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Lydiann Guzman Per. 5 Muscular System - Coggle Diagram
Lydiann Guzman Per. 5 Muscular System
3 types of muscles and their functions
Cardiac
walls of heart
Branching chains of cells; uni- or binucleate; striations
Muscle functions
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
Smooth
unitary muscle in walls of hollow visceral organs (other than the heart); multi unit muscle in intrinsic eye myscles, airways, large arteries
Single, spindle shaped, uninucleate; no striations
Skeletal
attached to bones or (some facial muscles) to skin
Single, very long, cylindrical, multinucleate cells with obvious striations
Disorders associated with the Muscular System
Muscle Fatigue
the physiological inability to contract despite continued stimulation
possible causes include:
decreased ATP and increased magnesium
Lack of ATP is rarely a reason, only in severely stressed muscles
decreased glycogen
Ionic imbalances can cause fatigue
Duchene Muscular Dystrophy (DMD)
most common and serious form of muscular dystrophies, muscle destroying diseases that generally appear during childhood
sex-linked disease, exclusively in males (1 in 3600 births); appears between 2 and 7 years old when boy becomes clumsy and falls frequently
affecting head, chest muscles, and cardiac muscle, can live up to 30 and older
caused by defective gene for dystophin (a protein that links thin filaments to extracellular matrix and helps stabilize sarcolemma
inflammation follows and regenerative capacity is lost resulting in increased apoptosis of muscle cells and drop in muscle mass
Myasthenia Gravis
disease characterized by drooping upper eyelids, difficult swallowing and talking, and generalized muscle weakness
involves shortage of Ach receptors b/c person's Ach receptors are attacked by own antibodies
autoimmune disease
Rigor Mortis
3-4 hours after death, muscles begin to stiffen' peak rigidity occurs about 12 hours postmortem
intracellular calcium levels increase because ATP is no longer being synthesized, so calcium cannot be pumped back into SR, results in cross bridge formation
Muscles stay contracted until muscle proteins break down, causing myosin to release
Neuromuscular Junction
Anatomy of neuromuscular junction
axon terminal
end of axon
junctional folds
infolding of sarcolemma
synaptic cleft
gel filled space seperating axon terminal and muscle fibers
Events at the Neuromuscular Junction
1) AP arrives at axon terminal
2) voltage gated calcium channels open, calcium enters motor neuron
3) calcium entry causes release of Ach neurotransmitter into synpatic cleft
4) Ach diffuses across to Ach recpetors (Na+ chemical gates) on sarcolemma
5) Ach binding to receptors, open gates, allowing Na+ to enter resulting in end plate potential
6) Acetylchoolinesterase degrades Ach
Action potential in a muscle fiber
caused by changes in electrical changes
Depolarization
generation and propaganda of an action potential (AP)
if end plate potential causes enough change in membrane voltage to reach critical level called threshold, voltage-gated Na+ channels in membrane will open
large influx of Na+ through channels into cell triggers AP that is unstoppable and will lead to muscle fiber contraction
AP spreads across sarcolemma from 1 voltage gated Na+ channel to next 1 in adjacent areas, causing that area to depolarize
Repolarization
restoration of resting conditions
Na+ voltage channels close, and voltage gated K+ channels open
K+ efflux out of cells rapidly brings cell back to initial resting membrane voltage
Refractory period: muscle fiber cannot be stimulated for a specfic amount of time, until repolarization is complete
Ionic conditions of resting state are restored by Na+ - K+ pump
Na+ that came into cell is pumped back out, and k+ that flowed outside is pumped back into cell
Generation of end plate potential
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+ diffueses but not much
because Na+ diffuses in, interior of sarcolemma becomes less negative
results in local depolarization called end plate potential
Sliding filament theory of muscle contraction
states that during contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more
neither thick nore thin filaments change length, just overlap more
when nervous system stimulates muscle fiber, myosin heads are allowed to bind to actin, forming cross bridges
which causes sliding (contraction) process to begin
cross bridge attachments form and break several times, each time pulling thing filaments a little closer toward center of sarcomere in a ratcheting action
causes shortening of muscle fiber
Z discs become closer
H zones disappear
I bands shorten
A bands move closer to each other
z discs are pulled toward M line
Major functions of the Muscular System
stabilize joints
state of a joint remaining or promptly returning to proper alignment through an equalization of forces
generate heat as they contract
generates heat through both contraction with the increase of ATP
during excessive, the heat produced in the contracting muscles causes internal body temp to rise
aerobic (endurance) exercise
(with breathing/oxygen)
jogging, swimming, biking, leads to:
increased number of mitochondria
results in greater endurance, strength, and resistance to fatigue
myoglobin synthesis increased
increased muscle capillaries
resistance excessive (typically anaerobic)
(without breathing/oxygen)
weight lifting or isometric exercises, lead to:
increased mitochondria, myofilaments, glycogen stores, and connective tissue
increased muscle strength and size
muscle hypertrophy
due primarily to increase in fiber size
maintain posture and body position
the proper alignment of your body when standing or sitting
produce movement
responsible for all locomotion and manipulation
ex: walking, digesting, pumping blood
Muscle Coverings
each skeletal muscle and muscle fiber is covered in connective tissue
support cells and reinforce whole muscle
shealths for external to internal:
Perimysium
fibrous connective tissue surrounding fascicles (groups of muscle fibers)
Endomysium
fine areolar connective tissue surrounding each muscle fiber
Epimysium
dense irregular connective tissue surrounding entire muscle, maybe blend with fascia
Names of all the skeletal muscles
Facial Muscles (Anterior)
Zygomaticus
Frontalis
Orbicularis Oris
Masseter
Temporalis
Orbicularis Oculi
Facial Muscles (Posterior)
Occipital (Epicranius Occipital Belly)
Torso Muscles (Anterior)
Sternohyoid
Sternocleidomastoid
Trapezius
Pectoralis Major
Torso Muscles (Posterior)
Teres Major
Rhomboid Major
Infraspinatus
Latissimus Dorsi
Trapezius
Gluteus Medius
Sternocleidomastoid
Gluteus Maximus
Serratus Anterior
External Obliques
Rectus Abdominis
lliopsoas
Tensor Fasciae Latae
Pectinus
Arm Muscles (Anterior)
Deltoid
Arm Muscles (Posterior)
Brachoradialis
Extensor Carpi Radialis
Triceps Branchii
Extensor Digitorum
Deltoid
Extensor Carpi Ulnaris
Flexor Carpi Ulnaris
Triceps Branchii
Bicep Brachii
Brachialis
Pronator Teres
Brachioradialis
Flexor Carpi Radialis
Palmaris Longus
Flexor Carpi Ulnaris
Leg Muscles (Anterior)
Adductor Longus
Leg Muscles (Posterior)
Semimembranousus
Soleus
Gracilis
Gastrocnemius
Adductor Magnus
Fibularis Longus
Bicep Femoris
Calcaneal
Semitendinosus
Vastus Lateralis
Rectus Femoris
Vastus Medialis
Sartotius
Gracilius
lliotibial tract
Gastrocnemius
Fibularis Longus
Soleus
Tibialis Anterior
Extensor Digitorum Longus
Sacromere
smallest contractile unit (function unit) of muscle fiber
contains A band with half of an I band at each end
Individual sarcomere align end to end along myofibril