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APHY 201 Exam 4a
Ch. 16 Respiratory Physiology Sec. 1-5 (I-V)
| Question | Answer |
|---|---|
| What are the three main processes included in the term respiration? | Ventilation, gas exchange, and oxygen utilization by tissues (cellular respiration). |
| What the mechanical process that moves air into and out of the lungs? | ventilation |
| How is the respiratory system anatomically divided? | Into the conduction zone and the respiratory zone. |
| What is the function of the conduction zone? | It transports air to the respiratory zone but does not participate in gas exchange. |
| What is the function of the respiratory zone? | It is the site of gas exchange. |
| Where do alveoli form clusters? | At the ends of respiratory bronchioles. |
| What are the narrowest branching airways in the lungs? These mark the transition from the conducting zone to the respiratory zone. | Respiratory bronchioles. |
| What structures do respiratory bronchioles directly connect? | Terminal bronchioles to the alveolar ducts. |
| What type of alveolar cells account for 95 to 97% of the total surface area and are the primary site of gas exchange? | Type I (squamous) alveolar cells. |
| What is the function of Type II cells and what are they named? | Great alveolar cells secrete pulmonary surfactant and reabsorb sodium and water to prevent fluid buildup. |
| (starred) What is the complete pathway of air through the respiratory system? | Nasal cavity -> Pharynx -> Larynx -> Trachea -> Primary bronchi -> Secondary bronchi -> Tertiary bronchi -> Terminal bronchioles -> Respiratory bronchioles -> Terminal alveolar sacs. |
| What are the primary functions of the conducting zone? | To transport, warm, humidify, filter, and clean the air, as well as enable voice production. |
| How is voice produced in the respiratory system? | By air passing over the vocal folds in the larynx. |
| How does the conducting zone clean the air? | Mucus traps small particles, and cilia move the mucus away from the lungs. |
| What is the mucociliary escalator? what does it have to do with mucociliary clearance? | The coordinated beating of cilia that moves mucus to the pharynx, where it can be cleared by swallowing or expectorating (mucociliary clearance). |
| Why does the mucociliary escalator fail in cystic fibrosis? | Abnormal mucus is too thick for the cilia to clear properly, due to faulty chloride pumps. |
| What structures are contained within the central mediastinum of the thoracic cavity? | The heart, trachea, esophagus, and thymus are within the central mediastinum. (the lungs fill the rest of the cavity.) |
| Which membrane lines the thoracic wall? | The parietal pleura. |
| Which membrane covers the surface of the lungs? | The visceral pleura. |
| What is the potential space between the parietal and visceral pleura called? | The intrapleural space. |
| What is the dome-shaped skeletal muscle of respiration that separates the thoracic and abdominal cavities? | diaphragm |
| what are the 3 types of air pressure? | atmospheric, intrapulmonary/intra-alveolar, intrapleural |
| which kind of pressure keeps the lungs pressed up against the thoracic wall and allows the lungs to expand during inspiration? | intrapleural pressure |
| what are the 4 pertinent laws of ventilation? | Boyle's, Law of LaPlace, Dalton's, Henry's |
| what are the physical properties of the lungs you should know? | lung compliance, elasticity, surface tension |
| what physical property of the lungs is exerted by fluid secreted in the alveoli? | surface tension |
| what is pneumothorax and what are the 2 types? | when air enters the pleural space, raising intrapleural pressure so that the pressure difference keeping the lung against the chest wall is eliminated; spontaneous pneumothorax and tension pneumothorax |
| What direction does air move in relation to pressure? | Air moves from higher to lower pressure. |
| What causes the pressure differences between the two ends of the conducting zone? | Pressure differences occur due to changing lung volumes. |
| What are three important physical properties of the lungs? | Compliance, elasticity, and surface tension are important physical properties of the lungs. |
| What is the term for the pressure of the air outside the body? | atmospheric pressure |
| What is intrapulmonary or intra-alveolar pressure? | It is the pressure inside the lungs. |
