MiniMidterm1

1) A 199 student was tracking the body temperature of lizards basking in the sun in Aldrich Park, one dark and one light colored lizard. A hawk flew overhead and both lizards dove into a burrow where the temperature was 12oC. Her data are in the graph below. The dark lizard cooled faster because, A) the temperature gradient was smaller for the light lizard. B) the light lizard had a higher surface area to volume ratio. C) emissivity is not a factor in a shaded environment.

When the light lizard entered the burrow, its starting temperature was much lower than the dark. Thus, the temperature gradient for the dark lizard was much greater, and heat transfer was faster. Because emissivity is not just based on visible light (the non- visible UV spectrum is also a factor), it will still be a factor in a shaded environment. If the light lizard had a higher SA:V ratio, then it would have cooled faster.

1) Blubber is a better insulator than copper because blubber has a a. lower thermal conductivity coefficient b. higher thermal conductivity coefficient c. lower heat capacity d. higher heat capacity

a. lower thermal conductivity coefficient Things with a low thermal conductivity coefficient are excellent insulators. Blubber has a very low coefficient, so it insulates, while copper has a very high coefficient, so it conducts heat. Heat capacity does not necessarily determine conductivity. The table below is a qualitative description of the conductivity and heat capacity of some common items.

3) A student took 4 different spheres that were all made of the same material and put a temperature probe in each one. Here are the characteristics of the 4 spheres. He made sure that the spheres were all at room temperature (22oC) and before putting them into a beaker of hot water (40oC). There was a magnetic stir bar in the beaker to stir the water. He recorded the change in temperature for 5 minutes. 4) In the previous question, what was the most likely type of heat transfer between the spheres and the temperature probes? A) Conduction B) Convection C) Conductivity

A) Conduction The sphere and the temperature probe are both solid, so heat is transferred by conduction. Heat is transferred between the water and the sphere by convection. Conductivity is not a type of heat transfer. After looking at the results and discussion with the TAs, we agreed that conduction was the single best answer.

6) When a patient is breathing with the assistance of a ventilator, respiratory specialists adjust the settings on the ventilator in order to regulate blood pH. If the patient develops an acidosis (acidic blood pH), what should the specialist do in order to restore pH? A) Increase minute ventilation (VE) B) Increase the Pco2 of inspired air. C) Decrease the tidal volume.

A) Increase minute ventilation (VE) H2O + CO2 <=> H2CO3 <=> H+ + HCO3 If the patient is acidic, then there is an excess of H+. Removing CO2 would shift the equilibrium to the left and restore pH. Of the options listed, increasing minute ventilation would increase the rate of CO2 removal from the alveoli. Respiratory therapists who monitor the ventilators in hospitals devote hours and hours to learning the intricacies of pH regulation through ventilation.

7) Which of the following could be a symptom of a metabolic acidosis (such as in kidney failure when acidic compounds cannot be removed from the blood)? A) Increased minute ventilation B) Decreased breathing frequency C) Increased FEV1.0/FVC D) Decreased tidal volume

A) Increased minute ventilation When the the blood is acidic, there is an excess of H+ ions and the way to decrease H+concentration is increase ventilation in order to remove CO2 (H2O + CO2 <=> H2CO3 <=> HCO3 + H+). Decreased breathing frequency or tidal volume will cause CO2 to build-up and further exacerbate the problem. FEV1.0/FVC isn't applicable to this problem

6) One effect of hot weather is dilation of peripheral blood vessels in order to improve heat loss. This will result in A) decreased resistance to blood flow B) higher hemoglobin-oxygen saturation C) lower ventilation frequency to counteract the change in blood flow

A) decreased resistance to blood flow You learned that changes in the radius of a tube can have dramatic effects on resistance. So, when blood vessels dilate, resistance to blood flow decreases.

10) Another parameter that is monitored while a patient is on a ventilator is the amount of alveolar ventilation. Based on the frequency and tidal volume, which patient below has the highest level of alveolar ventilation? A) f = 10 min-1, TV = 500ml B) f = 20 min-1, TV = 250ml C) f = 25 min-1, TV = 200ml

A) f = 10 min-1, TV = 500ml Alveolar ventilation is affected by the amount of dead space: VA = f * (TV - DS). So for patient A, VA=4000ml/min, for patient B, VA=3000ml/min and for patient C, VA = 2500ml/min.

