of the following represents the pathway of the respiratory system?
Which of the following represents the pathway of the respiratory system?
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The respiratory system begins in the nasal cavity and proceeds into the pharynx followed by the larynx and trachea. The trachea then branches into left and right primary bronchi, which continue to branch into secondary and tertiary bronchi. The tertiary bronchi contain all smooth muscle and continue to branch into bronchioles. The bronchioles are then divided into terminal bronchioles followed by respiratory bronchioles, which are then attached to the alveolar ducts containing the alveolar sac.
The respiratory system begins in the nasal cavity and proceeds into the pharynx followed by the larynx and trachea. The trachea then branches into left and right primary bronchi, which continue to branch into secondary and tertiary bronchi. The tertiary bronchi contain all smooth muscle and continue to branch into bronchioles. The bronchioles are then divided into terminal bronchioles followed by respiratory bronchioles, which are then attached to the alveolar ducts containing the alveolar sac.
Which fact about respiration and gas exchange is false?
Which fact about respiration and gas exchange is false?
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When the diaphragm contracts, the thoracic cavity actually expands, lowering the pressure in the thoracic cavity below atmospheric pressure. Air is drawn from high to low pressure ("negative-pressure breathing"). So, the statement about diaphragmatic contraction is false. All other choices are true.
When the diaphragm contracts, the thoracic cavity actually expands, lowering the pressure in the thoracic cavity below atmospheric pressure. Air is drawn from high to low pressure ("negative-pressure breathing"). So, the statement about diaphragmatic contraction is false. All other choices are true.
What is the correct path of air flow during inspiration?
What is the correct path of air flow during inspiration?
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Air travels through the nose and mouth through the pharynx. It then flows through the larynx and the trachea before entering the bronchi. The bronchi branch into the bronchioles and finally terminate into the alveoli, where gas exchange can take place between the lungs and the blood stream.
Air travels through the nose and mouth through the pharynx. It then flows through the larynx and the trachea before entering the bronchi. The bronchi branch into the bronchioles and finally terminate into the alveoli, where gas exchange can take place between the lungs and the blood stream.