| What is intrapleural pressure? | It is the pressure within the intrapleural space, which contains a thin layer of pleural fluid to serve as a lubricant. |
| How does intrapulmonary pressure compare to atmospheric pressure during inspiration? | Intrapulmonary pressure is lower than atmospheric pressure, generally about -1 mm Hg. |
| What is a pressure below that of the atmosphere called? | It is called subatmospheric or negative pressure. |
| How does intrapulmonary pressure compare to atmospheric pressure during expiration? | Intrapulmonary pressure is greater than atmospheric pressure, generally about +1 mm Hg. |
| How does intrapleural pressure compare to intrapulmonary and atmospheric pressures? | Intrapleural pressure is lower than both intrapulmonary and atmospheric pressures during both inspiration and expiration. |
| What is the difference between intrapulmonary and intrapleural pressure called? | It is called transpulmonary pressure. |
| What is the function of transpulmonary pressure? | It keeps the lungs pressed up against the thoracic wall and allows the lungs to expand during inspiration. |
| Which law states that the pressure of a gas is inversely proportional to its volume? | Boyle's Law |
| How does Boyle's Law explain inspiration? | An increase in lung volume decreases intrapulmonary pressure to subatmospheric levels, causing air to move in from high pressure outside to low pressure inside. |
| How does Boyle's Law explain expiration? | A decrease in lung volume increases intrapulmonary pressure above atmospheric levels, causing air to move out from high pressure inside to low pressure outside. |
| What is the term for the ease with which the lungs expand under pressure, defined as the change in lung volume per change in transpulmonary pressure? | lung compliance |
| What can reduce lung compliance? | It is reduced by factors that produce a resistance to distension, such as the infiltration of connective tissue proteins in pulmonary fibrosis. |
| What is the term for the ability of the lungs to return to their initial size after being stretched (recoil)? | lung elasticity |
| Why are the lungs always under elastic tension? | Because the lungs are stuck to the thoracic wall and contain lots of elastin fibers, they are always under tension like a partially stretched rubber band. |
| When does elastic tension in the lungs increase and decrease? | Tension increases during inspiration and is reduced by elastic recoil during expiration. |
| What creates surface tension in the alveoli and what is its effect? | Surface tension is exerted by a thin layer of fluid secreted in the alveoli, and it resists distension (stretching). |
| How is fluid balance maintained in the alveolar epithelial cells? | Fluid from blood capillaries is absorbed by osmosis driven by the active transport of Na+, and secreted by the active transport of Cl-. |
| How does surface tension affect the alveoli? | Surface tension raises the pressure of the alveolar air and acts to collapse the alveolus. |
| How does cystic fibrosis affect alveolar fluid? | A defect in the CFTR gene, which moves Cl- in and out, causes an imbalance of fluid absorption and secretion, making the fluid in the alveoli too viscous. The chloride pumps fai |
| What does the Law of Laplace state regarding alveolar pressure? | Pressure is directly proportional to surface tension and inversely proportional to the radius of the alveolus. |
| According to the Law of Laplace, what would happen to small alveoli without surfactant? | Small alveoli would be at a greater risk of collapse and emptying their air into larger alveoli. |
| What happens when air enters the pleural space? | Intrapleural pressure rises, eliminating the pressure difference that keeps the lung against the chest wall, causing the lung to collapse (atelectasis). |
| What can cause a spontaneous pneumothorax? | It can occur without disease or trauma from a broken rib puncture, or from lung disorders like COPD, cystic fibrosis, or a ruptured lung blister (bleb). |
| What is the serious condition caused by an open chest wound where air enters the pleural space from the outside but won’t leave? | tension pneumothorax |
| Why does a pneumothorax usually occur in only one lung? | Because each lung is isolated in a separate pleural compartment. |
