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Muscular System - Izabella Gendorf P:5 - Coggle Diagram
Muscular System - Izabella Gendorf P:5
Major functions
movement - enables body movement
posture - maintains posture and balance
heat - produces body heat
circulation - aids blood flow
breathing - powers respiration
digestion - moves food through digestion
protection - cushions internal organs
Sliding filament
Theory :
Basic Concept: Explains how muscles contract by sliding actin and myosin filaments over each other.
Key Proteins: Actin (thin filament) and myosin (thick filament) are the primary proteins involved.
Cross-Bridge Formation: Myosin heads attach to actin to form cross-bridges.
Power Stroke: Myosin heads pull actin inward, shortening the muscle.
ATP Role: ATP provides energy, detaching myosin heads and resetting them for another pull.
Calcium’s Role: Calcium ions bind to troponin, moving tropomyosin, which exposes binding sites on actin.
Repeating Cycle: This cycle of binding, pulling, and detaching continues for full contraction.
Skeletal muscle
Face muscles :
Frontalis: Raises eyebrows.
Orbicularis oculi: Closes eyelids.
Orbicularis oris: Puckers lips.
Zygomaticus: Smiling muscle.
Masseter: Chewing muscle.
Temporalis: Assists with jaw movement.
Neck muscles :
Sternocleidomastoid: Turns and tilts head.
Trapezius: Moves shoulder blades and neck.
Upper body muscles :
Pectoralis major: Chest muscle for arm movement.
Deltoid: Shoulder muscle, lifts arms.
Biceps brachii: Front of upper arm, flexes elbow.
Triceps brachii: Back of upper arm, extends elbow.
Core muscles :
Rectus abdominis: "Abs," flexes the spine
Obliques: Side abs, rotate the torso.
Low body muscles :
Gluteus maximus: Buttocks, hip extension.
Quadriceps: Front of thigh, straightens knee.
Hamstrings: Back of thigh, bends knee.
Gastrocnemius: Calf muscle, lifts heel.
Muscle coverings
Coverings :
Epimysium: Outer layer covering the entire muscle.
Perimysium: Surrounds bundles of muscle fibers (fascicles).
Endomysium: Wraps individual muscle fibers within a fascicle.
Fascia: Connects muscles to surrounding tissues and organs.
Tendon: Connects muscle to bone, formed by extensions of the above layers.
Disorders associated
disorders :
Muscular Dystrophy: Genetic disorder causing muscle weakness and degeneration.
Myasthenia Gravis: Autoimmune disease leading to muscle fatigue and weakness.
Fibromyalgia: Chronic pain and tenderness in muscles and soft tissues.
Cerebral Palsy: Affects movement and muscle tone due to brain injury.
Muscle Strain: Overstretching or tearing of muscle fibers.
Tendinitis: Inflammation of tendons, often from overuse.
Rhabdomyolysis: Muscle breakdown releasing proteins into the blood, potentially damaging kidneys.
Polymyositis: Chronic inflammation causing muscle weakness
Action potential
Potential :
Resting Potential: Muscle fiber starts at a negative resting charge.
Stimulation: Nerve impulse triggers muscle fiber activation.
Depolarization: Sodium ions enter, making the inside positive.
Action Potential Propagation: Electrical signal travels along the muscle fiber.
Repolarization: Potassium ions exit to restore a negative charge.
Refractory Period: Brief reset time where the fiber can’t be stimulated.
Contraction Trigger: Action potential causes calcium release, starting muscle contraction.
3 Types and the functions
Skeletal muscle :
Type: Voluntary, striated
Location: Attached to bones
Function: Enables movement, posture, and heat production
Cardiac muscle :
Type: Involuntary, striated
Location: Heart walls
Function: Pumps blood throughout the body
Smooth muscle :
Type: Involuntary, non-striated
Location: Walls of organs (e.g., stomach, blood vessels)
Function: Controls internal movements like digestion and blood flow
Neuromuscular junction
NMJ :
Definition: A synapse between a motor neuron and a muscle fiber.
Signal Transmission: Carries signals from nerves to muscles.
Neurotransmitter: Releases acetylcholine (ACh) to trigger muscle contraction.
Receptor Activation: ACh binds to receptors on the muscle, creating an electrical impulse.
Muscle Contraction: Impulse leads to calcium release, causing muscle fibers to contract.
Enzyme Role: Acetylcholinesterase breaks down ACh to stop the signal, ending the contraction.
Sarcomere
Sarcomere :
Basic Unit: Smallest functional unit of muscle contraction.
Structure: Made of overlapping actin (thin) and myosin (thick) filaments.
Z-Lines: Boundaries that mark each end of a sarcomere.
A-Band: Dark area where actin and myosin overlap.
I-Band: Light area with only actin, shortens during contraction.
H-Zone: Center area with only myosin, narrows during contraction.
Sliding Filament Theory: Actin and myosin slide past each other, shortening the sarcomere for muscle contraction.
ATP Requirement: Uses ATP to power the sliding action.