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Kayla Lay P2 Muscular System - Coggle Diagram
Kayla Lay P2 Muscular System
Disorders associated
Myasthenia gravis: toxins, drugs, and diseases interfere w/ events at neuromuscular junction
shortage of ACh receptors b/c person's ACh receptors are attacked by own antibodies
autoimmune disease
drooping upper eyelids, difficulty swallowing and talking, and generalized muscle weakness
Rigor mortis: muscles begin to stiffen 3-4 hrs after death
peak rigidity occurs about 12 hr postmortem
intracellular calcium increase b/c ATP is no longer synthesized, so calcium cannot be pumped back into SR; cross bridge formation
ATP needed for cross bridge detachment; results in myosin head staying bound to actin
muscles stay contracted until muscle protein break down; myosin release
Duchenne muscular dystrophy: muscle destroying disease that generally appear during childhood
sex link recessive disease; almost exclusively in males
caused by defective gene for dystrophin; sarcolemma tears easily, allowing excess calcium that damages contractile fibers
affects head, chest, and cardiac muscles; inflammation follows and regenerative capacity is loss
Muscular Dystrophy
causes or risk factors: genetic, duchenne, becker
symptoms: mental retardation, muscle weakness, eyelid drooping
muscle weakness and atrophy
Fibromyalgia
muscle pain
causes or risk factors: physical trauma, abnormal pain response, sleep disturbances
symptoms: muscle pain, tender points, joint pain
Cerebral Palsy
causes or risk factors: brain injury or abnormality, hypoxia, premature birth
symptoms: mild to severe, delayed development, muscle tightness
spastic paralysis causing muscle weakness
Myositis
inflammation of the muscle
causes or risk factors: autoimmune, infection, medical induced
symptoms: muscle weakness, swelling, tenderness
3 types of muscles and their functions
Cardiac
provides critical support for the heart and separates flow of electrical impulses through the heart
walls of heart
branching chains of cells; uni or binucleate; striations
Smooth
regulation of blood flow through vital organs and movement of materials along digestive and urinary passageways.
unitary muscles in walls of hollow visceral organs; multi unit muscle in intrinsic eye muscles, airways, large arteries
single, spindle shaped, uninucleate; no striations
Skeletal
enables movement, maintain posture, stabilize joints, and generate heat
attached to bones or (some facial muscles) to skin
single, very long, cylindrical, multinucleate cells w/ obv striations
Sliding filament theory of muscle contraction
mechanism of muscle contraction based on muscle proteins (myosin and actin) that slide past each other to generate movement.
Working (power stroke)
ADP is released; myosin head pivots and pulls thin filament toward M line
Cross bridge detachment
ATP attaches to myosin head, causing cross bridge
to detach
Cross bridge formation
high-energy myosin head attaches to actin thin
filament active site
calcium released from the sarcoplasmic reticulum; calcium causes conformational change in tropomyosin which exposes actin binding site
Cocking of myosin head
energy from hydrolysis of ATP “cocks” myosin head
into high-energy state
Neuromuscular junction
AP crosses from neuron to muscle cell vie neurotransmitter acetycholine
Axon branches end on muscle fiber; axon terminal and muscle fiber separated by synaptic cleft
stored within axon terminal are synaptic vesicles that contain ACh
junctional folds contain ACh receptors
Events
Calcium entry causes release of ACh neurotransmitter into synpatic cleft
ACh diffuses across to ACh receptors on sarcolemma
voltage-gated calcium channels open, calcium enters motor neuron
ACh binding to receptors, opens gates, allowing calcium ions to enter; end plate potential
AP arrives at axon terminal
Acetylcholinesterase degrades ACh
Major functions
Maintain posture and body position: muscle contraction
Stabilize joints: tendons extend over joints
Produce movement: responsible for all locomotion and manipulation; contracting then relaxing
Generate Heat: heat formed as muscles contract
Characteristics
Contractility: ability to shorten forcibly when stimulated
Extensibility: ability to be stretched
Excitability: ability to receive and respond to stimuli
Elasticity: ability to recoil to resting length
Action Potential in a muscle fiber
caused by changes of electrical charges
Occurs in three steps
Depolarization: generation and propagation of AP
if end plate potential causes enough change in membrane volatge to reach threshold, voltage gated calcium ion channels in membrane will open
large influx of calcium ions trigger AP that is unstoppable and lead to muscle fiber contraction
AP spreads across sarcolemma from one voltage gated calcium ion channel to next one
Repolarization: restoration of resting conditions
Potassium ion efflux out of cell rapidly brings cell back to initial resting membrane voltage
Refractory period: muscle fiber cannot be stimulated for a specific amount of time, until repolarization is complete
Calcium ion voltage gated channels close; voltage gated potassium ion open
End plate potential
causes chemically gated ion channels to open
Calcium ions diffuses into muscle fiber; interior becomes less negative
ACh released from motor neuron binds to ACh receptors on sarcolemma
Sarcomere
smallest contractile unit of muscle fiber
I band: lighter region
Thin actin filament: protein actin polypeptide made up of kidney-shaped G actin
Tropomyosin: exposes or covers binding site; troponin: attachment for calcium ions
H zone: lighter region in middle of A band
A band: dark region
Thick myosin filament: protein myosin that contains two heavy (tail) and four light (head) polypeptide chain
M line: myomesin that bisects H zone vertically
Z disc: coin-shaped sheet of proteins on midline of I band
Titin filament: connects Z line to myosin
Muscle coverings
Perimysium
fibrous connective tissue surrounding fascicles (group of muscle fibers)
Endomysium
fine areolar connective tissue surrounding each muscle fiber
Epimysium
dense irregular connective tissue surrounding entire muscle; may blend with fascia
Skeletal muscle names
Skull and cervical
Massester: cheekbone to jaw
Orbicularis oris: lip
Zygomaticus: cheekbone
Epicranius occipital: back of head
Orbicularis oculi: around eye
Sternhyoid: center of neck
Temporalis: side of head
Sternocieidomastoid: lateral neck
Epicranius frontalis: forehead
Upper limbs
Tricepts branchii: back upper arm
Pronator teres: forearm
Brachialis: lower upper arm
Branchioradialis: radial forearm
Bicepts branchii: upper arm
Flexor carpi radialis: medial forearm side
Deltoid: shoulder
Palmaris longus: medial forearm
Extensor carpi radialis longus: superficial back forearm
Extensor digitorum: lateral back forarm
Extensor carpi ulnaris: center back forearm
Flexor carpi ulnaris: medial back forearm
Lower limbs
Extensor digitorum longus: center lower leg
Gastrocnemius: back lower leg
Tibialis anterior: tibia
Soleus: calf
Garcilis: medial thigh near pubis
Fibularis longus: later lower leg
Adductor longus: medial upper thigh
Gleteus medius: upper buttock
Rectus femoris: center quads
Gleuteus maximus: buttock
Vastus medialis: medial quad near knee
Adductor magnus: short back thigh
Vastus lateralis: lateral quad
Semitendinosous: medial center hamstring
Iliotibial band: lateral thigh
Bicepts femoris: later center hamstring
Sartorius: thigh of hip and knee joint
Semimembranosus: lateral thin hamstring
Tensor fascia lata: proximal thigh
Pectineus: medial thigh
Iliopsoas: inner hip
Abdominal and torsal
Serratus anterior: ribs
External oblique: outer abdomen
Pectoralis major: chest
Rectus abdominis: abdomen
Trapezius: upper back and trunk
Infraspinatus: back shoulder
Teres major: scapula and humerus
Rhomboid major: scpaula
Latissimus dorsi: lower trunk