Module 3 part 2

Question 1

Myofibrils contain thick and thin filaments. What makes up each part?

Answer 1

Thick filaments -> myosin heads

Thin filaments -> actin

Question 2

Define sarcomeres

Answer 2

Thick and thin filaments arranged so that thin filaments are together, and thick filaments are together

Question 3

How does Ca2+ allow myosin to bind to actin?

Answer 3

Ca2+ binds to troponin, troponin slides off the binding site on actin, allowing myosin to bind

Question 4

What are the four steps of the excitation-contraction coupling?

Answer 4

1. Depolarization of muscle cell plasma membrane
2. Elevation of intracellular Ca2+
3. Contraction
4. Relaxation as Ca2+ returns to resting levels

Question 5

What are the two types of depolarizations that can occur in muscle cells?

Answer 5

Myogenic and Neurogenic

Question 6

Define myogenic depolarizations

Answer 6

Spontaneous AP, like heart beating

Question 7

Define neurogenic depolarizations

Answer 7

Synaptic input from motor neuron

Question 8

Define transverse tubules

Answer 8

They are invaginations in the sarcolema that enhance depth of action potential conduction