Muscles Flashcards
characteristics of muscles
excitability, contractility, extensibility, elasticity
excitability
ability of muscle tissue to receive and respond to stimuli
contractility
ability to shorten and thicken, contract, when a sufficient stimulus is received
extensibility
he ability of muscle tissue to be stretched
elasticity
ability of muscle to return to its original shape after contraction
3 functions of muscles
motion, posture and heat production
skeletal
striated, long cylindrical, multinucleated, voluntary and found anywhere attached to bone
fascia
sheet/ broad band of fibrous connective tissue beneath the skin/around muscles and other organs
superficial fascia
immediately deep to the skin, adipose tissue and loose connective
deep fascia
dense connective tissue that lines the body wall and extremities and holds muscles together separating them into functioning groups
epimysium
fascia around the entire muscle
fascicles
muscle bundles
perimysium
fascia around fascicles
endomysium
fascia around each muscle fiber
tendons
fibrous connective tissue that connects muscle fascia to perostium of the bone
tendon sheaths
tubes of fibrous connective tissue that encloses certain tendons
origin
less moveable end
insertion
more moveable end
what kind of nerve and blood supply penetrates a skeletal muscle
one artery and one or two veins, long winding capillaries go within endomysium, each skeletal muscle fiber usually makes contact with a portion of nerve cell called synaptic end bulb
sarcolemma
cell membrane of muscle fiber
sarcoplasm
cytoplasm of muscle cell
what is the sarcoplasmic reticulum
specialized smooth ER that regulates calcium concentration
where is the sarcoplasmic reticulum found
in muscle fibers
what are the terminal cisternae
internal sacs
what are T tubules
transverse tubules that are extensions of sarcolemma that conduct impulses from sarcolemma down into the cell
what are myofibrils
tiny structures found in muscle fibers
what are the 2 types of myofilaments
actin and myosin
thin filaments
actin
thick filaments
myosin
When the sarcomere shortens, what happens, if anything, to the I band, to the H zone, and to the A band
While the I band and H zone will disappear or shorten, the A band length will remain unchanged.
what is a muscle fiber
composed of fibrils, surrounded by sarcolemma
What are the myosin filaments composed of
head/cross bridges, ATP and actin binding sites
what are the actin filaments composed of
actin (f & g) tropomyosin, and troponin
where are the actin and ATP binding sites found
myosin
where are the myosin-binding sites found
actin
what might be covering the myosin binding sites
tropomyosin
troponin has a high affinity for 3 different substances
actin, tropomyosin and calcium ions
when a calcium ions bind with troponin what happens to the troponin tropomysin complex? What then happens?
moves to expose active sites on actin and no more tropomysin covering myosin
Where is the ATP binding and what happens
ATP binding is at the head of myosin releasing actin and myosin, then myosin head returns to original position
motor neuron
neuron that stimulates muscle tissue
what is a neuromuscular junction
axon terminal of a motor neuron along with the portion of the sarcolemma that is close to the axon terminal
what is a synapse
junction where signal is passed
name the neurotransmitter used at neuromuscular junctions
acetylcholine
substance that binds with acetylcholine and breaks down acetic acid and choline
acetylcholinesterase
motor unit
motor neuron and all muscle fibers that it stimulates
are all motor neurons the same size
no relationship between muscle cell size
eccentric contraction
Eccentric contraction occurs when the total length of the muscle increases as tension is produced
concentric contraction
the muscle tension rises to meet the resistance then remains stable as the muscle shortens.
isometric contraction
a muscle contraction without motion
isotonic contraction
tension remains the same, whilst the muscle’s length changes.
synapse
the points of contact between neurons where information is passed from one neuron to the next
