Please enable JavaScript.
Coggle requires JavaScript to display documents.
Amanda Gil Period 3 Muscular System - Coggle Diagram
Amanda Gil Period 3 Muscular System
3 types of Muscles + functions
Cardiac Muscle: works pumping action of the heart, branching, striated cells that interconnect in 3d networks, ONLY found in heart, involuntary has intercalated discs that join cells and transmit force
Smooth muscle: does movement of viscera, peristalsis, vascoconstruction, are elongated cells with tapered ends, lack striations, contain thick and thin filaments, has an undeveloped sarcoplasmic reticulum
Skeletal Muscle: movement of bones at joints and maintain posture, has striations, many nuclei, well developed transverse tubule system, voluntary, contracts and relaxes rapidly when stimulated by a motor neuron
skeletal muscles
extensor carpi ulnaris
flexor carpi ulnaris
extensor digitorium
semitendinous
flexor carpi radials
biceps femoris
brachials
semimembranosus
triceps brachii
fibularis longus
deltoid
soleus
trapezius
calcaneal tendon
sternocleidomastoid
gastrocnemius
adductor magnus
gracilis
gluteus maximus
latissimus dorsi
rhomboid
teres major and minor
infraspinatus
occipitalis
external oblique
frontalsi
tibialis anterior
orbicularis oris
pectoralis major
zygomaticus
sartorius
sternocleidomastoid
rectus femoris
sternohyoid
pectineus
rectus abdominis
Sarcomere
I bands(light): made up of actin filaments anchored to Z lines
A bands (dark): made up of overlapping thick and thin filaments
extends from one Z line to the next
H zone: center of A band and consists of myosin filaments only
myofibrils made up of many units-sarcomeres-joined end to end
M line: center of H zone and consists of proteins that hold the myosin filaments in place
Neuromuscular Junction
1.The action potential travels down the motor neuron to reach the axon terminal. Skeletal muscle fibers only contract when stimulated by a motor neuron.
Calcium channels open and calcium ions diffuse into the terminal.
Synaptic vesicles release acetylcholine via exocytosis. The acetylcholine will release into the synaptic cleft.
4.Acetylcholine diffuses across the synaptic cleft, which is a gap between membranes of a neuron and muscle fiber, then binds to acetylcholine receptors that contain ligand-gated Cation channels.
Acetylcholine binds to acetylcholine receptors then, ligand-gated cation channels open. This allows sodium ions to enter the muscle fiber and for potassium ions to exit the muscle fiber.
6.Sodium ions enter the muscle fiber and potassium ions exit the muscle fiber. The greater inward flux of sodium ions relative to the outward flux of potassium ions causes the membrane potential to become less negative.
Once the membrane potential reaches a threshold value an action potential propagates along the sarcolemma. Neurotransmission to a muscle fiber stops when acetylcholine is removed from the synaptic cleft.
synapse between motor neuron and muscle fiber that it regulated
Sliding Filament Theory of Muscle Contraction
Myosin head binds to actin and forms a crossbridge.
ADP and P release from myosin and causes the myosin to move. (the power stroke)
Calcium binds to tropopin on the actin filament causing tropomyosin to move and expose binding sites for myosin.
ATP binds to myosin causing it to release the actin and reverting ATP into ADP and P. The myosin is ready to form another crossbridge and the cycle of contraction will continue until the impulse stops
The impulse travels through the sarcolemma and down T tubules surrounding the myofibrils. As the impulse passes through the T tubules, it causes the sarcoplasmic reticulum surrounding the T tubule to release calcium ions into the sarcoplasm, eventually reaching the sarcomere.
When the impulse stops, calcium is released from tropopin causing tropomyosin to cove the binding sites and prevent contraction. Calcium returns to the SR and waits for another impulse. (relaxation)
The brain or spinal cord send an impulse to the muscle.The impulse travels down the motor neuron and reaches a neuromuscular junction where it releases acetylcholine, which triggers the impulse in the muscle.
Action Potential in a Muscle Fiber
sarcoplasm: cytoplasm of muscle cell contains many mitochondria and nuclei
myofibrils: active in muscle contraction, found in sarcoplasm
sarcolemma: cell membrane of a muscle
thick filaments: consist of protein myosin
fibers respond to stimulation by contracting
thin filaments: mainly composed of the protein actin and also contain troponin and tropomyosin
each muscle fiber - single, long , cylindrical muscle cell
pulling force exerted by binding myosin molecules to actin molecules
shortening results from an increase in the overlap between actin and myosin
energy for muscle fiber contraction comes from ATP
atrophy: decrease in muscle size and strength to to disuse
hypertrophy: enlargement of a muscle due to repeated excersize
agonist: prime mover, muscle that causes action and doess majority of the work
synergist: muscles that assist the prime mover
antagonists: muscles that oppose an action
Muscle Coverings
epimysium: layer of connective tissue around skeletal muscle, blends with fascia
perimysium: extends inward from epimysium, surrounds fascicles within each muscle
aponeuroses: broad sheets of connective tissue that muscles are sometimes connected to
fascicles: bundles of skeletal fibers
tendons:fused to periosteum of bones
endomysium: connective tissue layer that covers each muscle fiber/cell
fascia: layers of dense connective tissue that surround and separate muscles
Disorders
Muscular Dystrophy(muscle weakness and atrophy)- Causes: genetic, different types depending on mutation Symptoms: eyelid drooping, muscle atrophy, delayed motor skills Treatment: physical therapy, medication, surgery for improved function
Fibromyalgia(muscle pain)- Causes: exact cause unknown, physical trauma, infection, more common in women Symptoms: muscle pain, tender points, stiffness Treatment: physical therapy, massage, medication
Myasthenia Gravis(neuromuscular disorder that blocks neurotransmitters)- Causes: autoimmune, age, more common in women Symtpoms: double vission, drooping eyelids, shortness of breath Treatment: no known cure, medications, thymectomy
Cerebral Palsy(spastic paralysis causing muscle weakness)- Causes: premature birth, head injury, brain infections Symptoms: muscle tightness, abnormal gait, paralysis Treatment: no cure, medication for symptoms, physical therapy
Myositis(inflammation of the muscle)- Causes: autoimmune, infection, muscle trauma Symptoms: swelling, tenderness, myalgia Treatment: medication, antibiotics, reduce inflammation