Title: The Respiratory System
Course: Question Banks

Q: Organisms that exchange respiratory gases directly across surface membranes are ________.
- found only in water (Incorrect. These organisms are often found near water but this is not a requirement for direct diffusion.)
- covered in skin (Incorrect. Skin, or integumentary tissue, is actually too thick to allow for direct diffusion of gases.)
- less than 1mm in diameter (Correct. Direct diffusion is only possible when organisms have a large surface area that each cell within the body touches.)
A: less than 1mm in diameter

Q: Gills have folded surfaces to facilitate ________.
- space saving in animals without true heads (Incorrect. Some organisms with gills have heads, notably fish. This is not why gills are folded anyway.)
- oxygen absorption directly into cells (Incorrect. Gills are not found in animals that respire by direct diffusion. Oxygen will still enter the circulatory system of many animals, such as fish.)
- diffusion across a larger surface area (Correct. Oxygen diffuses across the gill surface into fish and other gilled organisms in the water. The many folds in the gills create more surface area for this process.)
A: diffusion across a larger surface area

Q: The respiratory system of ________ is the most direct and efficient in active animals.
- flatworms (Incorrect. Direct diffusion is not the most efficient respiratory system among the animals.)
- fish (Incorrect. Fish respiration is relatively inefficient as it is still based on diffusion into the bloodstream in the low oxygen environment of water.)
- insects (Correct. The tracheal system of insects consists of a network of tubes that carries oxygen directly to the entire body, without using the circulatory system to transport oxygen to tissues.)
A: insects

Q: Once air enters the lungs, it is diverted into ________.
- bronchioles (Incorrect. Air ends up in the bronchioles but it does not enter them directly after entering the lung.)
- alveoli (Incorrect. This is the last “stop” of air before oxygen enters the capillaries of the circulatory system.)
- bronchi (Correct. Air travels through progressively smaller bronchi as it from through the lungs to the bronchioles.)
A: bronchi

Q: There are approximately ________ alveoli per lung.
- 300 (Incorrect. This number is much too small.)
- 300 thousand (Incorrect. This is not the correct number of alveoli per lung.)
- 300 million (Correct. There are early 600 million alveoli total in the human lungs.)
A: 300 million

Q: Muscle contraction in the bronchi is controlled by the ________.
- endocrine system (Incorrect. Hormones from the endocrine system can impact respiratory rate, but do not control muscles in the bronchi.)
- sympathetic nervous system (Incorrect. The sympathetic nervous system controls relaxation of bronchi muscles.)
- parasympathetic nervous system (Correct. Muscles of the bronchi contract upon signals from the parasympathetic nervous system.)
A: parasympathetic nervous system

Q: The first mechanism that prevent particulate matter from entering the lungs is ________.
- mucus in the lungs themselves (Incorrect. This is not the first line of defense against irritants in the air.)
- cilia in the esophagus (Incorrect. There are no cilia in the esophagus.)
- hairs in the nose (Correct. The nose contains hair and mucus, both of which trap particulate matter in the air.)
A: hairs in the nose

Q: Cilia in the bronchi function to ________.
- trap particles before they damage the lung tissue (Incorrect. This is not the role of cilia in the bronchi)
- move particulate matter through the respiratory system (Incorrect. Ideally particular matter is removed from the respiratory system as soon as possible, not moved further through it.)
- move mucus and particles out of the bronchi (Correct. Cilia beat in unison to move mucus and particles out of the bronchi. Once removed from the bronchi and bronchioles, this material is passed to the throat where it is swallowed and eliminated via the esophagus.)
A: move mucus and particles out of the bronchi

Q: Damaged cilia within the bronchi can result in ________.
- a bloody nose (Incorrect. A bloody nose is usually the result of an injury or trauma to the sinuses or capillaries in the nasal cavity.)
- shortness of breath (Incorrect. Shortness of breath has a number of causes, but few relate directly to damaged bronchial cilia.)
- a persistent cough (Correct. If cilia cannot beat and move particulate matter and mucus from the bronchi, the lungs will attempt to physically expel the material via a cough.)
A: a persistent cough

Q: Gas exchange during respiration is ultimately driven by ________.
- gravity (Incorrect. Gravity does not drive respiratory gas exchange.)
- muscular contraction (Incorrect. Muscle contractions are not what drives gas exchange during respiration.)
- diffusion (Correct. Gas exchange during respiration occurs primarily through diffusion.)
A: diffusion

