Muscle

Question 1

sarcoplasmic reticulum AKA

Answer 1

Smooth ER

Question 2

skeletal muscle is derived from

Answer 2

mesenchyme

Question 3

myofibril

Answer 3

aligned protein structures made of thick and thin myofilaments

Question 4

thick filaments are made of

Answer 4

myosin, heavy and light

Question 5

thin myofilaments are made of

Answer 5

actin (filamentous or globular), troponin, tropomyosin

Question 6

A-band and I-band stand for

Answer 6

anisotropic and isotropic, referring to how they refract polarized light. A-bands are dark because they refract different planes of polarized light differently.

Question 7

the sarcomere is bounded by

Answer 7

two z-lines

Question 8

the z-line bisects the ___ and is attachment point of ___ filaments

Answer 8

i-band, thin (actin)

Question 9

M-line

Answer 9

cross-links centers of thick filaments

Question 10

h-zone

Answer 10

lightest area within the A-band, where thick and thin filaments don’t overlap

Question 11

during muscle contraction, the ____ filaments are pulled to the ___ band, causing the width of the ____, ___, and ___ to decrease

Answer 11

thing, I, H and sarcomere

Question 12

sarcolemma

Answer 12

plasmalemma, outer membrane of skeletal muscle fiber, with invaginations called T (transverse) tubules)

Question 13

T tubules

Answer 13

tranverse tubules. contain extracellular fluid and bring AP into muscle fiber.

Question 14

SR

Answer 14

sarcoplasmic reticulum, smooth ER, sleeve around myofibril.

Question 15

terminal cisternae

Answer 15

flank T tubules at A-I junctions in skeletal muscle

Question 16

triad

Answer 16

t-tubule, terminal cisternae,

Question 17

t-tubules are located at the ___

Answer 17

z-line

Question 18

how many triads are found in cardiac and skeletal muscle?

Answer 18

2 in skeletal

1 in cardiac

Question 19

how many nuclei do skeletal and smooth muscle have?

Answer 19

skeletal - multinucleated

smooth - uninucleated

Question 20

what are two other cytoplasmic components found in myofibrils

Answer 20

glycogen granules and mitochondria

Question 21

three fiber types

Answer 21

red, white, intermediate

Question 22

three characteristics of red fibers

Answer 22

slow contracting
darker in color (more mitochondria)
fatigue resistant

Question 23

myosatellite cells

Answer 23

?

Question 24

hyperplasia vs. hypertrophy

Answer 24

fusion of cells (dividing)

hypertrophy is increased size, not cell #

Question 25

motor unit

Answer 25

motor neuron + all of it’s muscle fibers (fewer fibers = more precise control)

Question 26

motor end plate AKA

Answer 26

neuromuscular junction

Question 27

motor end plate definition

Answer 27

wher neurons synapse with muscle fibers.

Question 28

junctional folds

Answer 28

at NMJ, sarcolemma is more foled, increasing area of synaptic cleft

Question 29

each muscle fiber is innervated by how many motor neurons?

Answer 29

1

Question 30

what are two components of muscle cells that make them specialized for integrated motion?

Answer 30

contractility and conductivity

Question 31

muscle cells stain ____. why?

Answer 31

acidophilically, due to abundance of actin/myosin proteins

Question 32

what is a muscle spindle? how are they arranged?

Answer 32

receptors that sense the length and degree of stretch in a muscle.
arranged in parallel with muscle fibers

Question 33

what is the composition of a muscle spindle?

Answer 33

intrafusal muscle fiers, fluid space, and capsule

Question 34

what are intrafusal fibers? what are the two types? what do these names refer to?

Answer 34

small muscle fibers in muscle spindles?

nuclear bag (larger) 
nuclear chain (smaller)
the names refer to the arrangement of nuclei, clustered or distributed along fiber

Question 35

what is the smallest muscle type?

Answer 35

smooth. 20-500um in length, 10-50umn in diameter

Question 36

what is the nucleus of a smooth muscle cell like?

Answer 36

leptochromatic, fusiform, centrally located.

Question 37

the cytoplasm of smooth muscle cells stain ____

Answer 37

acidophilically

Question 38

what is endomysium?

Answer 38

CT around (smooth?) muscle cells

Question 39

can you regenerate smooth muscle?

Answer 39

no, replaced with scar tissue except uterus.

Question 40

the sarcolemma of smooth muscles have special vesicles called ____. what do they do?

Answer 40

caveolae release Ca2+ and initiate contraction by activating myosin light chain kinase that phosphorylates myosin, activating it. these show up as studs on EM

Question 41

dense bodies

Answer 41

in smooth muscle cytoplams (sarcoplasm) and along plasmolemma, these are dark patches which intermediate and myosin filaments attach.