Anatomy + Physiology - Chapter 6 - Muscle Cells

50%

percentage amount of body mass muscle is

Contract

muscles are responsible for all types of body movement due to unique ability to _________

Skeletal, Smooth, Cardiac

three basic types of muscle found in body

Skeletal + Smooth

muscle types that are elongated

Fiber

muscle cell is the same as muscle _____

Microfilaments (Myofilaments)

contraction of muscles is due to the movement of this type of filament

Muscle

what do the roots myo and mys mean?

Flesh

what does the root sarco mean?

Skeletal

muscle type that:

- most are attached by tendons to bones

- cells are multinucleate

- straited and have visible banding

- voluntary, contract rapidly, great force, tire easily

- cells are surrounded by and bundled up by connective tissue

- largest and longest muscle fibers

Endomysium

connective tissue layer around a single muscle fiber

Perimysium

connective tissue layer around group of muscle fibers

Epimysium

connective tissue layer that covers the entire skeletal muscle "overcoat"

Fascia

connective tissue layer on the outside of perimysium

Epimysium

layer of connective tissue that blends into a connective tissue attachment

Tendon

cord-like connective tissue structure

Aponeurosis

sheet-like connective tissue structure

Bones, Cartilages, Connective Tissue Coverings

sites of muscle attachment (3)

Smooth

muscle type that:

- has no striations

- spindle-shaped cells

- uninucleate

- involuntary, slow sustained contraction

- propels substances along a pathway

- found mainly in the walls of hollow organs (stomach, bladder, resp tract)

Cardiac

muscle type that:

- has striations

- usually uninucleate

- joined to another muscle at an intercalated disc

- involuntary

- found only in heart where it serves as a pump to propel blood

All Types

which muscle types produce movements?

Skeletal

which muscle types maintain posture?

Skeletal

which muscle types stabilize joints?

Skeletal

which muscle types generate heat?

Multinucleate

muscle cells generally have many nuclei, or are _____________

Sarcolemma

specialized plasma membrane surrounding a muscle fiber

Sarcoplasmic Reticulum

specialized smooth endoplasmic reticulum (SR)

- sends final "go" signal for muscle contraction

Myofibrils

bundles of myofilaments

- align to give distinct bands

- I band = light

- A band = dark

Z Disc

midline interruption (darker area) in i band

H Zone

lighter central area of A band

M Line

in middle of the h-zone; tiny protein rods that hold together adjacent filaments

Sarcomere

contractile unit of a muscle fiber; z to z

Myosin (Thick) Filament

filaments that have ATPase enzymes; splits ATP to release energy

Actin (Thin) Filaments

filaments that are composed of actin and regulatory proteins that allow/prevent myosin heads from binding to actin

Myosin Filaments

filaments that have heads (extensions, or cross bridges)

Overlap

myosin and actin filaments _______ somewhat

Bare

when at rest, there is a ____ zone that lacks actin filaments

Irritability

activity to receive/respond to a stimulus

Contractility

ability to shorten (unique to muscle tissue)

Nerve

skeletal muscles must be stimulated by a _____ to contract

Motor Unit

one neuron + the muscle cells signaled by that neuron

Neuromuscular Junction

association site of nerve and muscle

Synaptic Cleft

gap between nerve and muscle

- area is filled with interstitial fluid

Neurotransmitter

chemical released by nerve upon arrival of nerve impulse (acetylcholine for skeletal muscles)

Graded Responses

different degrees of skeletal muscle shortening

Twitch

type of graded response:

- single, brief contraction

- not a normal muscle function

Tetanus

type of graded response:

- summary of contractions

- one contraction is immediately followed by another

- the muscle does not completely return to a resting state

Unfused Tetanus

type of graded response:

- some relaxation occurs between contractions

- the results are summed

Fused Tetanus

type of graded response:

- no evidence of relaxation before next contractions

- the result is a sustained muscle contraction

Seconds

Only 4-6 _______ worth of ATP is stored by muscles

Direct Phosphorylation

pathway for energy for muscle contraction that uses creatine phosphate, exhausted in about 15-20 seconds

Oxygen Debt

common reason for muscle fatigue (unable to contract)

Isotonic

contraction type where myofilaments are able to slide past each other during movement /contractions and the muscle shortens (flex elbow)

Isometric

contraction type where tension in the muscles increases and the muscle is unable to shorten (hold a plank)