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Rita Lomeli per: 5- Muscular system - Coggle Diagram
Rita Lomeli per: 5- Muscular system
Mayor functions of the muscular system
Produces movement : locomotion/ manipulation ex: walking, digesting
Stabilize joints
Maintains posture/ body position
Generates heat as they contract
3 types of muscles & their functions
Cardiac- The cardiac muscle is responsible for the contractility of the heart and therefore, the pumping action. The cardiac muscle must contract with enough force and enough blood to supply the metabolic demands of the entire body.
Smooth- In the cardiovascular system, smooth muscle is used in vessels to maintain blood pressure and flow; in the lungs, it opens and closes airways. It's responsible for maintaining and preserving every vital sign.
Skeletal-The main function of the skeletal muscle are to contract/ produce movement, sustain body posture/ position, maintain body temperature, store nutrients, and stabilize joints
Names of all skeletal muscles
Anterior muscles
Sternocleidomastoid, occipitalis, trapezius, infraspinatus
Posterior muscles
Deltoid , teres major, rhomboid major, latissimus dorsi
Liopsoas, tensor fasciae latae, adductor Longus, gracilis, vestus lateralis, fibularis longus, soleus, gastrocnemius, adductor Longus, rector femoris, vastus medialis, ribialis anterior, tibialis anterior, tibialis anterior
Biceps branchil, brachialis, flexor Carpi radiaus Longus, extensor digitorum, extensor Carpi ulnaris, flexor Carpi ulnaris
Gluteus maximus, adductor Magnus, gracilis, gastrocnemius, calcaneal, soleus, fibularis Longus, semimembranosus, semitendinosus, biceps femoris.
External oblique, deltoid, pectoralis major, rectus abdominis, transverse abdominis
Biceps branchi, brachialis, pronator teres, branchioradialis, flexor Carpi radialis, palmaris longus, flexor Carpi ulnaris, branchialis
platysma, trapezius, sternocleidomastoid,
Face muscles - Frontal, temporals, orbicularis oculi, orbicularis Oris, zygomatics, masseter
Sarcomere
I bands- light bands that contain only the thin filaments (actin) and are located between the two thick filaments.
Z disc- is an area that traverses the I bands and marks the point of the connection between the two neighboring actin filaments.That said, the sarcomere can also be described as the structure between the two z dicss
A bands- dark bands
The sarcomere is the main contractile unit of muscle fiber in the skeletal muscle. Each sarcomere is composed of protein filaments( myofilaments) that include mainly the thick filaments called myosin, and thin filaments called actin. The bundles of myofilaments are called myofibrils.
M line- marks the middle of the sarcomere and contains the protein called myomesin.
H zone- is the area between the M line and Z disc. The H zone contains only myosin.
Neuromuscular junction
When AP arrives at the axon terminal calcium channels open, once opened calcium releases Ach receptors on sarcolemma. It opens gates that allow Na+ to enter causing end plate potential.
The axon branches form neuromuscular junction; each muscle fiber has one neuromuscular junction with one motor neuron. Axon terminals bound synaptic vesicles which contain neurotransmitters called acetylcholine.
Finally, acetylcholinestarase degrades Ach. Once the nerve impulse reaches the neuromuscular junction, acetylcholine is released.
The neuromuscular junction is when skeletal muscles are stimulated by somatic motor neurons.
Sliding filaments theory of muscle contraction
sliding filament model of contraction- states that during contraction, thin filaments slide past thick filaments, causing acting and myosin to overlap more
When the nervous system stimulates muscle fibers, myosin heads are allowed to bind to actin, forming cross bridges, which cause sliding ( contraction) process to begin
Contraction- the activation of cross bridges to generate force
Cross bridge attachments form and break several times, each time pulling thin filaments a little closer toward center of sarcome in a ratcheting action
Action potential in a muscle fiber
ACh acts locally on the muscle fiber membrane to open ACh- gated cations channels.
the opening of Ch- gated channels allows large quantities of sodium (Na) ions to diffuse to the interior of the muscle fiber membrane.
2.At each motor nerve ending, the nerve secretes acetylcholine (ACh)
This action causes a local depolarization, leading to the opening of voltage- gated sodium (Na) channels, which initiates an AP at the membrane.
An action potential (AP) travels along a motor nerve to its endings on muscle fibers.
the AP depolarizes the muscle membrane, causing the sarcoplasmic reticulum (SR) to release large quantities of Ca ions stored within the reticulum.
The Ca ions produce attractive forces to act between actin and myosin filaments, causing them to slide alongside each other, leading to the contractile process.
After a fraction of a second, Ca ions are pumped back into the SR by a Ca- membrane pump and remain stored until a new muscle AP occurs.
The removal of Ca ions from the myofibrils causes muscle contraction to cease.
Muscle coverings ( connective tissue coverings)
Epimysium- Dense irrregular connective tissue surrounding the entire muscle; may blend with fascia.
Perimysium- Fibrous connective tissue surrounding fascicles( group of muscle fibers)
Endomysium- Fine areolar connective tissue surrounding each muscle fiber.
Disorders associated with the Muscular system
Duchenne muscular dystrophy (DMD) is most common and serious form of muscular dystrophies, muscle- destroying diseases that generally appear during childhood
. Inherited as a sex- linked recessive disease, so almost exclusively in males ( 1 in 3600 births)
Appears between 2 and 7 years old when body becomes clumsy and falls frequently
Disease progresses from extremities upward, finally affecting head, chest muscles, and cardiac muscle
With supportive care, people with DMD can live into 30s and beyond
Caused by defective gene for dystrophin, a protein that links thin filaments to extracellular matrix and helps stabilize sarcolemma
Sarcolemma of DMD patients tear easily, allowing entry of excess calcium which damages contractile fibers
inflammation follows and regenerative capacity is lost resulting in increased apoptosis of muscle cells and drop in muscle mass
Chest muscles, and cardiac muscle. The weakness continues to progress, but with supportive care, DMD patients are living into their 30s and beyond.
Parkinson's disease- a degenerative disorder of the central nervous system that mainly affects the muscular system and movement.
Tendinitis- inflammation of a tendon that occurs when its over extended or worked too hard without rest.
Myasthenia gravis- a neuromuscular disease causing weakness in skeletal muscles.