Anatomy Final Section 4

Front 1

myology

Back 1

the study of the muscular system

Front 2

what are the three kinds of muscle tissue?

Back 2

skeletal, smooth, and cardiacc

Front 3

what is the purpose of muscle tissue?

Back 3

to convert chemical energy in ATP to cellular energy

Front 4

what are some functions of muscles?

Back 4

movement, stability, control of opening and passagewats, heat production by skeletal muscles, glycemic control

Front 5

fascia

Back 5

connective tissue leading with bone

Front 6

epimysium

Back 6

the CT immediately surrounding muscles

Front 7

perimysium

Back 7

bundle/fascicles

Front 8

endomysium

Back 8

the muscle fibers that make up the bundle

Front 9

what are the muscle shapes?

Back 9

fusiform, parallel, triangular, unipennate, bipennate, multipennate, circular

Front 10

how are the strength of muscle and direction of its pull determined?

Back 10

by the orientation of its fascicles

Front 11

what are muscle compartments

Back 11

a group of functionally related muscles enclosed and separated from others by connective tissue fascia

Front 12

what are the 2 types of muscle attachments?

Back 12

1)indirect attachment to bone-tendons (aponeurosis, retinaculum-band of tendon-one on each side of wrist)
2) direct (fleshy) attachment to bone (in brachialis and triceps brachii)

Front 13

muscle origin

Back 13

bone that does not move when muscle contracts

Front 14

muscle belly

Back 14

fleshy part

Front 15

muscle insertion

Back 15

bone where muscle attaches and moves

Front 16

what are the 4 categories of muscles based on action/effect?

Back 16

1) prime mover/agonist-most of the force
2) synergist-helps facilitate prime mover
3) antagonist-opposite/against prime mover
4) fixator-prevents movement of bone

Front 17

what are all the muscles/actions involved in elbow flexion?

Back 17

prime mover-brachialis
synergist-biceps brachii
antagonist-triceps brachii
fixator-rhomboids major and minor-holds scapula firmly in place

Front 18

what is an intrinsic muscle?

Back 18

both originate and insert in the same place

Front 19

what is an extrinsic muscle?

Back 19

insert into one place and originate somewhere else

Front 20

spinal nerve plexus

Back 20

weblike network of spinal nerves adjacent to vertebral column

Front 21

from where do cranial nerves arise?

Back 21

the base of the brain

Front 22

neuromuscular juncton

Back 22

where the axon of a nerve meets a muscle (synapse or junction of the axon of a motor neuron with the motor end plate

Front 23

thoracic cavity shrinks during

Back 23

expiration

Front 24

thoracic cavity enlarges during

Back 24

inspiration

Front 25

hernia

Back 25

any condition in which the viscera protrude through a weak point in the muscular wall of the abdominopelvic cavity

Front 26

Inguinal hernia

Back 26

most common type-rare in women, viscera enter inguinal canal or even the scrotum

Front 27

Hiatal hernia

Back 27

stomach protrudes through diaphragm into thorax, found in overweight people over 40

Front 28

umbilical hernia

Back 28

viscera protrudes through the naval

Front 29

what are 5 universal characteristics of muscles

Back 29

1) responsiveness (excitability)
2) conductivity
3) contractibility
4) extensibility
5) elasticity

Front 30

striations

Back 30

alternating light and dark transverse bands

Front 31

muscle cell is the same thing as

Back 31

muscle fibers/myofibers

Front 32

sarcoplasm

Back 32

the cytoplasm of a muscle cell, contains myofibrils (bundles of protein), glycogen (storage form), and myoglobin (red pigment that carries oxygen in a muscle)

Front 33

a skeletal muscle fiber has

Back 33

multiple nuclei, myoblasts (stem cells that form muscle fibers), mitochondria, it has bundles of myofibril, the myofibril has bundle of myofilaments

Front 34

what does the extensive smooth ER of a muscle fiber do?

Back 34

serves as a reservoir for calcium

Front 35

sarcoplasmic reticulum

Back 35

smooth endoplasmic reticulum that forms a network around each myofibril

Front 36

terminal cisternae

Back 36

dilated end-sacs formed by SR that cross the muscle fiber from one side to the other (two of these surround a t tubule)

Front 37

transverse (t) tubules

Back 37

tubular infoldings of the sarcolemma that sits in between two terminal cisternae

Front 38

triad

Back 38

a t tubule and two terminal cisternae

Front 39

what are the three types of microfilaments

Back 39

1) thick filament
2) thin filament
3) elastic filament

Front 40

thick filament

Back 40

*15nm diameter
*made of a protein called myosin
*myosin molecule shaped like golf club, shaftlike tail and double globular head
*middle is the bare zone with no head

Front 41

thin filament

Back 41

*7nm diameter
*composed of two strands of protein called fibrous (F) actin
*F actin is like bead necklace-string of subunits called globular (G) actin)
*each G actin has active sit
*thin filament has 40-60 molecules of protein tropomysin
*tropomysin molecule has troponin-smaller calcium-binding protein

Front 42

elastic filament

Back 42

*1nm in diameter
*made of titin (connectin)-huge springy protein
*anchor thick filaments to Z disc

Front 43

contractile proteins

Back 43

myosin and actin-shorten the muscle fiber

Front 44

regulatory proteins

Back 44

tropomysin and troponin-act like a switch to determine when fiber can and cannot contract

Front 45

accessory proteins

Back 45

anchor myofilaments, regulate length, keep them aligned for contractile effectiveness

Front 46

what is the process of muscle contraction involving regulatory proteins?