9) A class of drugs called beta-blockers are commonly prescribed to cardiac patients in order to reduce their heart rate. Beta-blockers slow heart rate by reducing the conduction of action potentials through the A-V (atrioventricular) node. The most likely effect on an ECG is A) longer R-R interval B) shorter P-R interval C) shorter Q-T interval D) longer T wave

A) longer R-R interval Based on the information given and what you learned in discussion and in lab, if the heart rate is slow, the time time between beats, the R-R interval is longer. There is probably an effect on the P-R interval, but the interval will be longer (recall from discussion that a longer P-R interval is associated with bradycardia). Similarly, the Q-T interval is more likely to be longer than shorter. The duration of the T wave is determined by repolarization, not depolarization.

5) A student wanted to study drinking habits at the new UCI hydration stations. She asked 15 students from three majors (biology, music and psychology) to record how much water they drank at indoor or outdoor hydration stations. They repeated their measurements on three different days with different air temperatures (18oC, 23oC and 28oC). In this study, the dependent variable is A) air temperature B) amount of water consumed C) academic major D) hydration station location

B) amount of water consumed The amount of water consumed is the dependent variable that is being measured. The academic major, location of the hydration station and air temperature are independent because they were chosen by the investigator in order to analyze their effect on the amount of water consumed.

9) A class of drugs called beta-blockers are commonly prescribed to cardiac patients in order to reduce their heart rate. Beta-blockers slow the heart rate by reducing the conduction of action potentials through the A-V (atrioventricular) node. What is the most likely effect on an ECG? A) shorter R-R interval B) longer P-R interval C) shorter Q-T interval

B) longer P-R interval Decreased conduction through the A-V node will delay the QRS complex, so the PR interval will be longer. If heart rate is reduced, the R-R interval will be longer. The QT interval will likely be unchanged.

2) A good insulator will have A) high conductivity B) low conductivity

B) low conductivity

5) A good insulator will have A) high conductivity B) low conductivity C) low heat capacity D) high heat capacity

B) low conductivity Good insulators do not transfer heat very efficiently, so they have a low conductivity.

7) A researcher wanted to study the factors that affect seals ability to hold their breath. He trained the seals to hold their breath and exhale into bags, and then he exposed them to gases with different amounts of CO2. He measured the partial pressure of CO2 in the air that they exhaled at the beginning of a breath hold, and at the end of a breath hold. He also measured their heart rate. What was the dependent variable? A) Pre-breath hold Pco2 B) Heart rate C) Breath hold duration

C) Breath hold duration The goal of the experiment was to measure the effect of CO2 on breath hold duration. Thus, breath hold duration was the dependent variable. Although heart rate was being measured, it wasn't being manipulated nor was it specified as a variable that would be affected by Pco2.

3) A student put temperature probes into 4 different spheres that were all made of the same material. Each sphere was a different color and each had a different surface area to volume ratio. First, she made sure that the spheres were all at room temperature (22oC). Then she put them into a hot water bath at 40oC with a small pump to circulate the water. She recorded the change in temperature in each sphere for 5 minutes. 4) In the previous question, what was the primary mode heat transfer for heating the spheres? A) Conduction B) Conductivity C) Convection

C) Convection The question specified that the fluid was moving, therefor the answer was convection.

11) During a panic attack, patients will hyperventilate. Doctors used to recommend breathing into a paper bag to help the patients. Why did they suggest this? A) It decreased ventilatory drive and helped calm the patient. B) It reduced arterial Po2 and decreased the activity of respiratory motor neurons. C) It helped the patient retain CO2 that was being lost during hyperventilation. During hyperventilation, CO2 is lost and there is a risk of developing an alkalosis. The goal of the paper bag is to retain CO2. The increased CO2 actually increases ventilatory drive, so it ultimately doesn't help control breathing. It would have decreased arterial Po2, but that would have increased the activity of the motor neurons, not decreased it.

C) It helped the patient retain CO2 that was being lost during hyperventilation. During hyperventilation, CO2 is lost and there is a risk of developing an alkalosis. The goal of the paper bag is to retain CO2. The increased CO2 actually increases ventilatory drive, so it ultimately doesn't help control breathing. It would have decreased arterial Po2, but that would have increased the activity of the motor neurons, not decreased it.

