Muscles

Question 1

this type of muscle is multinucleated, contains mitochandria, is mainly voluntary, and its basic contractile unit is a sarcomere

Answer 1

skeletal muscle

Question 2

true or false- the number of skeletal muscle fibers is set before you are born

Answer 2

true

Question 3

enlargement of existing muscle fibers

Answer 3

hypertrophy

Question 4

shrinkage of existing muscle fibers

Answer 4

atrophy

Question 5

these two hormones stimulate hypertrophy

Answer 5

testosterone and GH

Question 6

This motor protein makes up thick filaments

Answer 6

myosin

Question 7

what are the 3 components of thin filaments in skeletal muscle?

Answer 7

actin
troponin
tropomyosin

Question 8

what are the 3 subunits of troponin?

Answer 8

T- attaches to tropomyosin
I- inhibits binding of actin and myosin
C- binds calcium

Question 9

These are two structure proteins in skeletal muscle that hold the filaments together and anchor them to the cell membrane

Answer 9

titin and dystrophin

Question 10

what is the basic contractile units of skeletal muscle?

Answer 10

sarcomere

Question 11

This is a voltage sensor in skeletal muscle that activates ryanodine receptors, allowing Ca2+ release

Answer 11

dihydropyridine (DHP)

Question 12

this receptor forms a Ca2+ channel

Answer 12

Ryanodine receptor

Question 13

What part of the thin filament blocks myosin from binding actin?

Answer 13

tropomyosin

Question 14

________ occurs when Ca2+ is pumped back into the SR

Answer 14

relaxation

Question 15

at neuromusclular junctions, motor neurons release ________ and it attaches to _______ ____ receptors

Answer 15

ACh; nicotinic ACh

Question 16

this results from a single AP resulting in a fixed amount of Ca2+ release

Answer 16

twitch

Question 17

this occurs due to a sustained contraction because of the repeated firing of a motor neuron

Answer 17

tetanus

Question 18

this type of contraction occurs when the muscle contracts but does not shorten

Answer 18

isometric

Question 19

this type of contraction occurs when the muscle changes length but the force remains the same

Answer 19

isotonic

Question 20

This type of muscle is spindle-shaped, can divide throughout the lifetime, has a single nucleus and lacks troponin

Answer 20

smooth muscle

Question 21

This type of muscle’s thin filaments are anchored to the plasma membrane or to dense bodies

Answer 21

smooth muscle

Question 22

This is the molecule that Ca2+ binds to in smooth muscle

Answer 22

calmodulin

Question 23

what molecule does calcium calmodulin activate?

Answer 23

myosin light chain kinase (MLCK)

Question 24

What is the function of MLCK in smooth muscle?

Answer 24

phosphorylation of myosin, which allows the binding to actin

Question 25

What enzyme is responsible for the dephosphorylation of myosin in smooth muscle?

Answer 25

myosin light-chain phosphatase (MLCP)