Back 46

*calcium ions released into sarcoplasm to activate contractioncalcium binds to troponintroponin is bound to tropomysintropomysin blocks active actinmyosin cannot bind to it when the muscle is not stimulated

Front 47

dystrophin

Back 47

enormous protein links actin filaments to protein inside sarcolemma, ultimately link to the basal lamina and endomysium to move muscle CT as a whole

Front 48

what bands are present in striated muscle?

Back 48

dark A bands (anisotrophic) alternating with lighter I bands (isotrophic) [dArk and lIght]

Front 49

what is the part of the A band that is especially dark?

Back 49

part of A band where thick and thin filaments overlap

Front 50

what is the lighter middle region of the A band?

Back 50

H band

Front 51

where do thick filaments originate?

Back 51

at dark M line in middle of H band

Front 52

what bisects the light I band

Back 52

bisected by dark narrow Z disc (Z line)-anchorage for thin filaments and elastic filaments

Front 53

sarcomere

Back 53

each segment of a myofibril from one Z disc to the next-the functional contractile unit of the muscle fiber

Front 54

why does a muscle shorten?

Back 54

because its individual sarcomeres shorten and pull the Z discs closer to each otherdystrophin and linking proteins pull on the extracellular proteins of the musclesas Z discs pulled closer together during contraction, pull on sarcolemma to shorten the cell

Front 55

when does skeletal muscle contract?

Back 55

when stimulated by nerve or electrodes

Front 56

paralyzed muscle will go through shrinkage called what?

Back 56

denervation atrophy

Front 57

somatic motor neurons

Back 57

nerve cells that serve skeletal muscles-cell bodies are in brainstem and spinal cord

Front 58

somatic motor fibers

Back 58

axons of the somatic motor neurons

Front 59

motor unit

Back 59

one nerve fiber and all the muscle fibers innervated by it

Front 60

effective muscle contraction requires what?

Back 60

activation of several motor units at once

Front 61

How many muscle fibers are innervated by each motor neuron?

Back 61

200

Front 62

small motor units

Back 62

fine control

Front 63

large motor units

Back 63

when strength is more important than fine control

Front 64

neuromuscular junction/motor end plate

Back 64

synapse when the target cell is a muscle fiber

Front 65

synapse

Back 65

the point where a nerve fiber meets its target cell

Front 66

synaptic knob

Back 66

bulbous swelling where the nerve fiber ends at each synapse

Front 67

synaptic cleft

Back 67

the space that separates knob from muscle fiber

Front 68

Schwann cell

Back 68

envelopes entire junction and isolates it from surrounding tissue fluid

Front 69

synaptic vesicles

Back 69

spheroidal organelles filled with acetylcholine

Front 70

acetylcholine

Back 70

neurotransmitter, functions as a chemical messenger from nerve cell to muscle cell

Front 71

ACh receptors

Back 71

proteins incorporated into its plasma membrane

Front 72

junctional folds

Back 72

infoldings in the sarcolemma of the muscle fiber to increase surface area of Ach sensitive membrane

Front 73

myasthenia gravis

Back 73

muscle paralysis caused by a deficiency of ACh receptors

Front 74

basal lamina

Back 74

surrounds muscle fiber and schwann cell of the neuromuscular junction to separate them from surrounding CT (composed of collagen and glycoproteins)

Front 75

acetylcholinesterase

Back 75

enzyme in sarcolemma and part of basal lamina that breaks down ACh after it stimulates muscle cellallows muscle to relax

Front 76

in what way are muscle fibers electrically excitable?

Back 76

because their plasma membrane changes in voltage when stimulated

Front 77

because their plasma membrane changes in voltage when stimulated

Back 77

excess of sodium ions in ECF, excess of potassium ions in ICF

Front 78

electrical potential/voltage

Back 78

difference in electrical charge from one point to another

Front 79

what happens when muscle cell is stimulated?

Back 79

inside of PM becomes positive briefly this is called depolarization (sodium goes into the cell)

Front 80

what happens to the muscle cell after depolarization?

Back 80

the sodium gates close and potassium gates open and potassium goes out of the cell

Front 81

repolarization occurs after the potassium gates open, what does this mean?

