Histology: Muscle Cells

Front 1

Describe smooth muscle.

Back 1

Smooth muscle fibers are small spindles that lack visible striations and have elongated nuclei which lie in the center of the cell. They show slow and sustained contractions and are spontaneous with involuntary control

Front 2

Describe striated muscle.

Back 2

Skeletal muscle fibers form large individual strips and are strongly cross striated. The nuclei is found at the periphery of the cell and is round or oval. Striated muscle have strong and rapid, voluntary control

Front 3

Describe cardiac muscle

Back 3

Cardiac muscle fibers are weakly striated, possess intercalated disks and their elongated nuclei are in the center of cell.

Front 4

describe smooth muscle in detail

Back 4

collection of spindle shaped cells with contractile proteins- organization not visible in light microscope. has special basement membrane (matrix) around each cell that is molecularly attached around and connected to other cells. indiv cells, but act as syncitium, contraction via gap junction. Rich symp/parasymp innervation. act antag to enhance or inhibit contraction

Front 5

What is mytenric plexus?

Back 5

plexus of nerve cells lying between 2 muscle cell layers

Front 6

what does smooth muscle cell look like?

Back 6

torpedo shaped individual nucleus. surrounding by matrix and connective tissue. nuclei looks larger than in fibroblast

Front 7

describe contraction of smooth muscle

Back 7

smooth muscle cells twist up when contracting and nucleus twists up.

Front 8

can smooth muscle proliferate?

Back 8

yes- endometrium in pregnancy, sometimes not good, like in vascular and respiratory disease

Front 9

hypertrophy of muscle cells

Back 9

increase in cell size

Front 10

What does sarcolemma refer to?

Back 10

cell membrane of muscle fiber

Front 11

What is sarcoplasm?

Back 11

cytoplasm of muscle fiber

Front 12

What is sarcoplasmic reticulum?

Back 12

ER of muscle fiber

Front 13

What is a syncitium?

Back 13

shares nucleus

Front 14

special features of skeletal muscle

Back 14

individual cells are multinucleated, syncitium, cytoplasm filled with filamentous bundles- myofibrils

Front 15

What is a sarcomere?

Back 15

whole unit of myofibril organization

Front 16

thick filaments vs thin

Back 16

thick are myosin, thin are actin
they overlap and on contraction the thin and thick filament ratchet closer to each other. in slide,

Front 17

m- line

Back 17

mid line where filaments are anchored

Front 18

what causes muscle contraction

Back 18

change in polarization and conformation change caused by Ca concentration. uses ATP, for thin sliding past thick thus sarcomere shortens. Size of thin filament are shortens.

Front 19

Transverse tubules

Back 19

invaginations of membranes that dip down perpendicular to long axis of fiber

Front 20

regulation of contraction

Back 20

actin and myosin interact from conformational change by Ca binding to troponin

Front 21

What causes depolarization

Back 21

neural stimulation causes influx of extracellular calcium ions into cell

Front 22

neural control of muscle contraction

Back 22

an axon from a motor neuron has a terminal bud or end plate near the sarcolemma of muscle fiber

Front 23

Release of acetycholine

Back 23

end plate has synaptic vesicle with this and under stimulation the synaptic vesicle exocytoses acetylcholine causing local depolarization that is propogated

Front 24

motor unit

Back 24

motor neuron axon and muscle fibers that innervates

Front 25

what causes atrophy?

Back 25

loss of motor neuron input, like polio

Front 26

endomysium

Back 26

delicate layer of connective tissue surrounding each muscle fiber

Front 27

perimysium

Back 27

connective tissue around a bundle of muscle fiber

Front 28

epimusium

Back 28

surrounds muscle bundle

Front 29

how does striated muscle contract

Back 29

epimysium blends with connective tissue of tendons and transduces the force generated by contraction of muscle fibers

Front 30

myoblasts

Back 30

striated muscle pre-cursors

Front 31

myotubes

Back 31

myoblasts that fuse to form small multinucleated fibers

Front 32

how does smooth muscle recover from injury since it is striated and is post-mitotic and does not divide

Back 32

normally resting satellite cells proliferate in response to stimuli, giving rise to myoblasts. these become new muscle fiber

Front 33

What are satellite cells?

Back 33

muscle stem cells

Front 34

cardiac muscle features

Back 34

made of muscle fibers
not a synctium, individual cells with discrete membranes, connect to each other
acts like synctium because attached to transduce force, gap junctions, desmosomes, basal lamina, no satellite cells so no regeneration

Front 35

myocytes

Back 35

fibers of individual cardiac muscle cells

Front 36

how does heart pump

Back 36

electrical signal sent thru attachments points

Front 37

what does cardiac muscle look like?

Back 37

fibers, individual nuclei (centrally placed in fiber), Hallmark is intercalated disk. looks like rope and may make branch

Front 38

Intercalated disk

Back 38

run across cardiac fiber with desmosomes and gap junctions, with proteins. place for sending signal

Front 39

fasicle

Back 39

bundle of muscle cell

Front 40

motor end plate

Back 40

the site of innervation, where the nerve loses its myelin sheath and forms a dilated termination that sits in a trough in the muscle cell surface

Front 41

acetylcholine

Back 41

chemical mediator present in synaptic vesicle of all pre-ganglionic endings and parasympathetic postganglionic endings

Front 42

Are you still awake?

Back 42

who me?