Muscle tissue

Question 1

eip-pera-endomysium

Answer 1

a dense irregular connective tissue sheath around muscle.
epi- covers entire muscle
pera- covers facets
endo- covers muscle fibers

Question 2

four steps to make muscle contract

Answer 2

1. events at neuromuscular junction
2. MF excitement
3. excitation-contracting coupling
   4- cross bridge cycling

Question 3

step 1- events at neuromuscular junction

Answer 3

1. AP arrives at head of axon
2. V-gated ion channels open causing calcium to enter motor neuron
3. calcium entry causes release of neurotransmitter ACh that makes its way down synaptic cleft
4. ACh binds to chemically gated ion channels that allow sodium to be released into muscle fiber.

Question 4

Step 2- Muscle fiber excitation

Answer 4

Muscle is in resting state before introduction of Na+
1. end plate potential- Na+ diffused into muscle fiber and consequentially become fore positively charged.
2- depolarization- If end gate potential is strong enough, V- gated channels along muscle fiber open to allow even more Na+ to enter muscle fiber, making it even more charged
3-repolarization- K+ channels open, rushing sodium out and K+ in. Cannot be used again until refractory period is over.

Question 5

step 3- Excitation/contraction coupling

Answer 5

positively charged muscle fiber caused v-gated ion channels on T-tubules to open, releasing calcium.

Question 6

step 4- contraction

Answer 6

at high Ca+ level, Ca+ binds to troponin which changes its shape, allowing myosin heads to attach to actin. The myosin head pulls the actin, causing contraction.