Histology

Question 1

Skeletal Muscles

Answer 1

Striated
Multinucleated (peripheral)
large cells

Question 2

Myofiber

Answer 2

muscle cell

made up of myofibrils which is a chain of sacromere linked together

Question 3

Myofibril

Answer 3

Chain of sarcomeres

Question 4

Sarcromere

Answer 4

contractile unit made up of actin and myosin

Question 5

Fascicle

Answer 5

group of myofibers surrounded by perimysium

Question 6

Muscle

Answer 6

group of fascicles which is surrounded by epimysium

Question 7

Myosin

Answer 7

Thick filaments
2 heavy chains with globular heads
-actin binding site with ATPase domains
2 light chains
Titin connects proteins to Z-disk

Question 8

Actin

Answer 8

Thin filaments
made of F-actin monomers
monomers bind forming double stranded chains
Nebulin determines length
Tropomyosin strands wrap between actin filament
Troponin sits on tropomyosin to cover myosin binding sites on actin

Question 9

Nebulin

Answer 9

determines the length of actin filament

Question 10

Tropomyosin

Answer 10

part of actin

strands wrap between actin strands

Question 11

Troponin

Answer 11

part of actin

sits on tropomyosin strands and covers myosin binding site on actin filaments

Question 12

M-line

Answer 12

attachment site for myosin

middle part of sarcomere

Question 13

Z-disk

Answer 13

separates sarcomeres

attachment site for actin and titin

Question 14

H-band

Answer 14

space on either side of M-line where there is no actin

Question 15

A-band

Answer 15

distance from the end of one myosin head to the headof the opposite myosin
-overlap of actin and myosin with H band

Question 16

I-band

Answer 16

space on either side of the Z-disk where there is no myosin

Question 17

Muscle Contraction

Answer 17

bind actin to myosin

• Troponin blocks the myosin binding sites on actin
• Ca released from the SR binds troponin to cause a conformational change
• -makes the actin binding sites accessible to myosin head
• Thin filaments slide past thick
• Z disks are brought closer together
• actin and myosin don’t change in lenght

Question 18

Type 1 Muscle Fiber

Answer 18

slow less powerful contraction
many mitochondria
abundant myoglobin
slow fatiguability

Question 19

Type 2 Muscle Fiber (A and B)

Answer 19

Fast/Powerful contraction
Fewer mitochondria
few myoglobin 
Rapid fatiguability 
*Type 2 B is fewer mitochondria/myoglobin

Question 20

Sarcolemma

Answer 20

membrane around each muscle cell

Question 21

Transverse (T) tubules

Answer 21

membrane system penetrating the muscle cell to convey electrical impulses from sarcolemma into cell
-get Ca deep into cells

Question 22

Sarcoplasm

Answer 22

cytoplasm of muscle cell

Question 23

Sarcoplasmic Reticulum

Answer 23

tubular system acting like smooth-ER

-Terminal Cisternae

Question 24

Terminal Cisternae

Answer 24

flattened sac of SR on either side of a transverse t-tubule to house Ca

Question 25

Triad

Answer 25

T-tuble+2 terminal cisternae (1 on either side)

Question 26

End feet

Answer 26

connect T-tubules with SR to allow Ca release

Question 27

Innervation of Skeletal Muscles

Answer 27

peripheral alpha motor neuron from anterior horn of spinal cord

Question 28

Neuromuscular Spindle Apparatus

Answer 28

reflexive response to prevent over-stretching of muscle - extrafusal muscle fibers - intrafusal muscle fibers - Type 1a sensory fibers - a-motor nerves - g-motor nerves

Question 29

Extrafusal Muscle fibers

Answer 29

responsible for contraction of a muscle

Question 30

Intrafusal muscle fibers

Answer 30

sense length and rate of change of muscle