Download Key - Creighton Biology

Name: __________________________
Biology 449 - Animal Physiology
Spring 2007
Midterm 3 - Key
Fill in your scantron form as follows:


Write and bubble in your name in the upper left (last name first).
Sign your form in the upper right. By so doing you verify that you are abiding
by Creighton’s policy on academic honesty.
Multiple choice: As always, choose the best answer for each multiple-choice question.
Answer on your scantron form. Each question is worth 3 points.
In a two-pigment system of oxygen transport (e.g. hemoglobin-myoglobin), the second pigment
a. normally has a higher affinity for oxygen than the first pigment so it can take more
oxygen from the first pigment.
b. normally has a lower affinity for oxygen than the first pigment so it can take more
oxygen from the first pigment.
c. normally has a higher affinity for oxygen than the first pigment so it can give up more
oxygen to the first pigment.
d. normally has a lower affinity for oxygen than the first pigment so it can give up more
oxygen to the first pigment.
e. I thought you said “two pig-men.”
Most carbon dioxide released by tissues is transported in the bloodstream in the form of
f.
g.
h.
i.
j.
bicarbonate ions.
carbamino compounds.
dissolved carbon dioxide.
Two of the above forms transport equally large amounts of carbon dioxide.
All three of the above forms transport roughly equal amounts of carbon dioxide.
Which of the following would directly trigger an increase in ventilation when sensed by
peripheral chemoreceptors?
k.
l.
m.
n.
o.
An increase in CO2
An increase in H+.
An increase in HCO3-.
An increase in O2.
None of the above would trigger an increase in ventilation.
Which of the following terms is associated with the enzymatic breakdown of food?
p.
q.
r.
s.
t.
Absorption
Digestion
Mastication
Motility
Segmentation
1
Which of the following would be most likely to reduce the amount of gastrin released by the
stomach?
u.
v.
w.
x.
y.
The presence of peptides in the stomach
Low pH in the stomach
Increased distention of the stomach
Increased mucus release into the stomach
Parasympathetic stimulation of the stomach
If a person was injected with a drug that interfered with the effects of cholecystokinin, which of
the following might result when the person ate a meal?
z. The stomach would be too acidic.
aa. Stomach emptying would be too rapid.
bb. The small intestine would be too acidic.
cc. The small intestine would not show peristalsis.
dd. The digestion of fats and proteins would be compromised.
Which of the following is not released by the pancreas?
ee. Amylase
ff. Bicarbonate
gg. Bile salts
hh. Lipases
ii. Proteases
Most of the glucose used to supply the nervous system with energy during the post-absorptive
period comes from
jj. adipose tissue.
kk. the liver.
ll. the muscles.
mm. the pancreas.
nn. storage in the neurons themselves.
Individuals with Type I diabetes can no longer produce insulin and (without treatment) will have
very high blood glucose levels after a meal. Based on what you know about the effects of
insulin, the reason for the high blood sugar levels is most likely that
oo. the small intestine absorbs glucose more quickly.
pp. the kidneys excrete glucose more slowly and thus levels remain high.
qq. adispose tissue releases large amounts of glucose into the bloodstream.
rr. muscle cells release large amounts of glucose into the bloodstream.
ss. glucose is not taken up by cells and thus remains in the bloodstream.
2
The hormone glucagon is released by the
tt. hypothalamus.
uu. liver.
vv. pancreas.
ww. small intestine.
xx. stomach.
One of the signals that increases appetite is
yy. decreased metabolic rate.
zz. increased size of fat stores.
aaa. increased levels of leptin.
bbb. increased levels of neuropeptide Y.
ccc. increased levels of secretin.
Which of the following is not an important function of the kidney nephron?
ddd. Adjustment of blood glucose levels
eee. Adjustment of overall osmolarity of the extracellular fluid
fff. Adjustment of specific ion levels
ggg. Adjustment of total body water
hhh. Removal of waste products
I meant to write “nephron” in place of “kidney,” since the kidney as a whole does
release some glucose. Credit was given for any answer.
The concentration of a substance K is found to be 1 µg/ml in the primary urine in Bowman’s
capsule and 1000 µg/ml in the final urine leaving the collecting duct. Assuming the nephron
is reabsorbing all but 1% of the water that passes through it (a typical amount), we can
determine that K is being
iii. reabsorbed.
jjj. secreted.
kkk. neither reabsorbed nor secreted.
lll. Either a or c could be true.
mmm. Either b or c could be true.
In the proximal tubule of the nephron, glucose leaves the urine and moves into the interstitial
fluid because
nnn. the glucose concentration is higher in the urine than in the ISF.
ooo. there is a primary active transport system for glucose.
ppp. there is a secondary active transport mechanism for glucose involving sodium.
qqq. the glucose is carried in the water that moves out of the tubule.
rrr. No glucose is present in the urine that enters the proximal tubule.
3
Which of the following is a direct effect of angiotensin II on renal function?
sss. It increases the reabsorption of water.
ttt. It decreases the reabsorption of water.
uuu. It increases the reabsorption of sodium.
vvv. It decreases the reabsorption of sodium.
www. Angiotensin II does not have direct effects on renal function.
Which of the following does not affect glomerular filtration rate?
xxx.
yyy.
zzz.
aaaa.
bbbb.
Changing shape of the podocytes covering the glomerulus.
Contraction of Bowman’s capsule to increase pressure in the nephron.
Release of paracrine agents by the macula densa.
Myogenic regulation by the afferent arterioles.
All of these affect glomerular filtration rate.
A decrease in central venous pressure is most likely due to
cccc.
dddd.
eeee.
ffff.
gggg.
a decrease in heart rate.
a decrease in stroke volume.
a decrease in blood volume.
a decrease in total peripheral resistance.
an increase in total peripheral resistance.
