MUSCLES LECTURE Flashcards
Basic functions of muscles are ?
- heartbeat
- maintenance of posture
- respiration
- body heat
- body movement
- constriction organ and vessels
- communication
What are the properties of muscle?
- contractility: ability of a muscle to shorten with force
- excitability: ability of muscle to respond to stimulus
- extensibility: muscle able to be contracted to normal resting length and further to a degree
- elasticity: ability of muscle to recoil to original resting length after stretched
what is the function of skeletal muscle?
- Skeletal movement: simple motions such as extending leg to walk to highly complex movements like martial arts, swimming or dancing
- maintain posture and body position: constant muscular contraction necessary to maintain posture. for example holding head in position when reading book or balancing body above feet when walking involves contraction muscles stabilize joints.without constant contraction we would topple over
- support soft tissues: muscles support weight visceral organs protect internal tissues from injury
- regulates entering and exiting of material: encircle openings and provide voluntary control over swallowing, defacatation and urination
what is the functions of smooth muscle?
-regulates blood flow,dilates/constricts pupils, mixes food in digestive tract
what is the function of cardiac muscle?
- only found in heart
- cells form extensive connection with each other;occur at special regions called intercalated discs
- incapable dividing; muscle tissue damaged by injury or disease unable to regenerate
- primary function is too push blood through arteries and veins of circulatory system
What is the structure of Skeletal Muscle?
- composed of muscle cells(fibers) connective tissue, blood vessels and nerves
- fibers long cyndrical and multi nucleated
- small diameter small muscles larger in larger ones(1-4 mm in length)
- developed from myoblasts.numbers remain constant.
- striated appearance due to dark banding
layers and function of Connective Tissue?
- each skeletal muscle has 3 concentric layers or wrappings of connective tissue. outer epimysium, central perimysium and inner endomysium.
- epymysium: layer dense irregular connective tissue surrounds entire skeletal muscle. separates muscle from surrounding tissues and organs and connected to deep fascia.
perymysium-connective tissue fibers divide muscles into series internal compartments, each which contain bundle muscle fibers called fascicle. perymisium contains blood vessels and nerves that branch to supple each fascicle.
endomysium-surrounds each skeletal muscle fiber, binds each muscle fiber to neighbour and supports capillaries that supply individual fibers. consists of a complex network of reticular fibers. scattered myosateie cells lie between endomysium and muscle fibers. these stem cells function in regeneration and repair of damaged muscle tissue
Function of Fascia?
- forms layer under skin
- holds muscles together separates them into functional groups
- allows free movement of muscles
- carries nerves, blood vessels and lymphatics
- continuous with connective tissues of tendons and periosteum
Nerve and blood supply function?
-Connective tissues of (epimysium,perimysium, endomysium contain nerves and blood vessels that supply muscle fibers.
Nerves: provide conscious control to muscles
-muscular contraction requires tremendous quantities energy, blood vessels enter epimysium alongside nerves and vessels and nerves follow same branching pattern through perimysium.
-neuromuscular synapse is where chemical communication between synaptic terminal of neutron and skeletal muscle fibre occurs.
- muscle contraction requires an incredible amount energy. an extensive vascular supply delivers oxygen and nutrients needed for production of tap in skeletal muscles.
- blood vessels enter epimysium alongside nerves an vessels and nerves follow same branching pattern through perimysium. once withn endomysium arteries supply extensive capillary network around muscle fiber.
what are sarcomeres?
-all proteins within myofibril organized repeating units called sarcomeres
-smallest function units of muscle fiber. interactions between thick filaments(myosin) and thin filaments(actin) responsible for skeletal muscle fiber contractions.
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what make up muscle fibers?
-sarcomeres. which are made of myofilaments actin and myosin.
Function of Actin?
- 2 strands of double helix attached at each end of sarcomere;extends length of myofilament
- composed g actin monomers each of which have an active site
- actin site can bind myosin during muscle contraction
what is tropomyosin and what is its function?
- elongated protein that winds along groove of F actin double helix
- form long chain covers active sites. prevents actin-myosin interaction
Troponin?
composed 3 subunits: 1 binds to actin. second binds to tropomyosin. 3rd binds to calcium ions.
-tropomyosin/troponin complex regulates interaction between active sites on g actin and myosin.
Function of Myosin?
breaks down atp releasing energy. part of energy used to bend hinge region of myosin molecule during contraction
primary function skeletal muscle
move body by pulling bones skeleton( dance,walk,play sports)
primary function cardiac muscle tissue
pushes blood through arteries and veins circulatory system.
primary function smooth muscle
pushes fluids and solids along digestive tract and performs various functions in other systems.
what is the function of tendons and aponeuroses?
collagen fibers epimysium,perimysium and endomysium come together form a tendon attaches muscle to bone,cartilage,skin or another muscle. resemble thick cords or cables. tendons that form thick sheets aponeuroses.
what makes skeletal muscle different?
- fibers extremely large. A leg muscle finer could have diameter 100 um length equal to entire muscle.
- multinucleate. during development groups embryonic cells called myobasts fuse together to create individual muscle fibres
- each fiber consists of hundreds of nuclei deep to the sarcolemma(cell membrane) this distinguishes skeletal muscle from cardiac or smooth muscle.
- when skeletal muscle injured, these stem cells may differentiate and assist in repair and regeneration of the muscle.