Q: In order for oxygen to enter the bloodstream, blood must have ________.
- less carbon dioxide than the air in the lungs (Incorrect. The concentration of carbon dioxide will not affect the movement of oxygen.)
- very high partial pressure (Incorrect. Partial pressure is the concentration of individual components in a gas mixture.)
- lower oxygen levels than the air in the lungs (Correct. Since gas exchange is “powered” by diffusion, the concentration of oxygen must be less in blood if oxygen is to enter it from the lungs.)
A: lower oxygen levels than the air in the lungs

Q: The diffusion of a gas is proportional to ________.
- surface area (Incorrect. A larger surface area will facilitate more diffusion, but this is not what drives the rate of diffusion (just total diffusion).)
- temperature (Incorrect. Molecules do move faster at higher temperatures, but this is not what drives diffusion itself.)
- partial pressure (Correct. Partial pressure is the concentration of individual components in a gas mixture; diffusion is therefore proportional to the concentration of an individual gas in the mixture.)
A: partial pressure

Q: The amount of air inhaled during a normal breath is ________.
- inspiratory reserve volume (Incorrect. This is the amount of additional air that can be inhaled after a normal breath.)
- vital capacity (Incorrect. This is the maximum amount of air that can be moved in or out of the lungs in a single respiratory cycle.)
- tidal volume (Correct. On average this is around 0.5 liter of air.)
A: tidal volume

Q: The ________ usually averages about 3.6 liters of air.
- vital capacity (Incorrect. This is the maximum amount of air that can be moved in or out of the lungs in a single respiratory cycle, usually around 4.8 liters.)
- tidal volume (Incorrect. On average the amount of air inhaled during a normal breath is around 0.5 liter of air.)
- inspiratory reserve volume (Correct. This is the amount of additional air that can be inhaled after a normal breath.)
A: inspiratory reserve volume

Q: ________ volume cannot be measured directly.
- Tidal (Incorrect. Tidal volume can be measured.)
- Forced expiratory (Incorrect. FEV1 can be measured directly.)
- Residual (Correct. Residual volume must be calculated because the lungs cannot be totally emptied of air.)
A: Residual

Q: As gases move through respiratory structures, they hit vessel walls and generate ________.
- partial pressure (Incorrect. Partial pressure relates to the concentration of an individual gas in a mixture.)
- atmospheric pressure (Incorrect. Atmospheric pressure is the sum of all the partial pressures of atmospheric gases added together.)
- gas pressure (Correct. Collisions with vessel walls cause pressure to build up within the vessel.)
A: gas pressure

Q: At high altitudes, ________ decrease(s).
- gas concentrations (Incorrect. The concentration of gases in the air at high altitudes does not decrease.)
- lung capacity (Incorrect. Lung capacity does not decrease with changes in altitude.)
- atmospheric pressure (Correct. Because atmospheric pressure decreases, so too does partial pressure.)
A: atmospheric pressure

Q: Partial pressure dictates the ________ during respiration.
- efficiency of gas exchange (Incorrect. Efficiency of gas exchange is influenced more by the respiratory structures themselves.)
- gas mixture absorbed (Incorrect. Animals with respiratory systems need to obtain oxygen from the atmosphere. They will not absorb other gases. Plus, partial pressure is a characteristic of a single component in a gas mixture.)
- rate of gas exchange (Correct. Since partial pressure is the concentration of an individual gas, higher partial pressure indicates a steeper concentration gradient. As a result, a gas will diffusion into respiratory tissue more rapidly.)
A: rate of gas exchange

Q: The ________ is the ratio of carbon dioxide production to oxygen consumption.
- alveolar partial pressure (Incorrect. This is the partial pressure of a gas in the alveolar spaces.)
- venous quotient (Incorrect. There is no venous quotient, but there is a venous partial pressure.)
- respiratory quotient (Correct. The RQ is influenced by the fuel a body is consuming, carbohydrates compared to proteins or fats.)
A: respiratory quotient

