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Muscular System Jenifer Barrios - Coggle Diagram
Muscular System Jenifer Barrios
Disorders:
Myasthenia gravis: disease characterized by drooping upper eyelids, difficulty swallowing and talking, and generalized muscle weakness
Duchenne muscular dystrophy : most common and serious form of muscular dystrophies, muscle-destroying diseases that generally appear during childhood.Caused by defective gene for dystrophin, a protein that links thin filaments to extracellular matrix and helps stabilize sarcolemma.
Rigor mortis: 3–4 hours after death, muscles begin to stiffen.Intracellular calcium levels increase because ATP is no longer being synthesized,
3 types of muscles and function:
Cardiac: are found in walls of heart. Branching chains of cells, uni- or binucleate, striations.Transports oxygen and involuntary contraction and relaxation to pump blood
Smooth: Unitary muscle in walls of hollow visceral organs. Single, spindle shaped, uninucleate, no striations. Helps digestion and gets rid of toxins.
Skeletal: attached to bones or some facial muscles as well, Single very long cylindrical multinucleate cells with obvious striations produces all movement and allow humans to do activities
Neuromuscular junction:
Voltage-gated calcium channels open, calcium enters motor neuron
Calcium entry causes release of ACh neurotransmitter into synpatic cleft
AP arrives at axon terminal
ACh diffuses across to ACh receptors (𝑁𝑎+chemical gates) on sarcolemma
ACh binding to receptors, opens gates, allowing 𝑁𝑎+to enter resulting in end plate potential
Acetylcholinesterase degrades ACh
Axon branches end on muscle fiber, forming neuromuscular junction
Major functions of the muscular system:
Maintain posture and body position
Stabilize joints:
Produce movement: responsible for all locomotion and manipulation ex. walking, digesting, pumping blood
Generate heat as they contract
Action potential in a muscle filber: Action potential is caused by changes in electrical charges. Occurs in three steps.
Depolarization: generation and propagation of an action potential. If end plate potential causes enough change in membrane voltage to reach critical level called threshold, voltage-gated𝑁𝑎+channels in membrane will open. AP spreads across sarcolemma from one voltage-gated 𝑁𝑎+channel to next one in adjacent areas, causing that area to 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.Refractory period is muscle fiber cannot be stimulated for a specific amount of time, until repolarization is complete
End plate potential: ACh released from motor neuron binds to ACh receptors on sarcolemma . Causes chemically gated ion channels on sarcolemma to open
Sacrome: Smallest contractile unit of muscle fiber
Consists of area between Z discs
The whole fiber is surrounded by thr sacrolemma.
Contains A band with half of an I band at each end
smooth muscle cells do not contain sarcomeres.
sarcomere contains two types of myofilaments: thick filaments and thin filaments
Muscle coverings:
Epimysium: dense irregular connective tissue surrounding entire muscle; may blend with fascia
Perimysium: fibrous connective tissue surrounding fascicles(groups of muscle fibers)
Endomysium: fine areolar connective tissue surrounding each muscle fiber
Posterior:
semimembranosus
extensor digiorium
gluteus maximus
extensor carpiradialis longus
biceps femoris
deltoid triceps brachii
semitendinous
latissmus major
rhomboid major
gastrocnemuis
teresmajor
soles
fibulas longus
infraspinatus
trapezius
Sliding filament theory of muscle contraction:
The impulse travels down the membrane and into transverse tubules. It causes calcium to be released from the sacroplasmic reticulum.
Calcium binds to a structure on the actin that causes it to change shape.
A muscle contraction starts in the brain, where signals are sent along the motor neuron.
The change in shape allows myosin heads to form cross bridges between the actin and myosin.
Energy from ATP creates a power stroke between the two filaments.
Then they slide forward and shortens or contracts the whole muscle.
Muscles on the face
orbicularis oculi
zygomaticus
temporal
masseter
frontal
orbicularis oris
platysma
buccinator
Anterior:
external oblique
ilopsoas
rectus abdominis
adductor longus
serrates anteriori
sartorius
pectoralis major
gracillis
flexor carpi ulnas
sartorious
flexor carpi radialois
rectus femoris
brachior radiallis
vastus medials
biceps brachi
vastus lateralis
deltoid
tibias anterior
trapezius
extensor digitorium longus
sternocleidomastoid