Muscular System

Question 1

what are the functions of muscles?

Answer 1

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

Question 2

what are the 4 characteristics of muscles

Answer 2

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

Question 3

which type of tissue wraps and reinforces muscles?

Answer 3

connective

Question 4

what are the three types of muscle

Answer 4

smooth, skeletal, cardiac

Question 5

describe the structure of smooth muscle

Answer 5

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

Question 6

describe the structure of skeletal muscle

Answer 6

voluntary, striated and multinucleated

Question 7

describe the structure of cardiac muscle

Answer 7

striated and involuntary

Question 8

what’s a sacromere?

Answer 8

single contractile unit

Question 9

write a note on muscle fibres

Answer 9

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

Question 10

write a note on sarcomeres

Answer 10

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

Question 11

what function has the myosin head, tropomyosin and troponin?

Answer 11

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

Question 12

What is the sliding filament model?

Answer 12

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

Question 13

What is the process of muscle contraction

Answer 13

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.

Question 14

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

Answer 14

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

Question 15

what is a muscle cramp?

Answer 15

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)

Question 16

write a note on isotonic contraction

Answer 16

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

Question 16

how are muscle cramps treated?

Answer 16

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

Question 16

write a note on isometric contractoin

Answer 16

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

Question 17

what does origin mean in terms of muscle orientation?

Answer 17

where the muscle is attached to immovable or less movable bone

Question 18

what does insertion mean in terms of muscle orientation

Answer 18

the muscle is attached to movable bone

Question 19

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

Answer 19

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

Question 20

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

Answer 20

maximus, minimus, longus, brevis

Question 21

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

Answer 21

biceps and riceps

Question 22

how might a triangular and a trapezoidal muscle be described?

Answer 22

deltoid and trapezius

Question 23

what words describe the adduction and extension action of muscles

Answer 23

adductor and extensor

Question 24

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

Answer 24

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

Question 25

which embryonic cells do muscles develop from?

Answer 25

myoblasts

Question 26

what happens when myoblasts fuse?

Answer 26

muscle fibres are formed

Question 27

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

Answer 27

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

Question 28

what impact has aerobic or endurance exercise have on the body

Answer 28

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

Question 29

what are the effects of resistance/isometric exercise

Answer 29

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.

Question 30

what happens to muscle mass with age?

Answer 30

mass decreases and muscles become more sinewy.

Question 31

by how much does muscle mass decrease by age 80?

Answer 31

50%`

Question 32

What is a fascicle?

Answer 32

Bundle of muscle cells

Question 33

What are the layers of membrane?

Answer 33

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