Skeletal Muscle Contraction

Question 0

This is made up of multiple fascicles…

Answer 0

Muscle

Question 1

What is the Epimysium?

Answer 1

Connective tissue surrounding the entire muscle

Question 2

Perimysium

Answer 2

Connective tissue surrounding individual fascicle

Question 3

What is a fascicle?

Answer 3

A bundle of myofibers

Question 4

The delicate connective tissue surrounding each myofiber

Answer 4

Endomysium

Question 5

What is the sarcolemma?

Answer 5

Cell membrane of muscle fiber

Question 6

What is the myofiber?

Answer 6

Individual multinucleated muscle cell

Question 7

A chain of sarcomere within a myofiber is?…

Answer 7

Myofibril

Question 8

What is a Myofilament?

Answer 8

Actin and myosin filaments that make up a sarcomere

Question 9

Invaginations of the sarcolemma, two per sarcomere, lie close to the cisternae of sarcoplasmic reticulum, and form triads with cisternae. I am?…

Answer 9

the T-tubules

Question 10

Located at each end of the sarcomere that anchor actin filaments

Answer 10

Z discs

Question 11

Composed entirely of actin and width changes during contraction

Answer 11

I-band

Question 12

Composed of actin and myosin and the width does Not change during contraction

Answer 12

A-band

Question 13

Composed entirely of myosin and width changes during contraction

Answer 13

H-band

Question 14

Characteristic of skeletal muscle, sarcomeres are aligned to produce what?

Answer 14

A banding pattern

Question 15

Excitation coupling of the muscle include which events?

Answer 15

1) action potential causing release of calcium ions

2) reuptake of calcium ions in repolarization

Question 16

Voltage sensitive L type calcium channels arranged in quadruplets

Answer 16

Dihydropyridine receptors (DHP)

Question 17

Causes a conformational change in the ryanodine receptor

Answer 17

DHP receptor

Question 18

DHP receptors are located where?

Answer 18

Sarcolemma T-tubules

Question 19

Opens in response to a conformational change by the DHP receptor

Answer 19

Ryanodine receptor

Question 20

Ryanodine receptors are located?…

Answer 20

On the terminal cisternae of the sarcoplasmic reticulum

Question 21

Ryanodine receptors release which ion into the cytosol from the SR?

Answer 21

Calcium

Question 22

T/F is ATP required to pump calcium back into the SR?

Answer 22

True, using the SR calcium ATPase.

Question 23

Which protein maintains an optimum concentration of Calcium in the SR?

Answer 23

Calsequestrin

Question 24

What are the three uses of ATP required for muscle contraction?

Answer 24

* pump calcium back into the Sarcoplasmic reticulum * pump sodium and potassium through the sarcolemma to reestablish resting potential * used for the sliding filament mechanism

Question 25

What is the concentration of ATP in a muscle fiber?

Answer 25

~4mmol, enough to maintain contraction for 1-2 seconds

Question 26

There are three energies of rephosphorylation. What are they?

Answer 26

Oxidative metabolism Glycolysis Phosphocreatine

Question 27

Provides energy for ~ 95% of all energy needed for long term contraction

Answer 27

Oxidative metabolism

Question 28

Causes a lactic acid build up and can sustain contraction for up to 1min.

Answer 28

Glycolysis

Question 29

Rapid release of energy using ATP to provide enough energy for 5-8 seconds of contraction

Answer 29

Phosphocreatine

Question 30

What are the two types of muscle contractions?

Answer 30

Isometric and isotonic

Question 31

When does isometric contraction occur?

Answer 31

When there is an increase in tension but not in length. Ex: pushing against a brick wall

Question 32

In isotonic contraction, the muscle length changes. What are the two definitions to describe this type?

Answer 32

Eccentric-occurs when muscle lengthens Concentric- occurs when muscle shortens

Question 33

Fiber types are classified mainly on?...

Answer 33

Endurance (resistance to fatigue) and speed of contraction

Question 34

What are the two types of fibers?

Answer 34

Dark, slow fibers (red) Light, fast fibers (white)

Question 35

Myofiber types are determined by?

Answer 35

The innervating neuron

Question 36

Contract rapidly, less endurance, fewer mitochondria, uses primarily anaerobic respiration, larger concentration of ATPases, little myoglobin

Answer 36

Fast twitch fibers

Question 37

Contract slowly, more endurance, aerobic respiration, more mitochondria, less concentration of ATPase, more myoglobin

Answer 37

Slow twitch fibers

Question 38

Lost muscle tissue is replaced by?

Answer 38

Scar tissue (fibrous connective)

Question 39

Some muscles are almost entirely of one fiber type. | Soleus muscle is predominately? Gastrocnemius muscle is predominately?

Answer 39

Dark. Light

Question 40

A neuron and the myofibers it innervates constitutes?...

Answer 40

A motor unit.

Question 41

T/F all or none response refers to a motor unit.

Answer 41

True

Question 42

Describe tetany?

Answer 42

The frequency of spikes is fast enough in which there is no time for relaxation. The muscle remains at maximal contraction

Question 43

When electrical events occur faster than mechanical events. Additional spike can occur before previous Ca ions have been returned to the SR

Answer 43

Summation

Question 44

This electrical event increases the total amt of Ca ions in the cytosol and increases the rate of cycling between the myosin and actin cross bridges thereby increasing muscle tension.

Answer 44

Summation

Question 45

Lever systems are classified according to position of the fulcrum in relation to the in-force and the out-force. What is the first class? There are three total. Give an example

Answer 45

Fulcrum is in middle. In and out forces move in opposite directions. Ex. Raising your chin using sternocleidomastoid or similar muscles. Fulcrum= atlas/axis complex.

Question 46

What is the second class lever system?

Answer 46

Resistance (out force) is in the middle In and out force is on the same side of the fulcrum Ex: raising the body on the ball of the foot Fulcrum: ball of foot

Question 47

Third class lever system?

Answer 47

Effort (in force) is in the middle In and out force in on the same side of the fulcrum Both forces move in the same direction Ex: lifting a weight in the palm of your hand