P215 Basic Human Physiology Summer 2003 Lab Exam #3

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Kerry Cross
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1 PLEASE BE AWARE CONTENT COVERED ON EXAMS VARIES FROM ONE SEMESTER TO ANOTHER. THIS EXAM MAY NOT CONTAIN MATERIAL THAT WILL BE ON YOUR EXAM THIS SEMESTER, AND/OR MAY CONTAIN MATERIAL THAT WILL NOT BE COVERED ON YOUR EXAM. P215 Basic Human Physiology Summer 2003 Lab Exam #3 Name I recommend answering the question on the exam itself first, then marking your answer sheet at the end once you have decided on an answer. Avoid erasing answers from the answer sheet. Good luck! Either/Or Questions (2 points each, 14 points total). Select the correct term of the two provided to make the statement true, and mark the corresponding letter (a or b) on your answer sheet. 1. The (a. end-systolic volume / b. end-diastolic volume) is the maximum amount of blood contained in the heart at any point in the cardiac cycle. 2. According to Boyle s Law, as the volume of a gas increases, pressure (a. increases / b. decreases). 3. Secretion of pancreatic juice by the pancreas is triggered by a hormone produced by the small intestine called (a. secretin / b. enterokinase). 4. The (a. atrioventricular valves / b. semilunar valves) close at the beginning of ventricular systole. 5. An obstructive lung disorder is typified by an abnormally (a. low forced expiratory volume (FEV t ) / b. vital capacity (VC)). 6. In an oxidation reaction, the atom or molecule of interest (a. gains / b. loses) electrons. 7. Tidal inspiration is driven partly by the contraction of the (a. external / b. internal) intercostal muscles. B. Multiple choice questions. Choose the best answer (3 points each, 36 points total). 8. Most of the CO 2 transported in the blood is transported in the form of a) dissolved CO 2 in the blood plasma c) CO 2 bound to hemoglobin b) dissolved bicarbonate (HCO - 3 ) in the blood plasma d) HCO - 3 bound to hemoglobin 9. What is the amount of air present in the lungs at the end of a normal tidal expiration? a) Vital capacity (VC) c) Functional residual capacity (FRC) b) Total lung capacity (TLC) d) Residual volume (RV) 10. The QRS wave of an ECG recording indicates a) atrial depolarization c) ventricular repolarization b) ventricular depolarization d) ventricular hyperpolarization

2 11. Salivary enzymes such as ptyalin function best under ph conditions. a) neutral c) alkaline b) acidic d) radioactive 12. Newly absorbed fat is combined with protein to form structures called, which are then picked up by the lymphatic system for transport through the body. a) chylomicrons c) micelles b) lacteals d) bile salts 13. Chemical digestion of carbohydrate begins in the a) stomach c) esophagus b) mouth d) small intestine 14. Calculate the forced expiratory volume (FEV 1 ) of an individual with a vital capacity of 6.0 L who can expire 5.1 L of air in 1 second. a) 0.9 L c) 85% b) 11.1 L d) The amount of time it takes an electrical signal from the SA node to trigger depolarization of the ventricles is indicated by the interval of an ECG recording. a) R-T c) P-R b) T-R d) R-P 16. Which of the following substances is capable of chemically digesting complex polymers into simple monomers? a) pepsin c) mucus b) HCl d) bile salts 17. What is the alveolar ventilation (V A ) of an individual with a respiratory frequency of 12 breaths/min and a resting tidal volume of 750 ml? a) 62.5 ml c) 9000 ml b) 762 ml d) 6000 ml 18. Which of the following plots best depicts the relationship between the rate of an enzyme-catalyzed reaction and temperature over a wide range of temperatures? a) b) c) d)

3 19. The first sound of the cardiac cycle, produced at the beginning of systole, is caused by a) the atrioventricular valves closing c) the semilunar valves closing b) the atrioventricular valves opening d) the semilunar valves opening Short and Not-so-short answer questions: 1. Outline, in detail, the pathway of electrical signal conduction during cardiac excitation (8 points). 2. You are to conduct an experiment that tests the ability of pepsin (stomach) and trypsin (pancreas) to digest egg white protein under different ph conditions. A. Predict the results of the experiment by indicating whether each test would have a positive result (protein digestion occurs) or negative result (no protein digestion). (3 points) Mark + or - Pepsin: ph 4 Trypsin: ph 4 ph 7 ph 7 ph 10 ph 10 B. Explain the difference between pepsin and trypsin in their ability to function at different phs (6 points)

4 3. Explain how CO 2 levels within the blood influence ph, and how the respiratory system is used to regulate blood ph (8 points). Some equations for you V T RF ERV + RV RF (V T V DS ) V T + IRV + ERV + RV 1/3 V T V T + IRV + ERV (Volume expired in 1 second / VC) 100% V T + IRV P α 1/V HR SV

5 Answer Key Question Answer Question Answer 1 B 11 A 2 B 12 A 3 A 13 B 4 A 14 C 5 A 15 C 6 B 16 A 7 A 17 D 8 B 18 B 9 C 19 A 10 B 1. Action potentials originate at the sinoatrial node. They are conducted through tracts of pacemaker cells that extend through the atria, rapidly inducing depolarization through the atrial myocardium and triggering atrial systole. The wave of depolarization reaches the atrioventricular node, but the slow conduction velocity of these pacemaker cells delays the continuation of the signal for a brief period of time. Once through the atrioventricular node, the signal then propagates down the Bundle of His through the interventricular septum. Once reaching the apex of the heart, the Bundle of His gives rise to branched Purkinje fibers that carry the wave of depolarization up the lateral walls of the ventricle, inducing the ventricular myocardium to undergo systole. 2. Pepsin: ph 4 + Trypsin: ph 4 - ph 7 - ph 7 - ph 10 - ph 10 + Pepsin is a gastric protease with an optimal ph of ~2. Digestion will proceed under acidic conditions, but the two higher ph solutions are too alkaline for pepsin to have the proper shape to its active site for catalytic activity. Similarly, the pancreatic protease trypsin functions optimally under alkaline conditions found in the small intestine, and loses catalytic ability under neutral or acidic conditions 3. CO 2 can react with water to form carbonic acid, which in turn will dissociate into bicarbonate and H +. Bicarbonate formed via erythrocytes will act as a buffer in the plasma to stabilize ph against other acids. However, as dissolved CO 2 in the blood increases, the amount of carbonic acid formed in the blood (and hence the amount of H + in the blood) will increase. By regulating the amount of dissolved CO 2 present as a dissolved gas in the plasma, therefore, ph can be regulated by controlling the amount of carbonic acid in the plasma. Increasing ventilation will increase CO 2 removal from the blood, and is used to compensate for increased metabolic production of CO 2 to prevent acidosis. Conversely, ventilation is reduced when metabolism is low, preventing alkalosis due to low acid levels in the blood.

CARDIOVASCULAR SYSTEM

CARDIOVASCULAR SYSTEM Overview Heart and Vessels 2 Major Divisions Pulmonary Circuit Systemic Circuit Closed and Continuous Loop Location Aorta Superior vena cava Right lung Pulmonary trunk Base of heart