Asked by Lechaun Duhart on Jun 11, 2024
Verified
Which statement about precapillary sphincters is CORRECT?
A) They contract when oxygen levels in the tissue are low.
B) They can close off the capillaries by contracting.
C) They are openings that allow large molecules and blood cells to leave the capillary.
D) When the precapillary sphincters are open, blood flows only through the thoroughfare channels.
E) They are voluntary.
Precapillary Sphincters
Circular muscular valves located at the entrance of capillary beds, controlling blood flow into those beds.
Thoroughfare Channels
In traditional Chinese medicine, energy pathways that allow Qi and blood to circulate throughout the body, connecting different organs and bodily functions.
Contracting
The process of muscle fibers shortening to produce movement or increase tension against a load.
- Understand the significance and management of precapillary sphincters in the modulation of blood flow.
Verified Answer
ET
Eddie TuckerJun 12, 2024
Final Answer :
B
Explanation :
Precapillary sphincters are rings of smooth muscle located at the entrance of capillary beds. By contracting, they can control blood flow into the capillaries, effectively closing them off to regulate the distribution of blood to tissues based on the body's needs. This mechanism does not involve the voluntary control or the passage of large molecules and blood cells out of the capillaries, nor does it imply that blood flows only through thoroughfare channels when they are open.
Learning Objectives
- Understand the significance and management of precapillary sphincters in the modulation of blood flow.