Chapter 9: Muscles & Muscle Tissue Flashcards
muscle functions
produce movement
maintain posture & body position, and stabilize joints
support soft tissues
guard body entrances & exits
maintain body temperature
types of muscle
skeletal muscles
cardiac muscles
smooth muscles
skeletal muscles
attached to bones or (some facial muscles) to skin
cardiac muscles
walls of the heart
smooth muscles
unitary muscle in walls of hollow visceral organs; multi unit muscle in intrinsic eye muscles, airways, large arteries
origin
attachment to immovable or less moveable bone
insertion
attachment to moveable bone
muscle fiber
skeletal muscle cell
muscle fascicle
a bunch of muscle fibers
epimysium
surrounds entire skeletal muscle, continuous with tendons
dense irregular connective tissue
perimysium
separates adjacent muscle fascicles, vessels & nerves travel through
fibrous connective tissue
endomysium
surrounds single muscle fiber
areolar connective tissue
sarcolemma
cell membrane of muscle fibers
sarcoplasm
cytoplasm of muscle fiber
does a muscle fiber have more than one mitochondria or just one?
multiple mitochondria
glycosomes
carry stored glycogen
myoglobin
stores oxygen
myofibrils
contain contractile elements
sarcoplasmic reticulum & T tubules
stimulate and coordinate muscle contractions
what are T Tubules?
tubular extension of sarcolemma that extend deep into sarcoplasm
what does action potential in T tubules cause?
release of calcium by the sarcoplasmic reticulum
what does the sarcoplasmic reticulum surround?
tubular network around each myofibril
what does the sarcoplasmic reticulum do?
regulates levels of calcium & storage site of calcium
myofibril
organized collection of myofilaments
myofilaments
fine protein filaments
how many myofibrils are in one muscle fiber?
100s-1000s
how much of the cellular volume is myofibrils?
80%
sarcomere
function unit of skeletal muscle
characteristics of thick filaments
bundle of myosin
club-shaped head
head binds to active binding site of actin
characteristics of thin filaments
twisted strand of actin
active site on actin
tropomyosin
binds to active site of actin at rest
troponin
binds to tropomyosin and calcium
elastic filaments
composed of protein titin
dystrophin
links thin filaments to proteins of sarcolemma
nebulin, myomesin, C proteins bind filaments, sarcomeres together
maintain alignment of sacromere
what elicits/causes the contraction?
neurons stimulate the sarcolemma/T-tubules via neurotransmitter at the neuromuscular junction
true or false: each muscle fiber is controlled by a motor neuron
true
motor unit
motor neuron and all the muscle fibers it innervates
what are the 4 steps that must occur for skeletal muscle to contract?
1.) events at the neuromuscular junction
2.) muscle fiber excitation
3.) excitation-contraction coupling
4.) cross bridge cycling
steps in the neuromuscular junction:
1.) AP in prestnaptic neuron
2.) Ca+ voltage-gated channels open causing Acetycholine (ACh) to be released
3.) ACh diffuses across the cleft
4.) ACh binds to receptors on sarcolemma
5.) Binding of ACh causes an EPSP
6.) Excitatory graded potential travels along the sarcolemma
7.) AP is stimulated in the sarcolemma
8.) AP travels along sarcolemma to the T tubes
excitation-contraction coupling steps:
1.) AP in T-tubules cause shape change in voltage-sensitive tubule protein
2.) Calcium is released into the sarcoplasm
3.) Calcium binds to troponin
4.)Tropomyosin moves away from actin active binding sights
5.) Myosdin can now bind to actin and form a cross bridge in the presence of ATP
