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Muscle System - Brianna Mayorga p.6 - Coggle Diagram
Muscle System - Brianna Mayorga p.6
The Major Functions of the Muscle System
Produce movement: responsible for all locomotion and manipulation
▪ Ex:digesting, pumping blood
Maintain posture and body position
Stabilize joints
Generate heat as they contract movement
3 Types of Muscles and their Functions
Skeletal Muscle- found near bones; functions in movement for daily activities
Smooth Muscle- found in intestines and stomach; aids in digestion and aids in recollecting aid
Cardiac Muscle- found near the heart; aids in pumping blood and contractions.
Names of all the Skeletal Muscles
Face
Zygomaticus
Temporalis
Frontalis
Orbicularis oculi
Orbicularis oris
Masseter
Buccinator
Sternocleidomastoid
Neck
Sternocleidomastoid
Trapezius
Chest and shoulder
Pectoralis major
Deltoid
Stomach
Serratus anterior
External oblique
Rectus abdominis
Arm
Biceps brachii, bracioradials, flexor carpi radialis, & flexor poliicis longus (F)
Triceps brachii, extensor digitorum, & extensor carpi radialis
Back
Infraspinatus
Teres major
Latissimus dorsi
Gluteus maximus
Legs
Iliaposoas, sartorius, adductor longis, vastus lateralis, gastronemius, tibialis anterior, gracilis, rectus femoris, vastus medialis, soleus, fibularis longus, extensor digitorum longus (F)
biceps femoris, semimembranosus, semitendinosus, gastrocnemius, soleus, fibularis longus
Sarcomere
A sarcomere is the basic contractile unit of muscle fiber. Each sarcomere is composed of two main protein filaments: actin and myosin
Neuromuscular Junction
Made up of axons, axon terminal, synaptic vesicles, acetylcholine, ACh, and receptors
Events:
AP arrives at axon terminal
Voltage-gated calcium channels open, calcium enters motor neuron
Calcium entry causes release of ACh neurotransmitter into synpatic cleft
ACh diffuses across to ACh receptors (𝑁𝑎 +
chemical gates) on sarcolemma
ACh binding to receptors, opens gates, allowing 𝑁𝑎 +
to enter resulting in end plate
potential
Acetylcholinesterase degrades ACh
Sliding Filament Theory of Muscle Contraction
This theory explains muscle contraction where muscle fibers slide against each other to generate tension. First, a signal is sent from the brain to the motor neuron. The vesicles in the motor neuron release acetylocholine into the receptors which then travels to the t tubules. This causes the sarcoplasmic reticulum to release calcium. The calcium then binds to a structure on the actin which causes it to change shape. This change allows myosin heads to form cross-bridges between actin and myosin. The energy from ATP is used to create a "power stroke" between the filaments, therefore actin is pulled inward and contracts.
Action Potential in a Muscle Fiber
There is a process
• Action potential is caused by changes in electrical charges
• Occurs in three steps
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 diffuses
– Because 𝑁𝑎 + then sarcolemma becomes less negative and more positive
– Results in local depolarization called end plate potential
Depolarization
generation and propagation of action potential
If end plate potential causes enough change in membrane voltage to reach critical level called threshold
then voltage gates channels in membrane will open
Repolarization
restoration of resting conditions
Refractory period: muscle fiber can't be stimulated for a specific amount of
time, until repolarization is complete
Muscle Coverings
...
Superficial Fascia, which is mostly associated with the skin;
Deep Fascia, which is mostly associated with the muscles, bones, nerves and blood vessels; and.
Visceral (or Subserous) Fascia, which is mostly associated with the internal organs.
Disorders
Duchenne muscular dystrophy (DMD) is the most common and serious form of muscular
dystrophies, muscle-destroying diseases that appear during childhood, it is recessively sex-linked therefore inherited
