Muscle Tissue

Question 1

functions of muscle tissue

Answer 1

movement, posture maintenance, and generation of body heat

Question 2

special properties of muscle tissue

Answer 2

contractility, excitability, extensibility, and elasticity

Question 3

sarcolemma

Answer 3

plasma membrane of muscle cells

Question 4

sarcoplasm

Answer 4

cytoplasm of muscle cells that contains organelles like:
- mitochondria
- glycogen (for energy production)
- myoglobin (for oxygen storage)

Question 5

skeletal muscle

Answer 5

• striated
• voluntary movements
• attached primarily to bones
• multiple nuclei per cell

Question 6

cardiac muscle

Answer 6

• striated
• involuntary control
• forms most of the heart
• single nucleus

Question 7

smooth muscle

Answer 7

• nonstriated
• involuntary
• walls of hollow internal structures (visceral)
• single nucleus

Question 8

fibrous connective tissue

Answer 8

makes up skeletal muscle alongside muscle cells

Question 9

fascia

Answer 9

a sheet or band of fibrous connective tissue that is deep to the skin and surrounds muscles and other organs of the body

Question 10

superficial fascia (subcutaneous layer)

Answer 10

separates muscle from skin and functions to provide a pathway for nerves and blood vessels, stores fat, insulates, and protect muscles from trauma

Question 11

deep fascia

Answer 11

lines the body wall and limbs and holds muscles with similar functions together, allows free movement of muscles, carries nerves, blood vessels, and lymph vessels, and fills spaces between muscles

Question 12

epimysium

Answer 12

extension of the deep fascia covering the entire muscle

Question 13

perimysium

Answer 13

extension of the deep fascia covering the fascicles

Question 14

endomysium

Answer 14

extension of the deep fascia covering individual fibers

Question 15

tendon

Answer 15

a cord of dense connective tissue that attaches a muscle periosteum of a bone

Question 16

aponeurosis

Answer 16

a tendon that extends as a broad, flat layer

Question 17

origin

Answer 17

attachment of muscle tendon to stationary bone

Question 18

insertion

Answer 18

attachment of other muscle tendon to movable bone

Question 19

tendonitis

Answer 19

inflammation of tendons and synovial membranes surrounding certain joints

Question 20

intramuscular injections

Answer 20

used to administer relatively large doses (up to 5 mL) of drugs that could be dangerous or even fatal if injected into the bloodstream; cause less tissue irritation than subcutaneous injections and are absorbed more quickly

Question 21

fascicle

Answer 21

single bundles of cells (fibers)

Question 22

muscle fiber

Answer 22

a single muscle cell
- long, cylindrical, multinucleate cells formed by the fusion of embryonic myoblasts
- number of these cells is set before you are born
- most last a lifetime

Question 23

hypertrophy

Answer 23

muscle growth occurs this way, an enlargement of existing muscle fibers

Question 24

myofibrils

Answer 24

• specialized contractile organelles in skeletal muscle tissue
• parallel and threadlike
• contain contractile proteins (myofilaments)
• form the light and dark striations

Question 25

T tubules

Answer 25

tiny invaginations of the sarcolemma that quickly spread the muscle action potential to all parts of the muscle fiber

Question 26

sarcoplasmic reticulum

Answer 26

encircles each myofibril and is similar to smooth endoplasmic reticulum *stores calcium ions*

Question 27

myofilaments

Answer 27

- composed of thick (myosin) and thin (actin) filaments (proteins) - arranged in units called sarcomeres

Question 28

sarcomere

Answer 28

- repeating subunit along myofibrils - basic unit of contraction in skeletal muscle

Question 29

myosin

Answer 29

- main component of thick filaments - functions as a motor protein (converts energy from ATP into mechanical energy of motion or force)

Question 30

actin

Answer 30

- main component of thin filaments - connects to the myosin for the sliding together of the filaments

Question 31

contractile proteins

Answer 31

actin and myosin

Question 32

regulatory proteins

Answer 32

tropomyosin and troponin

Question 33

tropomyosin

Answer 33

blocks myosin-binding sites on actin, preventing myosin from binding there

Question 34

troponin

Answer 34

holds tropomyosin in place

Question 35

structural proteins

Answer 35

titin and dystrophin - keep thick and thin filaments in alignment, give myofibril elasticity and extensibility, link myofibrils to the sarcolemma and ECM

Question 36

titin

Answer 36

elastic protein that helps a sarcomere return to its resting length after a muscle has contracted or been stretched

Question 37

dystrophin

Answer 37

enormous protein located between the sarcolemma and outermost myofilaments that links actin filaments to a peripheral protein on the inner face of the sarcolemma

Question 38

somatic motor neurons

Answer 38

nerve cells with cell bodies in the brainstem and spinal cord that stimulate muscle fibers via their axons, called somatic motor fibers

Question 39

motor unit

Answer 39

a single motor fiber and all the muscle fibers it innervates - small motor units present where fine control is needed (like eye movement) - large motor units present where strength is more important that fine control (like gastrocnemius)

Question 39

neuromuscular junction

Answer 39

synapse between a somatic motor neuron and a skeletal muscle fiber

Question 40

action potential

Answer 40

nerve impulse that travels down the motor neuron to the axon terminal and causes release of the neurotransmitter acetylcholine

Question 41

acetylcholine

Answer 41

neurotransmitter that binds to receptors on the sarcolemma of the muscle fiber and causes muscle contraction

Question 42

acetylcholinesterase

Answer 42

enzyme that is attached to the sarcolemma and breaks down acetylcholine into acetyl and choline fragments to stop stimulation of the muscle fiber

Question 43

muscle depolarization

Answer 43

travels along the sarcolemma, down T-tubules, causing release of calcium from sarcoplasmic reticulum into the sarcoplasm

Question 44

sliding filament mechanism

Answer 44

the sliding of filaments and shortening of sarcomeres causes the shortening of the whole muscle fiber and ultimately the entire muscle

Question 45

rigor mortis

Answer 45

a state of muscular rigidity following death that results from a lack of ATP to split myosin-actin cross bridges

Question 46

curare

Answer 46

- plant poison used on arrows and blowgun darts - causes muscle paralysis by blocking ACh receptors and inhibiting sodium ion channels - derivatives used during surgery to relax skeletal muscles

Question 47

botulinum toxin

Answer 47

- blocks release of ACh from synaptic vesicles - used as a medicine (Botox) for cosmetic and noncosmetic procedures

Question 48

myoglobin

Answer 48

an oxygen-storing reddish pigment found in muscle fibers

Question 49

slow oxidative (slow twitch) fibers

Answer 49

- red in color - resistant to fatigue - least powerful, smallest diameter - make ATP aerobically - lots of mitochondria - prolonged, sustained contractions - postural muscles

Question 50

fast oxidative-glycolytic

Answer 50

- pink in color - hand and eye muscles - lots of mitochondria, myoglobin, and blood vessels - split ATP at a very fast rate - walking, marathon running

Question 51

fast glycolytic (fast twitch)

Answer 51

- white in color - anaerobic activity for short duration - largest diameter - make ATP via glycolysis - fatigue quickly