Skeletal Muscle Structure

Question 1

If you have more glycogen you will haven more water. T/F

Answer 1

True

Question 2

Glycogen provides what?

Answer 2

In muscle to provide carbs for energy

Question 3

Fat in muscle cells is good for endurance? T/F

Answer 3

True

Question 4

How much muscle mass is lost until it’s deathly?

Answer 4

30%

Question 5

Surgery creates a catabolic situation. Loses muscle mass. T/F

Answer 5

True

Question 6

Skeletal Muscle Organization

Answer 6

Whole muscle (belly)
Muscle fascicle (bundle of m.fibers)
M.fibers (muscle cell)
Myofibril (sarcomeres in series)
Sarcomere (Z-disc to Z-disc)
Myofilament (actin and myosin)

Question 7

Sarcomere

Answer 7

Z line to Z line
Thin - actin
Thick - myosin

Question 8

Costamere

Answer 8

Attaches myofibril to sarcolemma

Comes off z-line and goes lateral to muscle line of pull, pulls on costamere then sarcolemma

Question 9

Costamere transmits which direction?

Answer 9

Lateral, parallel

There are different types of costameres (3)

Question 10

What happens if you get a disruption of one protein?

Answer 10

Can cause muscle problems in patients! Entire muscle can get scarred!

Question 11

Intermediate filaments

Answer 11

Around myofibrils and hold them in place

Question 12

Titan

Answer 12

Largest molecule of protein in muscle
PEVK domain - important
Helps keep the thick filament centered between 2 Z-lines during contraction, believed to control the # of myosin molecules contained in the thick filament

As sarcomere lengthens passive tension increases.

Question 13

What provides passive tension in muscles?

Answer 13

PEVK titan

Question 14

Titan

Answer 14

Large molecule that’s wound up (protein), expands and provides higher tension and contributes to force of muscle specifically eccentric of muscles.

Question 15

What combines to Troponin C for myosin to move and bind to actin? Tropomyosin to move and expose site.

Answer 15

4 Ca++

Question 16

Troponin T binds to

Answer 16

Tropomyosin

Question 17

Troponin I binds to

Answer 17

G-actin

Question 18

ATPase is responsible for

Answer 18

Breaking down ATP

Question 19

Why are there lots of actin surrounding myosin?

Answer 19

So when it opens it can easily attach

Question 20

M line

Answer 20

Strength & integrity of muscle fiber
Stabilizes thick-filament lattice
Thicker in Type 1 - high fatigue resistance, faster contracting, postural, holds up longer overtime, slow oxidative)

Question 21

What creates an AP in motor neuron?

Answer 21

Alpha-neuron

Question 22

What does Ca++ do for muscle contraction?

Answer 22

Binds to troponin C and get action…

The opening of Ca++ channels causes vesicles emptying of ACh into synaptic cleft

Question 23

What causes the diffusion of post-synapse and combines w ACh receptor R?

Answer 23

Na+ and K+ permeability, depolarization of muscle cells

Question 24

THe DHP channel is connected to what receptor in the SR that causes Ca++?

Answer 24

Ryanodine

Question 25

The reason for lack of production in muscle

Answer 25

Disruption in DHP/Ryanodine receptors, reduced number of junctions in older adults.

Question 26

E-C coupling

Answer 26

Conversion of electrochemical energy into mechanical energy

Question 27

Men and women both produce 4-6pM on one myosin head. T/F

Answer 27

True

Question 28

What is the one difference men vs women at the molecular level?

Answer 28

Testosterone levels

Question 29

What makes a triad?

Answer 29

T-tubule lined by two sarcoplasmic reticula

Question 30

Too much Ca++ released can cause

Answer 30

Twitch and tetanic tension | Too much can have muscle damage

Question 31

Once ca gets in how fast does Ca need to get removed?

Answer 31

Fast! Back into SR. Calmodulin Parvalbumin Calquestrin Can lead to fatigue/cramping if Ca++ doesn't get back to SR fast enough

Question 32

ATP is needed for

Answer 32

Myosin and actin release

Question 33

Winding Filament

Answer 33

Titan involved in twists at end of actin for shortening and passive tension

Question 34

Optimal length of sarcomere

Answer 34

2.0-2.2 micrometers!

Question 35

Too much overlap or not enough overlap causes lost of force production. T/F

Answer 35

True