Phys stuff to know

Question 1

Pt presents with paralysis/weakness and exertional fatigue. What is the issue?

Answer 1

something blocking the Ca+ into the presynaptic membrane

NOT Achesterase inhibitor

Question 2

If no Ach, what happens?

Answer 2

No activation of Na channels, so Na can’t go into the cell and K and get out, (?) so the cell can’t depolarize?

Question 3

If Achesterase inhibitor is broken, what happens?

Answer 3

Ach hangs out too long and causes stimulation of the post synaptic membrane and then gets washed ouut and the parts can’t be reused insude te cell

this is why you get contraction followed by paralysis

Question 4

what happens if the Ach nicotinic receptr is open too long:?

Answer 4

Adjacent tissue–> increased threshold because of all the Na+ coming in

this is why succ. initally causes fasciulations and then paralysis

Question 5

Pt presents with anasthesia exposure followed by rapid rise in body temp (malign. hyperthermia) Why?

Answer 5

Ryr inability to close becayse ca leaks out and allows muscle to contract continually increasing body temp

Question 6

ATP and muscle contractions

Answer 6

1. Tight bidning in the rigor state. The cross brisghe is at a 45’ angle relative to the filaments. ATP binding site is empty and attached to myosin binding sites
2. ATP binds to its binding site on the myosin. Myosin then dissociates from actin
3. The ATPase activity of myosin hydrolyzes teh ATP. ADO and Pi remain bound to myosin
4. the myosin head swings over and binds weakly to a new actin molecule. The cross bridge is now at 90’ relative to the filaments
5. Release of Pi initates the power stroke. The myosin head rotates on its hinge, pushing the actin filament past it.
6. At the end of thepower stroke, the myosin head releases ADP and resumes teh tightly bound rigor state.

Question 7

If you run out of ATP, contraction can’t happen (duh) this happens in

Answer 7

Rigor Mortis

Question 8

Starling Froces

Answer 8

As length increases, force efficency increases to a point and then as it stretches to far becomes inefficient again

talking about length of the sarcomere.

super tight, condensened sarcomere–> muscle is flaccid

for cardiac muscle, want it to be in the Goldilock’s Zone of max. efficiency