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Karla Moreno Dorantes Period 3 Muscular - Coggle Diagram
Karla Moreno Dorantes Period 3 Muscular
Major Functions of the Muscular System
4 important functions
Muscles produce movement and locomotion & manipulation such as walking, digesting, pumping blood
Maintaining posture and the bodies position
Stabilizes joints
Generates heat as muscles contract
3 main functional groups
Prime mover/agonist
(Holds the responsibility of producing specific movement)
Antagonist
(Opposes or reverses movement. If the prime mover and antagonist are on the opposite sides of joint they oppose movements)
Synergist
(Aides prime movers and add extra force to the same movement. It minimizes unnecessary movements.
Fixators
are a type of synergist that immobilizes the bone or muscleβs origin instead of enhancing it. Allows for a stable base)
3 types of muscles and their functions
Smooth
(In the walls of hollow organs and is spindle shaped and the only one with no striations)
Skeletal
(Attached to the bone and is long and is cylindrical with striations)
Cardiac
(On the walls of the heart and has striations, branch)
Names of all the skeletal muscles
Masseter
(Cheek and closes jaw)
Orbicularis Oris
(Around and closes mouth, not oculi)
Sternocleidomastoid
(Flexes the neck and rotates)
Serratus Anterior
(Raisees ribcage)
Triceps Brachii
(Extends forarm at elbow, back of top arm)
Erector Spinae
(Extends the Vertebral Column)
Gluteus Medius
(Abducts and medially rotates the thigh)
Brachioradialis
(Flexes the forearm at the elbow)
Gracilis
(Adducts the thigh and flexes the leg)
Sartorius Muscle
(Diagonal and attaches to the tibia)
Tibialis Anterior
(Calf, dorsiflexion and inversion of foot)
Soleus
(Back of leg)
Gastrocnemius
(Above soleus in the back)
Flexor Carpi Radialis
(Flexes and Abducts the wrist)
Extensor Carpi Radialis
(Wrist extensors)
Extensor Digitorum
(Extends the fingers)
Flexor Digitorum Superficialis
(Flexes wrist & fingers 2-5)
Levator Scapulae
(Raises the scapula)
Quadriceps
(Made up of rectus femoris, vastas medialis, vastas latralis)
Hamstring
(Made up of bicep femoris, semitendinosis, semimembranosis)
Extensor Digitorum Longus
(Dorsiflexes toes and foot)
Buccinator
(Sucking in cheeks)
Platysma
(Superficial muscles of the front of the neck)
Sarcomere
The smallest contractile/functional unit of a muscle fiber
It has an A band with half of an I band at each end and has an area between Z discs
Individual sarcomeres align end to end along the myofibril
Neuromuscular junction
Action potential arrives at the axon terminal
Voltage-gated calcium channels start to open allowing for calcium to enter the motor neuron
The entrance of calcium causes the release of ACh neurotransmitter into the synpatic cleft
Acetylcholine diffuses across to ACh receptors (ππ + chemical gates) on sarcolemma
ACh binds to receptors, the gates open allowing for ππ + to enter, resulting in end plate potential
Acetylcholinesterase degrades ACh into two
Sliding filament theory of muscle contraction
When contraction occurs, thin filaments slide past thick filaments, making actin and myosin overlap (Neither thick nor thin filaments change length, overlap more)
When a muscle fiber is stimulated by the nervous system, myosin heads bind to actin and form cross-bridges, which cause the sliding (contraction) process to begin.
Cross-bridge attachments form and break frequently, but each time, thin filaments are pulled closer toward the center of the sarcomere in a ratcheting action, causing the shortening of the muscle fiber.
Z discs are pulled toward M line, I bands shorten then Z discs become closer. The H zones disappear and A bands move closer to each other
Muscle coverings (connective tissue coverings)
Epimysium
(Its dense irregular connective tissue that engulfs the entire muscle and sometimes blends with fascia)
Perimysium
(Fibrous connective tissue which surounds fascicles which is a groups of muscle fibers)
Endomysium
(The fine areolar connective tissue which surrounds every muscle fiber)
Disorders associated with the Muscular system
Myasthenia Gravis
(A neuromuscular disorder that blocks neurotransmitters. Autoimmune that causes drooping upper eyelids, difficulty swallowing, and talking. Shortage of Ach receptors because a personβs ACh receptors are attacked usually by their own antibodies.)
Muscular Dystrophy
(Muscle weakness and atrophy that causes the loss of strength is genetic and has no known cure)
Fibromyalgia
(Muscle pain from physical trauma, infection, and causes tenderness in joints that's cured by physical therapy)
Cerebral Palsy
(Spastic paralysis causing muscle weakness that is incurable and can be caused by a head injury)
Myositis
(Inflammation of the muscle, an autoimmune disease that causes swelling and rash)
Action potential in a muscle fiber
Depolarization
The generation and propagation of an action potential (AP)
When the end plate potential creates enough change in the membrane voltage to reach a critical level called threshold, voltage-gated ππ + channels in the membrane open
A large influx of ππ+ through channels into the cell starts an unstoppable Action Potential and leads to muscle fiber contraction
AP spreads across the sarcolemma from one voltage-gated ππ + channel to the next one in adjacent areas, causing that area to depolarize
Repolarization
The restoration of resting conditions
ππ + voltage-gated channels have closed and voltage-gated πΎ + channels will open
πΎ + efflux leaves a cell and rapidly brings cells back to its initial resting membrane voltage
The refractory period is where a muscle fiber can't be stimulated for a specific set of time until repolarization is complete
Ionic conditions of the resting state are restored by ππ + βπΎ + pump
ππ + from a cell gets pumped back out, and πΎ + that was outside is pumped back into cell
End plate potential
This causes chemically gated ion channels (ligands) on the sarcolemma to open
ππ + diffuses into muscle fiber and then some πΎ + diffuses outward, but not much
ππ + diffuses into the interior of the sarcolemma, becomes less negative & more positive.This results in local depolarization called end plate potential
ACh is from the motor neuron and binds to ACh receptors on the sarcolemma
Changes in electrical charges can cause an action potential