Please enable JavaScript.
Coggle requires JavaScript to display documents.
Muscular System By: Iara Garro Period 1 - Coggle…
Muscular System By: Iara Garro Period 1
3 Muscle Types/Functions: Skeletal Muscle, Smooth Muscle, Cardiac Muscle
Skeletal Muscle Contraction: (Four Steps): 1) Contraction: neuromuscular junction events; 2) Muscle fiber excitation 3) Excitation- contraction couples; 4) Cross bridge cycling
Neuromuscular junction
Cross bridge cycling: myosin head attaches to actin thin active site; power stroke: head pivots and is pulled to M line; Cross bridge detachment: caused by ATP attaching to myosin head; Cocking of myosin head: ATP's energy cocks myosin head; high energy state occurs for preparation of next cross bridge cycle
Cardiac muscle functions: cardiac cells activated on each heartbeat, is walls of heart; pumps blood through the body
Smooth muscle function: Muscle in visceral organs; helps digestion and intestines; delivers nutrients to body, releases toxins, balances electrolytes
Skeletal Muscles: (Names):
Facial Muscles: Temporalis, Frontalis, Orbicularis oculi, Masseter, Platysma, Orbicularis oris, Zygomaticus
Arms: Bicep brachii, Tricep brachii, deltoid, brachialis, brachidialis, extensor carpi radialis, flexor carpi radialis,extensor digitorium
Trunk: Pectoralis major/minor, external/internal oblique, serratus anterior, plasymus (neck) stenohyoid(small part in neck) stenocleidomastoid (neck)
Legs: illopsoas, adductors, gracilias, gastronemicus, rectus femoris, bicep remoris; Hamstrings: semimembraneous, semitendeous, soleus, tibialis anterior, fibularis brevis
Sarcomere: Functional unit of a muscle fiber
Smallest unit of contraction; composed of actin and myosin filaments; A band (thick, dark); I band (thin, light); A band has both, I band only has actin
Major Functions of Muscular System
3) Stabilizes joints
4) Generates heat
2) Maintains posture and body positions
1) produces movement; responsible for all locomotion
Neuromuscular Junction
2) Calcium enters motor neuron; calcium channels open
3) The calcium entering causes ACH neurotransmitter to go into synaptic cleft
1) AP moves to axon terminal
4) ACH diffuses-> to ACh receptors on sarcolemma; Na+ goes through protein channel to get in. K (Potassium) goes through different protein channel to get out
5) ACh binds to the receptors, which opens the gates; Na+ enters= end plate potential
6) Acetylcholine degrades ACh
Sliding Filament Theory
Muscle filaments= myofilaments: Myosin (A band), thick; Actin (I and A band, thin)- proteins that make up myocytes, which make up fascicles, which make up entire muscle
Sliding filament theory is that muscle fibers do NOT get shorter when contraction occurs; they slide over each other. This is achieved by myosin heads pulling on the actin. The troponin is a padlock, while the tropomyosin is a bike chain. It needs ATP to make the lock open, and once it does the tropomysin and troponin fall away. ATP turns into ADP and phosphate; they stay on the myosin, which is where the energy to cock and bind comes from. They are now bound to actin; they're released and the myosin head goes back into position by SLIDING (power stroke). It is stuck to the actin until another ATP molecule binds and th head is released ( energy conserved until the next)
Muscle Fiber AP: Action Potential; Skeletal muscle fibers; long, cylindircal with multiple nuclei;
Sarcolemma: plasma membrane of muscle fiber; Sarcoplasm: Muscle fiber cytoplasm
Muscle Covering: Epimysium, perimysium, and endomysium
Perimysium: Covers bundles of muscle fiber (fasciclus)
Endomysium: inside each bundle there are myocytes (individual muscle cells, muscle fibers); this is covered by endomysium
Epimysium: Outside covering ; connective tissue sheath; fascia= outside epimysium; separates muscles
Muscle Disorders:
Muscle dystrophy: DMD; (Duchenne Muscular Dystrophy) 1 in 3600 male births; extremities rise in a fireball affect and affect the head, chest muscles (cardiac muscles); with proper care patients can live up to 30+
Cause: recessive gene (dystrophian) defective gene; the proteins get linked to thin filaments in order to balance out the sarcolemma; this sarcolemma tears easily. The cardiac muscle mass drops significantly/regenerative capacity lost