BIO 365S Lecture Notes - Lecture 17: Cardiac Muscle, Skeletal Muscle, Digestive Enzyme
Ch14: the electrical and
mechanical events of
the heart
Use skeletal muscle part to help understand how cardiac muscle
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contract.
When exercising, muscle contracts (physical distance becomes shorter)
= how able to create movement, because it attaches to two parts of the
bone. Both skeletal and cardiac muscle use fibers, and in smooth
muscle (striated pattern) also has thick and thin fibers but more evenly
spaced together – not designed to produce a big force (present in GI
tract, function is to mix food with digestive enzyme and push down in
one direct action, so not to produce a big force).
Thick filament, made of myosin (main protein).
Thin filament, made of 3 proteins, mainly actin.
Actin and myosin like to glue together.
Muscle fibers line up and overlap. These two filaments move together.
If only have these two filaments, would only do contraction and no
relaxation. These two filaments are like magnets, so has a piece of
paper that comes in b/w them and separate (tropomyosin - bind the
binding site of actin; actin and myosin still attach but not as long;
usle o’t otrat as hard ut ill if eed to ia sesor = tropoi,
detect signal to trigger muscle contraction via Calcium, when bound,
asks tropomyosin to move away so myosin and actin and bind together
strongly).
ATP function is NOT on muscle contraction. Its function is for muscle
RELAXATION, detachment of myosin part requires ATP.
Beause usle otratio does’t eed ATP et, he people are
dead = rigid, rigor ortis, do’t hae ATP for relaatio so alas
contract. When muscle contract, create crossbridge structure and
powerstroke = physical distance b/w muscle becomes shorter. When
done, detaches, head moves even closer and then detach.
Skeletal uses a lot of calcium and ATP.
Cardiac muscle is the same molecularly. Also uses actin and myosin,
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Document Summary
Ch14: the electrical and mechanical events of the heart. Use skeletal muscle part to help understand how cardiac muscle contract. When exercising, muscle contracts (physical distance becomes shorter) = how able to create movement, because it attaches to two parts of the bone. Thin filament, made of 3 proteins, mainly actin. If only have these two filaments, would only do contraction and no relaxation. Be(cid:272)ause (cid:373)us(cid:272)le (cid:272)o(cid:374)tra(cid:272)tio(cid:374) does(cid:374)"t (cid:374)eed atp (cid:455)et, (cid:449)he(cid:374) people are dead = rigid, rigor (cid:373)ortis, do(cid:374)"t ha(cid:448)e atp for rela(cid:454)atio(cid:374) so al(cid:449)a(cid:455)s contract. When muscle contract, create crossbridge structure and powerstroke = physical distance b/w muscle becomes shorter. When done, detaches, head moves even closer and then detach. Skeletal uses a lot of calcium and atp. Also uses actin and myosin, also has fibers lined up pretty well (striated pattern), need calcium to treat (cid:373)us(cid:272)le (cid:272)o(cid:374)tra(cid:272)tio(cid:374). Signal initiated by motor cortex; consciousness decides which muscle you want to move.
