Histo - 6 Muscular Tissue

Front 1

strong, quick, discontinuous voluntary contraction is the activity of which type of muscle?

Back 1

skeletal muscle

Front 2

activity of cardiac muscle

Back 2

strong, quick continuous involuntary contraction

Front 3

which muscle type has weak, slow involuntary contraction

Back 3

smooth muscle

Front 4

skeletal muscle CELLS are referred to as

Back 4

fibers

Front 5

general appearance of skeletal muscle cells

Back 5

roughly cylindrical, elongate and multinucleate ("syncitium")

Front 6

loose CT surrounding the entire muscle, also called fascia

Back 6

epimysium

Front 7

CT which divides the muscle into smaller functional units called muscle fascicles

Back 7

perimysium

Front 8

CT which divides the muscle fascicles into individual muscle fibers

Back 8

endomysium

Front 9

a bundle of several muscle fibers is called

Back 9

fascicle

Front 10

fascicles are surrounded by

Back 10

perimysium

Front 11

principle cytoplasmic component of the muscle fiber

Back 11

myofibrils

Front 12

myofibrils are composed of serially repeating segments of identical structures known as

Back 12

sarcomeres

Front 13

myofibrils are composed of what two myofilaments?

Back 13

actin and myosin

Front 14

arrangement/orientation of myosin filaments

Back 14

antiparallel

Front 15

myosin filaments are held down at which part of the sarcomere?

Back 15

M-line

Front 16

A band

Back 16

dark band

Front 17

I band

Back 17

light band

Front 18

Z-line

Back 18

bisect the pale I bands

Front 19

H band

Back 19

central zone w/in the A band

Front 20

M line

Back 20

marks the center of the H band

Front 21

what binds myosin at the M line?

Back 21

myomesin

Front 22

what is the functional unit of the myofibril?

Back 22

sarcomere

Front 23

what are the limits of the sarcomere?

Back 23

Z line

Front 24

cell membrane of a muscle fiber

Back 24

sarcolemma

Front 25

cytoplasm of a muscle fiber

Back 25

sarcoplasm

Front 26

principal role of the sarcoplasmic reticulum

Back 26

sequester calcium

Front 27

where are the thousands of nuclei in a skeletal muscle fiber located?

Back 27

in the periphery of the fiber beneath the sarcolemma

Front 28

what is the function of glycogen in muscle contraction?

Back 28

energy store that is mobilized during contraction

Front 29

where do the invaginations of the T-tubule system occur in skeletal muscle?

Back 29

at the level of transition between the A and I bands twice in every sarcomere

Front 30

in skeletal muscle, the association of the T-tubules with the terminal cisternae of the SR form what?

Back 30

triads

Front 31

what surrounds the sarcolemma in skeletal muscle?

Back 31

basal lamina and reticular fibers

Front 32

cells that are located w/in the basal lamina which can divide and contribute new muscle fiber in response to minor injury

Back 32

satellite cells

Front 33

function of satellite cells

Back 33

they divide and contribute to new muscle fiber following an injury that leaves the basal lamina and satellite cells intact

Front 34

what replaces large deficits in skeletal muscle?

Back 34

noncontractile connective tissue

Front 35

where does the connection between depolarization and muscle contraction occur in skeletal muscle?

Back 35

at the triad

Front 36

components of a triad

Back 36

T-tubule and 2 terminal cisterns

Front 37

how does a depolarization of a skeletal muscle fiber lead to contraction?

Back 37

depolarization
SR releases Ca ions sequestered in the terminal cisternae into the sarcoplasm
Ca ion release allows actin and myosin to interact
sarcomeres shorten and muscle contracts

Front 38

binding of actin and myosin that becomes stabilized when ATP is not available

Back 38

rigor mortis

Front 39

how many motor end plates does each skeletal muscle fiber have?

Back 39

one

Front 40

one nerve may innervate a hundred muscle fibers in what type of skeletal muscle?

Back 40

postural

Front 41

one nerve may innervate as few as three muscle fibers in what type of skeletal muscle?

Back 41

ocular or digital muscles

Front 42

where the muscle fiber sarcolemma expands at the neuromuscular junction

Back 42

junctional folds

Front 43

autoimmune disease where antibodies directed against Ach receptors on the sarcolemma result in fewer Ach receptors available for binding of Ach released from motor neuron
results in weaker muscle contraction

Back 43

myesthenia gravis

Front 44

type of muscle that contracts spontaneously, rhythmically and continuously

Back 44

cardiac muscle

Front 45

where does cardiac muscle exist?

