Synaptic Transmission Flashcards
Point of attachment for actin
Z-disk
Zone where only actin is present in cross section and is adjacent to the Z-disk
I-band
Represents the cross-sectional area containing myosin
A-band
Cross-section contains only myosin
H-zone
Central region of myosin filaments are linked by proteins
M-line
Long molecule that helps align actin
Nebulin
Large, long elastic protein associated with myosin and anchors it with sarcomere. Also acts to return a stretched sarcomere to resting length.
Titan
Huge protein that connects muscle cytoskeleton including actin the ECM
Dystrophin
At the termination of the AP, SR begins sequestering Ca2+ via what pump?
SERCA (Ca2+/ATPase)
contraction requires availability of ATP
- stores sources as phosphocreatine
- derived from glycolysis thus producing lactate
- derived from OXPHOS in mitochondria (requires constant O2)
peripheral fatigue
perception of fatigue or loss of motivation brought on by increasing levels of byproducts of contraction
- H+ ion
- lactate
central fatigue
- red: myoglobin and mitochondria
- small diameter
- uses O2
- fatigue resistance
slow-twitch oxidative
- white
- large diameter
- uses phosphocreatine and glucose
fast-twitch glycolytic
between the slow-twitch oxidative and fast-twitch glycolytic in characteristic
fast-twitch oxidative
What does force of contraction depend on?
- starting length of sarcomere
- max force near middle of length extremes
- most efficient relationship b/w actin binding sites and myosin heads
- distance between actin and myosin is less
- max force near middle of length extremes
- how rapidly fiber is stimulated by nerve
What happens if the sarcomere is short?
- Myosin cannot pull actin far before it hits Z-line.
- Cross-sectional area is also increased thus pushing actin and myosin apart.
What happens if a second twitch is initiated before complete relaxation?
second twitch requires a greater force
What are some things that can cause greater force generation?
- neuron that innervates MORE fibers
- muscle with MORE glycolytic fibers (but fatigues quicker)
- MORE motor neurons and thus MORE motor units
moving an object associated with muscle shortening
concentric contraction
allowing an object to moe while muscle is lengthening
eccentric contraction (or controlled relaxation)
when muscle shortening occurs without change in the load
isotonic contraction
contraction in the absence of load movement
isometric contraction
4 things that reflexes require:
- sensory receptor
- afferent input to CNS
- processing by CNS
- efferent output to approrpiate tissue
resists change
negative feedback
anticipates required change and prepares or activates appropriate tissue
feedforward mechanism
