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Muscles
Organs made up of specialized cells using chemical energy to pull on structures to which they attach
What are the 3 muscle types?
skeletal, smooth, and cardiac
What are the functions of muscle?
movement, posture, stabilize joints, and generate heart
Skeletal muscle is…
on organ composed of skeletal muscle tissue, nervous tissue, blood, and connective tissues
What is fascia?
Layers of dense connective tissue, separate individual skeletal muscles and old it in place
What is Aponeuroses?
Broad sheets of connective tissue, may attach to bone or other muscles
What are the three layers of connective tissue surrounding muscles?
Epimysium, perimysium, and endomysium
What is epimysium?
Outermost layer surrounding the entire muscle
What is perimysium?
Separates and surrounds individual fascicles (muscle fiber bundles)
What is endomysium?
Surrounds individual muscle fibers
Muscle fiber is…
single cell that contracts (shortens0 in response to stimulation and them relaxes at the end of stimulation
Cytoplasm is…
(sarcoplasm) contain many small nuclei
Sarcoplasm also contains many parallel…
myofibrils
Myosin is…
thick protein filaments
Actin is…
thin protein filaments
Organization of these filaments forms…
striations
Striations form repeating units called…
sarcomeres
I bands are…
lights bands- thin (actin)
A bands are…
dark bands- thick (myosin
I bands attach to…
Z lines
Sarcoplasmic reticulum…
Networks of channels surrounding each myofibril (stores calcium ions)
Transverse tubules (T tubules)…
Extent inward from the fiber’s membrane (extension of sarcolemma aka cell membrane)
Neurons works to help…
control muscle action
Motor neurons…
control effectors
Synapse is the…
connection (gap) between neuron and muscle fiber
Neurons communicate with other cells by releasing chemical called…
neurotransmitters
Synapse between motor neuron and muscle fiber is called a…
neuromuscular junction
Motor end plate
folded region to allow communication
Neurons stores neurotransmitters in
Synaptic vesicles
Neurotransmitters travel the gap (________) to stimulate contraction
synaptic cleftMyo
Myosin binds to actin and exerts…
pulling force
What is the resulting movement in actin and myosin filaments?
they slide past each other and shorten the muscle fiber
Myosin is made of many
cross-bridges
Actin as _______ for where myosin ________
binding sites; cross-bridges attach
Sarcomeres shorten from cross-bridges pulling on what?
actin filaments
Sliding filament model is…
the process by how sarcomeres shorten from actin-myosin interactions
What is ATPase?
an enzyme which breaks down ATP, an energy molecule
Where is acetylcholine (Ach) stored?
Vesicles in motor neuron axons
What are the 2 events that cause muscles to relax?
ACh gets broken down
Once ACh is broken down, calcium (Ca) ions are transported back into the sarcoplasmic reticulum (SR). This causes actin-myosin links to break and muscle fibers to relax.
creatine phosphate is…
much more abundant than ATP in muscle fibers but also can’t directly supply energy
Oxygen is carried by red blood cells by a molecule of what?
hemoglobin
What is made by muscle fibers to accept oxygen?
Myoglobin (red-brown color to muscles)
Strenuous activity doesn’t take long for muscles to produce energy without oxygen and creates what?
lactic acid
Where does lactic acid et broken down which also requires ATP?
the liver
Amount of oxygen liver cells need to break down lactic acid plus the amount muscle cells need to restore ATP
oxygen debt
Lose ability to contract
Fatigue
when muscles exercise for a long period of time, they can become…
fatigued
What do skeletal muscles do after death?
Contract and are rigid
What prevents muscles from relaxing?
an increase in Calcium (Ca) ions and a decrease in ATP
A major generator of heat in the body
Muscle tissue
transports heat from muscles to other tissues or to skin surface to regulate body temp
blood
less than half the energy released during cellular respiration is used to make…
ATP
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