muscle_tissue_powerpoint_that56684531

[Audio] Physiology of Muscle Tissue Vyomkesh ameta Akash kumar Shailesh pahadiya Vikas.

[Audio] Muscle Tissue Types • Skeletal – Attached to bones – Nuclei multiple and peripherally located – During development, 100 or more myoblasts, a type of mesodermal cell, fuse to form a skeletal muscle fiber. – Striated, Voluntary and involuntary ( reflexes) • Smooth – Walls of hollow organs, blood vessels, eye, glands, skin – Single nucleus centrally located – Not striated, involuntary, gap junctions in visceral smooth • Cardiac- In the heart only. – Single nucleus centrally located – Striations, involuntary, intercalated disks.

[Audio] Muscular System Functions • Body movement • Maintenance of posture • Respiration • Production of body heat • Communication • Constriction of organs and vessels • Heart beat.

[Audio] Properties of Muscle • Contractility – Ability of a muscle to shorten with force – It DOES NOT produce force by lengthening/pushing! • Excitability – Capacity of muscle to respond to a stimulus • Extensibility – Muscle can be stretched to its normal resting length and beyond to a limited degree • Elasticity – Ability of muscle to recoil to original resting length after stretched.

[Audio] Cardiac Muscle • Branching cells • One/ two nuclei per cell • Striated • Involuntary • Medium speed contractions.

. . Intercalated disks Cross-striations Myocytes Nuclei.

. . Microscopic Anatomy of Cardiac Muscle Nucleus Intercalated discs Cardiac muscle cell Gap junctions (a) Cardiac muscle cell Intercalated disc i Nucleus Sarcolemma (b) Fasciae adherens Mitochondrion Nucleus Mitochondrion T tubule Sarcoplasmic reticulum.

. . •KuéfeusQ intercalated disk.

[Audio] Smooth Muscle • Fusiform cells • One nucleus per cell • Nonstriated • Involuntary • Slow, wave-like contractions.

[Audio] Copyright © 2008 Pearson Education, Inc., publishing as Single-Unit Muscle Figure 12.35 b.

[Audio] Copyright © 2008 Pearson Education, Inc., publishing as Multi-Unit Muscle Figure 12.35a.

[Audio] Copyright © 2008 Pearson Education, Inc., publishing as Multi vs. Single-Unit Muscle Figure 12.35.

[Audio] Skeletal Muscle • Long cylindrical cells • Many nuclei per cell • Striated • Voluntary • Rapid contractions.

[Audio] Muscle Muscle fibers Muscle fiber Myofibril Sarcomere Modified from McMahon, Muscles, Reflexes and Locomotion Princeton University Press, 1984. A little less than half of the body's mass is composed of skeletal muscle, with most muscles linked to bones by tendons through which the forces and movements developed during contractions are transmitted to the skeleton. Structural hierarchy of skeletal muscle.

[Audio] Muscle Proteins • Contractile Proteins ( actin and myosin) • Regulatory Proteins (i.e. tropomyosin and troponin) • Structural Proteins (i.e. Titin).

[Audio] Myosin is a hexamer: 2 myosin heavy chains 4 myosin light chains C terminus 2 nm Coiled coil of two a helices Myosin is a molecular motor Myosin S1 fragment crystal structure Ruegg et al., ( 2002) News Physiol Sci 17: 213- 218. NH2-terminal catalytic (motor) domain neck region/ lever arm Nucleotide binding site Myosin head: retains all of the motor functions of myosin, i.e. the ability to produce movement and force. Modified from Vander, Sherman, Luciano Human Physiology, McGraw-Hill..

[Audio] Working stroke produced by opening and closing of the nucleotide binding site, resulting in rotation of the regulatory domain ( neck) about a fulcrum ( converter domain). Sub-nanometer rearrangements at active site are geared up to give 510 nm displacement at the end of the lever arm. Hypothetical model of the swinging lever arm Ruegg et al., ( 2002) News Physiol Sci 17: 213- 218..

[Audio] Skeletal Muscle • Produce movement • Maintain posture & body position • Support Soft Tissues • Guard entrance / exits • Maintain body temperature • Store nutrient reserves • Makes up aprox. 40% of body weight.

. . TABLE 12.2 Comparison of Skeletal, Smooth, and Cardiac Muscle Property Striations (sarcomeres) Actin and myosin Level of control Neural input Neuroeffector junction Hormonal control Source of calcium Regulatory protein that binds calcium Gap junctions Pacemaker activity Myosin ATPase activity Recruitment Skeletal Yes Yes Voluntary Somatic Neuromuscular junction—specific None Troponin Fastest Yes Smooth (single-unit) No Yes Involuntary Autonomic Varicosities—diffuse Several, depending on location SR and ECF Calmodulin Yes Yes Slowest No Smooth (multi-unit) No Yes Involuntary Autonomic Varicosities—diffuse Several, depending on location SR and ECF Calmodulin No (or few) No Slowest Yes Cardiac Yes Yes Involuntary Autonomic Varicosities—diffuse Epinephrine SR and ECF Troponin Yes Yes Intermediate.

[Audio] Skeletal Muscle Structure. . . Skeletal Muscle Structure.

[Audio] - Sarcoplamsic Reticulum ( SR): Fluid filled sacks that encircle each myofibril. It is similar to the smooth endoplasmic reticulum in other cells. -Terminal cisterns ( cistern-reservoir): Dilated ends of SR, butt against T tubule from both sides. -T bubule and 2 terminal cisterns on either side of it form a TRIAD. -In relaxed muscle fiber, SR stores calcium ions - Release of calcium ions from terminal cisterns of SR triggers muscle contraction..

