Chapter 10- Muscles Flashcards Preview

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Flashcards in Chapter 10- Muscles Deck (66)
1

Myology

scientific study of muscles

2

how much mass do muscles account for

~45%

3

functions of muscles

maintain posture and body position
movement
heat production
guard orifices
support visceral organs

4

properties of muscle tissue

Excitability
-the ability to receive and respond to electrical or chemical stimuli
Contractility
-the ability to shorten forcibly when stimulated
Extensibility
-ability to be stretched without damaging the tissue
Elasticity
-ability to return to original shape after being stretched

5

composition of mucles

-muscles are organs
-consist of many tissue types
-connective tissue
-arteries/veins
-nerves
-lymphatics
-contractile muscle cells

6

skeletal muscle characteristics

-attaches to bone, skin, or fascia
-striated with light and dark bands
-voluntary control
-long, thin and multi-nucleated fibers
-arranged into packages that attach to and cover the bony skeleton
-contracts rapidly, but tire easily
-may exert great force
-fiber=1 muscle cells

7

muscle structure

-belly: main portion of a muscle (thick part)
-belly is attached to tendons
-tendons are attached to bone

8

fascia

-deep fascia
--dense irregular CT around muscle
--holds it in place and separates it form other muscles
-subcutaneous fascia
--loose CT beneath skin, surrounds several muscles

9

skeletal muscle organization

-many muscle fibers are bundled together into groups called fascicles
-10-100 muscle cells
-several fascicles make up a muscle (so several hundred fibers(cells))

10

skeletal muscle CT

-epimysium
-perimysium
-endomysium

11

epimysium

surrounds the whole muscle

12

perimysium

surrounds fascicles

13

endomysium

separates individual muscle fibers

14

tendon formed from what

all connective tissue extended beyond the muscle belly

15

aponeuroses

tendons that form thick flattened sheets

16

myoblasts

embryonic cells that fuse to form muscle fibers
-causes the length and multinucleation

17

myosatellite cells

myoblasts that do not fuse
-assist in repair of damaged cells

18

fiber structure

-sarcoplasm: fiber cytoplasm
-sarcolemma: plasma membrane of a fiber
-transverse (T) tubule: extensions of the sarcolemma into the sarcoplasm

19

myofibrils

contractile organelles
-extend the length of fiber

20

sarcoplasmic reticulum

surrounds the myofibrils
-similar to ER
-contains calcium ions which tell muscle to contract

21

sarcomere

functional unit of the myofibril
-made of thick and thin filaments

22

thick filaments

myosin
-twisted protein with globular heads

23

thin filament

actin
-structural protein
-coiled "beads"
regulatory proteins
-allow/prohibit attachment between actin and myosin
-tropomyosin
-troponin

24

sarcomere bands

cause the striated appearance
bands
-A band: entire thick filament range
-I band: only thin filaments
-H band: only thick filaments
- Zone of overlap: both filaments

25

Sarcomere lines

divide and flank the sarcomere
-Z line:
--end of sarcomere
--made of actin protein
--anchor thin filaments
-M line:
--middle of the sarcomere
--stabilize thick filaments

26

structural proteins

titin: anchors a thick filament to a Z line
-accounts for elasticity and extensibility
nebulin: holds F actin together on thin filaments (runs through center)
actinin: makes up Z line

27

sliding filament theory

actin slides over myosin
-zone of overlap enlarges
-h band shrinks
-I band shrinks
- A band remains the same
- Z line moves closer to A band

28

Neuromuscular junction is made up of

-motor unit
-neuromuscular junction
-synaptic termical
-motor end plate
-synaptic cleft
-neurotransmitter

29

motor unit

neuron and all the muscle cells stimulated by the neuron

30

neuromuscular junction

point of contact between the neuron and the muscle

31

synaptic cleft

end of axon that contacts motor end plate

32

neurotransmitter

chemical released into synaptic cleft
-acetylcholine

33

events of muscle contraction

Ach stored in synaptic vesicles
-impulse reaches end of neuron-Ach released
-Ach crosses gap and binds to receptors
-impulse tracels through motor end plate down T-tubules to SR
-Ca2+ ions diffuse out of SR into sarcoplasm
-Ca2+ exposes the active site
-myosin binds to active site
-ATP is used and contraction occurs
-contraction continues as long as Ca2+ concentration is high
-Ach decomposed by acetylcholinesterase
-Ca ions transported back to SR
-actin and myosin links broken
-cross bridges moved back
-active site is blocked again

34

acetylcholinesterase

breaks down acetylcholine

35

tension produced by muscle

determined by
-frequency of stimulation
-number of motor units stimulated
brain tells muscle how much tension to apply

