Muscular System Flashcards

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1
Q

what are the functions of muscles?

A

movement, maintaining posture, protects organs, generates heat, stabilise joints, valves, pupil dilation, raising hair

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2
Q

what are the 4 characteristics of muscles

A

excitability (responding to stimuli), contractility, extensibility, elasticity (can recoil to resting length after being stretched)

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3
Q

which type of tissue wraps and reinforces muscles?

A

connective

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4
Q

what are the three types of muscle

A

smooth, skeletal, cardiac

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5
Q

describe the structure of smooth muscle

A

visceral- meaning it lines hollow organs. it is non-striated and involuntary

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6
Q

describe the structure of skeletal muscle

A

voluntary, striated and multinucleated

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7
Q

describe the structure of cardiac muscle

A

striated and involuntary

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8
Q

what’s a sacromere?

A

single contractile unit

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9
Q

write a note on muscle fibres

A

are a multinucleated cell. may be up up to 30cm in length. the cell membrane of the muscle fibre is called the sarcolemma. the sarcoplasm is the muscle fibre cytoplasm, and the myofibril is the rod like organelle containing contractile elements (sarcomeres). myofibrils have alternating Light (I) and Dark (A) bands

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10
Q

write a note on sarcomeres

A

smallest contractile unit of muscle fibres. they are the region between two successive Z discks and have thick filaments (myosin) and thin filaments (actin)

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11
Q

what function has the myosin head, tropomyosin and troponin?

A

myosin head forms cross bridges with thin filaments to contract muscle cells.
Tropomyosin is a protein strand that stabilises actin.
Troponin is bound to actin and is affected by Ca2+.
*learn the diagram for this

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12
Q

What is the sliding filament model?

A

during contraction thin filaments slide past thick ones so that they overlap. Myosin heads latch to active sites on actin forming a cross bridge. Tiny rachets propel thin filaments to centre of the sarcomere

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13
Q

What is the process of muscle contraction

A
  1. Action potential travels down axons and arrives at neuromuscular junction where there is a release of acetylcholine (ACh) into the synaptic cleft.
  2. ACh diffuses across the cleft and attaches to ACh receptors on the sarcolemma of muscle fibre.
  3. A rush of sodium into the sarcoplasm produces action potential in the sarcolemma where ACh is broken down.
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14
Q

describe what happens at a neuromuscular junction and then how this results in muscle contraction

A

action potential travels down the sarcolemma where calcium is released from SR. Calcium binds to troponin resulting in a change of shape, as myosin binding sites are exposed on actin. The myosin cross bridge forms with actin. Myosin head pivots and pulls the actin filament to the M line. ATP attaches to myosin and the cross bridge detaches. the myosin can be reactivated

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15
Q

what is a muscle cramp?

A

sudden or involuntary contraction of muscles due to long periods of exercise, medications, dehydration, muscle strain nerve/kidney/thyroid disorders, inadequate blood supply, nerve compression or mineral depletion (Ca, K, Mg)

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16
Q

write a note on isotonic contraction

A

has the same retention, the muscle length changes i.e in bicep curls, bending knee or smiling

16
Q

how are muscle cramps treated?

A

stretching, muscle relaxants, hydration, Vit B supplements, cold/heat therapy

16
Q

write a note on isometric contractoin

A

muscle length stays the same, tension increases i.e moving against heavy load or immovable objects or lifting heavy weights

17
Q

what does origin mean in terms of muscle orientation?

A

where the muscle is attached to immovable or less movable bone

18
Q

what does insertion mean in terms of muscle orientation

A

the muscle is attached to movable bone

19
Q

give the scientific names for muscle direction: parallel, right angles, converging, circular, feather-like, spindle shaped

A

rectus, transverse/oblique,convergent, obicularis, pennate, fusiform

20
Q

what are the scientific names for the follow relative sizes of muscles: largest, smallest, long, short

A

maximus, minimus, longus, brevis

21
Q

what is the scientific wording for muscles that have two origins and three origins?

A

biceps and riceps

22
Q

how might a triangular and a trapezoidal muscle be described?

A

deltoid and trapezius

23
Q

what words describe the adduction and extension action of muscles

A

adductor and extensor

24
Q

give an example of each of the following muscles: circular, convergent, parallel, unipennate, multipennate, fusiform, bipennate

A

orbicularis oris, pectoralis major, sartorius, extensor digitorumlongus, deltoid, biceps brachii, rectus femoris

25
Q

which embryonic cells do muscles develop from?

A

myoblasts

26
Q

what happens when myoblasts fuse?

A

muscle fibres are formed

27
Q

what % body mass is comprised muscle in men and women?

A

42% in men and 36% women- due to testosterone

28
Q

what impact has aerobic or endurance exercise have on the body

A

stronger, more flexibility, resistance to fatigue. does not increase muscle size. increased blood supply + mitochondria and o2 storage. efficiency of metabolism and heart function

29
Q

what are the effects of resistance/isometric exercise

A

this exercise includes muscles vs immovable object. have an increase in muscle cell size as there are more contractile units. increase in muscle size and strength.

30
Q

what happens to muscle mass with age?

A

mass decreases and muscles become more sinewy.

31
Q

by how much does muscle mass decrease by age 80?

A

50%`

32
Q

What is a fascicle?

A

Bundle of muscle cells

33
Q

What are the layers of membrane?

A

Epimysium - outer
Perimysium - membrane between fascicles
Endomysium - membrane of fascicles
Blood vessels