Factors Affecting the Cardiac Cycle

Part A

Complete the following statements:

1. The primary function of the heart is to _

2. The_normally controls the heart rate.

3. Parasympathetic nerve fibers that supply the heart make up part of the_nerve.

4. Endings of parasympathetic nerve fibers secrete_, which causes the heart rate to decrease.

5. Endings of sympathetic nerve fibers secrete_, which causes the heart rate to increase.

6. The cardiac control center is located in the_of the brain stem.

7. Baroreceptors (pressoreceptors) located in the walls of the aorta and carotid arteries are sensitive to changes in

8. If baroreceptors (pressoreceptors) in the walls of the venae cavae are stimulated by stretching, the cardioaccelerator center sends_impulses to the heart.

9. Rising body temperature usually causes the heart rate to_.

10. Of the ions that affect heart action, the most important are ions of calcium and_.

Part B

1. Describe the actions of the frog heart chambers during a cardiac cycle.

2. Attach a short segment of the normal frog heart recording in the following space. Label the atrial and ventricular waves of one cardiac cycle.

3. Temperature effect results: Temperature Heart Rate

10°C (50°F)

Room temperature

35°C (95°F)

4. Summarize the effect of temperature on the frog's heart action that was demonstrated by this experiment.

Part C

Complete the following: 1. Describe the effect of an increased calcium ion (Ca++) concentration on the frog's heart rate.

2. Describe the effect of an increased potassium ion (K+) concentration on the frog's heart rate.

Critical Thinking Application

| In testing the effects of different ions on heart action, why were chlorides used in each case?

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


  • bisrat
    What factors regulate the cardiac cycle?
    6 years ago
  • Isaia
    What seven factors effect the cardiac cycle?
    5 years ago
  • armaan
    What thing affect the cardiac cycle?
    4 years ago

Post a comment