| What is the term for atelectasis caused by blood entering the intrapleural space instead of air? | The term for blood entering the intrapleural space is a hemothorax. |
| What cells secrete surfactant? | Surfactant is secreted by type II alveolar cells. |
| What is surfactant composed of? | Surfactant consists of hydrophobic protein and phospholipids. |
| How does surfactant reduce surface tension? | It reduces surface tension between water molecules by reducing the number of hydrogen bonds between them. |
| When does surfactant become most concentrated? | It becomes more concentrated as alveoli get smaller during expiration. |
| What are two major functions of surfactant in the lungs? | Surfactant prevents the collapse of alveoli upon expiration and allows a residual volume of air to remain in the lungs. |
| Why are premature babies at high risk for infant respiratory distress syndrome (RDS)? | Production of surfactant begins late in fetal life, making it hard for premature babies to open up their alveoli on each breath. |
| How is infant respiratory distress syndrome treated? | It is treated with mechanical ventilators and exogenous surfactant delivered through an endotracheal tube. |
| What causes acute respiratory distress syndrome (ARDS) in adults? | ARDS in adults can be caused by sepsis or pneumonia. |
| How does ARDS affect lung function? | Protein-rich fluid fills the lungs, reducing lung compliance and surfactant production, which produces hypoxemia. |
| What is pulmonary ventilation? | Another name for breathing. |
| How is breathing accomplished? | Breathing is accomplished by changing the thoracic cavity and lung volume. |
| (starred) Which muscles work with the external intercostals to perform inspiration? | The parasternal intercostal muscles, also called the interchondral part of the intercostal muscles, work with the external intercostals to perform inspiration. |
| (starred) Which muscles are considered the accessory muscles used for forced inspiration? | The scalenes, pectoralis minor, and sternocleidomastoid are used for forced inspiration. |
| (starred) How does quiet expiration occur? | Quiet expiration is a passive process that occurs with the relaxation of the inspiratory muscles and thoracic cage recoil. |
| (starred) Which muscles are used for forced expiration? | The abdominal muscles and internal intercostals are used for forced expiration. |
| What is the mechanism of inspiration? | During inspiration, thoracic and lung volumes increase, which decreases intrapulmonary pressure and forces air in. |
| What is the mechanism of normal expiration? | During expiration, thoracic and lung volumes decrease, which increases intrapulmonary pressure and forces air out. |
| How does the thoracic cavity volume decrease during quiet expiration? | Volume decreases vertically when the diaphragm relaxes into a dome shape, and laterally when the external and parasternal intercostals relax. |
| How does the thoracic cavity volume decrease during forced expiration? | The internal intercostals, excluding the interchondral part, contract to lower the ribs. |
| How much does intrapulmonary pressure decrease during forced inspiration? | Aided by accessory muscles, forced inspiration decreases intrapulmonary pressure to -27 cmH2O or lower. |
| How much does intrapulmonary pressure increase during forced expiration? | Aided by abdominal and internal intercostal muscles, forced expiration increases intrapulmonary pressure to +40 cmH2O or higher. |
| What do positive and negative pressures mean in the context of pulmonary ventilation? | Positive pressure means the pressure is more than atmospheric pressure, and negative pressure means it is less than atmospheric. |
| Why must intrapulmonary pressure remain greater than intrapleural pressure during normal ventilation? | This pressure difference keeps the lungs pressed up against the thoracic wall and prevents them from collapsing. |
| What is the standard atmospheric pressure referenced in breathing mechanics? | The standard atmospheric pressure is 760 mmHg. |
| What characterizes a restrictive lung disorder? | In restrictive disorders, lung tissue is damaged and vital capacity is reduced, but the forced expiratory volume (FEV) rate remains normal. |
| What are examples of restrictive lung disorders? | Examples include pulmonary fibrosis and anthracosis, also known as black lung disease. |