36

all or none law

all fibers in a motor unit full contract if stimulated

37

recruitment

steady increase in tension by increasing the number of contracting motor units

38

tetanus

muscle never begins to relax, continuous fused contraction

39

muscle tone

-motor units contract randomly
-tension, but no movement
-can stabilize joints, hold objects in place, maintain posture

40

hypertrophy

-constant, exhaustive stimulation increases the number of organelles/proteins in a fiber
increases:
-mitochondria
-glycolytic enzyme reserves
-myofibrils (more and thicker)
-filaments within myofibrils
Muscle fibers DO NOT reproduce

41

atrophy

-lack of constant motor neuron stimulation reduces organelles and proteins
-due to:
age
hormones
lack of use
nerve damage
-reversible if fiber is not dead

42

muscle attachments

-origin: attachment site that does not move
-insertion: attachment site that moves
-force= tension
-fascicle arrangement varies based on position of muscle

43

parallel muscles

-fascicles parallel to long axis
-unidirectional force
ex= biceps brachii

44

convergent muscles

-fan shaped
-multi-directional force
-versatility
-generates least amount of force
-not all parts pulling in same direction at same time
ex. pectoralis major

45

pennate muscles

feather shaped
-fascicles oblique to long axis
-tendon passes THROUGH the muscle
-greatest force
ex=deltoid, quadricep
con=distance. cannot pull as far because of angle

46

circular muscles

-concentric fascicles around opening
-contraction decreases lumen diameter
ex= orbicularis oculi (eye)
mouth

47

articulations and muscle actions: uniaxial

rotation around one axis
movements: rotation (atlantoaxial); pivot joints
Angular: knee, IP joints

48

articulations and muscle actions: biaxial

movement occurs along 2 axes
angular motions:
-flexion/extension
-abduction/adduction
-ex: ellipsoidal joint, radiocarpal, metacarpal phelange, carpometacarpal (2-5)

49

articulations and muscle actions: multiaxial

-movement on all axes
-angular motion: same as biaxial
-rotation
-circumduction
ex=ball-and-socket

50

Actions: agonist

main muscle causing directional force
-this can be any muscle of interest

51

actions: antagonist

muscle that contracts to oppose the agonist
ex=bicep brachii vs tricep brachii

52

actions: synergist

muscle that assits/modifies movement
ex=brachialis and pronator teres

53

actions: fixator

muscle that stabilizes elements associated with agonists
-deltoid stabilizes glenohumeral joint

54

levers

lever systems modify movements
-can change:
-magnitude of force
-speed
-direction
-distance of limb movement

55

components of lever system

-lever(L): skeletal element
-effort (E): applied force (muscle pulling)
-fulcrum (F): joint
-resistance (R): body part or object moved

56

types of levers: first class

teeter totter/see saw
-R opposite of E with central F
ex= neck extension
-E=neck extensors
F=atlanto-occipital joint
-R=skull

57

Second class levers

-wheel barrow
-E opposite of R to move R
Ex=plantar flexion
-E=calf
-F=MP joint
-R=weight of body

58

Third class levers

-shovel, broom
-E in between F and R
Ex= elbow flexion
-E= biceps brachii
-F=elbow joint
-R=weight distal to joint

59

types of skeletal muscle fibers: fast fibers

-fast acting; high energy requirements
-anaerobic
-large diameter
-densely packed myofibrils
-large glycogen reserves
-few mitochondria
-rapid, powerful, brief contractions
LIGHTER, less myoglobin

60

types of skeletal muscle fibers: slow fibers

-more myoglbin; slower sustained contraction
-aerobic
-smaller diameter
-longer to contract
-contract for longer time
DARKER b/c myoglobin

61

types of skeletal muscle fibers: intermediate fibers

-attributes of both
-similar to fast fibers
-greater resistance to fatigue
-exercise (or lack of) can change one muscle type to another

62

smooth muscle characteristics

-attached to hair follicles in skin
-in walls of hollow organs and blood vessels
-nonstriated
-involuntary control
-contractions are slow and sustained
-spindle shaped
-very elastic
do not fuse like muscle cells do

63

smooth muscles

characteristics:
-contract slowly
-resistant to fatigue
-stimulated by:
-nervous system
-hormones
-ions
-stretching

64

smooth muscle types: single unit

-many gap junctions
-sheets of spindle shaped cells
-contract together
ex: BV's, digestive tract, resp. tract, urinary tract.
-either closed or open, no precision

65

smooth muscle types: multi-unit

-no or few gap junctions
-separate fibers; contract independently
-only contract when stimulated by motor nerve
-ex: walls of large BV's, uterus, iris of the eye
-lots of precision, degree of refinement/contraction

66

cardiac muscle characteristics

-striated in appearance
-involuntary control
-autorhythmic
network of fibers with intercalated disks at ends
-found only in heart