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68 Cards in this Set
- Front
- Back
Higher vertebrates have developed respiratory systems whereby gas exchange occurs at a single place, known as
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The respiratory surface, the lungs
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How does air enter the respiratory tract?
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Through the external nares or nostrils
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After moving through the external nares and being filtered by mucous and nasal hairs, it passes through the pharynx and into a second chamber called what?
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The larynx
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Does ingested food also pass through the pharynx?
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Yes it does, en route to the esophagus
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What is the piece of tissue called that covers the glottis and what is the glottis?
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The glottis is the opening to the larynx, and the epiglottis covers it
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After passing through the larynx, where does air pass?
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Through the trachea
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What is the trachea primarily composed of?
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Cartilage
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How many branches does the trachea branch off to?
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They divide into two bronchi
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Where do they each go?
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One goes into the right lung and the other enters the left
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What ciliates both the trachea and bronchi?
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Epithelial cells
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What is their function?
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They filter and trap particles inhaled along with the air
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After the bronchi branch repeatedly into smaller bronchi, they reach the terminal branches which are called?
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Bronchioles
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What is each bronchiole surrounded by?
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Clusters of small air sacs called alveoli
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Where does gas exchange between the lungs and the circulatory system occur?
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Across the very thin walls of the alveoli
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What is each alveolus coated with?
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A layer of liquid containing surfactant
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And what is each alveolus surrounded by?
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An extensive network of capillaries
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What does surfactant do?
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It lowers the surface tension of the alveoli and facilitates gas exchange across the membranes
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How many alveoli provide 100 m2 of moist respiratory surface for gas exchange?
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There hundred million alveoli
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What is ventilation of the lungs?
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When air is inhaled and exhaled
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What is the purpose of ventilation?
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To take in oxygen from the environment and eliminate carbon dioxide from the body
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Pressure changes are dependent on the ventilating mechanism known as what?
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The thoracic cavity
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What is the thoracic cavity?
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The body cavity that contains the heart and lungs
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What is the thoracic cavity separated by from the abdominal cavity?
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A muscle known as the diaphragm
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Where is the diaphragm bounded to on its sides?
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By the chest wall
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What membranes are the lungs surrounded by?
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The visceral pleura and the parietal pleura
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What is the space between the two pleura known as?
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The intrapleural space
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What does it contain?
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A thin layer of fluid
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What is the pressure differential between the intrapleural space and the lungs responsible for?
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It prevents the lungs from collapsing
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During inhalation, when the diaphragm contract and flattens, what muscles contract?
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The external intercostals muscles
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What do they do?
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They push the rib cage and chest wall up and out
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What does this cause?
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The thoracic cavity to increase in volume
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What does this volume increase cause?
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A reduction in the intrapleural pressure
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What does this cause?
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The lungs to fill with air
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What is this referred to as?
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Negative-pressure breathing
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Is exhalation an active or passive process?
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A passive process
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When the diaphragm and external intercostals muscles relax causing the chest wall to push inward, is there an increase or decrease in thoracic cavity volume?
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A decrease
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What does this cause?
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It causes the air pressure in the intrapleural space to increase
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What does this do?
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It causes the lungs to deflate, forcing air out of the alveoli
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During forced exhalation what muscles contract?
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The internal intercostals muscles
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What does this cause?
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It causes the rib cage to move down
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What does surfactant reduce?
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The high surface tension of the fluid lining the alveoli, preventing collapse during exhalation
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Where are the neurons located that regulate ventilation?
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In the medulla oblongata
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How do they regulate ventilation?
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They rhythmically discharge stimulating the intercostals muscles and or the diaphragm to contract
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How can these neural signals be modified?
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By chemoreceptors in the aorta
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Why do the signals change?
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The signals change in order to respond to changes in the pH and the partial pressure of CO2 in the blood
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When the partial pressure of CO2 rises, does the medulla oblongata stimulate a decrease or increase in the rate of ventilation?
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An increase
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Can ventilation be controlled at all by the cerebrum?
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To some extent
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What is the purpose of hyperventilation?
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It lowers the partial pressure of CO2 in the blood below normal
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In response to this, what do chemoreceptors do?
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They sense it and send signals to the respiratory center which temporarily inhibits breathing
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What does a spirometer do?
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It measures the amount of air normally present in the respiratory system and the rate at which ventilation occurs
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What is the vital capacity?
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It is the maximum amount of air that can be forcibly inhaled and exhaled from the lungs
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What is the amount of air normally inhaled and exhaled with each breath called?
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Tidal volume
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What is the residual volume?
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The air that always remains in the lungs, preventing the alveoli from collapsing
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What is the volume of air that can be forcibly exhaled following a normal exhalation?
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The expiratory reserve volume
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What is total lung capacity?
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It is equal to the vital capacity plus the residual volume
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What is the dense network of minute blood vessels called that surrounds the alveoli?
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The pulmonary capillaries
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How does gas exchange occur across these capillary walls and the alveoli?
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By diffusion
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When blood enters the pulmonary capillaries, is it in an oxygenated or deoxygenated state?
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It is in a deoxygenated state
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What does this imply?
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It implies that it has a lower partial pressure of O2 than does the inhaled air in the alveoli
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Once O2 diffuses down its gradient into the capillaries where it binds to hemoglobin, what does it do next?
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It returns to the heart via the pulmonary veins
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Is the partial pressure of CO2 in the capillaries greater to that of the inhaled alveolar air or smaller?
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It is greater
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What does imply?
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It implies that CO2 will diffuse from greater concentration to smaller concentration from the capillaries into the alveoli, where it is released into the external environment during exhalation
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What happens at high altitudes?
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The partial pressure of O2 in the atmosphere declines, making it more difficult to get sufficient oxygen to diffuse into the capillaries
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What does the body do to compensate?
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It increases the rate of ventilation and also increases the production of red blood cells to carry more oxygen
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What happens to the affinity of hemoglobin for oxygen?
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It decreases to facilitate unloading of oxygen in tissues
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Does active transport facilitate gas exchange in the lungs at any point?
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No
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The intrapleural space in the lungs is bounded by what?
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The visceral pleura and the parietal pleura
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The lungs can collapse from what?
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It can collapse from insufficient surfactant production and a rupture of the parietal pleura
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