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  1. 1. Zulcaif Ahmad Muscles
  2. 2. Specialized cells for movement which containsnumerous filaments of special protein actin and myosin
  3. 3. MusclesThese are the part of body which spots the body functions.More than 600 muscles present in our body
  4. 4. MusclesClassification:It based in three different factors: Depending upon striations Depending upon control Depending upon function
  5. 5. Muscles1. Depending upon striations:It is further divided into two groupsa) striated MusclesTrasverse lines at regular intervals(skeletal and cardiac musles)a) non-striated MusclesWithout cross striations(smooth muscles)
  6. 6. Muscles2) Depending upon control:Divided into two types:a) Voluntry musles: in our control - Skeletal muscles inervated by somatic nervesb) In-voluntry muscles: Not in our control – Cardiac muscles and smooth muscles inervated by autonomic nerves
  7. 7. Muscles3) Depending upon functions/situation:Further divided into three typesa) Skeletal Muscles (in association with bone forming skeletal system – 40 – 50%)b) Cardiac Muscles (forms musculature of heart)c) Smooth Muscles (they are in association with viscera – internal organs, GIT, Urinary system, respiratory system)
  8. 8. MusclesContractility:Skeletal muscles gives response to a stimulus in the form of contraction.- Contraction: The internal events of the muscles which are menifested by change in either the length or tension of the muscles fibers. (Has two types)
  9. 9. Muscles1. Isotonic contraction: iso = same tonic = tension - Simple Flexion of arms2. Isometric contraction: - length same and tension increase - pulling any heavy object
  10. 10. Changes during muscles contractionIntroduction:Muscles is contract when it is stimulated.It is physical and mechanical event. Other changes also occur.Other changes:a) electrical changesb) physical changesc) histological changesd) thermal changese) chemical changes
  11. 11. Changes during muscles contraction Electrical changes:When muscles is stimulated, electrical changes occur before theonset of mechanical changes. Resting membrane potential (the electrical potential difference across the cell membrane between inside and outside the cell). Action potential (series of changes in membrane potential - A wave of electrical discharge that travels along the membrane of the cell).It occurs in two phaseso Depolarizationo Repolarization
  12. 12. Changes during muscles contraction Ionic bases of electrical changes. Ionic imbalancea) Sodium potassium pumpb) Selective permeability of cell membrane
  13. 13. Changes during muscles contraction Graded potential (stimulation of the reseptors, synaps or nuromuscular junction produces some mild changes in the membrane potential, it losses its intensity as its starts spreading)
  14. 14. Changes during muscles contraction Physical changes:Change in length of muscles fiber or change in tensiondeveloped in muscle (contractility) Chemical changes:o Liberation of energy (the energy neccesery for muscular contraction is librated during the processes of breakdown and resynthesis of ATP)  Breakdown of ATP:I. spread of action potential into the musclesII. libration of calcium ion from sisternae of L-tubules into the sarcoplasmIII. movement of myosin headIV. sliding mechanism
  15. 15. Changes during muscles contraction resynthesis of ATP: ADP attaches with high energy phosphate redical except combining with Pi. Sources for high energy phosphateo Synthesis of ATP from creatine phosphate ADP + CP ATP + Creatineo Synthesis of ATP By carbohydrates metabolism Glycolysis, cori’s circle, Krebs cycles
  16. 16. Changes during muscles contractionChanges in pH:o In resting condition. reaction of muscle is alkaline with a pH of 7.3.o During onset of contraction. at the beginning of muscular contraction, the reaction become acidic. The acidity is due to dephosphorylation of ATP into ADP and Pi.o During later part of contraction. the muscle become alkaline, it is due to resynthesis of ATP from Cl.o At the end of contraction the muscles become once again acidic, this acidity is due to the formation of pyruvic acid and or lactic acid.
  17. 17. Changes during muscles contraction Histological changes:o acto-myosin complex (Bands)o excitation contraction couplingo role of troponin and tropomyosino sliding theory or ratchet theory
  18. 18. Changes during muscles contraction Thermal changes:During musclar contraction heat is produce not all theheat is librated at a time it release in different stageso Resting heato Initial heatI. heat of activation (produce during the release of Ca ions from L-tubules)II. heat of shortening (produce due to various structural changes in the muscle fiber like movement of cross bridges and myosin heads)III. heat of relaxationo Recovery heat Due to chemical processes involved resynthesis of chemical substances broken down during contraction
  19. 19. Refrence: Essentials of medical physiology by jaypee (4th edition) ch#28,29,30,31 ( page 145,146,149,154,155,163,164,165,166,168,169,170,171, 172,173) Text book of physiology by guyton n hall ( 11th edition) , ch#06(pg 72 to 79 )