Chp. 7 Muscular System Flashcards by Kayleigh S

contractile tissue that comprises the muscles in the walls of internal organs

smooth muscle

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cardiac muscle

heart muscle consisting of striated muscle cells that interlock

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skeletal muscle

contractile tissue that comprises the muscles attached to the skeleton

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striated

has stripes

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intercalated disk

membranous boundary between adjacent cardiac muscle cells

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muscle

soft tissues

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fascicle

small bundle of muscle fibers

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muscle fiber

muscle cell

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epimysium

top layer of connective tissue in a muscle

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perimyseum

middle layer of connective tissue in a muscle

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endomysium

lower layer of connective tissue in a muscle

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tendon

tissue that connects muscle to bone

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myofibril

Contractile portion of muscles fibers

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actin

one of the two major proteins of muscles; makes up thin myofilaments in myofibrils of muscles cells

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myosin

thick myofilament in myofibrils that is made of protein and is capable of breaking down ATP

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thin filament

filament made up of actin

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thick filament

filament made up of myosin

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synaptic cleft

small gap between the synaptic knob on one neuron and the dendrite on another neutron

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neurotransmitter

Chemical made at the ends of axons that is responsible for transmission across a synapse

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acetylcholine

neurotransmitter secreted at the ends of many neurons; responsible for the transmission of a nerve impulse across a synaptic cleft

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troponin

a globular protein complex involved in muscle contraction. It occurs with tropomyosin in the thin filaments of muscle tissue.

tropomyosin

a protein involved in muscle contraction. It is related to myosin and occurs together with troponin in the thin filaments of muscle tissue.

power stroke

When actin pulls during the contraction cycle

creatine phosphate

the main high-energy, phosphate-storage molecule of muscle

cellular respiration

the process by which organisms use oxygen to break down food molecules to get chemical energy for cell functions

fermentation

glucose turns into lactic acid and produces 2 ATP

lactic acid

a chemical your body produces when your cells break down carbohydrates for energy

all-or-none law

a muscle fiber contracts completely or not at all

muscle twitch

a single contraction that lasts only a fraction of a second

motor unit

a nerve fiber together with all of the muscles fibers it innervates; obeys all-or-none law b/c all fibers are stimulated at once

recruitment

increase in the number of motor units activated as intensity of stimulation increases

atrophy

wasting away or decrease in sized of an organ or tissue

hypertrophy

increase in muscle size

origin

end of a muscle that is attached to a relatively immovable part

insertion

end of a muscle that is attached to a movable part

prime mover

muscle most directly responsible for a particular movement

synergist

muscle that assists the action of the prime mover

antagonist

muscle that acts in opposition to a prime mover

Muscles contract when the thin (actin) and thick (myosin) filaments move past each other, shortening the skeletal muscle cells

What is the sliding filament theory of muscle contraction?

SMOOTH: - cells are tapered and rod shaped; not striated; 1 nucleus - involuntary, rhythmic CARDIAC: - cells are branched and striated; 1 nucleus; intercalated disks - involuntary, rhythmic, strong contractions SKELETAL: - cells are striated; multiple nuclei - voluntary; strong contractions

What are the differences the three types of muscles?

SMOOTH: - internal organ walls, blood vessels CARDIAC: - heart SKELETAL: -attached to skeleton

Where are the three types of muscles located?

1. support the body and oppose gravity 2. movement 3. facial expressions 4. help move fluid through lymphatic vessels and veins 5. protection 6. joints 7. homeostasis

What are the functions of muscles?

A motor unit innervate

How are muscle fibers innervated?

During muscle contraction, the myosin head groups attach to actin and pull the mtoward the center of the sarcomere, which causes the sarcomere to shorten.

How do muscle fibers contract?

1. Creatine phosphate 2. Respiration 3. Fermentation 4. Free ATP (used up in seconds)

Identify the sources of ATP used in muscle contraction.

SLOW-TWITCH: - aerobic - type 1 fibers - steady power -endurance FAST-TWITCH: - anaerobic - type 2 fibers - explosive power - fatigues easily

Contrast slow-twitch and fast-twitch muscle fibers.

muscle mass and strength is replaced by connective tissue, which is eventually replaced by fat; mitochondria degenerates with age; endurance decreases

How do muscles change as we age?

Frontalis

wrinkles skin of forehead, elevates eyebrows; draws scalp anteriorly

Orbicularis oculi

depresses upper eyelid, elevates lower eyelid, tightens skin around eyes

Nasalis

compresses bridge, depresses tip of nose; elevates corners of nostrils

Masseter

elevates mandible and closes jaw

Temporalis

elevates and retracts mandible