Muscle System

Question 1

3 types of muscle

Answer 1

Skeletal, cardiac, and smooth

Question 2

Skeletal muscle

Answer 2

Striated. Voluntary somatic muscle. Gross skeletal muscles for movement (isotonic contraction). Large, long, unbranched cylindrical fibers w/transverse striations (stripes), arranged in parallel bundles

Question 3

Cardiac muscle

Answer 3

Striated. Involuntary visceral muscle, walls of the heart, great vessels like the aorta

Question 4

Smooth muscle

Answer 4

Un-striated or un-striped. Involuntary visceral muscle, walls of the most vessels, hollow organs, sphincter activity

Question 5

Satellite cells

Answer 5

For injury repair and are a source of myoblasts

Question 6

Skeletal muscle form and function

Answer 6

1. Can be attached to bones, ligaments, cartilage, fascia, and organs
2. Most have a fleshy red contractile head or belly
3. Most have a fibrous white non-contractile organized collage tendon
4. Some skeletal muscles are attached to organs like the eyeball, skin, and mucous membranes (tongue)
5. Organs of movement, stabilization, body form, and heat
6. Some skeletal muscles have their tendons form or attach into broad flat structures like aponeurosis
7. Named by basis of their shape, function, position, length, and attachment point
8. Muscle fibers can be replaced after an injury by myoblasts from satellite cells

Question 7

Flat skeletal muscles

Answer 7

Have parallel fibers often with an aponeurosis. Sartorius muscle (longest muscle) is a narrow flat muscle with parallel fibers

Question 8

Penate muscles

Answer 8

1. Feather-like belly fiber arrangement, uni, bi, and multi-pennant
2. Extensor digitorum longus (unipennate)
3. Rectus femoris (bipennate)
4. Deltoid (multitenant)

Question 9

Fusiform muscles

Answer 9

Spindle shaped with a round thick belly or bellies and tapered ends (biceps brachii)

Question 10

Convergent muscles

Answer 10

Muscles that originate from broad areas of attachment to a narrow area of insertion into bone (pectoral is major)

Question 11

Quadrate muscles

Answer 11

Skeletal muscles that have four equal sides (rectus abdominals between tendonous intersections)

Question 12

Circular muscles

Answer 12

Circular or sphincteral muscles surround a body opening or orifice (orbicularis oculi)

Question 13

Multiheaded/multibellied muscles

Answer 13

Muscles that have more than one head (belly) of attachment

Question 14

Contraction of muscles

Answer 14

1. Skeletal muscles function by contracting (pulling NEVER pushing)
2. During contraction one muscle end remains fixed while the other end is pulled towards it
3. The proximal end (origin) stays fixed while the distal end (insertion) is the point of movement or action
4. Some muscles can act in both directions under different circumstances, such as weight bearing (closed chain) and non-weight bearing (open chain)

Question 15

Types of contractions

Answer 15

Reflexive, tonic, and phasic

Question 16

Reflexive contraction

Answer 16

Skeletal muscles are voluntary, but some contraction is autonomic

Question 17

Tonic contraction

Answer 17

When relaxed, muscles of a conscious person are slightly contracted, this slight contraction is called muscle tone, no movement but gives muscles their firmness, supports posture, readiness for contraction when called upon

Question 18

Phasic contractions

Answer 18

Two phases:
1. Isometric - muscle length remains the same during contraction (no motion)
2. Isotonic - muscle changes its length and produces motion at insertion

Question 19

Concentric isotonic contractions

Answer 19

Causes the muscle to shorten

Question 20

Eccentric isotonic contraction

Answer 20

Muscle is lengthening while contracting

Question 21

What is the structural unit of a muscle?

Answer 21

Striated muscle fiber

Question 22

What is the functional unit of a muscle?

Answer 22

Motor unit

Question 23

Muscle contraction physiology

Answer 23

1. A nerve impulse reaches the end of a motor neuron and triggers release of the neurotransmitter acetylcholine (ACh)
2. ACh diffuses rapidly across the gap of the neurotransmitter junction and binds to ACh receptors on the motor endplate of the muscle fiber
3. Stimulation of ACh receptors initiates an impulse that travels across the sarcolemma through the tubules, to the sacs of the sarcoplasmic reticulum (SR)
4. Ca++ is released from the SR into the sarcoplasm, where it binds to troponin molecules in the thin filaments
5. Tropomyosin molecules in the thin myofilaments shift and expose actins active sites
6. Energized myosin cross bridges of thick myofilaments bind to actin and use their energy to pull thin myofilaments toward the center of each sarcomere
7. The cycle repeats itself many times a second, as long as adenosine triphosphate (ATP) is available

Question 24

Hiltons law

Answer 24

“Rule of thumb”, nerves supplying a joint also supply the muscles moving the joint, and skin covering their distal attachments

Question 25

Functions of muscles

Answer 25

Prime mover, fixation, synergist, antagonist

Question 26

Prime mover

Answer 26

“Agonist”. Main muscle responsible for producing a specific movement (isotonic concentric contraction)

Question 27

Fixator

Answer 27

A muscle that steadies proximal part of limb through isometric contraction while movement occurs to distal limb part

Question 28

Synergist

Answer 28

Compliments the action of the prime mover directly, or as a fixator of intervening joint the prime mover is acting on

Question 29

Antagonist

Answer 29

A muscle that opposes the action of another muscle. A primary antagonist directly opposes a primary mover. Antagonists eccentrically contract to ensure a smooth movement of limb

Question 30

Energetics

Answer 30

A branch of science dealing with the. Properties of energy and how it is redistributed in physical, chemical, and biological processes

Question 31

3 metabolic pathways

Answer 31

Phosphagen, glycolytic, oxidative

Question 32

Phosphagen pathway

Answer 32

Activated during the first 10-20 seconds of high intensity exercise and it fueled by ATP-CP (anaerobic)

Question 33

Glycolytic pathway

Answer 33

The primary system for exercise lasting 15 seconds - 3 minutes. Stored glucose used in muscle to form ATP. This pathway creates a lactic acid build up, causing fatigue. (Aerobically or anaerobically)

Question 34

Oxidative pathway

Answer 34

Requires oxygen (aerobic), increased respiration rate meets oxygen demand. System is slow but most efficient pathway. Uses fat as primary energy substrate for moderate intensity activity