Unit 5: Muscular system Viriahelyn Cavillo P: - Coggle Diagram
Unit 5: Muscular system
Viriahelyn Cavillo P:
Major Functions of the Muscular system:
Produce Movement: responsible for all locomotion and manipulation ( Ex. walking, digesting, pumping blood)
Maintain posture and body position
Generate heat as they contract
3 types of Muscles and their functions
attached to bones or (some facial muscle) to skin
single,very long, cylindrical, multi nucleate cells with obvious sitrations
walls of heart
branching chains of cells, uni- or bi nucleate; sitrations
unitary muscle in walls of hollow visceral organs; multi unit muscle in intrinsic eye muscle, airways, large arteries
single,spindle shaped, uni-nucleate; no sitrations
Names of all the Skeletal Msucle
Neck: Sternocleidomastoid, Trapezius
Shoulder/ upper arm: deltoid, biceps brachii
Forearm: brachior radiallis, flexor capri radialois, flexor carpi ulnas
Chest: pectoralis major
Abdomen: serrates anteriori, rectus abdominis
Lower abdominal: external oblique & illopsoas
Thigh: adductor longus,gracillis, sartorius, rectus femoris,vastus medialis & vastus lateralis
Lower leg: tibias anterior, extensor digitorium longus
Back:trapezius, infraspinatus,teresmajor,rhomboid amjor, latissimus major
Upper arm?shoulder: deltoid,triceps brachii
Forearm: extensor carpi radialis longus,extensor digitorium
Butt: gluteus maximus
lower leg: gastrocnemius,soles,fibulas longus.
mouth: oribuclaris oris
smallest contractile unit of muscle fiber
contains A band with half of an I band at each end
consist of area between Z discs
individual sacromere align end to end along myofibril, like boxcars of train
myofilament-composed of thick and thin
Mitochondrua-dispersed through the muscle fibers and supplies muscle with energy needed for contraction
Sacroplasmic Reticulum-a network of tubes used for transport that run parallel to the myofilament;is similar to the endoplasmic reticulum in other cells.
T tubules-also used for transportation runs perpendicular to filaments
Sacrolemma-membrane that surround the entire muscle fiber
Light and Dark bands: when expanded, the light and dark bands are shown as individual thick and thin filament
AP arrives at axon terminal
Voltage gated calcium channels open, calcium enters motor neuron
Calcium entry causes releaseof ACh neurotransmitter into synpatic cleft
ACh diffuses across to ACh receptors on sacrolemma
ACh binding to receptors, opens gates, allowing NA+ to enter resulting in end plate potential
6 .Acetylcholinesterase degrades ACh
Sliding filament theory of muscle contraction
The Brain or spinal cord sends an impulse to the muscle. The impulse travels down the motor neuron and reaches a negro muscular junction where it releases acetylcholine, which triggers the impulse in the muscle.
2.The impulse travels through the plasma membrane and down T tubules surrounding the myofribils. As the impulse passes through the T tubules, it causes the sacroplasmic reticulum surrounding the T tubule to release calcium ions into the sacroplasm, eventually reaching the sacromere
3.The Ca+2 binds to troponin located on the actin filament, causing tropomyosin to move and expose binding sites for myosin.
4.The myosin head now binds to actin and forms a cross bridge.
5.ADP and P, are released from myosin, which causes myosin to move.This movement is called the power stroke.
6.ATP binds to myosin causing it to release the actin and reverting ATP into ADP and P. The myosin is now ready to form another Cross bridge and the cycle of contraction will continue until the impulse stops.
Once the impulse stops Ca+2 is released from troponin to cover tropomyosin to cover the binding sites and prevent contraction
Action potential in a muscular fiber
neurons and muscle cells are excitable cells capable of action potential. there are 4 steps that must occur for skeletal muscle to contract
Events of Neuromuscular Junction
Muscle fiber Excitation
EPP triggers an AP in adjacent sarcolemma
excitation contracting coupling
AP in sarcolemma travels down to T Tubules
Sarcoplasmic Reticulum releases calcium
Calcium binds to troponin, which shifts tropomyosin to undercover the myosin binding sites to actin. Myosin head then bind actin.
4.Cross Bridge Cycling
contraction occurs via bridge cycling
membrane that covers all three muscles
Muscle cover, or connective tissue sheaths, support the cells and reinforce the entire muscle
espiselysium - dense irregular CT surrounding the entire muscle which consists of hundreds of muscle cells, blood vessels, and nerve fibers
Perimysium- fibrous CT surroundig the fascicles which are discrete bundles of muscle cells.
Endomysium- fine areolar CT surrounding each muscle fiber, which are elongated multi nucleate cells.
Myasthenia Gravis- a disease characterized by drooping upper lids, difficulty swallowing or talking, or generalized muscle weakness
Involves shortage of ACh receptors due to the presons Ach receptors being attached by own antibodies
suggest this is a autoimmune disease
Rigor Mortis-disorder where muscle stiffens 3-4 hours after death
intracellular calcium levels increase because ATP is no longer being synthesized, so calcium cannot by pumped back into SR; results in cross bridge function
lack of atp also prevents cross bridge detachments resulting in myosin head staying attached to actin, causes constant state of contraction
muscles stay contracted until muscle protien breaks down,causing myosin to release.
Duchenne Musuclar Dystrophy (DMD)- most common and most serious form of muscular dystrophies (muscle-destroying diseases that generally appear during childhood)
disease progresses from extremeties upwards,finally affecting head,chest muscles, and cardiac muscles
caused by a 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.