Skeletal Muscle

Question 1

sarcolemma

Answer 1

cell membrane

Question 2

sarcomere

Answer 2

functional unit of muscle

Question 3

sarcoplasmic reticulum

Answer 3

internal tubular structure where Ca++ is stored and released for excitation-contraction coupling

Question 4

T tubules

Answer 4

carry electrical information deep into the cell

Question 5

muscle fiber

Answer 5

basically a muscle cell

Question 6

myofibril

Answer 6

bundles found in muscle fibers

Question 7

titin

Answer 7

spring like projection

Question 8

dystrophin

Answer 8

large protein that forms a rod that connects the thin actin filaments to a transmembrane protein

Question 9

ryanodine receptor

Answer 9

Ca++ release channel in the Ca++ATPase pump

Question 10

DHP receptors

Answer 10

voltage-senstive protein that has a conformational change when depolarized

Question 11

Actin filament

Answer 11

anchored a Z liens

present in I bands

Question 12

What does the actin filament contain

Answer 12

actin, tropomyosin, and troponin

Question 13

Myosin filament

Answer 13

present in the A band in the center of the sarcomere
has 6 polypeptide chains, 1 pair of heavy chains, and 2 pairs of light chains
each molecule has 2 heads attached to 1 tail

Question 14

What does the myosin filament contain

Answer 14

myosin

Question 15

Sliding filament theory

Answer 15

The thin and thick filaments are sliding over each other. When it’s fully contracted, there is an opposite actin to every myosin head.

Question 16

ATP in muscle contraction

Answer 16

ATP binds to myosin head, reducing it’s affinity for actin. It breaks down into ADP and Pi, causing the myosin head to go into the “cocked” position. After Ca++ binds to troponin C, the myosin ADP-Pi complex binds to actin. Pi gets released and you get the power stroke. To complete the cycle ADP gets released, but remember it is stuck in the rigid state (actin and myosin are still bound!) In order to relax, another ATP has to come along and bind.

Question 17

role of Ca++ in skeletal muscle contraction

Answer 17

Ca++ binds to troponin C which exposes an active site on actin so myosin can bind. When you lose the Ca++, tropomyosin moves back, covers the active site again.

Question 18

role of Ca++ATPase pump

Answer 18

The Ca++ATPase pump transports Ca++ from intracellular fluid into the SR interior, which keeps intracellular Ca++ low.

Question 19

role of calsequestrin

Answer 19

Ca++ is loosely bound to calsequestrin

Question 20

Phosphocreatine and creatine kinase

Answer 20

re-phosphorylates ADP to ATP using a high energy bond from phosphocreatine

Question 21

glycogen

Answer 21

can be metabolized to pyruvate with rapid production of ATP

Question 22

What type of motor units are in muscles that need fine control

Answer 22

very small (few muscle cells)

Question 23

What type of motor units are in muscles that do not need fine control

Answer 23

very large motor units

Question 24

How to produce graded muscle contraction

Answer 24

1. Increase the number of motor units contracting at any one time - multiple motor unit summation.
2. Increase the rate of stimulation of a single motor unit.

Question 25

Function of Dystrophin-Glycoprotein Complex

Answer 25

The complex adds strength to muscles partially by connecting fibrils to extracellular matrix.

Question 26

Duchenne muscular dystrophy

Answer 26

severe reduction in dystrophin in skeletal and cardiac muscle, X-linked recessive inheritance, usually fatal by 30 years of age

Question 27

Becker muscular dystrophy

Answer 27

less severe disease since functional dystrophin present but altered or reduced in amount

Question 28

Limb-girdle dystrophies

Answer 28

many different types associated with mutations of genes coding for other components of the dystrophin-glycoprotein complex and other muscle proteins

Question 29

Isometric contraction

Answer 29

muscle does not shorten during contraction

Question 30

Isotonic contraction

Answer 30

muscle does shorten during a contraction, but the tension on the muscle remains the same

Question 31

are individual muscle fibers connected by gap junctions/electrical synpases of skeletal muscle

Answer 31

no

Question 32

myofibrils

Answer 32

cylindrical structure ade up of an end-to-end chain of repeating unit, the sarcomeres

Question 33

what does sarcoplasm contain

Answer 33

mitochondira, nuclei, and ER

Question 34

sarcolemma

Answer 34

cell membrane of the muscle fiber

Question 35

what are the 2 components of the sarcolemma

Answer 35

plasma membrane | transverse tubules

Question 36

transverse tubules

Answer 36

extesnions of cell membrane

Question 37

what does the lumen of T tubules contain

Answer 37

extracellular fluid