Back 45

in myocardium of the heart and proximal portions of the aorta and vena cava

Front 46

how many nuclei does a cardiac muscle cell have?

Back 46

1 or 2 central nuclei

Front 47

what lines each cardiac cell?

Back 47

external (basal) lamina

Front 48

poles of the cardiac cell nucleus
where mitochondria and glycogen are commonly located

Back 48

sarcoplasmic cone

Front 49

what enables myocardium to "wring out" blood from the chambers of the heart?

Back 49

the arrangement of cardiac muscle in a whorled pattern

Front 50

how are cardiac cells joined?

Back 50

intercalated disks

Front 51

specialized junctional complexes that appear as dark transverse lines between cardiac muscle fibers

Back 51

intercalated disks

Front 52

anchoring sites for the cardiac sarcomere nearest the end of the cells

Back 52

fascia adherens (transverse region only)

Front 53

bind cardiac cells to prevent separation during contraction

Back 53

macula adherens/desmosome (in both transverse and lateral components)

Front 54

provide direct electrotonic communications between cardiac cells

Back 54

gap junctions

Front 55

passes the stimulus for cardiac contraction from cell to cell

Back 55

gap junctions

Front 56

what are the 5 differences between cardiac and skeletal muscle?

Back 56

1. cardiac muscle has larger T-tubules
2. SR of cardiac muscle is poorly developed
3. cardiac cell T-tubule systems form dyads, not triads
4. dyads are located at Z lines in cardiac and at the A-I junction in skeletal
5. cardiac muscle has more and bigger mitochondria

Front 57

what is the function of the nervous innervation of cardiac muscle?

Back 57

to speed up or slow down the intrinsic beat

Front 58

where do the sympathetic and parasympathetic nervous system branches terminate in cardiac muscle?

Back 58

NEAR, not on, the muscle cells

Front 59

what initiates the stimulus for contraction in cardiac muscle?

Back 59

sinoatrial node

Front 60

how do purkinje fibers communicate with the cardiac muscle cells?

Back 60

via gap junctions

Front 61

how do purkinje fibers differ from cardiac muscle cells?

Back 61

they are larger, have more gap junctions, lower myofibril content, and higher glycogen content

Front 62

hypertrophy

Back 62

enlargement of muscle fibers

Front 63

smooth muscle is prominent in the walls of what 2 systems?

Back 63

respiratory and GI

Front 64

how does the speed of contraction of smooth muscle compare with skeletal?

Back 64

smooth contracts ~10x slower

Front 65

smooth muscle can contract up to how much of their length?

Back 65

75%

Front 66

spindle shaped cell with a single centrally located nucleus and an eosinophilic cytoplasm

Back 66

smooth muscle cell

Front 67

where are cytoplasmic organelles generally located in smooth muscle cells?

Back 67

the conical regions at the ends of the centrally located nuclei

Front 68

most of the sarcoplasm of smooth muscle is occupied by thin actin filaments which insert into what?

Back 68

dense bodies

Front 69

location of dense plaques

Back 69

dispersed in cytoplasm or associated with cell membrane

Front 70

dense bodies are equivalent to what of striated muscle?

Back 70

Z lines

Front 71

What are the 4 ways that the smooth muscle contractile apparatus differs from skeletal?

Back 71

1. thick and thin filaments are not arranged in sarcomeres
2. actin and intermediate filaments insert into dense bodies
3. dense bodies are connected to actin and myosin filaments
4. during contraction, actin pulls dense bodies forming a corkscrew-shaped nucleus

Front 72

which of the 3 types of muscle is capable of undergoing mitosis in response to injury?

Back 72

smooth muscle

Front 73

how do the uterus muscle fibers respond to hormones during pregnancy?

Back 73

increase in number (hyperplasia) and size (hypertrophy)

Front 74

new smooth muscle cells can arise from what?

Back 74

undifferentiated mesenchymal cells present among differentiated ones

Front 75

cells in the walls of small blood vessels that are capable of differentiating into smooth muscle cells for growing blood vessels

Back 75

pericytes

Front 76

which part of the sarcomere decreases in width during contraction?

Back 76

I band

Front 77

does the A band width change during skeletal muscle contraction?

Back 77

no

Front 78

what activates calcium-gated channels on the sarcoplasmic reticulum?

Back 78

voltage sensor proteins in membrane of T-tubules

Front 79

contraction of smooth muscle is stimulated by what?

Back 79

endocytosis of calcium vesicles

Front 80

what happens when calcium is brought into smooth muscle cell?

Back 80

calcium binds to calmodulin which leads to myosin phosphorylation