| What characterizes an obstructive lung disorder? | In obstructive disorders, lung tissue and vital capacity can be normal, but forced expiration is reduced, making it hard to expel air. |
| What are examples of obstructive lung disorders? | Examples include asthma, chronic emphysema, and chronic obstructive bronchitis. |
| What is the term for a subjective feeling of shortness of breath or difficulty breathing that people with pulmonary disorders frequently experience? | dyspnea |
| What test is usually used to diagnose obstructive lung disorders? | Obstructive lung disorders are usually diagnosed using forced expiratory volume (FEV1) tests, which measure the percentage of vital capacity that can be expelled in one second. |
| What are the symptoms and causes of asthma? | Asthma symptoms include dyspnea and wheezing, and it is caused by inflammation, mucus secretion, and constriction of the bronchioles. |
| What triggers allergic or atopic asthma? | Allergic asthma is triggered by allergens that stimulate T lymphocytes to secrete cytokines and recruit eosinophils and mast cells, causing inflammation and producing IgE antibodies. |
| Besides allergens, what else can trigger asthma? | Asthma can also be triggered by cold or dry air, exercise, or aspirin. |
| How is asthma typically treated? | Asthma is generally reversible with bronchodilator drugs, such as albuterol. |
| Why might farm children be less likely to develop asthma than city children? | Evidence suggests that exposure to a little dirt and a less sterile environment may help prevent the development of asthma. |
| What structural changes occur in the lungs due to emphysema? | Emphysema causes the destruction of alveoli and loss of alveolar walls, leading to larger confluent alveoli and reduced surface area for gas exchange. |
| Why do bronchioles collapse during expiration in patients with emphysema? | There are fewer alveoli to exert pressure on the bronchioles, causing them to collapse and obstruct the outflow of air. |
| What is the most common cause of emphysema? | Smoking is the most common cause because it triggers inflammation and the destruction of alveoli by immune cells. |
| What conditions are included under Chronic Obstructive Pulmonary Disease (COPD)? | COPD includes emphysema and chronic obstructive bronchiolitis, characterized by chronic inflammation, airway narrowing, and alveolar destruction. |
| How does COPD affect FEV1? | COPD causes an accelerated decline in FEV1, which otherwise normally declines slowly with age. |
| Which immune cells are involved in the inflammation associated with COPD? | The inflammation in COPD involves macrophages, neutrophils, and cytotoxic T cells. |
| How does smoking contribute to COPD beyond causing inflammation and mucus production? | Smoking promotes the infiltration of obstructing fibrous tissue and muscle in the airways and remodels blood vessels in the lungs, leading to pulmonary hypertension. |
| What is cor pulmonale in the context of COPD? | Cor pulmonale is a potential complication of COPD characterized by pulmonary hypertension accompanied by hypertrophy and eventual failure of the right ventricle. |
| Is there a cure for COPD? | No, there is no cure for COPD, and it is the third leading cause of death worldwide. |
| What is the third leading cause of death worldwide? | COPD |
| What happens in the lungs of a patient with pulmonary fibrosis? | Fibrous tissues accumulate in the lungs when the alveoli are damaged. |
| What can cause pulmonary fibrosis? | It can be caused by the inhalation of small particles, such as the carbon coal particles that cause black lung (anthracosis) in miners. |
| which 2 laws have to do with partial pressures? | Dalton's and Henry's |
| (starred diagram) What are the partial pressures of oxygen and carbon dioxide in the alveoli? | In the alveoli, PO2 is ~104 mmHg and PCO2 is ~40 mmHg. |
| (starred diagram) What are the partial pressures of oxygen and carbon dioxide in arterial blood? | In arterial blood, PO2 is ~100 mmHg and PCO2 is ~40 mmHg. |
| (starred diagram) What are the partial pressures of oxygen and carbon dioxide in resting body tissues? | In resting tissues, PO2 is 40 mmHg or lower, and PCO2 is 45 mmHg or higher. |
| (starred diagram) What are the partial pressures of oxygen and carbon dioxide in venous blood? | In venous blood, PO2 is ~40 mmHg and PCO2 is ~45 mmHg. |
| What is ventilation (V) in the context of the lungs? | Ventilation is the amount of air reaching the alveoli. |
