W3006 Fall 00 Physiology Final Exam NAME_________________________________________

1. You have a container with two compartments, separated by a semipermeable membrane, which allows water to pass, but not solute. Side A has one mole of starch, Side B has one mole of protein. .
Water will move into A move into B show no net movement 1
You add an equal amount of amylase to A and to B, and let it stand for a while, at the appropriate temperature and pH.
Water will move into A 1 move into B show no net movement
Explain your answer . (5 points)
Osmosis depends on the number of particles, 1 not their size, and there's no difference in the number of particules in the first part. In the second part, amylase breaks down starch (a polysaccharide) to produce maltose (disaccharide) so one starch molecule is broken down into many more maltose molecules, implying a great increase in the number of particles. There is therefore an increase in osmotic pressure in A, and water moves into A. 2

2. In a giraffe's leg, the blood pressure is much higher than in a person's legs for two reasons: The heart pumps blood at very high pressures, to give it the push it needs to travel ten feet upwards to the head. In addition, the heart is 8 feet above the feet, and the very high column of blood exerts additional pressure due to gravity's pull. Despite the high hydrostatic pressure in the leg capillaries, edema doesn't occur, because of 3 physiological adaptations. Circle the appropriate direction of each adaptation below, and explain how each on helps to prevent edema. (9 points)

Edema occurs when excess fluid remains within the extracellular tissues, which can occur either because more fluid enters the ECF or because less fluid leaves the ECF. (1 pt for less/more, 2 points for correct explanations)

A. Capillaries are (less) (more) permeable to proteins
Size of capillary pores determines how much protein can leave the blood for the ECF. If pores are smaller, capillaries are less permeable, and there's less chance of blood proteins getting into the ECF. This maintains high osmotic pressure within the blood, retaining water in the blood, and preventing it from entering the tissues.

B. Precapillary sphincters are (less) (more) open
Capillary sphincters are at the entrance to the capillaries, and determine how much blood flows into that capillary. If sphincters are less open, less fluid moves into that capillary, and therefore less fluid is present to potentially move into the ECF.

C. Skin is pulled (less) (more) tightly around the tissues
Skin pulled tightly around the tissues puts pressure on the ECF in this area, so that hydrostatic pressure in the ECF increases, which would oppose the hydrostatic pressure which forces fluid out of the blood vessels, thereby decreasing fluid flow to ECF.

3. Consider a fatty acid side chain on a triglyceride molecule, which is digested and absorbed and remains in the blood for at least 12 hours. Number the structures, to indicate which the fatty acid will be found in first, which second, and so on, from the time it is ingested through the 12 hours it is in the blood. Use 0 if the fatty acid will not be in that structure at all during this period.

1 lumen of stomach 2 lumen of small intestine 3 micelle 4 epithelial cell of small intestine 5 chylomicron 6 lacteal 7 lymph node 8 chylomicron remnant 9 VLDL 8 LDL 0 epithelial cell of stomach 0 lumen of large intestine 0 epithelial cell of large intestine (6 points)

 W3006 Fall 00 Physiology Final Exam NAME_________________________________________

4. This adorable face belongs to the vampire bat, Desmodus rotundus. It hangs around in caves in South America, venturing out at night to land on unsuspecting vertebrates. It swoops down onto a sleeping cow or horse or pig,  makes an incision with its razor-sharp teeth, and as the blood oozes out, it quickly slurps it up. You wouldn't  take your time over dinner, either, if your dinner might wake up any minute. A bat will consume so much of the  delicious red blood -- about 60% of its body weight in 20-30 minutes -- that it can become, as its name implies,  quite rotund and too heavy to fly away. In order to decrease its weight, it urinates as it eats, even before it has digested its meal, in that way getting rid of the fluid it has imbibed, while retaining the protein-rich cells.

