Unit I

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Smooth muscle (LP) : (Nucleus, Sarcoplasm, Myofibrils, Connective tissue)L.S. T.S.Cardiac Muscle: (Myofibril Intercalated discs (HP): (Branching bundles-Connective tissue-capillaries) & anastomosis of myofibres)26
Smooth muscle (LP): Smooth muscle fibre is a single cell with single central nucleus. Layers of smoothmuscles are commonly subdivided into bundles of fibres each of which is invested with connective tissuesupplying it with capillaries and nerve fibres. The ends of fibres in one bundle interdigitate with those inother bundles. Muscle fibres are elongated and tapered at the ends having length 30µ to 500µ. Averagelength is 200µ with 8µ diameter while longest are seen in pregnant uterus. The nucleus lies in the widest partof the fibre i.e. in the middle. The cytoplasm is eosinophilic and uniform. Relaxed smooth muscle is spindleshaped with smooth outline while contracted muscle assumes a more ellipsoid shape and the cell membraneand cytoplasm bulge out into bubble like expansions. They lack striations because filaments overlap eachother in no definite pattern and Z lines are absent. This sacrifies speed of contraction for relativeindefatiguability.Cardiac Muscle: It is present in the heart. It is striated and is involuntary in action. The structure of thesarcomere is the same as that in the skeletal muscle.Cardiac Muscle: Muscle fibres are not strictly parallel but they branch and anastomose to form anetwork . Each muscle cell is about 80µm length and l5µm in diameter with single central nucleus. Themyofibrils are relatively few so that the striations are not as distinct as in skeletal muscles.The slit likespaces between anastomosing fibres contain endomysium that carries capillaries and lymphatics close tothe muscle fibres. These spaces show the nuclei of fibroblast.Cytoplasm of the cardiac fibre iseosinophilic.Intercalated discs (HP): The junctions between adjacent muscle cells are seen as dark staining transverselines running across the fibres called intercalated discs. They may appear broken into number of steps.These discs lie close to the I band of the striations. The cytoplasm near the cell junctions shows denseappearance with actin filaments embedded in it. These cell junctions consists of numerous desmosomes,gap junctions and tight junctions. Gap junctions allow electrical continuity thus cardiacmuscle is a physiological syncytium but not an anatomical one.Notes:27
Page 4: Mitochondrion Golgi apparatusSmooth
Page 7 and 8: . Nonmembrane bound: These organell
Page 9 and 10: Nucleus: It is made up of deoxyribo
Page 11 and 12: Intercellular contactsThe plasma me
Page 13 and 14: 3. Epithelial tissueHuman body is m
Page 15: Compound epithelium: They have two
Page 18 and 19: 4. Connective tissueFibroblast. Fib
Page 20 and 21: Collagen fibres Elastic fibresLoose
Page 22: 5. Muscular TissueStriated muscle L
Page 25: Sarcomere (Relaxed): Each myofibril
Page 30 and 31: Astrocyte (Fibrous) Astrocyte (Prot
Page 32: Peripheral nerve T.S: (Epineurium -
Page 35 and 36: 7. CartilageIt is a specialised con
Page 37 and 38: White fibrocartilage: It shows bund
Page 40 and 41: Decalcified bone T.S.: (Fibrous and
Page 42 and 43: 9. Blood VesselsElastic artery: (Tu
Page 44 and 45: VeinCapillaries: (Endothelium- Basa
Page 46 and 47: 10. Lymphoid TissueLymph node (LP):
Page 48 and 49: Spleen (LP): ( Capsule - Trabeculae
Page 50 and 51: Thymus: (Capsule-Septa-Lobules-Cort
Page 52 and 53: Palatine Tonsil (LP): (Stratified s
Page 54 and 55: Morphological classification of exo
Page 56 and 57: Serous salivary gland e.g Parotid g
Page 58 and 59: Mucous salivary gland (LP): (Interl
Page 61 and 62: Mixed salivary gland (LP): A saliva
Page 63 and 64: 12. Integumentary SystemSkin, the l
Page 65 and 66: Hair: In humans, hairs are not impo
Page 67 and 68: Sebaceous gland: It is seen on the
Page 69: Tooth: The tooth shows a projected

Unit I

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