Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Physiology > Physiology wk4 > Flashcards

Physiology wk4 Flashcards

1
Q

what are the functions of skeletal muscles

A
  • Force production for locomotion
  • force production for breathing
  • Force production for postural support
  • Heat production during cold stress
  • Acts as an endocrine organ
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the muscle actions

A
  • Flexors (decrease joint angle)
  • Extensors (increase joint angles)
  • Attached to bones by tendons (origin end (fixed)), insertion end (moves)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the structure of skeletal muscles

A

Epimysium – surrounds entire muscle
Perimysium – surrounds fascicles
Endomysium – surrounds muscle fibres
Basement membrane – just below endomysium
Sarcolemma – muscle cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is the microstructure of muscle fibers

A

Myofibrils – contain contractile proteins ((actin thin) and (myosin thick))
Sarcomere – z line, m line, h zone, a band and I band
Sarcoplasmic reticulum – storage sites for calcium, terminal cisternae
Transverse tubules – extend from sarcolemma to sarcoplasmic reticulum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what do satellite cells do

A

key role in muscle growth and repair, increase the amount of nuclei in mature muscle fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the myonuclear domain

A

volume of sacroplasm surrounding each nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does more myonuclei lead to

A

more protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the neuromuscular junction

A

junction between motor neurone and muscle fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the motor end plates

A

pocket formed around motor neurone by sarcolemma
these are the post synaptic clefts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the neuromuscular cleft

A

short gap between neuron and muscle fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does ACH do at the neuromuscular junction

A

causes end-plate potential (EPP) leads to depolarization and signals for muscle contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the sliding filament theory

A

muscle shortening occurs due to movement of actin filament over the myosin filament, reduction in the distance between z-lines of the sacromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the actin filament

A

thin filament with 2 chains of actin proteins in a double row, twisted with a tropomyosin thread and troponin at the binding site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the myosin filament

A

thick filament with a myosin head and tail
The heads upon the myosin attach to the actin-binding site on the thin (actin) filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the steps of excitation-contraction coupling

A
  1. Signal from motor nerve fibre enters synaptic knob
  2. Synaptic vessels release Ach receptors on the sarcolemma of muscle fibre
  3. Release of Ach causes excitation of muscle fibre, travels to T tubule and causes depolarization
  4. Depolarization open calcium ion channels from sarcoplasmic reticulum and terminal cisterna or sarcoplasmic reticulum
  5. Calcium ions bind to troponin on actin, causes move of tropomyosin and exposes binding sites (ATP used)
    6-8. energized myosin cross-bridge binds to active site on actin, pulls on it making back and forth movement
  6. Ach release stops, fibre is repolarised
  7. Calcium is pumped from cytosol into the sarcoplasmic reticulum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the main ion needed for contraction

A

calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the definition of fatigue

A

a decline in ability to produce muscular power output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

decline in muscle power may be due to

A
  • Decrease in muscle force production at cross-bridge level
  • Decrease in muscle shortening velocity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

posssible cause of fatigue in high intensity exercise

A
  • Decreased ca2+ release from sarcoplasmic reticulum
  • Accumulation of metabolites that inhibit myofilament sensitivity to ca2+ (increased Pi and reduced pH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what key metabolites/ions contribute to fatigue

A
  • Pi, h+ and free radicals
  • Pi and free radicals modify cross-bridge head and reduce number of cross-bridge formations
  • H+ ions bind to ca2+ binding sites on troponin, preventing ca2+ binding and contracting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

possible causes for fatigue during moderate intensity

A
  • Increased radical production
  • Glycogen depletion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

key metabolites contributing to fatigue in moderate intensity

A
  • Radical accumulation modifies cross-bridge head and reduces number of cross-bridge bound to actin
  • Depletion of muscle glycogen reduces TCA cycle intermediates and decreases ATP production via oxidative phosphorylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are some things that can increase chance of cramps

A
  • Repeated electrical stimulation
  • Dehydration
  • Electrolyte imbalance
  • Not stretching
24
Q

strategies to relieve cramps

A
  • Passive stretching
  • Activating ion channels in the mouth/throat could send inhibitory signals to the spinal cord to inhibit overreactive motor neurons
25
what does concentric mean
muscle contracts and gets shorter (force>resistance)
26
eccentric meaning
muscle contracts and gets longer (force < resistance)
27
isometric contraction is
muscle contracts and doesn't change length
28
what does isotonic refer to
when muscle tension remains unchanged when muscle length decreases
29
what does the word isokinetic refer to
muscle length decreases with constant velocity
30
what did Ranvier (1873) discover
different muscles had different colours and contractile properties
31
what are the key bio-mechanical characteristics important to muscle fibers
* Oxidative capacity – amount of mitochondria, capillaries and myoglobin * Type of myosin isoform expressed – differ in rate of ATP breakdown * Abundance of contractile proteins – amount of actin/myosin * Type of motor neuron innervation
32
what are the types of muscle fibers
Type 1 – slow twitch, slow-oxidative fibres Type 2a – intermediate fibres, fast oxidative glycolytic fibres Types 2x – fast twitch, fast glycolytic fibres
33
what causes intra-inadividual differences within muscles
genetics hormones training habits
34
how do skeletal muscle fibers differ in functional properties
* Maximal force production * Speed of contraction * Maximal power output * Fatigue resistance * Muscle fibre efficiency
35
what does a shortening sacromere look like
change and shortening of the I band but no change in A band length
36
how are muscle fibers typed
* Contractile properties * Oxidative capacity – capillaries, mito, myofibril * Staining for type of myosinATPase (amount of enzymes)
37
what is muscle twitch
contraction resulting from a single stimulus
38
how is contraction caused within the intramuscular fibers
calcium release from SR, tension developed due to cross-bridge formation
39
what does relaxation cause
uptake of calcium ions into SR resulting in cross-bridge detachment
40
why is speed of shortening faster in type2
* SR releases Ca2+ at a faster rate * Higher ATPase activity
41
what two factors result in greater force of contraction
more motor units - spatial faster motor units- temp
42
what are the 3 type of firing rates of neurons
1. Simple 2. Summation 3. Tetanus
43
within muscles there is a varied amount of
motor units number of fibers within each unit
44
what do larger motor units have
* Larger cell bodies * Larger diameter axon * More axonal branches * Sparse afferent innervation * More complex and extensive motor end plate (post synaptic cleft) of neuromuscular junction
45
whats the difference in excitement between slow and fast motor units
slower are more excitable compared
46
do muscles have an ideal length
yes, too short or long will negatively affect force production
47
what does tetanus mean
stimulating the muscle again before it has time to relax
48
what decreases with age in terms of muscles ability
muscle strength power and velocity
49
why do elders have less muscle strength
less muscle mass lower muscle qaulity lower innervation
50
how much muscle mass do we lose
0.5 to 1% every year over 40
51
besides muscle mass what else could cause muscular loss
neuromuscualr alteration loss of nerve innervation
52
what happens to the different types of muscle fibers with age
type1 fibers take on the responsibility of type2 fibers (collateral reinnervation)
53
how does denerve/innervation affect
* More Co-expression of myosin isoforms * Less force output * Less velocity of contraction * Increased motor unit size * Preservation of some muscle mass
54
what does contractile proteins refer to
actin and myosin
55
definition of muscle cramps
spasmodic involuntary muscle contraction
56
what factors control force regulation
amount and type of motor neurons stimulated muscle length firing rate

Physiology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions