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Kathy Ramirez Per.2 Muscular System - Coggle Diagram
Kathy Ramirez Per.2 Muscular System
Major functions of the muscular system
Stabilize joints
Generate heat
heat created when contracted
Maintain posture
maintain body position
Produce movement
responsible for all locomotion and manipulation
EX
digesting
pumping blood
walking
Sarcomere
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, like boxcars of train
Smallest contractile unit of muscle fiber
Names of all the skeletal muscles
orbicularis oculi
orbicularis oris
zygomaticus
masseter
temporalis
buccinator
Epicranius
sternohyoid
Sternocleidomastoid
Trapezius
Frontalis
Deltoid
biceps brachii
Triceps brachii
Biceps femoris muscle
Tibialis anterior muscle
Latissimus dorsi
Tibialis anterior
Adductor longus
Rectus abdominis
Pectoralis major
Brachialis
sartorius
Vastus lateralis
soleus
Vastus medialis
Gluteus maximus
3 types of muscles & their functions
Smooth muscle
digestion and respiration
Skeletal muscle
responsible for their movement.
Cardiac muscle
cardiac muscle causes the muscle to beat
Neuromuscular junction
synaptic connection between terminal end of a motor nerve and a muscle
AP arrives at axon terminal
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 on sarcolemma
ACh binding to receptors, opens gates, allow Na+ to enter resulting in end plate
potential
Acetylcholinesterase degrades ACh
Sliding filament theory of muscle contraction
thin filaments
slide past thick filaments, causing actin and myosin to overlap more
When nervous system stimulates muscle fiber, myosin heads are allowed to bind to actin
Cross bridge attachments form and break several times, each time pull thin filaments
Neither thick nor thin filaments change length, just overlap more
Causes shortening of muscle fiber
form cross bridges, which cause sliding process to begin
Action potential in a muscle fiber
End plate potential
ACh released from motor neuron binds to ACh receptors on sarcolemma
Causes chemically gated ion channels on sarcolemma to open
Resting sarcolemma is polarized
meaning a voltage exists across membrane
Depolarization
generation and propagation of an action potential
end plate potential causes enough change in membrane voltage
Large influx of 𝑁𝑎+ through channels into cell triggers AP that is unstoppable
AP spreads across sarcolemma from one voltage-gated Na+ channel to next one
lead to muscle fiber contraction
reaches level called threshold, voltage gated Na+ channels in membrane will open
adjacent areas cause area depolarize
Repolarization
restoration of resting conditions
𝑁𝑎+ voltage-gated channels close, and voltage-gated 𝐾+ channels open
𝐾+ efflux out of cell rapidly brings cell back to initial resting membrane voltage
Muscle coverings
Perimysium
fibrous CT
surrounding fascicles
Epimysium
surrounds entire muscle
may blend with fascia
dense irregular CT
Endomysium
fine areolar connective tissue
surrounding each muscle fiber
Disorders associated with the Muscular system
DMD
muscle-destroying diseases that generally appear during childhood
almost exclusively in males
sex-linked recessive disease
Caused by defective gene for dystrophin
Sarcolemma of DMD patients tear easily,