BHS Muscle Physiology

epimysium

outermost layer of muscle

perimysium

connective tissue dividing muscles into fascicles

muscle fascicle

made of bundles of muscle fibers

endomysium

innermost connective tissue dividing fascicles into muscle fibers

sarcolemma

cell membrane of muscle cell

myosin

thick filament

actin

thin filament

myofibrils

cells in a skeletal muscle (filled with actin and myosin)

sarcomere

THE UNIT OF CONTRACTION IN A MUSCLE FIBER; repeating unit of myofilaments like actin and myosin

Z line

where actin is attached

sarcoplasmic reticulum

network of membranous channels around myofibrils; contains Calcium ions

motor neurons

neurons that control muscle contraction

neurotransmitters

chemicals that travel over synaptic cleft (like acetylcholine)

synaptic cleft

gap between motor neuron axis and motor end plate

sliding filament model

actin and mysoin (myosin pulls actin toward m line/middle) moving past each other to shorten sarcomere

acetylcholine

neurotransmitter for muscle contraction

Na+

stimulates electrical impulse by rushing into sarcolemma

Ca+

intiates sarcomere contraction

motor unit

A motor neuron and all of the muscle fibers it innervates

Glycolysis

first step in releasing the energy (2ATP) of glucose, in which a molecule of glucose is broken into two molecules of pyruvic acid

aerobic respiration

last energy pathway which gathers the most ATP (32-38ATP) but, oxygen must be utilized

motor end plate

synapse between the axon terminal of a motor neuron and the section of the membrane of a muscle fiber with receptors for the acetylcholine released by the terminal

sliding filament theory

theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still

TERM

Z disc

DEFINITION

Tendons

Connect muscle to bone. Made of very tough collagen fibers continuous with the fascia layer surrounding a muscle

Sarcolemma

Cell membrane of a muscle cell.

Myofibrils

Long fibers that make up muscle cells. Made of thick filaments (myosin) and thin filaments (actin) that contract the muscle.

Epimysium

A sheath of elastic tissue that surrounds an entire muscle and protects muscles from friction against bones and other muscles.

Perimysium

Holds the fascicles together, provides structural support for the muscle.

Endomysium

Connective tissue surrounding each individual muscle fiber. Contains nerves and blood vessels.

Fascicle

A bundle of muscle fibers.

Which types of muscle move voluntarily?

Skeletal muscle (not cardiac or smooth)

Z disc

Separates the sarcomeres from one another; where actin filaments intersect.

A band

The entire length of myosin.

I band

Thin filaments only.

H zone

Thick filaments only.

Do the lengths of actin and myosin change during a muscle contraction?

No. They just move so that they are overlapping more.