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Muscle System - Britane Olvera Per.2 - Coggle Diagram
Muscle System - Britane Olvera Per.2
Major Functions of the Muscular System.
Produce movement.
Maintain posture/body position
Stabilizes joints
Generates heat as they contract.
3 Types of Muscles & Functions.
Prime Mover (agonist)
Produces specific movement.
Antagonist
Opposes or reverses particular movement.
Synergist
Helps prime movers by adding extra force to same movement, reducing undesirable or unnecessary movement, and has fixators.
Fixators is a type of synergist that immobilizes bone or muscle’s origin rather than enhancing movement of prime movers.
Sarcomere
The basic contractile unit of muscle fiber.
Composed of two main protein filaments.
Actin: The most abundant protein in most eukaryotic cells.
Myosin: A fibrous protein that forms the contractile filaments of muscle cells.
Neuromuscular junction
Consists of axon terminals, synaptic cleft, and junctional folds.
Axon terminal : End of axon.
Synaptic Cleft : Gel-filled space that separates muscle fibers.
Junctional folds: Infoldings of sarcolemma that contains millions of ACh receptors.
Involves 6 events.
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 (𝑁𝑎+ chemical gates) on sarcolemma
ACh binding to receptors, opens gates, allowing 𝑁𝑎+ to enter resulting in end plate potential
Acetylcholinesterase degrades ACh
Disorders Associated with the Muscular System
Duchenne Muscular Dystrophy (DMD)
Most common and serious form of muscular dystrophies. Muscle-destroying diseases generally appear during childhood. Caused by a defective gene for dystrophin, a protein that links thin filaments to extracellular matrix and helps stabilize sarcolemma.
Myasthenia Gravis
disease characterized by drooping upper eyelids,
difficulty swallowing and talking, and generalized muscle weakness.
Fibromyalgia
Muscle pain with the exact cause being unkown. Pressumed to be hysical trauma, abnormal pain respinse, and sleep disturbance.
Cerebral Palsy
Spastic paralysis causing muscle weakness which is caused by a brain injury or abnormality, premature birth, brain infections, and head injury.
Myositis
Inflammation of the skeletal muscles caused by an infection. Caused by autoimmune, infection, medication induced, and muscle trauma.
Action Potential Across the Sarcolemma
Caused by changes in electrical charges.
Involves 3 steps.
Generation of end plate potential
ACh released from motor neuron binds to ACh receptors on sarcolemma which causes chemically gated ion channels (ligands) on sarcolemma to open.
Depolarization
Generation and propagation of an action potential (AP).
Repolarization
Restoration of resting conditions.
All Skeletal Muscles
Anterior/Superior View
Bicep brachii
Brachialis
Brachioradialis
Deltoid
External obliques
Flexor carpi radialis
Flexor carpi ulnaris
Frontalis (Epicranius frontal belly)
Iliopsoas
Masseter
Orbicularis oris
Orbicularis oculi
Palmaris longus
Pectinus
Pectoralis major
Rectus abdominis
Serratus anterior
Sternocleidomastoid
Temporalis
Tensor fasciae latae
Trapezius
Zygomaticus
Anterior/Inferior View
Adductor longus
Fibularis longus
Extensor digitorum longus
Gastrocnemius
Gracilis
Rectus femoris
Sartorius
Soleus
Tibialis anterior
Vastus lateralis
Vastus medialis
Posterior/Superior View
Brachioradialis
Deltoid
Extensor carpi radialis
Extensor carpi ulnaris
Extensor digitorum
Flexor carpi ulnaris
Gluteus maximus
Gluteus medius
Infraspinatus
Latissimus dorsi
Occipitalis (Epicranius occipital belly)
Rhomboid major
Sternocleidomastoid
Teres major
Trapezius
Tricep brachii
Posterior/Inferior View
Bicep femoris
Adductor magnus
Gastrocnemius
Gracilis
Soleus
Fibularis longus
Semitendinosus
Semimembranosus
Sliding Filament Theory
A muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber.
Muscle coverings (connective tissue coverings)
Epimysium
The innermost layer surrounding individual muscle fibers.
Perimysium
The middle layer surrounding bundles of muscle fibers.
Endomysium
The innermost layer surrounding individual muscle fibers.