[Audio] Skeletal Muscle Fiber. . . Skeletal Muscle Fiber.

[Audio] Connective Tissue, Nerve, Blood Vessels • Connective tissue – External lamina – Endomysium – Perimysium – Fasciculus – Epimysium • Fascia • Nerve and blood vessels – Abundant.

[Audio] -Some myoblasts (the cells that congegrate to form skeletal muscle fibers in the embryo) remain, they are referred to as satellite cells. - Satellite cells maintain ( repair, etc.) skeletal muscle fibers. They can divide and they can fuse with one another and with muscle fibers to repair them, etc. -Mature muscle fibers range from between 10 to 100 micrometers in diameter. The "typical" muscle fiber is around 4 inches (10cm). There are muscle fibers that are up to a foot ( 30cm) long..

[Audio] Embryologic origin:. . . Embryologic origin:.

[Audio] -The plasma membrane of a muscle cell is referred to as the sarcolemma. The nuclei of skeletal muscle fibers lie just below the sarcolemma. -There are numerous invaginations of the sarcolemma that tunnel from the surface of the fiber to the center of the muscle fiber. They are open to the outside of the fiber and filled with interstitial fluid. These are called transverse tubules or T tubules. - Action potentials propagate along sarcolemma and T tubules, this insures a uniform contraction of a given muscle fiber. - Sarcoplasm: cytoplasm of the muscle fiber. - Glycogen is abundant in the sarcoplasmplasm that can quickly be split via hydrolysis into glucose which can be used to generate ATP..

[Audio] - Myoglibin is also abundant in the sarcoplasm. Myoglobin is red in color. It is found only in muscle tissue. It binds free oxygen molecules that diffuse into muscle fibers from interstitial fluid, which obtained the free oxygen from the capillaries in the blood. - Mitochondria are abundant in muscle tissue. They lie very close to muscle proteins that utilize ATP during muscle contractions. - Myofibrils: contractile element of the skeletal muscle fibers. -They are about 2 micrometers in diameter and extend the entire length of the muscle fiber that they are in. -Myofibrils have prominent striations ( stripes), thus the name " striated muscle tissue." These striations make the entire muscle appear striated..

. . Striations:. I band I band A band H zone Zone ot overla Sarcomere A band M line Z line Z line Titin Thin filament Thick filament Z line M line Zone of overlap Sarcomere.

. . I band (a) A band H band Zone of overlap M line Sarcomere Sarcomere Z line Titin Thin Thick filament filament.

[Audio] - Myofibrils are composed of filaments. These are 1 to 2 micrometers long. The diameter of the THIN FILAMENTS is about 8 nanometers and those of the THICK FILAMENTS are around 16 nanometers. -In general, there are 2 thin filaments for each thick filament. - Filaments inside of the miofibril do not extend the entire muscle length. They are arranged in small compartments known as sarcomeres. These are the basic functional unit of the miofibril. -Z discs are narrow plate-shaped regions of dense material that separate sarcomeres from each other..

[Audio] -Thick and thin filaments overlap one another to varying degrees. This is dependent on whether the muscle is contracted, relaxed or stretched. -The pattern of this overlap, that consists of a variety of zones and bands creates the striations that are characteristic of skeletal muscle..

[Audio] Organization of myofilaments I:. . . Organization of myofilaments I:.

[Audio] Organization of myofilaments II:. . . Organization of myofilaments II:.

. . Myofibril LTJ Z line Sarcomere H band nr UUUUU nnr M line Actinin Z line Titin (a) Z line and thin filaments Troponin Active site Nebulin Tropomyosin G-actin molecules F-actin strand (b) Thin filament.

. . Myofibril (c) Thick filaments LTJ Z line M line Sarcomere H band nr UUUUU nnr M line Myosin tail (d) Myosin molecule Titin Myosin head Hinge.

[Audio] Sliding Filament Model I: • Actin myofilaments sliding over myosin to shorten sarcomeres – Actin and myosin DO NOT change length – Shortening sarcomeres responsible for skeletal muscle contraction • During relaxation, sarcomeres lengthen.

[Audio] Z line Z line. . . . Z line Z line.

[Audio] -Some components of muscle tissue are elastic. They stretch slightly before they transfer tension generated by sliding filaments. -Elastic components include titin molecules, connective tissue around muscle fibers ( endomysium, perimysium and epimysium, as well as tendons..

[Audio] -As skeletal muscles shorten, the elastic components are stretched and become taut. The tension then pulls the body part that it is attached to, resulting in movement. - Contractions do not always result in shortening of muscle fibers: Isometric contractions are where the myosin heads rotate and generate tension but thin filaments are unable to slide toward M line due to excessive opposing tension. Isotonic contractions result in the shortening of the muscle..

[Audio] Sarcomere Relaxed. . . . Sarcomere Relaxed.

[Audio] Sarcomere Partially Contracted. . . . Sarcomere Partially.

[Audio] Sarcomere Completely Contracted. . . . Sarcomere Completely.

. . . . .

[Audio] Sliding filament model II:. . . Sliding filament model II:.

[Audio] Sarcomere Shortening. . . Sarcomere Shortening.

[Audio] Structure of Actin and Myosin. . . Structure of Actin and Myosin.

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. . STEP I ADP ACTIVE-SITE EXPOSURE Sarcoplasm Active site Ca2+ ADP.

. . STEP 2 ADP Ca2+ CROSS-BRIDGE FORMATION ADP ca2+.

. . STEP 3 PIVOTING OF MYOSIN HEAD Ca2+ ADp+ p.