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MEDSCI 142 - Respiratory Physiology Exam
Tidal volume is always: a) greater than zero and less that total lung capacity b) greater than residual volume c) greater than functional residual capacity d) greater than residual capacity and less than total lung capacity e) all options are correct - ANSWER a - correct; tidal volume is the amount you breathe in and out when relaxed so is less than maximum but more than zero b - no; cant measure residual volume so dont know c - no; FRC includes residual capacity which cant be measured d - no; less than total lung capacity but dont know volume of residual capacity e - no
The lung: a) exchanges CO2 between alveolar air and pulmonary capillary blood b) exchanges H2O between alveolar air and ambient air c) exchanges heat between alveolar air and ambient air d) exchanges O2 between alveolar air and pulmonary capillary blood e) all of the above - ANSWER e - all of the above; the lung serves all of these functions
Excitation of the phrenic nerve will: a) increase volume of thorax by causing elevation of diaphragm b) reduce volume of thorax by causing elevation of the diaphragm c) increase volume of the thorax by causing relaxation of the diaphragm d) increase volume of the thorax by causing contraction of the diaphragm
e) reduce volume of the thorax by causing contraction of the diaphragm - ANSWER a - no; elevation of diaphragm will decrease volume b - no; excitation of the nerve will not cause elevation of diaphragm c - no; excitation will not relax the diaphragm d - correct; excitation will contract the diaphragm, which for a dome-shaped muscle means going down and increasing volume of the thorax e - no; contraction causes expansion of volume
During inspiration: a) the glottis is open and alveolar air pressure is above atmospheric b) the glottis is open and alveolar air pressure is equal to atm c) the glottis is open and alveolar air pressure is less that atm d) the glottis is closed and alveolar air pressure is above atm e) the glottis is closed and alveolar air pressure is below atm - ANSWER If alveolar air pressure was above atmospheric, it would want to equilibrate and the air would leave the lungs, not go in. Because of expansion of the alveoli, the pressure drops. The glottis is only closed for swallowing food, so c - correct
Pneumonia In pneumonia, a bacterial infection causes the alveoli to fill with fluid, thereby reducing the space for air. This condition would be expected to: a) decrease the surface area for diffusive exchange of O2 b) decrease the surface are for diffusive exchange of CO2 c) increase the diffusion distance of O2 between air and blood d) increase the diffusion distance of CO2 between air and blood e) all of the above - ANSWER Decreased space for air means there is less surface area available for gas exchange, but it also means more thickness that the exchange needs to have to work through e- all of the above
Ventilation is increased by: a) a decrease in partial pressure of CO2 in the cerebrospinal fluid
d-yes, mechanoreceptors e-correct
Which is NOT a function of the respiratory system? a) transport of O2 and CO2 to tissue cells b) intake of O2 and elimination of CO c) filtering inspired air d) regulation of acid-base balance a) production of sound - ANSWER a - correct; this is what the blood does. The respiratory system transports O2 and CO2 to the blood, not tissues b - true c - true d - CO2 can change blood pH e - yes, via the larynx
During normal resting pulmonary ventilation, all of the following are true, EXCEPT: a) thoracic volume increases as diaphragm contracts during inspiration b) the diaphragm forms a dome as it relaxes c) air enters during inspiration because alveolar pressure drops below atm d) phrenic nerve depressed diaphragm contraction e) intrapleural pressure rises above atm during exhalation - ANSWER a - true, diaphragm descends and makes room b - true c - true, as lungs expand alveolar pressure decreases and air rushes in d - true e - correct; intrapleural pressure rises during inspiration, but never above atmospheric
The fact that the gradients for carbon dioxide can be smaller than those for oxygen, yet
still meet the body's requirements is because of the following: a) much of the O2 but not the CO2 is consumed by RBCs during transport b) CO2 is a smaller molecule than O2 c) O2 forms ions once it enters the alveoli and the electrical charge slows its movement across membranes d) CO2 receives assistance crossing membranes from a carrier molecule e) CO2 is more water-soluble than oxygen - ANSWER a - no, RBCs carry the O2, not consume it b - no, O2 is smaller c - no - O2 does not make ions d - no, CO2 diffuses across e - correct, by elimination and CO2 is much more water-soluble
Expired air has a greater oxygen content than alveolar air because: a) more oxygen diffuses in across the mucosa of the bronchioles and bronchi b) new inspired air is entering as expired air is leaving c) O2 is being produced by microbes in the upper respiratory tract d) some CO2 is being converted to O2 in respiratory passages e) alveolar air is mixing with air in the anatomical dead space on its way out - ANSWER a
- no, oxygen diffuses into the blood much lower down b - no, either inhale or exhale, not mixing c - no d - no e - correct, no gas exchange happens in the dead space so will have O2 still in it when it leaves
To say that hemoglobin is fully saturated means that: a) it is carrying both O2 and CO2 simultaneously b) the RBCs contain as many hemoglobin molecules as possible c) O2 is attached to both the heme and globin portions of the molecules d) some molecule other than O2 is attached to the O2 binding sites on hemoglobin
e - this would relate to the amount that can be taken in
