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Janelle Cardenas Muscular System per.5 - Coggle Diagram
Janelle Cardenas Muscular System per.5
skeletal muscles
CONNECTIVE TISSUE SHEATHS
each skeletal muscle is covered in connective tissue
SHEATHS
PERIMYSIUM
: fibrous connective tissue surrounding
fascicles
ENDOMYSIUM
: fine areolar connective tissue surrounding each muscle fiber
EPIMYSIUM
: dense irregular connective tissue surrounding entire muscle
ATTACHMENTS
INSERTION
: attachment to movable bones
ORIGIN
: attachment to immovable or less movable bone
NERVE & BLOOD SUPPLY
each muscle receives a nerve, artery, & veins - controlled skeletal muscle has nerves supplying every fiber
contracting muscle fibers require huge amounts of oxygen & nutrients
3 types of muscles
CARDIAC
walls of heart
SMOOTH
unitary muscle in walls of hollow visceral organ; multi-unit muscle in intrinsic eye muscles, airways, large arteries
SKELETAL
attached to bones or to skin
CHARACTERISTICS
CONTRACTIBILTY: ability to shorten forcibly when stimulated
EXTENSIBILITY: ability to be stretched
EXCITABILITY (responsiveness): ability to receive & respond to stimuli
ELASTICITY: ability to recoil resting length
major functions of the muscular system
MAINTAIN
POSTURE
AND BODY POSITION
STABILIZE JOINTS
PRODUCE MOVEMENT
: responsible for all locomotion & manipulation
ex:
walking, digesting, pumping blood
GENERATE
HEAT
AS THEY CONTRACT
muscle coverings
PERIMYSIUM
: fibrous connective tissue surrounding
fascicles
ENDOMYSIUM
: fine areolar connective tissue surrounding each muscle fiber
EPIMYSIUM
: dense irregular connective tissue surrounding entire muscle
sliding filament theory
: thin and thick filaments slide past each other, causing actin & myosin to overlap
action potential in muscle fiber
DEPOLARIZATION
: generation & propagation of an AP
REPOLARIZATION
: restoration of resting conditions
GENERATION OF END PLATE POTENTIAL
: ACh released from motor neuron bind to ACh receptors on sarcolemma causes
chemically gated
ion channels (ligands) on sarcolemma to open
sodium diffuses into muscle fiber
sarcomere
contains A band with half of an I band at each end
individual sarcomeres align end to end along myofibril like boxcars of trains
smallest contractile unit of muscle fiber
muscular disorders
MYASTHENIA GRAVIS
: neuromuscular disorder that blocks neurotransmitters
causes:
: autoimmune, possible tumor, age
CEREBRAL PALSY
: spastic paralysis causing muscle weakness
causes:
brain injury, hypoxia, premature birth
FIBROMYALGIA
: muscle pain
causes:
physcial trauma, abnormal pain response, infection
MYOSITIS
: inflammation of muscle
causes:
autoimmune, infection, muscle trauma
MUSCULAR DYSTROPHY
: muscle weakness & atrophy
causes:
genetic, becker, Duchenne
neuromuscular junction
STEP 3
: calcium entry causes synaptic vesicles. the calcium entry lets the synaptic vesicles release acetylcholine (ACh)
STEP 4
: ACh is released across the synaptic cleft. then attaches to the ACh receptors
STEP 2
: voltage-gated calcium channels open & calcium ions diffuse into the terminal.
STEP 5
: the ACh receptors consist of ligand-gated cation channels. the ligand-gated cation channels open.
STEP 1
: an AP travels down the axon of a motor neuron to an axon terminal which makes its way to the motor end plate
STEP 6
: sodium ions enter the muscle fiber whereas potassium ions exit the muscle fiber. this creates potassium & sodium ion channel. if there is a greater increase of sodium ions the membrane potential becomes less negative
an AP travels to the brain or spinal cord to activate the contraction of skeletal muscles.
STEP 7
: the membrane potential reaches the maximum threshold value which leads AP to travel along the sarcolemma. the enzyme acetylcholinesterase degrades the ACh & breaks them down into both acetic acid & choline. choline returns to the axons as the acetic acid diffuses away from the synaptic cleft.
the myosin head detaches ending the neuromuscular junction leading to the cross-bridge cycle