Please enable JavaScript.
Coggle requires JavaScript to display documents.
Imogen Ecal Period 1 Muscular System - Coggle Diagram
Imogen Ecal Period 1 Muscular System
Major Functions of the Muscular System
Stabilize Joints
As they contact, they generate heat
Maintain Posture and Body Position
Produce Movement
3 Types of Muscles & Their Functions
Cardiac Muscle: involuntary movement, helps pump out blood
Smooth Muscle: involuntary movement, located in organs to help with digestion, push urine out, etc
Skeletal Muscle: voluntary movement, aids in movement of the body
Skeletal Muscles (Face Muscles)
masseter: prime mover of jaw closure, elevates mandible
platysma: tenses skin of neck
orbicularis oculi: closes eyelids
orbicularis oris: closes lips, purses and protrudes lips
Temporalis: closes jaw, elevates and retracts mandible
zygomaticus: raises lateral corners of mouth (smiling muscle)
Frontalis: moves eyebrows, wrinkles forehead, moves scalp posteriorly or back
Sarcomere: smallest functional contractile unit of muscle fiber
Z line
Myofilaments: arrangement of myofilaments in sarcomere
actin: thin filaments
myosin: thick filaments
Neuromuscular Junction
ACh diffuses across to ACh receptors on sarcolemma
ACh binding to receptors causes gates to open, NA+ enters which causes an end plate potential
Calcium entry causes release of ACh neurotransmitter into synaptic cleft
Acetylcholinesterase degrades ACh
Voltage-gated calcium channels open, calcium enters motor neuron
AP arrives at axon terminal
Sliding Filament Theory of Contraction
Myosin heads bind to actin and forms a crossbridge
ADP & P released from myosin, myosin moves. (powerstroke)
Impulse stops, Ca2+ released from troponin causing tropomyosin to cover binding sites and prevent contraction. Ca2+ returns to sarcoplasmic reticulum and waits for another impulse: relaxation
ATP binds to myosin which causes it to release actin which reverts ATP into ADP and P. Myosin is reader to form another crossbridge and cycle of contraction will continue until impulse stops
Impulse travels through sarcolemma and down T tubules which surrounds myofibrils. As it passes through T tubules, it causes sarcoplasmic reticulum surround T tubules to release calcium ions into sarcoplasm which will reach the sarcomere
Ca2+ binds to troponin located on actin filament, tropomyosin moves and exposes binding sites for myosin
Brain/spinal cord sends an impulse to the muscle; impulse travels down motor neuron and reaches neuromuscular junction, releases acetylcholine which triggers the impulse in the muscle
Cross Bridge Contraction: high energy myosin head attaches to actin filament
Working (power) Stroke: myosin heads pivot and pulls actin filament towards M line
Cross Bridge Detachment: ATP attaches to myosin head resulting in cross bridge detachment
Cocking of Myosin Head: energy from hydrolysis of ATP cocks myosin head into high-energy state, this energy is used for power stroking
Action Potential in a Muscle Fiber
Depolarization: generation and propagation of AP; voltage gated Na+ channels open if step 1 causes enough change to trigger membrane voltage critical level, Na+ influx triggers AP for muscle fiber contraction; the area is depolarized when AP spreads in sarcolemma from voltage gated Na+ channels
Repolarization: restoration of resting conditions; Na+ closes, K+ opens; K+ channels bring cells back to initial resting membrane voltage. Muscle fiber can't be stimulated for a limited time until repolarization is completed: refractory period
End Plate Potential (Generation): ACh from motor neuron binds to ACh receptors on sarcolemma; chemically gated ion channels open and Na+ diffuses into muscle fiber
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 surrounds entire muscle
Disorders
Duchenne muscular dystrophy (DMD): progressive muscle degeneration and weakness
Muscle dystrophy: causes progressive weakness and loss of muscle mass
Skeletal Muscles (Body anterior)
sternocleidomastoid: neck area
trapezius: shoulder
pectoralis major: chest area
deltoid: upper arm
serratus anterior: lateral side of chest
biceps brachii: upper arm anterior
rectus abdominis: abdomen
brachioradialis: forearm area (lateral)
flexor carpi radialis: forearm area (middle)
palmaris longus: forearm area (medial)
internal oblique: lateral side of abdomen
Iliopsoas: inner hip
sartorius: from hip to knee
adductor longus: medial thigh
vastus lateralis:lateral thigh
gastrocnemius: helps form achilles tendon, lateral
tibialis anterior: responsible for dorsiflexing and inverting the foot
gracilis: superficial & medial thigh
rectus femoris: midlde of the thigh
vastus medialis: medial bottom of thigh
fibularis longus: below gastrocnemius of calf
soleus: part of the calf
extensor digitorum longus: lateral part of front leg
Skeletal Muscles (Body posterior)
extensor carpi ulnaris: back of forearm, more medial
gluteus maximus: butt
extensor carpi radialis longus: back of forearm lateral
semitendinosus: medial muscle in back of thigh
latissimus dorsi: back
semimembranous: most medial muscle in back of thigh
triceps brachii: back of upper arm
biceps femoris: back of thigh, more laterla
teres major: lateral border of scapula
rhomboid major: connects scapula to vertebrae of spinal column
infraspinatus: inferior to scapula