physiology

Question 1

sarcomere is defined by

Answer 1

structure between two Z discs

Question 2

What is the A band

Answer 2

anisotropic

(dark)

lenght of the thick filament

Question 3

I Band

Answer 3

isotropic (lighter)

distance between two thick filaments

Question 4

which protein blocks the active sites on the actin at rest?

Answer 4

tropomyosin

Question 5

Troponin has which binding sites?

Answer 5

Toponin C: Ca is binding

Troponin T: binding to Tropomyosin

Troponin I (inhibitory): binds to actin

Question 6

Myosin contains of

and has which activity

Answer 6

tail, neck, head

ATPase activity

Question 7

At the neuromusc synapsis which channels open after depolarization of the sarkolemma through sodium influx?

Answer 7

voltage sensitive calcium channels

Question 8

on the neuromuskular junction, which structures does ACh bind to?

Answer 8

nicotinergic receptor 1 activates ion channel: allows massive influx of Sodium and little bit K out

Question 9

What are the two things maintaining resting membrane potential?

Answer 9

ATP pump pumpipng 3Na out and 2K in

K leaking channels: K leaks out

Question 11

What is the Ryanodine Receptor?

Answer 11

OPens up Sarkolemma for outflow of Calcium when stimulated by DHP Receptor on the T Tubule (this is stimulated by membrane depolarization)

Question 12

For muscle contraction Calcium released from the sarkolemma binds where?

Answer 12

binds to troponin

• > removal of tropomyosin from the actin binding sites
• >

Question 13

ATP is needed in muscle contraction for

Answer 13

1. detachement of actin from myosin and bending of the actin neck (by phosphate) and leads to “power stroke” and shortening of the muscle
2. additional ATP also needed to detach actin from myosin and go back to resting state

Question 14

How is calcium removed from the cytosol of muscle cells after contraction?

Answer 14

energy depended Ca pump on the sarcoplasmatic reticulum