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Lina Le Period 6 Muscular - Coggle Diagram
Lina Le Period 6 Muscular
Major Functions of the Muscular System
Maintain Posture and Body Position
Stabilize Joints
Produce Movement
Responsible or all locomotion and manipulation
Digesting
Puping blood
Walking
Generate Heat
3 types of Muscles and their Functions
Smooth Muscles
Body location
Multi unit muscle in intrinsic eye muscles
Airways
Large arteries
Unitary muscle in walls of hollow visceral organs (other than the heart)
Cell shape and appearance
Spindle shaped
Uninucleate
Single
No striations
Cardiac Muscles
Body location
Walls of the heart
Cell shape and appearance
Branching chains of cells
Uni- or binucleate
striations
Skeletal Muscles
Body location
Attached to bones or (some facial muscles) to skin
Cell shape and appearance
Cylindrical
Multinucleate cells with obvious striations
Very long
Single
Names of all the Skeletal Muscles
Abdomen
Internal oblique
Rectus abdominis
Serratus anterior
Upper arm
Anterior
Deltoid
Biceps brachii
Posterior
Deltoid
Triceps brachii
Back
Tres major
Latissiusdorsi
Rhomboid major
Infraspinatus
Trapezius
Lower arm
Anterior
Brachiordialis
Flexor carpi radialis
Palmaris longus
Posterior
Extesnor digitorum
Extensor carpi ulanris
Chest
Pectoralis major
Neck
Sternocleidomastoid
Trapezius
Upper leg
Anterior
Illopsoas
Sartorius
Adductor longus
Gracilis
Vastus medialis
Rectus femoris
Vastus lateralis
Posterior
Semitendinosus
Biceps femoris
Semimembranosus
Gluteus maximus
Facial Muscles
Zygomaticus
raises lateral corners of mouth
smile
Masseter
prime mover of jaw closer
elevates mandible
Orbicularis Oculi
closes eyes
blinking
squinting
pulls eyebrows inferiorly
Buccinator
compresses cheek
whistling
sucking
holds food between teeth during chewing
pulls corner of mouth laterally
Temporalis
elevates and retracts mandible
maintains position of the mandible at rest
deep anterior part may help protract mandible
closes jaw
Orbicularis Oris
closes lips
purses and protrudes lips
kissing and whistling
Frontalis
raises the eyebrows
wrinkles forehead skin horizontally
Platysma
tenses skin of neck
while shaving
helps depress mandible
pulls lower lip back and down
producing downward sag of mouth
Lower leg
Anterior
Soleus
Fibularis longus
Gastrocnemius
Extensor digitorum longus
Tibialis anterior
Posterior
Gastronemius
Soleus
Fibularis longus
Neuromuscular Junction
Calcium entry causes release of ACh neurotransmitter into synpatic cleft
ACh diffuses across to ACh receptors (Na+ chemical gates) on sacrolemma
Voltage-gated calcium channels open, calcium enters the axon terminal, moving down its electrochemical gradient
ACh binding to receptors, opens chemically gated ion channels allowing Na+ to enter into the muscle fiber and K+ out of the muscle fiber. More Na+ Ions enter that K+ ions exit resulting in end plate potential
AP arrives at axon terminal of motor neuron
Acetylcholinesterase degrades ACh
Sliding Filament Theory of Muscle Contraction
In the relaxed state, thin and thick filaments overlap only slightly at ends of A band
States that during contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more
Neither thick nor thin filaments change lengths, just overlap more
Contraction ends when cross bridges become inactive
When nervous system stimulates muscle fiber, myosin heads are allowed to bind to actin, forming cross bridges, which cause sliding (contraction) process to begin
Shortening occurs when tension generated by cross bridges on thin filaments exceeds forces opposing shortening
Cross bridge attachments form and break several times, each time pulling thin filaments a little closer toward center of sarcome in a ratcheting action
Causes shortening of muscle fiber
Contaction : the activation of cross bridges to generate force
Action Potential in a Muscle Fiber
Depolarization: generation and propagation of an action potential (AP)
If end plate potential causes enough change in membrane voltage to reach critical level called threshold, voltage-gated Na+ channels in membrane will open
Large influx of Na+ through channels into cell triggers AP that is unstoppable and will lead to muscle fiber contraction
AP spreads across sacrolemma from one voltage-gated Na+ channel to next one in adjacent areas, causing that area to depolarize
Repolarization : restoration of resting conditions
K+ efflux out of cell rapidly brings cell back to initial resting membrane voltage
Refractory period : muscle fiber cannot be stimulated for a specific amount of time, until repolarization is complete
Ionic conditions of resting state are restored by Na+ - K+ pump
Na+ that came into cell is pumped back out, and K+ that flowed outside is pumped back into cell
Na+ voltage-gated channels close, and voltage-gated K+ channels open
End plate potential
Na+ diffuses into muscle fiber
Some K+ diffuses outward, but not much
Because Na+ diffuses in, interior of sacrolemma becomes more positive
Causes chemically gated ion channels (ligands) on sacrolemma to open
Results in local depolarization called end plate potential
ACh released from motor neuron binds to ACh receptors on sarcolemma
Muscle Coverings
Sheaths from external to internal
Epimysium
Dense irregular connective tissue surrounding entire
May blend with fascia
Perimysium
Fibrous connective tissue surrounding fascicles (groups of muscle fibers)
Endomysium
Fine areolar connective tissue surrounding each muscle fiber
Support cells and reinforce whole muscle
Disorders
Duchenne Muscular Dystrophy (DMD)
Disease progresses from extremities upward, finally affecting head chest muscles, and cardiac muscle
Inflammation follows and regenerative capacity is lost resulting in increased apoptosis of muscle cells and drop in muscle mass
With supportive care people with DMD can live into 30s and beyond
Appears between 2 and 7 years olf when boy becomes clumsy and falls frequently
Inherited as a sex-linked recessive disease, so almost exclusively in males ( 1 in 3600 births)
Caused by defective gene for dystrophin, a protein that links thin filaments to extracellular matrix and helps stabilize sacrolemma
Most common and serious form of muscular dystrophies, muscle-destroying diseases that generally appear during childhood
Myasthenia gravis : disease characterized by drooping upper eyelids, difficulty swallowing and talking, and generalized muscle weakness
Involves shortage of ACh receptors because the receptors are attacked by the person's own antibodies
Suggests this is an autoimmune disease
Sarcomere
Contains A band with half os 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 (functional unit) of muscle fiber