| What is perfusion (Q) in the context of the lungs? | Perfusion is the amount of blood reaching the alveoli via the pulmonary capillaries. |
| What is the ideal overall Ventilation/Perfusion (V/Q) ratio for the entire lung? | The overall V/Q ratio is approximately 0.8. |
| How does gravity affect ventilation and perfusion in an upright person? | Gravity pulls both air and blood toward the base of the lungs, but it affects the heavier blood much more drastically. |
| Where in the lung are both ventilation and perfusion the highest? | Both ventilation and perfusion are highest at the base (bottom) of the lungs. |
| Describe the V/Q ratio and PO2 at the apex of the lung. | The apex is over-ventilated relative to its low blood flow, resulting in a high V/Q ratio and a highly oxygenated PO2 of about 130 mmHg. |
| Describe the V/Q ratio and PO2 at the base of the lung. | The base is over-perfused relative to its ventilation, resulting in a low V/Q ratio and a lower PO2 of about 89 mmHg. |
| Why is the PO2 of arterial blood leaving the lungs (~100 mmHg) lower than alveolar air (~105 mmHg)? | Gravity forces a V/Q mismatch where a massive volume of lower-PO2 blood from the lung base mixes with a tiny volume of high-PO2 blood from the apex, lowering the overall average. |
| What is the law that states that the total pressure of a gas mixture is equal to the sum of the partial pressures of each gas in it? | Dalton’s Law |
| How is the partial pressure of an individual gas calculated? | Partial pressure is calculated by multiplying the percentage of that gas by the total pressure. |
| What is the partial pressure of oxygen in the atmosphere at sea level? | Since oxygen makes up approximately 20% of the atmosphere, its partial pressure is roughly 159 mmHg (760 x 0.20). |
| What are the approximate percentages of the main gases in the atmosphere? | Nitrogen makes up 78% of the atmosphere, oxygen is 21%, and carbon dioxide is 1%. |
| How does the total pressure equation change when air enters our lungs? | Because the air becomes humid, the pressure of water vapor (PH2O) must be added: Pwet = PN2 + PO2 + PCO2 + PH2O = 760 mmHg. |
| Why does the addition of water vapor affect the calculation of the partial pressure of oxygen in the lungs? | Water vapor takes away from the total atmospheric pressure available for the other gases. |
| What is the constant pressure of water vapor at body temperature (37°C)? | The pressure of water vapor is a constant 47 mmHg. |
| How is the partial pressure of oxygen calculated for the humid air inside the lungs at sea level? | By subtracting the water vapor pressure from the total pressure and multiplying by the oxygen percentage: 0.21 x (760 - 47) = 150 mmHg. |
| How do the gas percentages change when comparing atmospheric air to alveolar air? | In the alveoli, the percentage of oxygen decreases and the percentage of carbon dioxide increases, which changes their respective partial pressures. |
| Why do the alveoli and blood capillaries quickly reach equilibrium for O2 and CO2? | Because there are many capillaries very close to the alveolar air, which maximizes the amount of gas dissolved in the fluid. |
| Which law states that the amount of dissolved gas depends on the gas's solubility, the fluid's temperature, and the partial pressure of the gas? | Henry's Law |
| According to Henry's Law, what is the primary determining factor for the amount of gas dissolved in blood? | The partial pressure of the gases is the primary determining factor, as solubility and temperature are relatively constant in the body. |
| What does the oxygen electrode method measure? | It only measures the oxygen dissolved in the blood plasma, not the oxygen bound to hemoglobin in red blood cells. |
| If the lungs are functioning properly, how does systemic arterial PO2 compare to alveolar PO2? | The PO2 of systemic arterial blood is only 5 mmHg less than the PO2 of alveolar air. |
| (highlighted) What is the oxyhemoglobin saturation level at a normal arterial PO2 of about 100 mmHg? | At 100 mmHg, hemoglobin is almost completely filled with an oxyhemoglobin saturation of 97%. |
| (highlighted) Why won't adding more oxygen significantly change the amount of O2 in red blood cells? | Because the hemoglobin is already 97% saturated, though it can increase the amount of dissolved oxygen in the plasma. |
