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Nanami Terrell p.3 Muscular system - Coggle Diagram
Nanami Terrell p.3 Muscular system
Major Functions
maintain; slight muscle contraction, help maintain posture and keep the body upright.
stabalize; Muscles stabilize joints during movement to prevent dislocation.
produce; attach to bones with tendons and contract to produce voluntary movements such as walking and running
generate; Muscle contractions produce heat as a byproduct, helping maintain normal body temperature.
Sarcomere
Function
The actin and myosin filaments slide past each other ( the sliding filament ).
sarcomere shortens, but the filaments themselves don’t change length.
shortening causes the entire muscle fiber to contract.
Structure
A band: The length of the thick filament (appears dark).
I band: The region with only thin filaments (appears light)
Myosin (thick filament): Lies in the center and overlaps with actin filaments.
H zone: The central part of the A band where there is only myosin (no actin overlap).
Actin (thin filament): Attached to the Z line and extends toward the center of the sarcomere.
M line: The center of the sarcomere, where myosin filaments are held together.
Z line (Z disc): Defines the boundaries of each sarcomere and anchors the thin filaments.
Sliding filalemt theory of muscle contraction
Power stroke
Actin pulled inward
ATP binds
Myosin detaches
Cross-bridge forms
Myosin binds actin
ATP hydrolysis
Myosin
Ca²⁺ released
Binding sites exposed
Ca²⁺ removed
Muscle relaxes
Muscle coverings
Epimysium; covers the entire muscle
Perimysium; A bundle of muscle fibers called a fascicle
Endomysium; Covers Each individual muscle fiber
Disorders
Osteogenesis Imperfecta; A genetic disorder causing fragile, easily broken bones
Osteomalacia / Rickets; Bones soften due to poor mineralization.
Paget’s Disease of Bone; Bone deformities, pain, enlarged skull or spine curvature.
Osteoporosis; Bones become porous, weak, and brittle due to loss of bone mass.
Names of all skeletal muscles
upper body
Biceps brachii
Flexes the elbow and rotates the forearm.
Triceps brachii
Extends the elbow.
Trapezius
Moves, rotates, and stabilizes the scapula which is the shoulder blade.
Latissimus dorsi
Extends, adducts, and rotates the arm; used in swimming and rowing.
Pectoralis major
Moves arm across the chest and helps in arm flexion.
Deltoid
Abducts (raises) the arm away from the body.
core
External obliques
Rotate and laterally flex the trunk.
Transversus abdominis
Compresses abdominal contents and stabilizes the core.
Rectus abdominis
Flexes the spine
Erector spinae
Extends and straightens the spine
head and neck
Masseter
Elevates mandible (main chewing muscle)
Sternocleidomastoid
Rotates and flexes the neck
Orbicularis oculi
Closes the eyelids
Frontalis
Raises eyebrows, wrinkles forehead
Temporalis
Helps close the jaw (chewing)
Orbicularis oris
Closes and shapes the lips
lowerbody
Hamstrings posterior
Flex the knee and extend the hip.
Gastrocnemius
Plantar flexes the foot
Quadriceps; anterior thigh
Extends the knee
Soleus
Aids in plantar flexion
Tibialis anterior
Dorsiflexes the foot
Gluteus maximus
Extends and rotates the hip
Action Potential in muscle fiber
depolarization; a motor neuron releases (ACh) at the neuromuscular junction, ACh binds to receptors on the sarcolemma
repolarization; Na⁺ channels close and voltage-gated K⁺ channels open.
Contracting; action potential in the T-tubules activates
Muscles and their functions
Smooth muscles – involuntary control and is found in organs and blood vessels.
Cardiac muscle – involuntary control and makes up the heart and pumps blood.
Skeletal muscles; voluntary control that move the skeleton.
Neuromuscular junction function
ACh binds receptor
Muscle depolarizes
Action potential in muscle
Muscle contracts
ACh released
Chemical signal crosses synapse
ACh broken down
Muscle relaxes
Nerve impulse arrives
Ca²⁺ enters neuron