Deck 34: Frog Cardiovascular Physiology

Question 1

In investigating the microcirculation of the frog foot, you note the following about blood flow: .

A) blood flows smoothly through arterioles, capillaries, and venules at the same velocity
B) blood flow in the arterioles and venules is slow and smooth; it is very slow in the capillaries
C) blood flow in the arterioles is rapid and pulsating; it is very slow in the capillaries, and slow and smooth in the venules
D) blood flow in the arterioles and venules is rapid and pulsating; it is slow in the capillaries

Answer 1

C

Question 2

The frog heart has .

A) 1 atrium and 2 ventricles
B) 2 atria and 1 ventricle
C) 1 atrium and 1 ventricle
D) 2 atria and 2 ventricles

Answer 2

B

Question 3

A pacemaker that appears unexpectedly at an abnormal site in the heart muscle is called a(n) _.

A) ectopic pacemaker
B) Heart muscle cannot serve as a pacemaker.
C) extrasystole
D) supplemental rhythmic center

Answer 3

A

Question 4

During the vagal stimulation experiment, the resumption of the heart beat is called .

A) sympathetic surge
B) vagal escape
C) vagal suppression
D) autonomic recovery

Question 5

The heart muscle is said to have automaticity, which means that .

A) the heart has a built-in automatic nerve
B) the heart muscle beats in a regular rhythm
C) the heart muscle depolarizes and contracts spontaneously without external stimulation
D) the nerves that innervate the heart cause the heart to beat automatically

Question 6

Which of the following chemicals causes vasodilation and increased capillary blood flow?

A) Ringer's solution
B) histamine
C) epinephrine

Question 7

Your observations of cooling and warming the beating frog heart include which of the following?

A) Warming the heart has no effect on heart rate.
B) Cooling the heart has no effect on heart rate.
C) Heart rate is very sensitive to temperature: it slows with cooling and beats faster with warming.

Question 8

During total heart block in the frog, .

A) the atria continue to beat, but the ventricle ceases beating
B) the atria and the ventricle continue to beat, but they beat independently of each other
C) the heart continues to beat in normal rhythm
D) the atria and the ventricle continue to beat, but the atria beat slower than the ventricle

Question 9

Below are several structures from the frog heart. Select the correct sequence that lists the structures from the one with the highest rate of contraction, to the one with the lowest rate of contraction.

A) atria, ventricle, sinus venosus
B) atria, sinus venosus, ventricle
C) sinus venosus, atria, ventricle
D) ventricle, atria, sinus venosus

Question 10

Given that impulses from parasympathetic nerves decrease heart rate, and that the neurotransmitter for parasympathetic postganglionic fibers is acetylcholine (ACh), predict how the following chemicals might affect heart rate.

A) Pilocarpine, a drug that simulates the action of ACh, will decrease heart rate.
B) Pilocarpine, a drug that simulates the action of ACh, will increase heart rate.
C) Pilocarpine, a drug that simulates the action of ACh, will increase heart rate; and atropine, a drug that blocks the action of ACh, will decrease heart rate.
D) Atropine, a drug that blocks the action of ACh, will decrease heart rate.

Question 11

Which of the following is likely to occur as a result of bathing the heart with K+, Na+, or Ca2+?

A) Contractions become weaker.
B) The heart stops beating.
C) Arrhythmias occur.
D) Contractions become more forceful.

Question 12

Tightening of the Stannius ligature between the atria and the ventricle can induce a complete heart block in a frog heart. During a complete heart block, _ .

A) the atria and ventricle beat independent of each other
B) there is a 2:1 ratio between atrial and ventricular contraction
C) there is a 1:1 ratio between atrial and ventricular contraction

Question 13

You have dissected the heart and gastrocnemius muscle from a frog. You observe that .

A) the heart contracts spontaneously, while the gastrocnemius has not contracted at all
B) the gastrocnemius continues to contract, while the heart ceases to beat
C) both muscles contract on the dissection tray

Question 14

Skeletal muscle can be tetanized; can heart muscle also be tetanized? Why or why not?

A) No, heart muscle does not show summation and tetanus because of the long refractory period of cardiac muscle cells.
B) Yes, extrasystoles are evidence of tetanus.
C) Yes, all muscle can be tetanized.

Question 15

Atropine sulfate when applied to the frog heart will _ .

A) slow down heart rate
B) increase heart rate
C) not affect the heart rate

Question 16

Although the heart beats without nervous innervation, can modify the heart rate.

A) hormones
B) various chemicals and ions
C) impulses from the autonomic nerves
D) impulses from the autonomic nerves, hormones, and various chemicals and ions

Question 17

You have observed an extrasystole in your recording of frog heart contractile activity. Where did it occur?

A) during ventricular diastole
B) during atrial contraction
C) during ventricular systole

Question 18

Which of the blood vessels associated with the capillary bed responds to changes in temperature?

A) Arterioles and venules respond equally, the capillaries show no response.
B) The arterioles show the greatest response.
C) The venules show the greatest response.
D) All of the vessels respond equally.

Question 19

The shunt between arteriole and venule in a capillary bed is called .

A) the pre-venule channel
B) the metarteriole-thoroughfare channel
C) the terminal arteriole
D) the precapillary thoroughfare

Question 20

During vagal stimulation of the frog heart, you observe which of the following?

A) The heart slows down.
B) The heart slows until it almost stops, then speeds up.
C) The heart slows, stops, and then begins to beat again.
D) The heart stops beating, and the frog dies.