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Muscular Karina Quinones P6 - Coggle Diagram
Muscular
Karina Quinones P6
Sliding Filament Theory of Muscle Contraction
A muscle contraction starts when signals are sent along the motor neuron
The impulse travels into the transverse tubules and calcium is released
The calcium binds to a structure on the actin, which causes it to change shape
The myosin heads form cross bridges between the actin (thin) and the myosin (thick) filaments
Energy from ATP creates a power stroke between the two filaments
The actin slides inward and contracts the whole muscle, then it returns to its normal state
Names of all Skeletal Muscles
Posterior Upper Half:
teres major
triceps brachii
rhomboid mauar
latissimus dorsi
infraspinatus
extensor carpi radialis longus
deltoid
extensor digitorum
trapezius
gluteus maximus
sternocleidomastoid
Anterior Bottom Half:
vastus lateralis
gastrecnemius
rastus medialis
soleus
rectus medialis
fibuavis longus
gracitis
tibalis anterior
adducter longus
tibalis anterior
sartonus
extensor digitonum longus
Anterior Upper Half:
bicep brachii
brachioradialis
serratus anterior
rectus abdominus
pectoralis major
internal oblique
deltoid
flexor carpi ulnavis
trapezius
palmaris longue
sternocleidomastoid
iliopsoas
Posterior Bottom Half:
semimembranosus
gastrocnemius
semitendinosus
soleus
biceps femoris
fibularis longus
Muscles of Face:
zygomaticus
masseter
orbicularis oculi
orbicularis oris
frontalis
platysma
temporalis
Major Functions of the Muscular System:
2) maintain posture and body position
3) stabilize joints
1) produce movement: responsible for all locomotion and manipulation
ex: walking, digesting, pumping blood
4) generate heat as they contract
Sarcomere: the smallest contractile unit of the muscle fiber
Surrounded by a membrane known as the sarcolemma
the myofilaments are the thick myosin filament and the thin actin filament
the sarcoplasmic reticulum run parallel to the myofilaments
the transverse tubules run perpendicular to the filaments ( formed by a protrusion of sarcolemma deep into the cell interior)
mitochondria are dispersed throughout the muscle fibers
the sarcomere is the region between two z lines
Dark A bands are myosin and light I bands are actin
3 Types of Muscles & Their Functions
Cardiac Muscle: involuntary contraction and relaxation vital to pump blood throughout the cardiovascular system, resists fatigue, transports oxygen
Smooth Muscle: located in the stomach and the intestines which helps with digestion and nutrition, and rids of toxins
Skeletal Muscle: produce all movement and allow humans to perform daily activities, help maintain posture and balance, and assist in respiration
Neuromuscular Junction:
Calcium entry causes release of ACh neurotransmitter into synaptic cleft
ACh diffuses across to ACh receptors (Na+ chemical gates) on sarcolemme
Voltage gated calcium channels open, calcium enters motor neuron
ACh binding to receptors, opens gates, allowing Na+ to enter resulting in end plate potential
AP arrives at axon terminal
Acetylcholinesterase degrades ACh
Axon branches on the end of the muscle fiber form the neuromuscular junction of the motor end plate ( each muscle fiber has a nueromuscular junction with one motor neuron)
Muscle Coverings:
The fascicle is a portion of the muscle that is a bundle of muscle cells that is segregated by a connective tissue sheath, which is surrounded by the perimysium
The muscle fiber is an elongated multi-nucleated cell that has a banded striated appearance and is surrounded by the endomysium
The muscle is an organ that consists of muscle cells, blood vessels, and nerve fibers, which is externally covered by the epimysium
Action Potential in a Muscle Fiber:
end plate potential: Ach is released from motor neuron and binds to receptor on sarcolemma, Sodium diffuses into muscle fiber as well as some potassium, interior of sarcolemma becomes less negative because of the diffusion of sodium, results in local depolarization called end plate potential
depolarization: is the generation and propagation of an action potential...If the end plate potential causes enough change to reach a critical level called threshold, the sodium channels in and membrane will open, this large influx of sodium through the channels triggers the AP that leads to muscle fiber contraction and spreads across the sarcolemma which causes the area to depolarize
three steps are: generation of end plate potential, depolarization, and repolarization
repolarization: is the restoraion of resting conditions which occurs when the Sodium voltage gated channels close and potassium channels open, the potassium effluxes out and brings the cell to its initial resting membrane voltage.. the refractory period is when the muscle fiber cannot be stimulated for a specific amount of time until repolarization is complete, ionic conditions of the resting state are restored by the potassium and sodium pump
action potential is caused by changes in electrical charges (inside of cell is negative compared to the outside)
Disorders:
Myostheni gravis: disease characterized by drooping upper eyelids, difficulty swallowing and talking, muscle weakness; involves shortage of Ach receptos because they are attacked by own antibodies
Duchenne Muscular Dystrophy: a muscle destroying disease that is caused by a defective gene for dystrophin, a protein that links thin filaments to extracellular matrix and helps stabilize sarcolemma and results in apoptosis of muscle cells and drop in muscle mass
Rigor mortis:after death; intracellular calcium levels increase because ATP is no longer being synthesized and muscles stay contracted until the proteins break down