Discussion:
Cardiac Output Homeostasis and Blood Distribution
Illustrates the distribution of the systemic cardiac output to the various organs at rest and during strenuous exercise. What physiological mechanisms produce the changes in blood distribution in each system depicted in the table? Consider the competing homeostatic demands strenuous exercise places on the body. Why might exercising on an extremely hot summer day result in fainting?
|
|
Flow at rest (ml/min)
|
Flow during strenuous exercise (ml/min)
|
|
Brain
|
650 (13%)
|
750 (4%)
|
|
Heart
|
215 (4%)
|
750 (4%)
|
|
Skeletal muscle
|
1030 (20%)
|
12,500 (73%)
|
|
Skin
|
430 (9%)
|
1900 (11%)
|
|
Kidneys
|
950 (20%)
|
600 (3%)
|
|
Abdominal organs
|
1200 (24%)
|
600 (3%)
|
|
Other
|
525 (10%)
|
400 (2%)
|
|
Total
|
5000
|
17,500
|