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Alexis Zatarain Per. 3 Muscular System - Coggle Diagram
Alexis Zatarain Per. 3 Muscular System
Major Functions of Muscular System
Produce movement: responsible for all locomotion and manipulation
Maintain posture and body position
Stabilize joints
Generate heat as they contract
3 Types of Muscles & Their Functions
Skeletal Muscle
generating force and movement in the body
Cardiac Muscle
When contracted, propels blood into circulation
Smooth Muscle
propels substances or onjects alonge internal passageways
Sarcomere
Smallest contractile unit (functional unit) of muscle fiber
Contains A band with half of an I band at each end
Consists of area between Z discs
Individual sarcomeres align end to end along myofibril
Neuromuscular Junction
Steps
AP arrives at axon termina
voltage-gated calcium channels open, calcium enters motor neuron
Calcium entry causes release of ACh neurotransmitter into synpatic cleft
ACh diffuses across to ACh receptors (๐๐ + chemical gates) on sarcolemma
ACh binding to receptors, opens gates, allowing ๐๐ + to enter resulting in end plate
potential
Acetylcholinesterase degrades ACh
Muscle coverings (connective tissue coverings)
Epimysium
dense irregular connective tissue surrounding entire muscle may
blend with fascia
Perimysium
ibrous connective tissue surrounding fascicles
Endomysium
fine areolar connective tissue surrounding each muscle fiber
Disorders with the Muscular system
Duchenne Muscular Dystrophy
muscle-destroying diseases that generally appear during childhood
Myasthenia Gravis
disease characterized by drooping upper eyelids,
difficulty swallowing and talking, and generalized muscle weakness
Rigor Mortis
3โ4 hours after death, muscles begin to stiffen
Intracellular calcium levels increase because ATP is no longer being synthesized so calcium cannot be pumped back into SR
Muscles stay contracted until muscle proteins break down, causing myosin to
release
Sliding Filament Theory
states that during contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more
Skeletal Muscles
Frontalis
raises eyebrows & wrinkles forehead
Orbicularis Oculi
closes eyelids
Zygonaticus
lifts corners of mouths
Orbicularis Oris
movements of lips
Sternocleidomastoid
turns and tilits head
Temporlis
helps close jaw
Masseter
chewing
Trapezius
moves shoulders and supports neck
Deltoid
Lifts arm
Pectoralis Major
moves arm across chest
Brachioradialis
Helps bend arm at elbow
Flexor carpi radialis
bends wrist
Rectus Abdominis
flexes spine
External Oblique
twist torso
Adductor Longus
brings leg toward body
Vastus Lateralis
extends knee
Sartorius
Flexes thigh
Gracilis
brings legs together
Gastrocnemius
Calf
Soleus
assists calf
Occipitalis
Moves scalp backward
Rhomboid
pulls shoulder blade together
Gluteus Medius
moves thigh to side
Gluteus Maximus
extends hip
Semitendinosus
bends knee
Biceps Femoris
main hamstrinf
Calcaneal tendon
connects calf to heel
Action potential in a muscle fiber
Resting sarcolemma is polarized, so voltage exist across membrane
Action Potential cause by changes in electrical charges
End plate potential: ACh released from motor neuron binds to ACh receptors on sarcolemma Causes chemically gated ion channels (ligands) on sarcolemma to open. Because ๐๐ + diffuses in, interior of sarcolemma becomes less negative (more
positive)
Depolarization: generation and propagation of an action potential (AP) โ If end plate potential causes enough change in membrane voltage to reach critical level called threshold, voltage-gated ๐๐ + channels in membrane will open โ Large influx of ๐๐ + through channels into cell triggers AP that is unstoppable and will lead to muscle fiber contraction AP spreads across sarcolemma from one voltage-gated ๐๐ + channel to next one
in adjacent areas, causing that area to depolarize
Repolarization: restoration of resting conditions โ ๐๐ + voltage-gated channels close, and voltage-gated ๐พ + channels open
โ ๐พ + efflux out of cell rapidly brings cell back to initial resting membrane voltage