A. Vampire bats have heat sensors in their nose. This allows them to find warm living bodies, , but it also helps them find the best place on the animal to take a bite. Why would a heat sensor help them know where to bite? (2)
Blood is warmed as it passes by the heat-generating tissues in the body's core. 1. Thus an increase in temperature indicates an area where more blood is present, due to a higher density of capillaries, or due to vasodilation, or it indicates an area where blood vessels are closer to the body's surface. 1 for any one of these explanations

 B. Scientists recently identified a chemical in the saliva of the vampire bat, and named it Draculin (I am not making this up!) It acts as an inhibitor of Factor X. What's this Draculin good for? Your answer should include an explanation of what Factor X is, the pathway in which it works, and why the bat would want to inhibit it. (8 points)
Factor X----> activated Factor X  catalyzes conversion of Prothrombin 1---> Thrombin 1which catalyzes conversion of Fibrinogen 1---> Fibrin1, which forms the fibrin clot.2  Inhibition of X means that no fibrin clot will form, which allows blood to flow instead of clotting, allowing the bat the needed time to finish feeding. 2

C. Compared to a human, the vampire bat has a very small small intestine, virtually no large intestine, and a proportionally larger stomach. The stomach is shaped like a blind sac, which fills with ingested blood. The vampire bat's stomach has many many more capillaries than a human's. The epithelial cells have much higher Na+/K+ ATPase activity. Explain why the bat's stomach has evolved in this way. How does this adapt it to its unique food-getting behavior? Your answer should include an explanation of what is occurring in the bat's stomach as it fills with blood, and how this differs from what occurs (in general terms) in a human stomach. (6)
The human stomach functions mostly as an organ of storage, with only a little digestion occurring.  The bats stomach is specialized for both digestion and absorption.   1
As blood fills the stomach, water must be extracted, so the fluid can be urinated out, so water absorption must occur here, rather than waiting till the large intestine, as occurs in humans 2 For water to be absorbed, a concentration gradient is necessary, so that water can move by osmosis.  The high concentration of Na/K pumps indicates that Na is pumped out of the stomach epithelial cells on the basolateral side, creating the concentration gradient of Na+, which will "pull" water out of the stomach lumen. 1   The abundance of capillaries is similar to what we saw in the villi in the human small intestines, and indicates that absorption  is occurring here. 1  The large sac expands to hold the blood, and digestion of the meal (mostly protein, but including other nutrients too) occurs here, and  subsequent absorption too.   1

W3006 Fall 00 Physiology Final Exam NAME_________________________________________

4. D. A bat ingests 800 times as much Fe/day as a human, but only a tiny fraction of this is absorbed into the bat's blood. If you looked inside the epithelial cells lining the bat digestive tract, you'd expect to see lots of a. calbindin b. ferritin c. transferrin d. bilirubin e. hemoglobin f. myoglobin (2)

E. Trace an ingested Fe++ backwards, from the bat's mouth to the cow, explaining where it probably was in the past 4 months. Assume the cow is like a human, and that the life of a cow's RBC is 2 months. (8 points)

 Bat drinks blood with Fe++ in RBC in blood vessel <---- Fe++ was packaged in RBC in association with hemoglobin   2 within the bone marrow 2 <----Fe++ reached the bone marrow in blood, carried by transferrin 2 <----- was secreted into the blood from the liver where it was stored with ferritin after the liver removed it from a previously broken down RBC 2

5. In 1822, Alexis St. Martin was shot in the upper left abdomen, and went to the local army doctor, William Beaumont, for medical care. Beaumont dressed the wound, but it never healed properly, and a small opening remained through which food sometimes came out. Beaumont gave St. Martin a job in his household, and, from time to time, performed experiments on St. Martin. Beaumont would attach different kinds of food to a string, shove them through the hole directly into St. Martin's stomach, and then pull them out after varying periods of time to see how they had changed. This was the basis for the first discoveries on how digestion works.

