Lecture 5

Question 1

What is an epimysium?

Answer 1

Connective tissue surrounding entire muscle

Question 2

What is a muscle made up of?

Answer 2

Multiple fascicles

Question 3

What is a perimysium?

Answer 3

Connective tissue surrounding individual fascicle

Question 4

What is a fascicle made of?

Answer 4

Bundle of myofibers

Question 5

What is an endomysium?

Answer 5

Delicate connective tissue around each myofiber

Question 6

What is the sarcolemma?

Answer 6

Cell membrane of muscle fiber

Question 7

What is the myofiber made of?

Answer 7

individual multinucleated muscle cells.

Question 8

What is a myofibril made of?

Answer 8

A chain of sarcomeres within a myofiber

Question 9

What is a myofilament made of?

Answer 9

Actin and myosin filaments that make up a sarcomere

Question 10

Sarcolemma = ?

Answer 10

plasmalemma

Question 11

What are the characteristics of Z discs

Answer 11

anchor actin filaments, located at each end of sarcomere

Question 12

What are the characteristics of I bands?

Answer 12

composed entirely of actin, width changes during contraction

Question 13

What are the characteristics of A band?

Answer 13

Composed of actin and myosin, width does not change during contraction

Question 14

What are the characteristics of H band?

Answer 14

composed entirely of myosin, width changes during contraction

Question 15

What does SERCA use and do?

Answer 15

Uses ATP to pump calcium back into the SR

Question 16

What does calsequestrin do?

Answer 16

a. in the SR maintains an optimum calcium concentration gradient to facilitate return of calcium to SR.
i. Rounds up calcium ions so they don’t contribute too much calcium allowing SERCA not to work too hard.

Question 17

What is DHP, where is it located and what does it do?

Answer 17

DHP= Dihydropyridine receptors.

i. Voltage sensitive L-type calcium channels arranged in quadruplets
ii. Located on the sarcolemma T-tubules
iii. Cause a conformational change in ryanodine receptors

Question 18

What are Ryanodine receptors, where are they located and what does it do?

Answer 18

i. Located on the cisternae of the sarcoplasmic reticulum

ii. Open in response to conformational change in DHP receptors allowing calcium into the cytosol from SR

Question 19

What is preload?

Answer 19

Load on a muscle in the relaxed state (before it contracts)

Question 20

The greater the preload the ____ the passive tension

Answer 20

greater

Question 21

What is afterload?

Answer 21

Load the muscle works against

Question 22

If the muscle generates more force than the afterload, an ____ contraction occurs.

Answer 22

Isotonic

Question 23

If the muscle generates less force than the afterload, an ____ contraction occurs?

Answer 23

isometric

Question 24

What is cross bridge cycling?

Answer 24

When myosin heads attach to filaments.

Question 25

When does cross bridge cycling start?

Answer 25

When free calcium is available and attaches to troponin

Question 26

ATP is not requires to form the cross-bridge linking to actin but is required for what?

Answer 26

Required to break the link with actin

Question 27

Cross-bridge cycling continues until when?

Answer 27

Withdrawal of calcium ion, ATP is depleted.

Question 28

Where is ATP required for muscle contraction?

Answer 28

Most used in the sliding filament mechanism

Question 29

What does phosphocreatine do?

Answer 29

Releases energy rapidly, reconstitutes ATP.

Question 30

Glycolysis in muscle contraction is what?

Answer 30

lactic acid build up

Question 31

Who can sustain contraction the longest?

Answer 31

Glycolysis

Question 32

What provides more than 95% of all energy needed for long term contraction?

Answer 32

Oxidative metabolism

Question 33

What is an isometric contraction?

Answer 33

When there is an increase in tension but not in length

Question 34

What is an isotonic contraction?

Answer 34

muscle length changes

Question 35

What is eccentric contraction? Give an example

Answer 35

Occurs when muscle lengthens. Ex; Hanging down from a pull up bar

Question 36

What is a concentric contraction? Give an example

Answer 36

Occurs when the muscle shortens. Ex; holding yourself up on the pull up bar

Question 37

How is the myofiber type determined?

Answer 37

By the innervating neuron

Question 38

What are the characteristics of light fibers?

Answer 38

* Fast twitch * Less endurance * Fewer mitochondria * Anaerobic respiration * buildup of pyruvic and lactic acids * Little myoglobin * Larger concentration of ATPase

Question 39

What are the characteristics of dark fibers?

Answer 39

* Slow twitch * More endurance * Mitochondria * Aerobic * Myoglobin * smaller concentration of ATPase

Question 40

What type of muscle is predominantly composed of dark fibers?

Answer 40

Soleus

Question 41

What type of muscle is predominantly composed of light fibers?

Answer 41

Gastrocnemius

Question 42

A neuron and the myofibers it innervates constitutes what?

Answer 42

A motor unit

Question 43

All-or-none really refers to what?

Answer 43

a motor unit

Question 44

What is tetany?

Answer 44

Frequency of spikes is fast enough, there is no time for relaxation between spikes and muscle remains at maximal contraction.

Question 45

In relation to muscles as levers, what is in the "middle" of first class?

Answer 45

Fulcrum is in the middle

Question 46

In relation to muscles as levers, what is in the "middle" of Second class?

Answer 46

Resistance (out-force) is in the middle

Question 47

In relation to muscles as levers, what is in the "middle" of third class?

Answer 47

Effort (in-force) is in the middle

Question 48

What is the in-force and out-force relation in first class and give an example.

Answer 48

In-force and out-force move in opposite directions | Example: Raising chin, or the see-saw

Question 49

What is the in-force and out-force relation in second class and give an example.

Answer 49

Both in and out forces are on the same side of the fulcrum. | Example: Raising the body on the ball of the foot.

Question 50

What is the in-force and out-force relation in third class and give an example.

Answer 50

Both in and out forces are on the same side of the fulcrum, both forces move in the same direction. Example: Lifting a weight in the palm of your hand