Muscular System

Question 1

Skeletal Muscle

Answer 1

Single, very long, cylindrical, multinucleate cells with striations

Question 2

Smooth Muscle

Answer 2

Single, fusiform, uninucleate; no striations

Question 3

Cardiac Muscle

Answer 3

Brancing chains of cells; uninucleate; striations; intercalated discs

Question 4

What is Neuromuscular Junction

Answer 4

Synaptic connection between terminal end of a motor nerve and a muscle

Question 5

Neuromuscular Junction Steps

Answer 5

1) Nerve impulse reaches axon terminal of motor neuron
2) Calcium channels open, calcium enters the axon terminal
3) Synaptic vesicles to release the neurotransmitter acetylcholine by exocytosis
4) Acetylcholine diffuses across synaptic cleft and binds to receptors in sacrolemma
5) ACh opens channels that allow simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber. More Na+ ions enter than K+ ion leave, producing a local change in the electrical conditions of the membrane (depolarization). This eventually leads to an action potential
6) The enzyme acetylcholineterase breaks down ACh in synaptic clever, ending the process

Question 6

Sliding Filament Model

Answer 6

1) ATP is split when myosin head is unattached
2) ADP and P are bound to myosin as cross-bridge forms between the myosin head and actin
3) Upon ADP and P release, power strike occurs; head bends and pulls actin
4) Binding of fresh ATP causes myosin head to return to resting position

Question 6

Sarcolemma

Answer 6

Plasma membrane in muscle fibers

Question 6

Sarcoplasm

Answer 6

The cytoplasm of a muscle cell

Question 6

Sarcoplasmic
reticulum

Answer 6

A specialized smooth endoplasmic reticulum

Question 7

T tubules

Answer 7

Consists of sarcolemma penetrating into the myocyte interior, allows transmission of the action potential

Question 8

Myofibrils

Answer 8

A cylindrical bundle of sacromeres within the skeletal muscle cell

Question 9

Sarcomeres

Answer 9

A functional unit of muscle fiber

Question 10

Myofilaments: Actin

Answer 10

Thin filaments made of actin,

Question 11

Myofilaments: Myosin

Answer 11

Thick filaments made of myosin

Question 12

Endomysium

Answer 12

Connective tissue sheath wrapped around muscle fiber

Question 13

Perimysium

Answer 13

Fibrous membrane wrapped around fascicles (bundle of muscle fiber)

Question 14

Epimysium

Answer 14

Connective tissue that covers the muscle

Question 15

Tendon

Answer 15

Indirectly attaches muscle to bone

Question 16

Isotonic

Answer 16

Same tension, changing length
Myofilaments slide, muscle shortens and movement occurs
E.g., bending knees, lighting weights

Question 17

Isometric

Answer 17

Same length, changing tension
Myosin filaments are ‘spinning their wheels’, trying to slide but muscle is pitted against some more or less immovable object
E.g., pushing the palms together in front of you causes arm and chest muscles to contract isometrically

Question 18

Origin

Answer 18

Attached to the immovable/less-moveable bone, anchor/leverage point

Question 19

Insertion

Answer 19

Attached to the moveable bone, when contraction occurs insertion moves towards origin

Question 20

Prime Mover

Answer 20

Major responsibility for causing a particular movement

Question 21

Antagonist

Answer 21

Muscles that oppose or reverse a movement, are stretched and relaxed when prime mover is active

Question 22

Synergist

Answer 22

Help prime movers by producing same movement or reducing undesirable movements

Question 23

Fixator

Answer 23

Hold a bone still/stabalize the origin of a prime mover so all tension can be used to move the insertion bone

Question 24

Flexion

Answer 24

decreases angle of joint and brings two bones closer together/BENDS

Question 25

Extension

Answer 25

Increases angle or distance between two bones or parts of the body

Question 26

Hyperextension

Answer 26

Extension that is greater than 180 degrees

Question 27

Rotation

Answer 27

Movement of bone along its longitudinal axis

Question 28

Abduction

Answer 28

Moving a limb away from the midline or median plane of the body

Question 29

Adduction

Answer 29

Movement of a limb towards the midline or median plane of the body,

Question 30

Circumduction

Answer 30

Proximal end of limb is stationary and its distal end moves in a circle, limb outlines as a cone

Question 31

Dorsiflexion

Answer 31

Lifting the foot so the superior surface approaches the shin, point towards head

Question 32

Plantar flexion

Answer 32

Pointing toes away from head

Question 33

Inversion

Answer 33

Turn the sole medially

Question 34

Eversion

Answer 34

Turn the sole laterally

Question 35

Supination

Answer 35

Forearm rotates laterally so that the palm faces anteriorly or up

Question 36

Pronation

Answer 36

Forearm rotates medially so that palm faces posteriorly

Question 37

Opposition

Answer 37

Saddle joint between metacarpal 1 and carpals allows opposition of thumb