Dalton's Law states that: a) the rate of diffusion is proportional to the surface area of the membrane b) at constant temperature the volume of gas is proportional to the pressure c) in a mixture of gases each gas exerts its own partial pressure d) at constant temperature the volume of a gas is directly proportional to the temperature e) at constant pressure, the volume of a gas varies inversely with the pressure - ANSWER a - no, it also depends on the membrane and molecular weight b - no, it is inversely proportional to pressure (Boyles) c - correct, this is Daltons d - no e - no this is almost Boyles but it is inversely proportional
Boyle's law states that: a) in a mixture of gases each gas exerts its own partial pressure b) rate of diffusion is directly proportional to surface area of membrane c) at constant temperature, the volume of a gas is directly proportional to the pressure d) at a constant pressure, the volume of a gas is directly proportional to the temperature e) at constant temperature the volume of a gas varies inversely with the pressure - ANS a - no, this is Daltons b - no c - no, it is inversely proportional d - no e - correct
Compliance is influenced chiefly by the volume of elastic tissue in the lungs and the:
a) volume of surfactant b) diameter of bronchioles c) thickness of cartilage in wall of bronchus d) temperature of inspired air e) partial pressure of O2 in inspired air - ANSWER a - correct; this reduces surface tension and allows the lungs to expand more easily (compliant) b - no, this effects resistance c - no d - no e - no
During internal respiration, O2 is transported: a) out of cells by primary active transport b) into cells by diffusion c) into cells by primary active transport d) into cells by secondary active transport e) out of cells by diffusion - ANSWER a - no, oxygen moves into cells b - correct, O2 can diffuse across membranes into tissues c - no, it is not carried in d - no it is not carried in e - no, oxygen moves into cells
Most oxygen is transported in blood by: a) the heme portion of hemoglobin b) simply dissolving in plasma c) the globin portion of hemoglobin d) any plasma protein
d) simply dissolving in plasma e) conversion to bicarbonate ion - ANSWER a - only a very small amount bound to protein b - no, not a thing c - some is, but not most d - some in solution, but not most e - correct, about 60%
If the partial pressure of O2 increases, then: a) less O2 can remain bound to hemoglobin b) breathing rate increases c) more bicarbonate ions are produced from carbonic acid d) the pH of blood decreases e) more oxygen can bind to hemoglobin ANSWER a - no, there will be increased affinity for Hb b - no, it would be more likely to decrease c - no, this happens when Pco2 increases d - no, it will increase e - correct, affinity for Hb will increase
Where would you expect to find the highest partial pressure of CO2? a) in the atmosphere b) in pulmonary veins c) in alveolar air d) in pulmonary arteries e) in the intracellular fluid - ANSWER a - no, this will be less than in the body b - no, the pulmonary veins carry oxygenated blood c-
d- e - correct, the CO2 is produced by the cells and diffuses here to be taken away by the blood
In metabolically active tissue you would expect: a) Pco2 will be at its lowest b) Po2 will be higher than in alveoli c) the percent saturation of hemoglobin will be less than it is near the lungs d) the pH will be slightly higher than it is in the fluid close to the lungs e) all of the above - ANSWER a - no it would be higher because it is producing it from cellular respiration b - no it would be lower because the O2 is used c - this is correct because it has been used by the tissues d - no it would be slightly lower because of more CO e - no
Residual volume is the volume of air: a) residual volume - remaining in the lungs after the lungs collapse b) volume stored in air spaces above the alveoli c) volume that may be inhaled over and above tidal volume d) volume that may be exhaled over and above tidal volume e) volume left in the lung after forced expiration ANSWER a - no, there would probably be nothing left! b - no c - no, that would be inspiratory reserve volume d - no, that would be expiratory reserve volume e - correct, and it cannot be measured
d) there is an increased rate of reaction converting carbonic acid into water and CO e) affinity of hemoglobin for O2 is falling - ANSWER a - no, this occurs under conditions of rising Pco2 via Le Chatelier b - no, not necessarily c - no, that occurs under conditions of rising Pco d - correct by elimination, opposite of reaction that occurs with increased Pco e - no, that occurs with increased Pco2, Le Chatelier, balancing equations
The patient is hypoventilating, then: a) cerebrospinal fluid pH is increasing b) partial pressure of CO2 is decreasing c. The rate of carbonic acid dissociating to H+ and bicarbonate ions is increasing d) the rate at which carbonic acid is dissociating to H+ and bicarbonate ions is decreasing e) more oxygen will be able to bind to hemoglobin - ANSWER Shallow breathing will give higher CO2 levels a - no, it would decrease as there is more H+ (acidic) b - no, it would be increasing c - correct, there is more carbonic acid in the system that needs to be converted to balance d - no e - no, this would happen with less CO
A 27 year old male weighs 70kg. Whilst at rest, his heart rate is 70 bpm and his cardiac stroke volume is 70 mL. His anatomical dead space is likely to be approximately: a) 140 mL b) 70 mL c) 14 mL d) 7 mL
e) 700 mL Answer Anatomical dead space is roughly 2mL per kg body weight therefore a - correct
For a healthy young adult at rest: a) both inspiration and expiration are active b) expiration is active while inspiration is passive c) both inspiration and expiration are passive d) expiration is passive while inspiration is active e) none of options above is correct - ANSWER a - no, only if forcing exhalation b - no c - no, it requires work to inspire d - correct, inspiration is innervated by the phrenic nerve and expiration is a recoil e -no