| (underlined) Why is measuring the blood gases of venous blood not very useful? | Venous blood gases fluctuate too much based on factors like exercise and tissue demand. |
| What is a pulse oximeter? | It is a noninvasive device that clips onto a fingertip or pinna and uses red and infrared lights to measure oxyhemoglobin saturation. |
| How does a pulse oximeter distinguish between oxygenated and deoxygenated blood? | Oxyhemoglobin and deoxyhemoglobin absorb different wavelengths of light. |
| What does an abnormally low reading on a pulse oximeter indicate? | It indicates that gas exchange has been compromised by impaired lung or heart function. |
| Why must the rate of blood flow through the pulmonary circuit equal the systemic circuit (5.5 L/min)? | Blood flow must be balanced to avoid a back-up of fluid in the lungs. |
| How does the pressure difference in the pulmonary circuit compare to the systemic circuit? | The pulmonary circuit has a very low pressure difference of only 10 mmHg, compared to the 100 mmHg difference in the systemic circulation. |
| (bolded) Why is it important that vascular resistance is very low in the pulmonary circuit? | A low pressure and low resistance pathway reduces the possibility of developing pulmonary edema. |
| (emphasized) How do pulmonary arterioles respond to changes in alveolar PO2? | They constrict when alveolar PO2 is low and dilate when alveolar PO2 is high. |
| How does the pulmonary arteriole response differ from systemic arterioles? | It is the exact opposite; systemic arterioles dilate when tissue oxygen is low to deliver more blood, while pulmonary arterioles constrict to divert blood away from poorly ventilated areas. |
| What is the cellular mechanism behind pulmonary arteriole constriction in response to low oxygen? | Low oxygen depolarizes smooth muscle cells by inhibiting the outward flow of K+, which opens voltage-gated Ca2+ channels and stimulates contraction. |
| What is ventilation-perfusion coupling? | It is the process where pulmonary arterioles respond to local oxygen levels to ensure that ventilation (airflow) matches perfusion (blood flow). |
| How does perfusion adjust if there is poor ventilation (no O2) in a lung lobule? | The body decreases perfusion by vasoconstricting vessels to stop sending blood to that poorly ventilated area. |
| How does perfusion adjust if there is great ventilation in a lung lobule? | The body increases perfusion by vasodilating vessels to send more blood to pick up the abundant oxygen. |
| How does ventilation adjust if there is poor blood flow to a lung lobule? | The body bronchoconstricts to stop sending air to an area where there is no blood to absorb it. |
| How does ventilation adjust if there is great blood flow in a lung lobule? | The body bronchodilates to send more air to the area where the blood flow is highest. |
| (bolded) What is the term for dangerous tissue damage caused by the oxidation of enzymes when breathing 100% oxygen at pressures of 2.5 atmospheres or more? | oxygen toxicity |
| (bolded) What is a condition that results in dizziness and drowsiness when nitrogen is inhaled under high pressure, such as in deep-sea diving? | nitrogen narcosis |
| (bolded) What is a condition where nitrogen bubbles form in the blood and block small vessels because a diver surfaced too fast or an airplane suddenly lost pressure? | decompression sickness ("the bends"), can also happen if an airplane suddenly loses pressure |
| Does Hyperbaric Oxygen Therapy (HBOT) increase the amount of oxygen carried by hemoglobin? | No, because hemoglobin is already practically full when breathing sea level air. |
| How does HBOT increase oxygen delivery in the body? | It significantly increases the amount of oxygen dissolved directly in the blood plasma. |
| How does HBOT help treat decompression sickness? | The high pressure makes the nitrogen bubbles smaller and forces nitrogen to dissolve back into the blood so it can be safely exhaled. |
| What are some common conditions treated with Hyperbaric Oxygen Therapy? | It is used to treat decompression sickness, gas gangrene, carbon monoxide poisoning, severe traumatic crush injuries, and diabetic sores. |
| Which areas of the brain control the contraction and relaxation of breathing muscles? | Contraction and relaxation are controlled by motor neurons from the cerebral cortex for voluntary breathing, and the medulla oblongata and pons for involuntary breathing. |
