Muscle Physiology Flashcards
types of muscle tissue
cardiac, smooth, skeletal
functions of muscle
produce movement, maintain posture, stabilize joints, create heat as they contract
attachment of muscle to moveable bone
insertion
attachment of immovable bone or less moveable bone
origin
layer of dense irregular connective tissue surrounding entire skeletal muscle
epimysium
fibrous layer of connective tissue that separates muscle into small bundles called fascicles
perimysium
layer of fine areolar connective tissue surrounding each individual muscle fiber
endomysium
cordlike part that attaches a muscle to a bone
tendon
muscle that bends a joint
flexor
muscle that straightens a joint
extension
muscle composed of bundles of
fascicles
fascicles composed of bundles of
muscle fibers
muscle fibers composed of bundles of
muscle cells
plasma membrane of muscle fiber
sarcolemma
network of connective tissue that extends throughout the muscular system
fascia
cytoplasm of muscle fiber
sarcoplasm (contains glycosomes and myofibrils)
contractile organelle of muscle fiber
myofibril
cellular organelle, modified endoplasmic reticulum of muscle fiber
sarcoplasmic reticulum (stores calcium)
muscle impulse is generated and travels deep into the fiber via
transverse tubule
small sections of myofibrils
sarcomeres (from one z disc to another)
neuron
motor nerve fiber
site where an axon of a motor neuron and muscle fiber meet
neuromuscular junction
(motor end plate)
muscle fiber connected to an axon at a
synapses
a neurotransmitter released at motor end plates by the axon terminals
Acetylcholine (ACh)
breaks down ACh into its building blocks, rendering it inactive
Acetylcholinesterase
diffuses of ___ across/into the cell membrane resulting in depolarization
sodium ions (Na+)
final chemical messenger and “trigger” for muscle contraction. bonds to troponin
calcium ions (Ca+2)
activates synaptic vesicles in axon terminals to fuse with plasma membrane of axon terminal
calcium ions (Ca+2)
moves calcium back into sarcoplasmic reticulum at rest
calcium (Ca+2) pump
covers binding sites on actin
troponin-tropomyosin complex
consist of a motor neuron and all muscle fibers
motor unit
minimum strength of stimulation of a muscle fiber required to cause contraction
threshold stimulus
contractile response of a single muscle fiber to a single impulse
muscle twitch
muscle contracts and changes length
isotonic contraction
(concentric: shorten & eccentric: lengthen)
muscle contracts but does not change length
isometric contraction
provides energy for contraction
ATP
sources of ATP
direct phosphorylation, anaerobic pathway, aerobic pathway
for muscles to return to pre-exercise state:
oxygen reserve replenished/ lactic acid reconverted to pyruvic acid/ glycogen stores replaced/ ATP and creatine phosphate reserves resynthesized
force of contraction depends on number of cross bridges attached, which is affected by 4 factors:
number of muscle fibers stimulated/ relative size of fibers/ frequency of stimulation/ degree of stretch
3 types of skeletal muscle fibers
slow oxidative fibers- low intensity movements
fast oxidative fibers- medium intensity movements
fast glycolytic fibers- short term intense movements
increase in size of muscles
hypertrophy
decrease in size of muscles
atrophy
muscle fibers that are spindle-shaped, 1 nucleus, lack striations, lack t-tubes, lack connective tissue sheaths
smooth muscle
neurotransmitters for smooth muscles
Acetylcholine & Norepinephrine
other difference between smooth muscle and skeletal muscle
slower to contract and relax
maintains a forceful contraction longer
can change length without change in tautness
2 types of smooth muscle
multi-unit smooth muscle
unitary (visceral) smooth muscle
multi-unit smooth muscle
function as separate units, (iris of eye, walls of blood vessels), stimulated by neurons & hormones
unitary (Visceral) smooth muscles
respond as a unit, sheets of muscle fibers, held together by gap junctions, conduct peristalsis, walls of hollow organs, most common