Q: The fact that ________ lowers the partial pressure of oxygen within the alveoli.
- lungs are inefficient (Incorrect. Lungs are reasonably efficient as respiratory structures. Otherwise they would not be so prevalent in animals.)
- glucose is not the only fuel for the body (Incorrect. This influences the respiratory quotient, but does not directly lower the alveolar partial pressure of oxygen.)
- lungs never fully deflate (Correct. This results in inspired air mixing with residual air in the alveoli.)
A: lungs never fully deflate

Q: The partial pressure of oxygen is highest in the ________.
- venous blood (Incorrect. Venous blood has the lowest concentration of oxygen.)
- arterial blood (Incorrect. Arterial blood does not have the highest concentration of oxygen.)
- inhaled air (Correct. Recently inhaled air still has the same oxygen concentration as ambient air: 160 mmHg.)
A: inhaled air

Q: ________ combine lungs and skin in order to obtain all the respiratory gases they need.
- Mammals (Incorrect. Mammals use lungs only, aided by the diaphragm to reduce the effort of “breathing.”)
- Birds (Incorrect. Birds use lungs and air sacs to counteract the unique challenges of breathing while flying.)
- Amphibians (Correct. Adult amphibians do not have a diaphragm, so using the lungs to breathe is a “forced” activity. They combine this with diffusion across moist skin to meet their respiratory needs.)
A: Amphibians

Q: Air flow in bird respiratory systems is ________.
- bidirectional (Incorrect. Air flow in mammalian respiratory systems is bidirectional; that is why there is always some mixing of oxygenated and deoxygenated air.)
- reversible (Incorrect. The path that air follows through a bird’s respiratory system cannot be reversed.)
- unidirectional (Correct. Air moves in one direction from posterior air sacs to lungs and out by way of anterior air sacs. This enables them to obtain sufficient oxygen even at high altitudes.)
A: unidirectional

Q: In mammals, air is expelled by ________.
- air sacs (Incorrect. Mammals do not have air sacs in their respiratory systems.)
- the skin (Incorrect. Skin does not play a role in mammalian respiration.)
- the lungs (Correct. Air is both inhaled and exhaled by lungs in mammals.)
A: the lungs

Q: The airways of the lungs are kept open by ________.
- positive pressure within the thoracic cavity (Incorrect. There is no positive pressure within the thoracic cavity.)
- increased volume in the bronchi (Incorrect. Bronchi and bronchioles are stiff structures that do not change in size.)
- negative pressure within the thoracic cavity (Correct. This decrease in pressure is caused by the increase in volume of the thoracic cavity due to the contraction of the diaphragm.)
A: negative pressure within the thoracic cavity

Q: ________ within lung tissues pushes back toward the interior of the lungs.
- Elastic pull (Incorrect. There is no elastic pull within lung tissues.)
- Intrapleural pressure (Incorrect. There is no pressure between the layers of visceral pleura that covers the lungs.)
- Elastic recoil (Correct. Lungs are elastic, therefore after they expand and fill with air, recoil will pull that tissue back in and deflate the lungs to force air out.)
A: Elastic recoil

Q: Movement of air ________ lungs is a passive event.
- into (Incorrect. Humans must exert muscular force to bring air into the lungs.)
- into and out of (Incorrect. Humans must exert muscular force to bring air into the lungs.)
- out of (Correct. There are no muscles at work to exhale air from the lungs; it rushes out due to pressure within the thoracic cavity relative to the environment.)
A: out of

Q: Lung elasticity is known as ________.
- resistance (Incorrect. This is how much obstruction exists in airways.)
- ventilation (Incorrect. Ventilation refers to how much air moves into and out of a respiratory structure, such as the alveoli (alveolar ventilation).)
- compliance (Correct. This is an important factor that influences the rate of gas exchange in lungs.)
A: compliance

Q: ________ diseases are ones in which the airways are stiff or fibrotic.
- Obstructive (Incorrect. In obstructive diseases, the airways are blocked or the surfaces damaged, reducing available area for gas exchange.)
- Inflammatory (Incorrect. Inflammation simply refers to increased blood flow to an area of injury or infection, which may result in redness and warmth.)
- Restrictive (Correct. The airways are less compliant in restrictive diseases like respiratory distress syndrome and pulmonary fibrosis.)
A: Restrictive

