Answers Lab07 Microcirculation

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S H E E T
NAME ____________________________________

EXERCISE

LAB TIME/DATE _______________________

Frog Cardiovascular
Physiology
Special Electrical Properties of Cardiac Muscle:
Automaticity and Rhythmicity
1. Define the following terms. automaticity: Ability to depolarize spontaneously in the absence of external stimulation. rhythmicity: Depolarization/repolarization events occur in a regular and continuous manner.
2. Discuss the anatomical differences between frog and human hearts. The frog heart has a single ventricle and two atria.
Dorsally there is an expanded area called the sinus venosus. The human heart has two atria and two ventricles. No sinus venosus
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Define partial heart block, and describe how it was recognized in the laboratory. When the 1:1 ratio of atrial to ventricular contractions was replaced by different whole number ratios, e.g. 2:1, 3:1, the heart was in partial heart block.

13. Define total heart block, and describe how it was recognized in the laboratory. No synchrony between depolarization waves of atria and ventricle. Impulses not being transmitted from atria to the ventricle; no whole number relationship between atrial and ventricular contractions was demonstrated.

14. What do your heart block experiment results indicate about the spread of impulses from the atria to the ventricles?
In normal heart activity, the ventricles are depolarized by the depolarization wave spreading from the atria.

Observing the Microcirculation Under Various Conditions
15. In what way are the red blood cells of the frog different from those of the human? Frog RBCs are nucleated; human RBCs are anucleate. On the basis of this one factor, would you expect their life spans to be longer or shorter? Longer
16. The following statements refer to your observation of one or more of the vessel types observed in the microcirculation in the frog’s web. Characterize each statement by choosing one or more responses from the key.
Key: a.

arteriole

b.

venule

c.

capillary

c

1.

smallest vessels observed

a

2.

vessel in which blood flow is rapid, pulsating

c

3.

vessel in which

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