The cells whose daughter cells are spermatozoa (sperm) are known as
hhhh. Leydig cells.
iiii. seminal cells.
jjjj. Sertoli cells.
kkkk. spermatogonia.
llll. Vas Deferen cells.
The activity of Leydig cells is promoted mainly by
mmmm. gonadotropin releasing hormone.
nnnn. follicle stimulating hormone.
oooo. inhibin.
pppp. luteinizing hormone.
qqqq. testosterone.
Which of the following is not normally a component of semen?
rrrr. Acidic secretions
ssss. Anti-coagulants
tttt. Coagulants
uuuu. Spermatozoa (sperm)
vvvv. Sugar
4
Short answer: Write a concise answer to each of the following questions. Your answers
should fit in the spaces provided. Diagrams may be used but must be accompanied by
written explanations. Each question is worth 8 points.
Answer the following questions based on the oxygen saturation curve below.
100
%HbO2
80
60
40
20
0
0
20
40
60
80
100
120
140
PO2
wwww. What are three factors or changes that could cause the oxygen affinity curve to shift
from the pattern shown in black to the pattern shown in grey?
A decrease in pH, an increase in CO2 (forming carbamino compounds with Hb), an increase
in temperature, an increase in 2,3-DPG (due to anemia, hypoxia, etc.)
xxxx.
If the lungs have normal PO2 levels, how much
oxygen (in units of %HbO2) will be unloaded at tissues with a PO2 of 20 torr? (Note: I am not
trying to trick you with these units. This is the same convention we used in class, just stated
explicitly.)
Black curve: ~100% - 32% = 68%
Grey curve: ~100% - 23% = 77%
yyyy.
If the PO2 in the lungs dropped to 60 torr (as might
occur at high altitude), how saturated would the hemoglobin be on leaving the lungs?
Black curve: ~90%
Grey curve: ~83%
zzzz.
If the lungs still have a PO2 of 60 torr, how much
oxygen (in units of %HbO2) will be unloaded at tissues with a PO2 of 20 torr?
Black curve: ~90% - 32% = 58%
Grey curve: ~83% - 23% = 60%
5
Describe the process by which fats are digested and then reach the bloodstream. You can
assume that any substances that are part of the digestive process are already in the small
intestine. (A sequential list of events might be the easiest approach. A diagram may be
included, but will need to be fully explained, and probably would be of limited benefit.)
Bile salts begin the process of fat by emulsifying fats to increase the surface area of fat
droplets exposed to lipases. Lipases digest the triglycerides into glycerol and fatty acids.
The fatty acids form small droplets called micelles with the bile salts; these fatty acids can
diffuse straight through the apical membrane of the SI to enter the epithelial cells. Here they
are converted back into fats, packaged up into phospholipid-covered chylomicrons, and
exported through the basolateral membrane. Once in the ISF, they are drawn into the
lacteals by the general flow of lymph, and then transported through the lymphatic system to
the circulatory system at the vena cava.
The following questions relate to the functioning of the collecting duct of the nephron.
aaaaa. What is the primary function of the collecting duct? (One sentence answer)
To determine the final concentration of the urine (and get the urine from the distal tubule to
the renal pelvis.)
bbbbb. How is this function related to the function of the loop of Henle? (Note: You do not need
to discuss the details of how the loop of Henle works; just describe the results.)
The loop of Henle is a counter-current multiplier that establishes and maintains the
concentration gradient in the ISF of the renal medulla. This gradient is what draws water
out of the urine in the collecting duct, allowing it to become hyperosmotic to normal body
fluids.
ccccc. What is the primary control mechanism for the function of the collecting duct?
A drop in MAP or an increase in blood osmolarity triggers the increased release of antidiuretic hormone by the posterior pituitary. This hormone controls the insertion of
aquaporins into the epithelium of the collecting duct. More ADH leads to more aquaporins
inserted, increasing the permeability of the epithelium to water and thus the reabsorption of
water.
6
The following questions concern metabolic acidosis.
ddddd. List two possible causes of metabolic acidosis.
Examples include lactic acid production during anaerobic metabolism, severe diarrhea,
catabolism of large amounts of proteins and fats, formation of ketones, and ingestion of
acidic substances.
eeeee. What is the ventilatory response to the acidosis, and why?
Ventilation will increase to help increase pH. This occurs because increased ventilation
decreases CO2 levels in the blood, which draws the bicarbonate buffering equation:
CO2 + H2O <―> H+ + HCO3to the left. This means that H+ will be reduced, increasing pH.
fffff.
What is the renal response to a prolonged acidosis?
The kidneys will tend to secrete H+ ions into the urine while retaining HCO3-. The HCO3can then combine with H+ to increase pH.
The following questions relate to fetal development of the male anatomical pattern.
ggggg. Describe the normal developmental pathway for the gonads and internal reproductive
organs a human male from fetal weeks 6 to 12. Be sure to indicate the cause of each event.
The Y chromosome in males has the SRY gene, which makes HY antigen. This antigen
triggers the development of testes from the protogonads. Testes develop Leydig cells, which
secrete testosterone. The testosterone promotes development of the Wolffian ducts into the
internal components of the male reproductive tract; it also promotes differentiation of the
external genitalia into the male pattern. The testes also develop Sertoli cells, which produce
Müllerian inhibiting factor (MIF). This factor causes the Müllerian ducts to regress.
hhhhh. What might be the development pattern if the fetus lacked receptors for MIF?
This was a speculative question, but what you should have been able to determine was that
the only way the above pattern would change is that the Müllerian ducts should develop
instead of regress, leading to the development of the internal female tract (uterus and
oviducts) as well as the entire male tract.
7