Lecture 9.1 Flashcards
main function of muscle
create motion, stabilize body positions and maintain posture, store substances within organs using sphincters, move substances through the body by peristaltic contractions, generate heat through thermogenesis
how is muscle tissue and nervous tissue similar
both are excitable, or “irritable”
they have the ability to respond to stimulus
how are muscle tissue and nervous tissue different
muscles are contractible, extensible, and elastic
what prefixes indicate muscle tissue
myo, mys, and sarco
properties of skeletal muscle
organs attached to bones and skin, elongated cells called muscle fibers, striated, multinucleate, voluntary , require nervous system stimulation for contraction
skeletal muscle fibers are also called what
skeletal muscle cell
properties of cardiac muscle
only in the heart (bulk of heart walls), branched short cells, striated, uni or binucleate, does not require nervous system for stimulation, involuntary
properties of smooth muscle
in walls of hollow organs (stomach, urinary, etc), non striated, uninucleate, can contract with or without nervous system stimulation, involuntary
each muscle is served by one artery, one nerve, and one or more veins. where do they enter and exit
near central part and branch through connective tissue sheaths
each muscle is served by one artery, one nerve, and one or more vein. by what and how is a skeletal muscle fiber controlled
supplied by a neuron ending that controls its activity
when contracting, what happens to the metabolic rate of muscle and how does that affect nutrient requirement and waste generation
high metabolic rate when contracting, uses large amounts of ATP, huge nutrient and oxygen needed, generates a lot of waste
connective tissue sheaths of muscle and their properties
epimysium - dense irregular connective tissue surrounding the entire muscle (may blend with fascia)
perimysium - fibrous connective tissue surrounding fascicles
endomysium - fine areolar connective tissue surrounding each individual muscle fiber
fascicles
groups of 10-100 muscle fibers, form the grain in meat (pulled pork analogy)
where does skeletal muscle attach
insertion - movable bone
origin - less moveable or immovable bone
what is the difference between direct and indirect attachment of skeletal muscle
direct - epimysium fused to periosteum of bone or perichondrium of cartilage
indirect - connective tissue wrappings extend beyond muscle as rope-like tendon or sheetlike aponeurosis
what is muscle fascia and what does it do
covers many muscles
what is an example of fascia from the powerpoints
fascia lata - envelopes the entire group of quadriceps and hamstring muscles
what is typically found traversing deep fascia
veins, arteries, and nerves
what is an aponeurosis
a thick flat fascia that connects two muscle bellies
epicranial aponeurosis connects what two muscles
occipitalis and frontalis which connects to form the occipitofrontalis
sarcolemma definition
plasma membrane of muscle cell
sarcoplasm defintion
cytoplasm of muscle cell
where are glycosomes found and why are they important
found is the sarcoplasm, they contain glycogen
(when sarcoplasmic glucose falls, glycogen stores can be hydrolyzed to provide glucose for ATP)
what is myoglobin, where is it found, why is it important
globular protein found only in muscle cells, binds oxygen that diffuses into the muscle cell from the interstitial fluid, releases oxygen when mitochondria needs to make ATP, function as quick oxygen reserve sarcoplasmic oxygen levels decline from high contractile rate leading to decrease blood flow
myofibril definition
densely packed rod like elements, about 80% of cell volume, contains sarcomeres (contractile units)
exhibit striations
what are striations
repeating series of dark A bands and light I bands
Transverse (T) tubules defintion
tunnels of sarcolemma that run from the surface of the muscle cell to the inner regions
open to the outside of the fiber and filled with interstitial fluid
muscle action potentials travel along sarcolemma and down into the T-Tubules
Sarcoplasmic reticulum definition
similar the smooth ER of typical cell, stores and releases calcium ions among many other functions
Triad definition
formed from a T-Tubule and two terminal cisterns
Terminal cisterns definition
dilated end sacks of the sarcoplasmic reticulum that butt against the T-tubules
allow for quick release of Calcium from the SR into the sarcoplasm when stimulated
sarcomeres definition
smallest contractile unit (functional unit) of skeletal muscle fibers
align like boxcars of a train
composed of thick and thin myofilaments made of contractile proteins
contains an A band with 1/2 of an I band at each end
Z-disc form sarcomere boundary
what are thin filaments of the sarcomere made of
actin myofilaments
twisted double strand of fibrous protein F actin
F actin consist of G (globular) actin subunits
what binding site is found on G actin in thin filaments
active site for myosin head attachment during contraction
what regulatory proteins are found on the thin filament
tropomyosin and troponin
what are thick filaments made of
composed of protein - myosin
each composed of two heavy and four light polypeptide chains
what composes the myosin tail in thick filaments
two interwoven heavy polypeptide chains - think shaft of golf club
what composes the myosin head in thick filaments
two smaller, light polypeptide chains per head that act as cross bridges during contraction
think head of golf club
what binding sites are on the myosin head
binding site for G actin of thin filaments
binding sit for ATP
myosin head is an ATPase
Titan (an elastic filament) performs what function in the sarcomere
holds thick filaments in place, helps recoil after stretch
also resists excessive stretching
what is the purpose of dystrophin
links thin filaments to proteins of sarcolemma
what is the purpose of nebulin, myomesium, and C-proteins
bind filaments or sarcomeres together, important in maintenance of alignment