| Where do the cell bodies of upper motor neurons that control voluntary skeletal muscle contractions reside? | They reside in the cerebral cortex. |
| Which nerves innervate the diaphragm and where do they arise? | The phrenic nerves innervate the diaphragm and arise from the cervical region of the spinal cord (C3, C4, C5). |
| Where do the motor neurons that innervate other breathing muscles arise? | They arise from the thoracolumbar region of the spinal cord. |
| What is the term for a loose aggregation of neurons in the ventrolateral region of the medulla that controls automatic breathing? | the rhythmicity center in the medulla oblongata |
| What is the suspected role of the Pre-Botzinger complex? | It is believed to generate the inspiratory rhythm, though it is not yet fully understood. |
| What is the dorsal respiratory group? | It is made up of inspiratory neurons (I neurons) that seem to stimulate neurons of the phrenic nerve. |
| What is the ventral respiratory group? | It is made up of neurons that seem to stimulate expiratory neurons (E neurons) that inhibit the phrenic nerve. |
| (bolded) How does the pons influence medulla activity? (2 centers) | The pons uses the apneustic center to promote inspiration and the pneumotaxic center to inhibit inspiration. |
| (bolded) Brainstem respiratory centers control breathing largely via the phrenic nerve from which spinal nuclei? (hint: cervical numbers) | C3-C6 (!) spinal nuclei |
| (bolded) What do chemoreceptors monitor to automatically control breathing? | They monitor the pH of fluids in the brain, as well as the pH, PCO2, and PO2 of the blood. |
| (bolded) Where are the central chemoreceptors located? Where are the peripheral chemoreceptors located? | central chemoreceptors are located in the medulla; peripheral are located in the aortic body and the carotid body. |
| (bolded) What kind of receptors monitor blood pressure in the aortic and carotid sinuses? | Baroreceptors monitor blood pressure, and should not be confused with the chemoreceptors in the aortic and carotid bodies. |
| (bolded) Which cranial nerve carries feedback from the aortic body to the medulla? | The vagus nerve. |
| (bolded) Which cranial nerve carries feedback from the carotid body to the medulla? | The glossopharyngeal nerve. |
| What is the rare neurological disorder where the brain loses the ability to automatically regulate breathing, often requiring a mechanical ventilator during sleep? | Ondine’s curse (Central Hypoventilation Syndrome) |
| Why is voluntary regulation of breathing not affected by Ondine's curse? | Because voluntary breathing involves descending corticospinal tracts from the cerebral cortex, bypassing the dysfunctional brainstem. |
| What is the most common cause of Ondine's curse? | It is most commonly congenital and caused by a defective gene (Congenital Central Hypoventilation Syndrome). |
| (starred - critical)What happens to blood pH and CO2 levels during hypoventilation? | CO2 levels rise (hypercapnia) and pH falls. |
| (starred - critical) What happens to blood pH and CO2 levels during hyperventilation? | CO2 levels fall (hypocapnia) and pH rises. |
| (starred - critical) What is the bicarbonate buffer equation? | CO2 + H2O <-> H2CO3 <-> HCO3- + H+ |
| (starred - critical) What do H2CO3 and HCO3- represent in the bicarbonate buffer equation? | H2CO3 is carbonic acid, and HCO3- is the bicarbonate ion. |
| (bolded and highlighted in red) Why are oxygen levels not a good index for the control of breathing? | Oxygen levels do not change as rapidly because of the large oxygen reserves in hemoglobin. |
| (bolded and highlighted in red) What is ventilation primarily controlled to maintain? | Ventilation is controlled to maintain constant levels of CO2 in the blood, and oxygen levels naturally follow. |
| (bolded and highlighted in red) What is the direct stimulus for central chemoreceptors in the medulla? | The direct stimulus is an increase in H+ ions (decreased pH) in the brain fluids. |
| (bolded and highlighted in red) How do central chemoreceptors detect changes in blood CO2 if H+ cannot cross the blood-brain barrier? | CO2 diffuses from the blood across the barrier and forms carbonic acid and H+ in the brain interstitial fluid, which then stimulates the receptors. |
