Muscle Physiology Terminology

Flashcards covering key terminology related to muscle physiology.

Skeletal Muscle

A type of voluntary striated muscle attached to bones.

Fascia

A thick layer of connective tissue that wraps around muscles.

Tendon

Connective tissue that attaches muscles to bones.

Endomysium

A thin layer of loose connective tissue surrounding each muscle fiber.

Perimysium

Connective tissue that surrounds a group of muscle fibers (fascicle).

Surrounding the skeletal muscle cells

Myofiber

An individual muscle cell.

Sacrolemma

The plasma membrane of a muscle fiber.

T-tubule

cross the diameter to skeleton muscle

Sarcoplasmic Reticulum

stores calcium ions.

Terminal Cisternae

Terminal Cisternae

dilated end-sacs of which cross musck fiber from one side to the other

Calcium Ion

An ion that binds to troponin to initiate muscle contraction.

Sacromere

The functional unit of muscle contraction, extending from one Z disc to the next.

Striation

The alternating light and dark bands found in skeletal muscle.

Myofilament

The two types of filaments in a muscle fiber: thick (myosin) and thin (actin and associated proteins, tropomin, and tropomyosin).

Motor Neuron

type of nerve cell transit signals from the brain and spinal cord to musle, enabing movements suches in voluntary/ involuntary actions.

Neuromuscular Junction (NMJ)

The synapse between a motor neuron and a muscle fiber.

Acetylcholine

A neurotransmitter that stimulates muscle contraction.

Motor Unit

A motor neuron and all the muscle fibers it controls.

Excitation-Contraction Coupling

Excitation-contraction coupling-link between the action potentials on the sacrolemma to interaction between the myofilaments

Cross-Bridge Cycling

The process of myosin heads binding to actin, pulling, and releasing during contraction.

Muscle Twitch

A single, brief contraction and relaxation cycle in a muscle fiber.

Tetanus

incomplete- Partial relaxation heteveen.

contraction

complete no relaxation between Contractions (Maximum tension).

Fatigue

Inability of muscle to maintain force of contraction after prolonged activity.

Isometric Contraction

Muscle contracts but does not change length.

Isotonic Contraction

Muscle changes length while maintaining constant tension.

ATPase

enzyme that breaks down ATP, found in myosin heads

Relaxation

muscle fiber relaxes and returning to its resting length.

Twitch phase: latent period

2 msec delay between the Onset of Stimulus and onset of twitch response

Contraction phase

muscle shortens

Twitch phase: Relaxation phase

Ca+2 removed from sacroplasm and tension declines, muscle returns. to resting length

Tension-

force produced by muscle fibers

Recruitment

-increasing the number of active motor units to produce more force.

Treppe

muscle still recovers fully between twitches, but each twitch develops more tension than the one be fore

Basal lamina

- thin layer surrounding the NMJ helping anchor components in place

Schwann cell

Glia cell that covers the NMJ and helps maintain it.

Acetylcholinesterase

enzyme that break. down Ach, stopping muscle simulation

Actional potential (impulse)

)- electrical signal. traveling along a neuron or muscle fiber or the T tubules

excitation

- process where a nerve signal leads to an action potential in a muscle fiber

Ligand gated ion-channels-

channels that open when a chemical like (ACh) binds to them.

Threshold

- minimum votage needed to trigger an action potential

voltage gated Ca+ channels

open in response to action potential, allowing calcium influx into sarcoplasm

Axon terminal

end of motor neurons axon

Synaptic knob:

swollen end of an axon at the NMJ, contains synaptic vesicles filled with Acetylocholine (ACh)

Synaptic vesicles

-small sacs containing a acetylcholine

Junctioned folds

- infolding of the sacrolemma at the NMJ to increase surface area for receptors

Innervation

a supply of nerves to a tissue or organ, such as motor neurons that Skeletal muscle for contraction.

nerve

a bundle of nerve fiber transmit electrical signals between the brain, spinal cord, and muscles. or other tissue

Nerve fiber

An individuals nerve cell process that transmit electrical impulse.

F-actin

-polymerized form of actin, consisting of two strands of G-actin molecules twisted together to form the thin filament of muscle fiber

Tropomyosin

-blocks myosin binding sites

Troponin

-it binds to calcium ions, causing conformational change that moves tropomyosin away from the myosin binding sites on actin

myosin; 1) head,’ 2) tail

head -the part of myosin bind to actin filament and use ATP for generate force for muscle contraction

Tail - achors protein within the thick filament and allows for the alignment of heads in a Specific direction

A-band

-width of Straining) thick filament (dark)

H band -

center of A Band - no thin filament overlap

m-line

bisect H Band

I-Band

connection zone of thin filaments. (Light staining)

2-bisc

- bisects. I band

G-Actin

have myosin head binding Site

triad

-a t-tubule and two terminal Cisterns

mult-nucleares

-flattened nuclei pressed against the inside of the sacrolemma.

myofibril

-collections of thick and thin filaments - Several next to one another long the length

fascicle

-- bundle of muscle fiber; surrounding by perimysium (a type connective tissue)

muscle (organ)

-responsiveness (excitability)

enidomysicom

- all blood vessel goes to the muscle cell for blood supply