Skeletal muscle and nerve tissue Flashcards
What surrounds individual muscle fibers?
endomysium
What are fascicles? what surrounds it?
groups of individual muscle fibers
perimysium
What surrounds the entire muscle?
epimysium
Where are the nuclei for skeletal muscle cells?
on periphery of cells
What is the cytoplasm of muscle cells composed of?
myofibrils
What are the two components of muscle cells that allow contraction?
actin (thin)
myosin (thick)
What is a Z line? what is the area between two z lines called?
z lines are the anchoring points for actin filaments
z line to z line is a sarcomere
What is a sarcomere?
the basic contractile unit of a muscle cell
What is the I band composed of?
actin
What is the M line?
anchor site for myosin (M line is in middle of thing)
What contained in the H zone?
myosin
What is the A band?
where actin and myosin overlap
Where is calcium stored in muscle cells?
sarcoplasmic reticulum surrounding each fascicle
What is the function of a T tubules?
allows the depolarization wave to move through the muscle tissue
What is the terminal cisternae?
dilated ends of sarcoplasmic reticulum that releases calcium
What is the relationship between myofibril and sarcomere?
myofibrils contain thousands of sarcomeres
What is the function of tropomyosin?
wrapped around actin, covers of myosin binding sites until activated by troponin T
What is the function of troponin C?
binds calcium
What is the function of troponin T?
bind tropomyosin once troponin C binds calcium
What is the function of troponin I?
inhibit muscle contraction
what is happening on the macromolecular level during muscle contraction?
actin is sliding past myosin towards the M line, this brings the z line together without changing the length of actin or myosin
What is needed to unbind actin and myosin
ATP
What are type I muscle fibers?
slow twitch (oxidative)
weak sustained contraction (aerobic)
contains lots of myoglobin
What are type IIa muscle fibers?
fast twitch (oxidative) strong, fast contraction that cant be sustained
What are type IIb muscle fibers
fast twitch (glycolytic)
largest and most prevelant
fast ATPase provides power and speed that cant be sustained for long
anaerobic
What are the components of a neuron?
cell body, axons, dendrites
What are clumps of neurons called in the CNS vs the PNS
CNS is nuclei
PNS is ganglia
What is a bipolar neuron?
one dendrite one axon
What is a pseudounipolar neuron?
the weird weird one idk, just go look at a picture
What is a multipolar neuron?
many dendrites and one axon
What is the substance in the rER of neurons
Nissl substance
What part sends signals? what part receives?
axons, dendrites
What is the function of schwann cells?
myelinate PNS axons
How does myelination speed up signal conduction?
creates nodes so the signal jumps from node to node
What surrounds entire nerve fascicles?
epineurium
What surrounds clusters of axons?
perioneurium
What surrounds individual axons
endoneurium
What is the function of a neuromuscular juntion
nerve innervating skeletal muscle by releasing ACh into the synaptic cleft
What are the steps of the cellular mechanisms in the neuromuscular junction?
- ACh released by axon
- ACh stimulates change in sarcolemma that excites fiber and carried down T tubule
- Enzymes break down ACh
What problems can arise in the neuromuscular juntion?
probably a shit enzyme that isnt breaking down ACh,
myasthenia gravis where antibodies bind antagonistically to the ACh receptors
What is the function of a muscle spindle receptor?
monitor change in length, rate of change, and tension in muscles
What are intrafusal fibers?
specialized fibers inside a muscle spindle receptor
What are nuclear bag fibers? What do they detect?
fibers wrapped by type Ia nerve fibers
-detect change in length/degree of tension
WHat are nuclear chain fibers? what do they detect?
wrapped at their ends by type II nerve fibers
-detect static muscle strength.
What are extrafusal fibers?
fibers outside the spindle (alpha motor fibers)
