Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Muscular Tissue Suzanne D'Anna 1 Types of Muscle Tissue skeletal cardiac smooth Suzanne D'Anna 2 Skeletal attached to bones, skin, deep fascia, or other muscles voluntary control striated , alternating light and dark bands along length of myofibrils many nuclei Functions: - movement - posture - respiration Suzanne D'Anna 3 Skeletal Muscle Nuclei Striation Suzanne D'Anna 4 Cardiac located only in the heart striated, single nucleus, branched fibers with intercalated discs involuntary control by autonomic nervous system regulation of heart rate is primarily due to hormones and neurotransmitters no regeneration capability propels blood through blood vessels Suzanne D'Anna 5 Cardiac Muscle intercalated disc Suzanne D'Anna 6 Smooth located in hollow organs, skin attached to hair follicles, etc. no striations, single nucleus, spindleshaped fibers involuntary control by autonomic nervous system some regeneration Suzanne D'Anna 7 Functions of Smooth Muscles mix and propel food though GI tract regulate flow of blood by changing diameter of lumen contraction of urinary bladder, gallbladder, and spleen, expels urine, bile and blood control sphincter muscles control muscles of eye contraction of arrector pili muscles Suzanne D'Anna 8 Types of Smooth Muscles Suzanne D'Anna 9 Multiunit Smooth muscle fibers are not well organized occur as separate fibers rather than sheets found in irises of eye, walls of blood vessels Suzanne D'Anna 10 Visceral Smooth composed of sheets of spindle-shaped cells in contact with one another more common type found in hollow visceral organs capable of stimulating each other display rhythmicity due to self-exciting fibers - responsible for peristalsis Suzanne D'Anna 11 Peristalsis wavelike motion occurs in various tubular organs helps force contents of these organs along their lengths Suzanne D'Anna 12 Contraction of Smooth Muscles acetylcholine and norepinephrine also affected by hormones slower to contract - slower to relax can maintain a forceful contraction longer than skeletal with same amount of ATP can change length without changing tautness Suzanne D'Anna 13 Smooth Muscle Suzanne D'Anna 14 Muscle Fibers many muscle fibers are enclosed in a delicate connective tissue sheath called endomysium several sheathed fibers are wrapped in perimysium in bundles called fascicles (10 -100 fibers) Suzanne D'Anna 15 Muscle Fibers (cont.) many fascicles are joined together by even tougher covering called epimysium fascia covers entire muscles which lead into tendons which attach to bones Suzanne D'Anna 16 Individual Muscle Fiber (single cell) sarcolemma - plasma membrane covering of muscle cell sarcoplasm - cytoplasm of a skeletal muscle cell Suzanne D'Anna 17 Individual Muscle Fiber (cont.) sarcoplasmic reticulum - network of membranous channels - within sarcoplasm (corresponds to endoplasmic reticulum) - surrounds each myofibril - channels run parallel to myofibril - stores calcium which is necessary for muscle contraction Suzanne D'Anna 18 Individual Muscle Fiber (cont.) transverse tubules - fingerlike inward invaginations or channels of sarcolemma - extend from membrane and pass through the fiber - open to outside of the muscle fiber - contain extracellular fluid - carry action potentials to sarcoplasmic reticulum Suzanne D'Anna 19 Individual Muscle Fiber (cont.) cisternae - enlarged portions of sarcoplasmic reticulum - lie on either side of transverse tubules - near region where actin and myosin overlap Suzanne D'Anna 20 Individual Muscle Fiber (cont.) myofibrils - long ribbon-like organelles - lie parallel to one another myofilaments - thread-like structures within myofibrils (contain two types of protein filaments) actin (thin & light) and myocin (thick & dark) Suzanne D'Anna 21 Actin and Myosin appear as light (thin) and dark (thick) bands arrangement of these fibers produces the characteristic striations of a skeletal muscle fiber slide past each other causing muscle cells to contract Suzanne D'Anna 22 Myosin located within the dark portions of the striations (A bands) Suzanne D'Anna 23 Actin located primarily within light areas (I bands) during muscle contraction actin filaments slide farther into A bands attached to the Z lines at end of I bands Z lines extend across muscle fiber enabling adjacent myofibrils to lie side by side segment between two Z lines is called a sarcomere Suzanne D'Anna 24 Sarcomeres repeating units composed of filaments inside myofibrils do not extend the entire length of the muscle fiber Suzanne D'Anna 25 Muscle Activity Suzanne D'Anna 26 Characteristics of Muscle Tissue excitability contractility extensibility elasticity Suzanne D'Anna 27 Excitability (irritability) ability to respond to stimuli generate action potentials or impulses stimuli that initiate action potentials in muscles are neurotransmitters neurotransmitters are released by axon terminals of neurons Suzanne D'Anna 28 Contractility ability to contract and shorten to generate a force muscles contract in response to action potentials Suzanne D'Anna 29 Extensibility ability to be stretched or extended when pulled with pairs of skeletal muscles - one muscle is contracted while the opposing one is usually stretched Suzanne D'Anna 30 Elasticity ability to return to original shape after contraction or extension Suzanne D'Anna 31