Lecture 15 & 16 Flashcards
What are the 3 types of muscle
skeletal
cardiac
smooth
striated muscle, voluntary movement, contraction regulated by the somatic n.s.
skeletal
striated muscle in heart, contraction regulated by the autonomic n.s.
cardiac
muscle in blood vessels, visceral tissues, contraction regulated by autonomic n.s.
smooth muscle
3 layers of connective tissue membranes
epimysium
perimysium
endomysium
layer of cells encasing entire muscle
epimysium
layer of cells encasing a bundle of muscle fibers
perimysium
layer of cells encasing individual muscle fibers
endomysium
cell membrane of individual muscle fibers
repeating unit that forms the myofibrils
sarcolemma
strand of interacting proteins (actin and myosin) that runs parallel to the length of the muscle
myofibrils
individual sacromeres separated by
z-disks
myofibrils are composed of what myofilaments (proteins)
thick (myosin)
thin ( 2 actin chains, trooponin, tropomyosin)
during muscle contraction, why does the sarcomere shorten?
there is a greater degree of overlap btwn the thick and thin filaments - NO CHANGES IN LENGTH
Muscle contraction needs what 3 things
ATP, nerve impulse (acetylcholine), and calcium
ATP is needed to do what in the sliding filament theory
separate actin from myosin from the previous contraction cycle
Myosin ATPase cleaves ATP to
ADP = Pi
attached to actin filaments and tropomysin, binds calcium
troponin
Ca2+ enters the cytoplasm due to
nerve stimulation
powerstroke
when thick and thin filaments slide over each other
smooth muscle contraction is dependent on
Ca2+ concentrations
single unit smooth muscle
“joined” by gap junctions
coordinated contraction
GIT, small blood vessels
multi-unit
cells as individual units, more direct neural control,
eyes, arteries, hair, erectors
cardiac cells are joined together with
intercalated disks
2 types of intercalated disks
gap junction and desmosomes
signals form one cell can move into another
gap junctions
hold cells tightly together
desmosomes
relationship between membrane depolarization and contraction
excitation-contraction coupling
releases Ca2+ upon membrane
sarcoplasmic reticulum
allows membrane depolarization deep into the muscle fiber
T-tubles
2 voltage gated calcium channels
T-tubules: DHRPs
Sarcoplasmic reticulum: RyR
distance btwn insertion (end of the muscle that attaches to the freely moving bone) and origin (end of muscle that attaches to the “fixed” bone in the joint) shortens
whole-muscle contraction
decreases joint angle
flexion
increases joint angle
extension
3 types of muscle fibers
1) slow oxidative
2) fast oxidative/glycolytic
3) fast glycolytic