Expiration: a) is passive at rest b) occurs despite a negative intrapleural pressure c) occurs during a sneeze d) can be assisted by contraction of ab muscles e) all options are correct - ANSWER a - true b - true c - true d - true, this makes it active e - correct
Breath-holding (hypoventilation) will cause the partial pressure of CO2 to :
e - no, the muscle contracts
Whale oil and blood plasma are separated by a membrane which is selectively permeable to O2. The solubility of O2 is greater in the whale oil (A) than in blood plasma (B). The partial pressure of O2 is greater in B than in A. Hence O2 will: a) diffuse down its partial pressure gradient but up its concentration gradient from B to A b) not diffuse between A and B c) diffuse up its partial pressure gradient and up its concentration gradient from A to B d) diffuse up its partial pressure gradient but down its concentration gradient from A to B e) diffuse down its partial pressure gradient and down its concentration gradient from B to A - ANSWER a - correct; the pressure will equilibrate and more O2 will dissolve in the oil b - no, there is a gradient so there will be diffusion c - no, the concentration is higher in A than B so won't go up in that direction d - no, partial pressure is higher in B than A e - no, concentration is higher in A than B so won't go down in that direction
A newborn baby that lacks pulmonary surfactant: a) must develop greater force in the inspiratory muscles in order to breathe b) can be treated using an artificial surfactant delivered by aerosol in the trachea c) was probably born prematurely d) will, if untreated, experience respiratory distress syndrome until the lungs are further matured e) all options are correct - ANSWER e - correct; all of these things are likely
Surface tension exists in alveoli because: a) polar water molecules are mores strongly attracted to each other than to gas molecules in the air
b) polar molecules are more strongly attracted to gas molecules in the air than to each other c) movement of gas molecules within alveoli creates electrical charges that attract each other d) surfactant is very sticky e) elastic fibres in the basement membrane form linkages that collapse alveoli - ANSWER a - correct b - no, they are more attracted to each other c - no d - no, it is very slippery like detergent e - no
Your turn. Using your knowledge of the gas laws and molecular activity which of the following would you predict would occur with an increased in temperature? a) partial pressure of gas will decrease b) more of a particular gas can be dissolved in a liquid c) particular gas will diffuse across membranes at a faster rate d) volume of a particular gas will decrease e) solubility coefficient of a particular gas will increase - ANSWER a - no, increase in temperature will increase pressure b- c - correct, membrane will become more fluid and allow more diffusion. Particles will also move faster d - no, volume will increase e
Emphysema is characterised by: a) increase in lung compliance b) trapping of air in dilated alveoli
The Antarctic 'Ice Fish' live in water of -1.5 celcius. The blood of this fish contains no hemoglobin. Despite this, the fish function normally. This is because: a) the solubility of O2 in water varies with temperature b) its blood is transparent c) its predators prefer prey with hemoglobin d) its metabolism is based on ozone rather than O e) its muscles do not require ATP to contract - ANSWER a - correct by elimination, colder water holds more O b - no, this does not have any effect c - no, predators do not make a fish function d - not very likely e - no, all muscles need ATP to contract, so need oxygen
Anatomic dead space: a) allows exchange of CO2 between air and tissues b) none of the options are correct c) allows exchange of nitrogen between air and tissues d) allows exchange of O2 between air and tissues e) allows exchange of water vapour between air and tissues - ANSWER a - no, CO levels are the same as when they came in b - no, see below c - no d - no, O2 levels are the same as when they came in e - correct; wet tissue in the airways gives water to the air that comes in
During heavy exercise, ventilation can be increase by about: a) 100%
b) 2-fold c) 50% d) 200-fold e) 20-fold - ANSWER e - correct; can increase from 5-6L per minute to 100L per minute
If air is introduced to the intrapleural space: a) the volume of the lung on the same side increases, as does the volume of the thorax b) the volume of the lung on the same side decreases, but the volume of the thorax increase c) the opposite lung's volume increases and thoracic volume increases d) all of the above are incorrect e) the volume of the lung on the same side decreases and the thoracic volume decreases - ANSWER a - no, the lung decreases b - correct, the lung decreases and the thorax volume gets larger as the pleura is no longer holding the lung to the thorax c - no, there is no effect on the opposite lung d - no e - no, thorax volume increases
During exercise: a) the increase of temperature of systemic arterial blood causes the oxyhemoglobin equilibrium relation to shift to the left b) all are correct c) increase of Po2 of systemic arterial blood causes oxyhemoglobin equilibrium relation to shift to the left d) increase in temperature of pulmonary capillary blood reduces its oxyhemoglobin saturation e) increase of pH of systemic arterial blood causes the oxyhemoglobin equilibrium relation to shift to the left - ANSWER a - refers to oxygen dissociation curve, increased temperature means lower affinity for O2, so shift to right not left