Back 81

the loss of positive potassium ions from cell turns inside of membrane negative again

Front 82

action potential

Back 82

the quick up and down voltage shift from negative RMP to positive value and back to negative value

Front 83

nerve impulse/nerve signal

Back 83

a wave of action potentials spreading along a nerve fiber

Front 84

Four major phases of muscle contraction and relaxation

Back 84

1) Excitation
2) Excitation-contraction
3) Contraction
4) Relaxation

Front 85

STEP ONE: Excitation

Back 85

*the process in which action potentials in nerve fiber lead to action potentials in muscle fiber
1. nerve signal arrives at synaptic knob, stimulates voltage-regulated calcium gates to open, calcium ions enter synaptic knob
2. calcium stimulates exocytosis of synaptic vesicles, release ACh into synaptic cleft
3. ACh diffuses across synaptic cleft and binds to receptor proteins on sarcolemma
4. ACh molecules bind to each receptor to open the gate, Sodium rushes into the cell, potassium rushes out, sarcolemma reverses polarity and becomes positive, this rapid fluctuation is called end-plate potential
5. areas of sarcolemma have gates that open in response to EPP, these ion movements create an action potential
The muscle fiber is now excited.

Front 86

STEP TWO: Excitation-Contraction Coupling

Back 86

*the events that link the action potentials on the sarcolemma to activation of the myofilaments, and so preparing them to contract
6. wave of action potentials spread from end plate in all directions, when the wave of excitation reaches T tubules, it continues down them into the sarcoplasm
7. open voltage-regulated ion gate in T tubules-physically linked to calcium channels in terminal cisternae of the sarcoplasmic reticulum, gates in SR open and calcium rushes out of SR into cytosol
8. calcium binds to troponin of thin filaments
9. troponin-tropomyosim complex changes shape, sinks deeper into thin filament, exposes active sites on actin filaments, makes them able to bind to myosin heads

Front 87

STEP THREE: Contraction

Back 87

*step in which the muscle fiber develops tension and may shorten-sometimes muscles contract without shortening
*sliding filament theory-myofilaments do not become any shorter during contraction, the thin filaments slide over the thick filaments and pull on the Z discs behind them, so each sarcomere as a whole shortens
10. myosin head must have ATP bound to it for this, myosin ATPase-an enzyme in the head, hydrolyzes this ATP, energy released activates head, the head keeps ADP and phosphate group bound to it
11. cocked myosin binds to exposed active site on thin filament-forms cross bridge between myosin and actin
12. myosin releases ADP and phosphate and flexes into low energy position (bent), tugging on the thin filament-this is the power stroke, head remains bound to actin until new ATP
13.myosin releases actin upon binding more ATP, then does it all over again, rehydrolyzes the ATP, recocks (the recovery stroke) attaches to new active site farther down thin filament and produce another power stroke

Front 88

STEP FOUR: Relaxation

Back 88

*a muscles fiber relaxes and returns to its resting length
14. nerve signals stop arriving at neuromuscular junction, so synaptic knob stops releasing ACh
15. ACh separated from receptor and AChE breaks it down into fragments that cannot stimulate muscle, synaptic knob reabsorbs these for recycling, this happens while muscle is contracting but when nerve signals stop, no new ACh is released to replace what is broken down, so stimulation of the muscle fiber by ACh ceases
16. active transport pumps in SR begin to pump calcium from cytosol back into cisternae, calcium binds to protein called calsequestrin, stored until fiber stimulated again, ATP is needed for relaxation and contraction of muscle (active transport)
17. calcium ions dissociate from troponin, and they are pumped into SR and are not replaced
18. tropomyosin moves back to block active sites of actin filament, myosin can no longer bind to actin, and muscle fiber ceases to produce or maintain tension
Muscle returns to resting length because of its elastic components and because the contraction of an antagonist lengthens the relaxed muscle

Front 89

Rigor Mortis

Back 89

*hardening of muscles and stiffening of body
*muscle relaxation requires ATP, & ATP production is no longer produces after death
*rigor mortis peaks about 12 hours after death, then diminishes over the next 48 to 60 hours

Front 90

ATP supply depends on availability of what?

Back 90

-oxygen
-organic energy sources

Front 91

Two main pathways of ATP synthesis

Back 91

-anaerobic fermentation (lactic acid)
-aerobic respiration

Front 92

properties of cardiac muscle

Back 92

-regular rhythm
-must contract in unison
-contractions must last long enough to expel blood
-must work in sleep or wakefulness
-must be highly resistant to fatigue

Front 93

Cardiac Muscle

Back 93

limited to the heart where it functions to pump blood

Front 94

how do damaged cardiac muscle cells repair ?

Back 94

fibrosis

Front 95

smooth muscle contraction

Back 95

triggered by calcium, energized by ATP, and achieved by sliding thin past thick filaments

Front 96

smooth muscle contraction begins in response to what?

Back 96

calcium that enters the cell from ECF, a little internally from the sarcoplasmic reticulum

Front 97

how does calcium bind to calmodunin on thick filaments?

Back 97

-activates myosin light-chain kinase; adds phosphate (ATP) to regulatory protein on myosin head
-myosin ATPase then hydrolyzes ATP