Q: Patients with restrictive diseases often have ________.
- large volumes of air trapped after exhalation (Incorrect. This is an effect of an obstructive disease.)
- increased surfactant levels (Incorrect. Respiratory distress syndrome, a type of restrictive disease, is actually caused by reduced surfactants in the airways.)
- reduced functional vital capacity (Correct. These patients cannot exhale the normal amount of air.)
A: reduced functional vital capacity

Q: If the amounts of air and blood in the lungs do not match, there is a ________.
- physiological/anatomical mismatch (Incorrect. There is no such thing as a physiological/anatomical mismatch.)
- recruitment/respiratory mismatch (Incorrect. There is no such thing as a recruitment/respiratory mismatch.)
- ventilation/perfusion mismatch (Correct. A V/Q mismatch occurs if the amount of air in the lungs does not match the amount of blood perfusing the capillaries and arteries of the lungs.)
A: ventilation/perfusion mismatch

Q: A V/Q mismatch produces ________.
- anatomical shunts (Incorrect. Not all V/Q mismatches produce anatomical dead space.)
- physiological dead space (Incorrect. Not all V/Q mismatches produce physiological shunts.)
- dead space (Correct. All V/Q mismatches produce regions of broken down or blocked lung tissue of some type.)
A: dead space

Q: If ventilation is greater than perfusion, ________.
- arterioles constrict and bronchioles dilate (Incorrect. This would be a response to greater perfusion than ventilation.)
- arterioles dilate and bronchioles dilate (Incorrect. This would maintain the perfusion to ventilation imbalance.)
- arterioles dilate and bronchioles constrict (Correct. This will increase blood flow to the lungs while decreasing air flow.)
A: arterioles dilate and bronchioles constrict

Q: Each hemoglobin molecule binds ________ oxygen molecule(s).
- one (Incorrect. Each subunit in hemoglobin can bind one molecule.)
- two (Incorrect. Hemoglobin molecules do not bind two oxygen molecules.)
- four (Correct. Hemoglobin is composed of four subunits, each of which can bind one molecule of oxygen.)
A: four

Q: A(n) ________ shows the binding of oxygen to hemoglobin graphically.
- oxygen association curve (Incorrect. This is not the term for the graph illustrating oxygen binding to hemoglobin.)
- oxygen affinity curve (Incorrect. This is not the term for the graph illustrating oxygen binding to hemoglobin.)
- oxygen dissociation curve (Correct. Even though this shows oxygen binding to hemoglobin, it is termed a dissociation curve because it shows how readily hemoglobin acquires and releases oxygen.)
A: oxygen dissociation curve

Q: An increase of carbon dioxide in the bloodstream will ________ the affinity of hemoglobin for oxygen.
- increase (Incorrect. Increased carbon dioxide does not increase affinity of hemoglobin for oxygen.)
- have no impact (Incorrect. Increased carbon dioxide will impact the affinity of hemoglobin for oxygen.)
- reduce (Correct. This is due to a subsequent decrease in pH that occurs with high carbon dioxide levels.)
A: reduce

Q: The majority of carbon dioxide molecules from body tissues are transported to the lungs by ________.
- direct dissolution into the blood (Incorrect. This is how the least number of carbon dioxide molecules are transported.)
- binding to hemoglobin (Incorrect. Only around 10 percent of carbon dioxide is transported to the lungs by hemoglobin.)
- the bicarbonate buffer system (Correct. 85 percent of carbon dioxide is transported in red blood cells through a pathway that converts them into bicarbonate and hydrogen ions.)
A: the bicarbonate buffer system

Q: The bicarbonate buffer system prevents ________.
- irreversible binding of carbon dioxide to hemoglobin (Incorrect. Carbon dioxide readily dissociates from hemoglobin.)
- the chloride shift (Incorrect. The chloride shift is actually part of the bicarbonate buffer system.)
- changes in blood pH (Correct. Because both positive and negative ions are produced when carbon dioxide is converted to bicarbonate and hydrogen ions, there is little change to the pH of the system. That’s why it is a buffer.)
A: changes in blood pH

Q: Carbon dioxide is removed from the human body by ________.
- urination (Incorrect. Mammals do not remove carbon dioxide by urination.)
- diffusion across the skin (Incorrect. Mammals do not use their skin as part of the respiratory process.)
- expulsion from the lungs (Correct. Regardless of which transport mechanism carried carbon dioxide from tissues, it ends up back in the lungs where it can be expelled.)
A: expulsion from the lungs