Compare and contrast intrinsic and extrinsic controls of cardiac activity
What will be an ideal response?
Intrinsic control of stroke volume (the heart's ability to vary stroke volume) depends on the relationship between end-diastolic volume and stroke volume. The more blood that returns to the heart the more blood the heart can eject. This occurs because the resting length of the heart is less than its optimal length. As more blood returns to the heart it stretches, becomes closer to its optimal length, and contracts with a greater strength. Extrinsic control is dependent upon factors originating outside the heart, especially sympathetic stimulation. Sympathetic activity directed at the heart increases the heart's contractility, resulting in stronger contractions and pumping out a greater percentage of blood.
You might also like to view...
An animal with an internal ion profile that resembles the ion composition of the external water is an __________
Fill in the blank with the correct word.
It's thought that fever may be beneficial to fighting an infection because it reduces the availability of ____________________, thus reducing bacterial growth
Fill in the blank(s) with correct word
What is a condition that results from infection and causes the alveoli to fill with fluid?
A. Emphysema B. Asthma C. Chronic bronchitis D. Pneumonia E. Tuberculosis
The ________ regulates digestive tract motility, secretion, and blood flow. Its neurons are found in the ________
A) autonomic nervous system; serosa B) visceral motor division; mucosa and submucosa C) visceral sensory division; muscularis externa and submucosa D) enteric nervous system; submucosa and muscularis externa E) central nervous system; muscularis externa and muscularis mucosae