Astronauts in zero gravity are able to move food through their digestive tracts because __________.
A. smooth muscle produces waves of contractions that propel material through the digestive tract
B. skeletal muscle puts pressure on the digestive tract
C. cardiac muscle maintains a high pressure that moves material through the digestive tract
D. striated muscle creates a pressure gradient that forces material from one end of the digestive tract to the other
E. skeletal muscle sphincters contract and allow materials to move through the digestive tract
A. smooth muscle produces waves of contractions that propel material through the digestive tract
You might also like to view...
Benign tumors can be damaging even though they do not spread to other parts of the body
Indicate whether the statement is true or false
Blood returning from the systemic circulation enters the right atrium via two large veins, the __________, one returning blood from above and the other returning blood from below heart level
Fill in the blank(s) with correct word
During exercise, the oxygen-hemoglobin dissociation curve
A. doesn't shift. B. shifts to the right. C. shifts to the left.
Lactation normally does not occur during pregnancy because
A. the breast ducts do not develop until after a baby is born. B. the high levels of estrogen and progesterone in maternal plasma inhibit prolactin effects on the breasts. C. maternal plasma levels of prolactin are low during pregnancy. D. high levels of androgens inhibit milk synthesis by the breasts. E. the low levels of circulating estrogen and progesterone during pregnancy inhibit milk synthesis by the breasts.