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Muscle has four major functional characteristics: contractability, excitability, extensibility, and elasticity.
Contractability is - the capacity of muscle to contract or shorten forcefully
Excitability is - respond to stimuli
Extensibility is - stretching
Elasticity is - returning to its original shape
When does lactic acid build up in our body? Due to lack of excercise
skeletal muscle "voluntary muscle" generally attached to bone
striated muscles "striped" skeletal muscle
smooth muscle "involuntary muscle" functions automatically
visceral muscle smooth muscle generally found in the walls of the viscera; functions automatically
non-striated muscle smooth muscle that does not appear striped
smooth muscle tone a state of continuous partial contraction of smooth muscle
cardiac muscle found only in the heart, where it functions to pump blood throughout the body
intercalated discs junctions where cardiac muscle cells fit together tightly; Rings that provide a strong connection between cardiac muscle cells, to prevent tears and leaks in the heart.
belly the enlarged fleshy body of the muscle between the slender points of attachment; composed of thousands of muscle fibers (muscle cells)
fascia layers of tough connective tissue that surrounds large skeletal muscle
epimysium the outer layer of fascia; Connective tissue layer surrounding an individual muscle
perimysium a layer of connective tissue that surrounds smaller bundles of muscle fibers
fascicles bundles of muscle fibers
endomysium A layer of connective tissue that surrounds individual muscle fibers
tendon a line cordlike structure that connects muscle to bone
compartment syndrome "crush syndrome"; when the muscle and nerves are deprived of oxygen and nourishment and begin to die
aponeurosis a flat sheet-like fascia that connects muscle to muscle or muscle to bone
sarcolemma a cell membrane that surrounds the nucleus of a muscle cell
transverse tubules "T tubules"; Deep infoldings in the sarcolemma that help propagate a muscle impulse
sarcoplasmic reticulum a specialized endoplasmic reticulum within the muscle fiber
myofibrils long cylindrical structures that each muscle is composed of
sarcomeres a series of contractile units that each myofibril is made up of
thin and thick filaments a unique arrangement of contractile proteins
thin filament a unique arrangement of contractile proteins; composed of actin and the troponin-tropomyosin complex
actin a protein of a thin filament; contains binding sites for the myosin
myosin A type of protein filament that interacts with actin filaments to cause cell contraction; makes up nearly half of the proteins in muscle cells.
troponin-tropomyosin complex regulates contraction function of actin and myosin
myosin heads extends from the thick myosin filaments; are along the entire length of the filament in smooth muscle
cross-bridges temporary connections formed when the myosin heads make contact with the myosin-binding sites on the actin
somatic motor nerve the type of nerve that supplies the skeletal muscle
motor neurons a motor nerve composed of many nerve cells
motor unit consists of a single motor neuron and the muscle fibers that are supplied by the motor neuron
recruitment the consequences of activation of additional motor units
neuromuscular junction "NMJ"; the area where the motor neuron meets the muscle
neurotransmitter a chemical substance that fills membranous pouches
acetylcholinesterase aka "cholinesterase"; an enzyme that is found within the NMJ, near the muscle membrane
tetanus "lockjaw"; sustained muscle contraction; a condition caused when the bacterium (Clostridium tetani) secretes a neurotoxin that causes excessive firing of the motor nerves. This causes excessive release of ACh,
botulism a very serious form of food poisoning; a disease caused by secretion of the bacterium (Clostridium botulinum) which appears most often when food has been improperly processed and canned.
spastic paralysis caused by an excess of ACh activity; a state of continuous muscle contraction
flaccid paralysis caused by a deficiency of ACh activity; a state in which the muscles are limp and unable to contract
twitch when a single electrical stimulus is delivered to a muscle fiber; the muscle fiber contracts and then fully relaxes
tonus muscle tone; refers to a normal continuous state of partial muscle contraction
creatine phosphate a storage form of energy that can be used to replenish ATP quickly during muscle contraction
muscle fatigue the inability of a muscle to contract forcefully following prolonged activity.
origin attaches muscle to the stationary bone
insertion attaches muscle to the more movable bone
prime mover "chief muscle"
synergists "helper muscles"; work with other muscles
antagonists muscles that oppose the action of another muscle
hypertrophy the response to overuse of a muscle
atrophy when prolonged inactivity results in the muscles getting smaller in size
contracture "frozen muscle" a abnormal formation of fibrous tissue within the muscle; freezes the muscle in a flexed position and severely restricts joint mobility
Created by: Abraham321