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Muscular Period 3 Julia Martinez - Coggle Diagram
Muscular Period 3 Julia Martinez
Major functions of the muscular system
Produce Movement, responsible for ALL locomotion and manipulation.
Maintain posture and body position.
Stabilize all joints
generate heat as they contract.
Sliding filament theory of muscle contraction
Contraction
Activation of cross bridges to generate force. Muscle shortening, when cross-bridge tension exceeds the opposing force. Contraction ends when cross bridge is deactivated. When in relaxed state, thin & thick filaments overlap and the ends of A bands.
Sliding Filament Model
During contraction, thin filaments slide past thick filaments, causing actin & myosin overlap. Z discs are pulled toward the M line. I band shortens. Z discs become closer. H zones disappear, and A bands move closer.
Action potential in a muscle fiber
ACh released from motor neuron binds to ACh receptors on sarcolemma Causes chemically gated ion channels (ligands) on sarcolemma to open 𝑁𝑎+ diffuses into muscle fiber. Some 𝐾+ diffuses outward, but not much. Because 𝑁𝑎+ diffuses in, interior of sarcolemma becomes less negative (more positive). Results in local depolarization called end plate potential.
Sarcomere
The smallest unit (functional unit) of muscle fiber. A band with I band at the end (area between Z discs)
Neuromuscular junction
Axons travel from central nervous system to skeletal muscle. Axon divides into branches, branches end on muscle fiber which then forms neuromuscular junction.
Events at Neuromuscular Junction
AP arrives at axon terminal 2. Voltage-gated calcium channels 3. Calcium entry causes the release of ACh neurotransmitters. 4. ACh diffuses across to ACh receptors (Na+ chem gates.) 5. ACh opens gates, Na+ in end plate potential. 6. Acetylcholinesterase degrades ACh.
Disorders associated with the Muscular system
Rigor mortis - Occurs 3-4 hours after death, muscles stiffens. Results in cross bridge formation (ATP is needed). Stays contracted until muscle protein protein breaks down and myosin is released.
Muscular Dystrophy - Muscle weakness and atrophy
Fibromyalgia - Muscle pain
Myasthenia Gravis - Neuromuscular disorder that blocks neurotrasmitters
Cerebral Palsy - Spastic paralysis causing muscle weakness
Myositis - Inflammation of the msucle.
3 types of muscles and their functions
Smooth
Found only in the heart and pumps blood throughout the body. It is involuntary, meaning that it works without conscious control.
Cardiac
In the walls of internal organs, such as the stomach, intestines, and blood vessels. They are responsible for involuntary movements
Skeletal
Attached to bones and are responsible for voluntary movements, such as walking, running, and lifting weights.
Muscle coverings (connective tissue coverings)
Epimysium
Dense irregular connective tissue surrounding the entire muscle.
Perimysium
Fibrous connective tissue surrounding fascicles.
Endomysium
Fine areolar connective tissue surrounding each muscle fiber.
Names of all Skeletal Muscles
Lower leg
Fibularis Longus - Outer leg, turns foot outwards, supports arch
Extensor digitorum longus - Front lower leg, lifts toes.
Tibialis anterior - Front of shin, lifts foot upward
Gastrocnemius - Calf, points toes (standing on tip toe)
Soleus - Under gastrocnemius, helps point toes
Hip & Thigh
Iliopsoas - Front of hip, bends thigh at hip.
Pectineus - Upper inner thigh, bring thigh toward the body.
Adductor Longus - Inner thigh, pulls leg toward midline.
Gracilis - Inner thigh, adducts thigh, flexes knee.
Tensor fascia latae - Outer hip, steadies and moves hip sideways.
Iliotibial Tract (IT band) - Side of thigh, supports leg movement.
Rectus Femoris - Front of thigh, straighten knee, bends hip.
Vastus lateralis - Outer front thigh, straighten knees.
Vastus medialis - Inner front thigh, straighten knee.
Sartorius - Long strap muscle across thigh, bends and rotates legs.
Upper body and Face
Biceps brachii - Front of upper arm, bends elbow
Brachialis - Under biceps, helps bend elbow
Brachioradialis - Forearm near thumb side, helps bend elbow
Deltoid - Shoulder, lifts arm
External Obliques - Sides of abdomen, twist and bend trunk.
Flexor Carpi Radialis - Front forearm, bends wrist toward thumb.
Flexor Carpi Ulnaris - Front forearm, bends wrist toward pinky.
Frontalis - Forehead races eyebrows.
Masseter - Jaw, closes mouth (chewing)
Orbicularis Oris - Around mouth, pucker lips
Orbicularis Oculi - Around eyes, closed eyelids.
Palmaris Longus - Middle of forearm, tenses palms, flexes wrists.
Pectoralis Major - Chest , moves arm forward and across body
Pronator Teres - Forearm, turns palm down.
Rectus abdominis - ¨Abs¨ , front of abdomen, bends trunk forward.
Serratus Anterior - Side of ribs, pulls shoulder forward
Sternocleidomastoid - Side of neck, turns and bends neck
Sternohyoid - Front of neck, lowers the hyoid bone (swallowing)
Temporalis - Side of head, helps close jaw
Trapezius - Upper back/head, lifts and moves shoulder
Triceps Brachii - Back of upper arm, straightens elbow
Zygomaticus - Cheek, lifts corners of mouth (Smiling)