skeletal muscles

what is the smallest component of the skeletal muscle

filaments or miofilaments: actin aka thin and myovin aka thick

what do multiple filaments combined make

a sarcomere

what do we get when we group sarcomeres

myofibril

what do you call multiple myofibril

a muscle fiber

multiple fibers are

a fassicle

multiple fassicles are called

muscle

what is the sarcolema

a muscle’s cell membrane

what surrounds the sarcollema

endomysium - endo means inside mysium means muscle and they also wrap around the muscle fibers

whats directly around the endomysium

paramysium

what detrmines the shape of a muscle

the fassicle arrangement

tru or false the dibers of a fassicle are not parallel

false they are all parallel within a fassicle

whats the tissue that surrounds and hikd the fassicles together

epimysium

whats a fascicle

the bundle of muscle fibers wrapped by the perimysium

aponeurosis vs tendon

aponeurosis is flatter whereas tendon is twisted

direct vs indirect attachment

direct: epimysium fused to periosteum(bone) or pericondrium(cartillage ex: pectoralis major at costal cartillage of ribs to sternum)

gassicke arrangements

parallel

almost parallel but taper off: fusiform

circular

triangular

pennate

types of pennate fassicle arrangements

multipennate: deltoid

bipennate: rectus femoris

unipennate: digital extensors

longer muscke equals what

longer range of motion

cross sectional area increase results in what

greater force

what is pennate

when the muscle attaches along the length of the tendon like feathers on feather

parralel muscle arrangement allows for greater what but less what than pennate

greater speed but less force

why are soe muscle fassicles arranged to generate more force

some muscles prioritize force while other prioritize range of motion

what do you call the muscle cell membrane

sarcolemma

what surrounds the myofibril

sarcoplasmic reticulum

purpose of termjnal cisternae

part of sarcoplasmic reticulum (buldgy part) stores Ca^2+

what are the t tubules

the space outside in betwen the terminal cisternae of the sarcolemma

continuous with extracellular space

contains the voltage sensors

what di the voltage sensors do

connect the calcium from rhe terminal cisternae ro the actin and myosin of rhe cell inside

myosin anatomy

2 heads and a tail (2gold clubs teisted together with the handles together)

binding site for actin and atp

atp binding site serves as an enzyme called ATPase that hydrolises ATP to ADO and phosphate

actin protein anatomy

intertwined pearl necklaces

active site for myosin

tropomyosim

troponin

troponin has a binding site for actin, troponin, calcium(stored in the terminal cisternae of the sarcoplasmic reticulum)

what is titin

an elastic protein gives msucle its ability to recoil

what are the contractile proteins

actin, myosin,

regulatory proteins

tropomyosin, troponin

strutural proteins

titin, actinin, myomesin, nebulin, dystrophin

what js a z disc

end of sarcomere

why is the a band cross section darkest

thick and rhinestone filaments, taken at the end of the myosin filaments

m line cross section

has thick filaments linked by accessory proteins, second darkest, taken at the middle line betwwen z discs

H zone cross secrion

thick filamets only, third darkest, taken within the mysin filaments where there is no actin

I band cross secrional

has thin filaments only, lightest where there is actin is on,y and no myosin(thick filaments)

what time of muscle does not need nervous innervation

cardiac muscle

what is an action potential

a nerve impulse sent by the nervous system

what 3 things need ro haple. for a skeletal muscle contraction

1. must be stimukated by a nerve ending

2. must generate and propagate an action potential

3. there must be a brief rise in intracellular calcium

what is the order of the congraction on a cellular level

1. action potential arrives at the axon terminal of motor neuron

2. voltage gated calcium channels open and calcium enters the axon terminal

3. calcium entry cause some synaptic vessicles ro release their contents (acetylcholines) by exocytosis

4. acerylcholine, a neurotransmitter, diffuses across the synaptic cleft and binds to the receptors in the sarcolemma.