8) During exercise, increased activity in the sympathetic nervous system causes A) decreased resistance because blood vessels constrict in the viscera B) increased MAP because of decreased peripheral resistance C) increased contractility, leading to increased stroke volume D) decreased venous constriction, leading to increased venous return

C) increased contractility, leading to increased stroke volume Sympathetic activity increases contractility, leading to increased stroke volume. It also causes venous constriction, but increases resistance. During exercise, peripheral resistance will decrease because localized factors (such as CO2 production and lactate accumulation) in working muscles cause vasodilation. This will help decrease MAP, not increase. Venous return increases during exercise because of increased venous constriction, not decreased. See Silverthorn Fig. 14.22 (6th ed) or 14.31 (5th ed).

8) If the Chordae Tendinae in the left ventricle were cut, A) oxygenated and deoxygenated blood would mix. B) blood flow into the pulmonary vein would decrease. C) oxygenated blood would flow into the atrium. D) deoxygenated blood would leak backwards during systole.

C) oxygenated blood would flow into the atrium. The chordae tendinae prevent the valves from hyper-extending under high pressure (i.e. during systole). If they are cut, blood will flow backwards. The left side of the heart receives oxygenated blood from the body, so if the chordae tendinae were cut, oxygenated blood would flow backwards during systole.

2) A student wanted to test the effectiveness of a new type of fabric that would facilitate evaporative cooling of human skin. She thought that senior biology majors would benefit the most from this new fabric because they are so active in lab classes. She recruited 10 Bio majors and gave 5 of them cotton shirts and gave 5 of them shirts made of the new fabric. She measured their skin temperature before and after a lab. She also recorded the humidity and air temperature in Steinhaus Hall because those affect evaporation. What was the dependent variable in her experiment? A) type of shirt B) air temperature C) skin temperature D) academic major

C) skin temperature The skin temperature was the dependent variable that was measured on each subject. The type of shirt and academic major are independent variables because they were chosen by the investigator. Although air temperature and humidity, were not chosen by the researcher, they are independent variables because they are not dependent on the type of shirt.

11) During the cardiovascular physiology lab, most of you observed that during exercise, cardiac output doubled, but mean arterial pressure did not increase by very much. One possible explanation is that A) abdominal pressure decreased as blood was diverted to muscles. B) thoracic pressure decreased because bronchioles dilated. C) total peripheral resistance decreased because arterioles dilated.

C) total peripheral resistance decreased because arterioles dilated. Look at the equation that was given to you. MAP = CO * TPR. If CO increased, in order for MAP to stay the same, TPR would decrease.

2) Heat is transferred from a hair dryer to hair primarily through A) conduction B) radiation C) evaporation D) convection

D) convection

7) When you measure blood pressure, the Korotkoff sounds are produced by A) ventricular depolarization B) ventricular repolarization C) valves closing D) turbulent blood flow

D) turbulent blood flow Korotkoff sounds are produced by the turbulent flow through the brachial artery when it is partially compressed by the blood pressure cuff. The sounds of the valves closing can only be heard through a stethoscope placed on the chest.

6) (2 pts) Explain the difference between independent and dependent variables. (2 sentences max).

The experimenter manipulates an independent variable, while dependent variables are measured. Dependent variables are the ones affected by the independent variable.

5) Obstructive lung diseases primarily affects a) Forced Vital Capacity b) FEV1.0 c) Inspiratory Capacity d) Alveolar elasticity

b) FEV1.0 Patients with obstructive lung disease have difficulty exhaling, so the volume of air that can be exhaled in 1 second is reduced (FEV1.0).

6) During the respiratory physiology lab you measured how long someone could hold their breath. Your group was curious about the effect of exercise on breath hold and repeated the control experiment after riding the bike for 3 minutes. The breath hold duration decreased because the subject's a) alveolar Po2 was lower after exercise b) metabolic rate was higher after exercise c) CO2 consumption was higher after exercise d) arterial O2 saturation decreased after exercise

b) metabolic rate was higher after exercise Exercise increases the rate of oxygen consumption and CO2 production. Because the rate of CO2 production is higher, CO2 accumulates in the arterial blood faster and the breath hold duration decreases.