Part 4: ANS, Muscle Fatigue, Sarcopenia Flashcards
1
Q
The sympathetic nervous system utilizes what two neurotransmitters?
A
- epinephrine and norepinephrine
- bind to type alpha and type b receptors
2
Q
Type beta adrenergic receptors:
A
- expressed in skeletal muscle
- bind epinephrine and/or norepinephrine released from sympathetic nervous system
- stimulate muscle anabolism and repair
3
Q
Glucocorticoids (cortisol and its derivatives) are released as part of:
A
- immune/anti-inflammatory responses
- stress-induced secretion
4
Q
Glucocorticoids (cortisol and its derivatives) are released from:
A
- adrenal cortex (sits on top of kidney)
5
Q
Effect of glucocorticoids (cortisol and its derivatives):
A
- Proteolytic effects:
- type II fiber atrophy
- myostatin elevation (blocks satellite cell mitosis)
- inhibition of IGF-1
6
Q
What is the goal of glucorticoid activation and its subsequent binding to glucocorticoid receptors?
A
- to maintain blood glucose levels
7
Q
The two components of muscle fatigue:
A
- central nervous system
- muscle tissue
8
Q
How does the CNS influence muscle fatigue?
A
- release of serotonin and cytokines
9
Q
What is the main reason for muscle fatigue?
A
inhibition of cross-bridge cycling via:
- proton accumulation
- potassium efflux from T-tubules
- decreased glycogen stores
- free radicals, superoxides, ROS
10
Q
Anaerobic metabolism leads to an increase in protons in muscle tissue. What does this effect?
A
- reduces development of tetanic force
- type II muscle fibers most effected
- no effect on rate of fatigability
11
Q
Sarcopenia:
A
- a physiologic decrease in muscle strength that occur with age
- type II muscle fibers (fast-twitch) primarily effected
- due to a decrease in growth hormones and anabolic androgens
12
Q
The process of sarcopenia begins at what age?
A
- sometime around age 30 years, after which muscle loss can approach 3-8% per decade.