| (bolded and highlighted in red) Which chemoreceptors are responsible for the majority of increased ventilation? | Central chemoreceptors are responsible for 70-80% of increased ventilation, even though they take longer to respond than peripheral ones. |
| (bolded and highlighted in red) What directly stimulates peripheral chemoreceptors in the aortic and carotid bodies? | They are directly stimulated by a rise in H+ (a fall in blood pH) induced by increases in blood CO2. |
| How does blood PO2 normally affect ventilation? | Normally, blood PO2 only indirectly affects ventilation by making the carotid bodies more sensitive to PCO2. |
| What is the term for the state where the carotid bodies respond directly to low oxygen dissolved in the plasma (below 70 mmHg) to stimulate breathing, overriding PCO2 as the primary stimulus? | hypoxic drive |
| what is the functionally important term for the body's response to acclimating in high altitude and in diseases like emphysema? | hypoxic drive |
| (starred, highlighted, bolded) Of the three chemical respiratory stimuli (pH, PCO2, PO2), which is the most powerful? | The pH of the cerebrospinal fluid (CSF) is the most powerful, followed by PCO2, with PO2 being the weakest. |
| Which chemical signals do the carotid bodies respond to? | The carotid bodies respond to all three chemical signals: rising PCO2, falling pH, and falling PO2. |
| Are central chemoreceptors affected by changes in blood pH? | No, central chemoreceptors are not affected by changes in blood pH because H+ cannot cross the blood-brain barrier. |
| (bolded) Which fibers in the lungs are affected by capsaicin (like pepper spray) and produce rapid, shallow breathing? | unmyelinated C fibers |
| (bolded) Which receptors respond to smoke and particulates to stimulate coughing? | Irritant receptors in the wall of the larynx. |
| (bolded) Which receptors respond to excess fluid in the lung's interstitial tissue? | Rapidly adapting receptors. |
| (bolded) What is the Hering-Breuer reflex? | It is a reflex stimulated by pulmonary stretch receptors that inhibits respiratory centers during inhalation to prevent inhaling too deeply and damaging lung tissue. |
| What effect does the hypocapnia from hyperventilation have on the brain? | Hypocapnia causes cerebral vasoconstriction, which results in inadequate brain perfusion and hypoxia that can produce dizziness. |
| How does hypocapnia affect blood pH and calcium levels? | It raises blood pH (respiratory alkalosis), which lowers plasma Ca2+ levels. |
| What are the physical symptoms of lowered plasma calcium caused by hypocapnia? | It can result in neuromuscular irritability and muscle spasms (tetany) in the legs, feet, and hands. |
| Why is breathing into a paper bag to treat hyperventilation potentially dangerous? | It can be dangerous if the person is hyperventilating because of an asthma attack or if they have angina or myocardial infarction. |
| What is the term for the sudden, unexplained death of an infant under one year old, most commonly striking between two and four months of age? | Sudden Infant Death Syndrome (SIDS) |
| What is a proposed physiological cause of SIDS? | Evidence suggests it may be due to a failure of the central or peripheral chemoreceptors to detect a rise in carbon dioxide. |
| What is the condition where there are 15 or more periods of apnea (cessation of breathing) during sleep caused by the temporary blockage of the upper airway? | obstructive sleep apnea |
| What triggers the gasp and jerk that ends a sleep apnea episode? | The temporary airway blockage causes PO2 to fall and PCO2 to rise, stimulating chemoreceptor reflexes that wake the person. |
| What are the cardiovascular dangers of severe obstructive sleep apnea? | It can lead to pulmonary hypertension, right ventricle hypertrophy, right-sided heart failure, and abnormal heart rhythms. |
| How is obstructive sleep apnea commonly treated? | People with the condition often wear CPAP (continuous positive airway pressure) devices when they sleep to keep the oropharynx air passage open. |
| what are the 2 parts of the respiratory rhythmicity center in the medulla oblongata of the brain? | dorsal and ventral respiratory group |
| what are the 2 types of receptors that stimulate coughing? | irritant receptors in wall of larynx responding to smoke, particulates; rapidly adapting receptors in lungs responding to excess fluid in interstitial tissue |
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