CIRCULATION

(ANSWERS ARE AT THE END)

1.    Which of the following statements is true when comparing the circulatory system of a squid and a mammal?

a.  The squid has a one-way flow of blood, while the mammal has a two-way flow.

b.  The branchial hearts of the squid and the right side of the mammalian heart are similar in that both send deoxygenated blood through the respiratory device.

c.  The systemic heart of the squid is similar to the mammalian heart, because it pumps deoxygenated blood to the gills and oxygenated blood to the tissues.

d.  The squid has an open circulatory system while the mammal has a closed system. 

2.  Which of the following can increase the amount of oxygen diffusing across respiratory membranes or carried by body fluids?

a.  equal partial pressures of oxygen on either side of the membrane.

b.  small membrane surface area.

c.  countercurrent exchange.

d.  the respiratory pigment, retinal, which is found in arthropods.

3.  Which of the following statements is true regarding the mammalian heart?

a.  The left side of the heart pumps oxygenated blood out to the tissues.

b.  Atrioventricular valves prevent a back flow of blood from the ventricles into the atria.

c.  Semi-lunar valves prevent a back flow of blood from the aorta and pulmonary artery.

d.  All of these are true.

4.    Hemolymph is:

1. the fluid that fills the water vascular system of echinoderms.
2. an oxygen-binding pigment found typically in annelids.
3. the coelomic fluid of animals that lack a circulatory system, like nematodes and cnidaria
4. the coelomic fluid of animals, such as insects, that have an open circulatory system

5.    The heartbeat in mammals:

1. is carried to the tip of the ventricle by Purkinge fibers
2. is triggered by the pacemaker, the atrioventricular node
3. is regulated by osmoreceptors in the hypothalamus that respond to blood pH
4. is increased by parasympathetic neurons releasing acetylcholine

6.    Which of the following animals uses a fluid-filled coelom to accomplish circulation?

1. nematodes
2. molluscs
3. annelids
4. cnidarians

7.     Which of the following is true of circulatory systems?

1. arthropods have a closed circulatory system
2. the open circulatory system in insects involves a hemocoel
3. nutrients and gases are exchanged in capillary beds in the Platyhelminthes
4. the coelom is the primary means of circulation in squid and annelids

8.    When a reptile dives:

1. capillary beds in the lungs constrict, causing a backpressure in the pulmonary artery that deflects blood from the right ventricle into the systemic arches.
2. the systemic circuit shuts down due to backpressure in the aorta caused constriction of body tissue capillaries, which deflects blood from the left ventricle into the pulmonary artery.
3. the heart stops beating temporarily, so that no blood is sent to the lungs.
4. none of these

ANSWERS:

1. b
2. c
3. d
4. d
5. a
6. a
7. b
8. a

SHORT ANSWER:

1.  You go for a 5 mile run.  At the end of it your heart is beating rapidly, you are covered with sweat, you have lost salt (Na+ ions) through perspiration, and you are very thirsty.  Which of the following do you know is true?

a.  Your rapid heartbeat is regulated by the cardiac center of the telencephalon, which sends nervous impulses to the atrioventricular node, which activates the ornithine cycle, resulting in the production of the enzyme, hementin, which causes the ventricle to contract from the bottom up.

b.  Your thirst results from the release of Diuretic Hormone from the adrenal glands, which stimulates the thirst center in your hypothalamus.

c.  Because of your increased need for oxygen, the capillaries in your peripheral tissues will constrict causing a back-pressure in the two systemic arteries, which will shunt blood past the incomplete septum into the pulmonary artery, and thus back to the lungs for further oxygenation.

d.  The loss of Na+ ions in your sweat will stimulate the Bowman's capsules of your nephrons to release angiotensin, which will cause the adrenal glands to increase their uptake of Na+.

e.  The transfer of oxygen from your blood into your heart muscles and skeletal muscles is aided by the respiratory pigment, myoglobin, which has a higher affinity for O2 than hemoglobin.

ANSWERS:

a.  False:  regulated by cardiac center of medulla oblongata, which sends impulses to sinatrial node, which activates atrioventriculare node, which sends impulses through Purkinge fibers to tip of ventricle, causing it to contract from bottom up.  Hementin is an anticoagulant produced by leaches.

b.  False:  thrist is stimulated by angiotensis, which is activated by renin, which is released from juxtaglomerular appartus in response to loss of Na+; diruetic hormone is produced in insects and decreases uptake of ions and water by rectal glands.

c.  False:  this is what happens in reptiles when then dive or hibernate.  Mammals have a complete septum and 4 chambered heart and cannot emphasize or deemphasize the pulmonary circuit by deflecting blood flow in the way that reptiles can.

d.  False:  will stimulate Juxtaglomerular appartus (not Bowman's capsule), which releases renin, which activates angiotensin, which stimulates adrenal glands to release aldosterone, which will increase the uptake of Na+ by the distal convoluted tubules of the nephrons.

e.  True:  myoglobin is a pigment found in striated muscle fiber that helps to pull O2 from the blood into the tissues.