Muscle System Flashcards
1
Q
sarco-
A
flesh
2
Q
myo-
A
muscle
3
Q
mys-
A
muscle
4
Q
functions of muscle system
A
- movement
- maintain posture
- stabilizes joints
- generates heat
5
Q
types of tissue
A
- skeletal
- cardiac
- smooth
6
Q
anatomy of skeletal muscle
A
- fibers are enclosed by endomysium
- many endomysii are wrapped together by the perimysium
- one group of fibers wrapped in perimysium is called a fascicle
- all fascicles are wrapped together in epimysium
- blended into tendons or aponeuroses
7
Q
aponeuroses
A
layers of flat, broad tendons
8
Q
sarcolemma
A
plasma membrane of skeletal muscle
9
Q
myofibrils
A
long, ribbon-like organelles filling majority of cytoplasm
10
Q
sarcomere
A
basic unit of muscle (I and A bands)
11
Q
I and A bands
A
myofilaments
-give the appearance of striation
12
Q
2 types of myofilaments
A
- thick
- thin
13
Q
thick filaments
A
composed of myosin and ATP enzymes
14
Q
thin filaments
A
composed of actin and regulatory proteins
15
Q
sarcoplasmic reticulum
A
- surrounds each myofibril
- plays a role in storing and releasing calcium during contraction
16
Q
2 main functions of muscles
A
-irritability and contractility
17
Q
irritability
A
-receive and respond to stimuli
18
Q
contractility
A
shorten when stimuli is applied
19
Q
nerve stimulis
A
- muscle cells must be stimulated by nerve impulses to contract
- cells join at neuromuscular junctions
- gap b/w is called synaptic cleft
- when impulse reaches neuromuscular junction, a neurotransmitter is released
- neurotransmitter travels across synaptic cleft and attaches to sarcolemma
- if enough neurotransmitter reaches the sarcolemma, then Na ions rush into muscle cell and generate electrical current called action potential
- causes contraction
20
Q
neuromuscular junctions
A
- where muscle cells join
- don’t touch, but very close
21
Q
synaptic cleft
A
gap between neuromuscular junctions
-filled w/ fluid
22
Q
motor unit
A
1 neuron and all skeletal muscles that it stimulates
23
Q
muscle contraction mechanism(sliding filament theory)
A
- when muscle fibers are activated by the nervous system, cross bridges attach and detach to myosin on the thin filaments and sliding begins
- powered by ATP
- contraction requires Ca until action potential ends, then Ca is stored into sarcoplasmic reticulum
24
Q
contraction of skeletal muscle
A
- skeletal muscles consist of thousands of muscle cells
- react with graded responses
- produced by changing frequency of muscle stimulation or changing # of muscle cells being stimulated
25
graded responses
different degree of shortenings
26
muscle twitches
single, brief, jerky contractions
27
fused tetanus(complete tetanus)
muscles move through an accumulation of nerve impulsed
28
unfused tetanus(incomplete)
steps leading to fused tetanus
29
of stimuli in contraction
force of muscle contraction depends on how many cells are stimulated
- when only a few cells are stimulated, contraction as a whole will be slight
- when all motor units are active, contraction is very strong
30
ATP for contraction
- as muscles contract, the bonds of ATP are hydrolyzed to release needed energy
- muscles store only 4-6 seconds worth, so ATP must be regenerated
31
3 pathways for ATP regeneration
- direct phosphorylation of ADP by creatine phosphate
- aerobic respiration
- anaerobic respiration
32
direct phosphorylation of ADP by creatine phosphate
- CP transfers high energy phosphate to ADP molecule, resulting in ATP (yields 1 ATP per CP)
- anaerobic
- muscles store 5x as much CP as ATP; however, CP supplies are exhausted in about 15-20 seconds
33
aerobic respiration
- glucose is broken down into CO2, H2O, and up to 36 ATP (per 1 glucose model)
- requires O2, amino acids, fatty acids
- slow process but allows muscles to contract for hours
34
anaerobic glycolysis and lactic acid formation
- glycolysis breaks glucose into pyruvic acid and 2 ATP (per 1 glucose molecule)
- if O2 is not present then pyruvic acid is broken into lactic acid (yields 5% of ATP for aerobic respiration) (faster process and provides ATP for 30-60 seconds of strenuous muscle activity)
35
muscle fatigue
inability of a muscle to contract even though it is being stimulated
- occurs bc of O2 debt
- depending on blood supply, lactic acid accumulation and low ATP, causes muscle to contract less and less effectively, then stop
36
o2 debt
-person can't take up enough o2 fast enough to keep muscle supplied
37
types of muscle contractions
isotonic
| -isometric
38
isotonic contraction
- myofilaments slide, causing muscle to shorten and movement occurs
- ex: bending knee, rotating arm, smiling
39
isometric contractions
- myofilaments attempt to slide but are unable to due to immovable object and tension builds up
- ex: attempting to move 400 lbs alone or pushing against a wall
40
adduction
movement of a limb toward the body midline
41
circumduction
combination of flexion, extension, abduction, and adduction, where proximal end of limb is stationary and its distal end moves in a circle
42
dorsiflexion
standing on heels
43
plantar flexion
pointing the toe
44
inversion
-turning the sole of the foot medially
45
eversion
-turning the sole laterally
46
opposition
movement of the thumb to touch the tips of the other fingers
47
supination
rotating the forearm laterally so the palm faces anteriorly (anatomical position)
48
pronation
rotating the forearm medially so the palm faces posteriorly