A. Although St. Martin did occasionally run a fever, in general, he did not develop massive infections from having unsterilized stuff stuck directly into his stomach. What prevents the development of infection in the stomach? (2)
HCl - hydrochloric acid inhibits bacterial growth

 B. St. Martin wasn't always so thrilled with his employer's hobby, and Beaumont noticed that when St. Martin was particularly angry, digestion took much longer. How would you explain this? Your answer should include the specific steps in the pathway that lead from the stressful emotion of anger to a decrease in the rate at which food is digested in the stomach. (8)

brain --> increased sympathetic ns activation and decreased parasympathetic 1
a. decreased smooth muscle contractions of digestive tract, so slower mixing of food, digestion, peristals, moving food along 2
b. decreased secretion of HCl from parietal cells 2  and decreased pepsinogen secretion 2, so less pepsin produced, and slower protein digestion
c. increased stimulation of alphareceptors on blood vessels to stomach, so vasoconstriction decreases blood flow to stomach, slows deliver of hormones (gastrin), thus indirectly decreasing HCl and pepsin secretion.  1

W3006 Fall 00 Physiology Final Exam NAME_________________________________________

6. Moses was stranded on a mountain top for 40 days and 40 nights without food. What happened to his body's glycogen over that period of time? (Assume normal Homo sapiens, no miracles accepted in your answer.) NOTE: Changes occur in many aspects of the body, but the question asks you to deal only with glycogen stores. Your answer should include glycogen, wherever it may be, and the factors that are responsible for the change. (8)

 Glycogen is stored in both the liver 2 and in muscle 2.  In response to low blood glucose, the pancreas 1 secretes glucagon 1, which stimulates breakdown of glycogen to glucose, which is released into the blood 1.    Glucose depletion, and the consequent lower insulin levels, causes muscle glycogen to be broken down into glucose, but this remains within the muscle cell, for its own use. 1

 7. Multiple choice, 3 pts each:

A. . If your arterial blood pressure dropped suddenly (jumping out of bed in the morning), what compensatory mechanisms would come into play to return your arterial blood pressure to normal?

a. decrease in heart rate
b. increase in contractility of your heart
c. decrease in peripheral resistance
d. dilation of veins
e. decrease in stroke volume

 B. Fatty acids are most effective at inhibiting stomach emptying when they are:

a. placed in the mouth
b. placed in the stomach
c. placed in the small intestine
d. placed in the large intestine
e. injected intravenously

C. You're about to take a drink of glucose, and you want to make sure to get every last bit of it absorbed. Which would most help you, if you added it to the glucose that you're drinking:

a. salt (NaCl)
b. table sugar (sucrose)
c. fatty acids
d. calcium
e. lemon juice (or other acid)

D. Which of the following hormones would most significantly lower plasma glucose levels after a carbohydrate meal?

a. glucagon
b. CCK
c. gastrin
d. GIP
e. secretin

W3006 Fall 00 Physiology Final Exam NAME_________________________________________

E. An increase in pressure in the carotid sinus will not do which of the following:

a. decrease sympathetic input to the heart.
b. increase firing of the sinus nerve (ie, baroreceptor).
c. decrease parasympathetic input to the heart.
d. decrease sympathetic input to the arterioles.
e. increase parasympathetic input to the heart.

F. Frank-Starling's Law of the Heart refers to increased myocardial contractility associated with:

a. a reduced venous return
b. parasympathetic stimulation
c. increased cardiac output
d. an increase in myocardial fibre length
e. blood viscosity

 G. Which is not a function of the liver:

a. store iron
b. make fibrinogen
c. store bile
d. activate vitamin D
e. detoxify wastes

H. Scavenger receptors are down-regulated by

a. high LDL
b. low LDL
c. oxidized LDL
d. all of the above
e. none of the above

I. All of these cause vasodilation, except:

a. histamine
b. endothelin
c. nitric oxide
d. rise in temperature
e. rise in carbon dioxide

J. End diastolic volume is ____ greater than end systolic volume (in a particular individual, at a particular point in time)

a. always
b. never
c. sometimes

K. Beta-2 receptors are found on:

a. sinoatrial node of the heart
b. cardiac muscle of the heart
c. veins bringing blood to lumen of heart
d. arterioles bringing blood to cardiac muscle of heart
e. none of the above

L. If blood becomes dehydrated, its viscosity increases, which would _____ blood pressure.

a. increase
b. decrease
c. have no effect on