Introduction to Human Tissues #3

1. Introduction to Human Tissues #3 Laura Fraser Cotlin, Ph.D. Fundamentals 2 – Dental/Optometry November 2, 2011

2. Classification of Connective Tissues • Embryonic connective tissues • 1. Mesenchymal • 2. Mucous • Connective tissue proper • 1. Loose (areolar) • 2. Dense • a. Dense irregular • b. Dense regular • -collagenous • -elastic • Specialized connective tissue • 1. Cartilage • 2. Bone • 3. Blood • 4. Adipose

3. Adipose Tissue

4. Adipocytes • -involved in energy storage, insulation, cushioning of organs and secretion of hormones • Large cells, can be up to ~100um • Lipid mass is not membrane bound • White (unilocular) or brown (multilocular) • Hormones involved in short-term weight control • ghrelin – stimulates appetite • Peptide YY – induces sense of fullness • Hormones involved in long-term weight control • leptin – produced exclusively by adipocytes. • -generally thought to reduce appetite (obese people have high levels and are thought to be resistant to leptin action) • insulin – enhances conversion of glucose into triglycerides

5. Fat absorption and release

6. White Adipose Tissue

7. Blood

8. The hematocrit of human blood -volume of cells and plasma is ~45 and 55% respectively -Hematocrit - volume of packed erythrocytes in a sample of blood Normal hematocrit ~39-50% in males ~35-45% in females Leukocytes and platelets constitute only ~1% of blood volume

9. Composition of Whole Blood • Fluid is called PLASMA • occupies ~55% of the total blood volume • liquid extracellular material • Plasma that lacks coagulation (clotting factors) is called SERUM.

10. Cartilage

11. a c d b c CARTILAGE Specialized connective tissue, part of skeletal system Functions: provide flexible support (bone rigid template for bone formation Locations: limited sites – respiratory system, joints, external ear Composition: cells + matrix (properties from matrix) 1. Matrix: a. Fibers: collagen II, elastic fibers b. Ground substance: proteoglycans and glycosaminoglycans (GAGs) 2. Cells: chondroblasts, chondrocytes,

12. FEATURES OF CARTILAGE • Avascular • No nerves • No lymphatics Perichondrium Isogenous group Chondrocyte in lacuna • CARTILAGE IS A SHOCK ABSORBER • Add pressure: water forced out of tissue, absorbs pressure • Release pressure: water rebinds PG aggregate and tissue returns to original size Territorial matrix around chondrocytes Interterritorial matrix between isogenous groups or single cells.

13. Chondrocytes in association with Matrix

14. TYPES OF CARTILAGE • Hyaline: most common – nasal septum, joint surface, ribs • Elastic: enriched with elastic fibers – ear, larynx • -Looks like hyaline cartilage with the addition of elastic fibers between cells • Fibrocartilage: found in interverterbral disks, tendon/ligament attachment. • -See rows of chondrocytes with increased fibrous matrix between between them

15. Hyaline Cartilage

16. Elastic Cartilage

18. Fibrocartilage

19. Bone Tissue

20. FUNCTIONS OF BONE • Support • Protection (skull) • Locomotion • Calcium store (also Mg and Na) • Hematopoiesis (marrow) • TYPES OF MATURE BONE • Cancellous (spongy): fine irregular plates – trabeculae • inside long bones (marrow) • gives strength without weight • Compact: highly ordered • Types: outer and inner circumferential lamellae • -contains Haversian systems (osteons)

21. COMPOSITION OF BONE: cells + matrix • Matrix • Organic a) fibers: type I collagen, highly organized • b) ground substance: little, some PG as cartilage • Inorganic: Calcium phosphate complexes forms 50% of the matrix, giving the material its rigidity • ***Bone looks solid but is alive, dynamic and continually remodeling. • ***Is highly vascularized (compared to cartilage)

22. PRIMARY CELLS IN BONE • Osteoblasts: immature, synthesize and secrete osteoid, which becomes mineralized to give bone; do not divide. • Osteocytes: surrounded by matrix, maintain matrix; do not divide. • Osteoclasts: large multinucleate cells, resemble macrophage in function, remodel bone by resorbing bone matrix.

23. Bone Cells Main cells include: -Osteoblast -Osteocyte -Osteoclast

24. Articular cartilage Cancellous bone EPIPHYSIS DIAPHYSIS EPIPHYSIS Compact bone Periosteum Marrow cavity

25. Compact (Ground) Bone

26. Spongy Bone(intermembraneous)

27. Muscle Tissue

28. Types of Muscle Tissue

29. Common Features of ALL MUSCLE TISSUE • Derived from mesoderm layer • Cell membrane = sarcolemma • Cytoplasm = sarcoplasm • ER = sarcoplasmic reticulum (SR) • Contraction of all muscle depends on the interaction of actin and myosin • Contraction of all muscle is regulated by cellular calcium

30. Skeletal Muscle Tissue • bundles of very long, cylindrical multinucleated cells showing cross striations. • contraction is quick, forceful --> caused by interactions of thin actin filaments and thick myosin filaments. • Cell size: length can be up to ~3cm diameter ranges 10-100um • Associated Connective Tissue • Epimysium - dense connective tissue surrounding the entire muscle. • Perimysium - connective tissue surrounding the bundles of fibers within a muscle. • Endomysium – basement membrane and delicate connective tissue surrounding each muscle fiber

31. Structure of Skeletal Muscle Tissue

32. Long. section of Skeletal Muscle

33. EM of Striated Muscle

34. The Sarcomere–extends from Z-line to Z-line -the smallest repetitive subunit of the contractile unit

35. Arrangement of Thick and Thin Filaments

36. Sarcomeres at different functional stages

37. Neuromuscular Junction

38. Cardiac Muscle Tissue

39. Cardiac Muscle Tissue • heart muscle consists of tightly knit bundles of cells which provide for a characteristic wave of contraction that leads to a wringing out of the heart ventricles. • exhibit a cross-striated banding pattern identical to that of skeletal muscle. • structure and function of the contractile proteins are almost the same as in skeletal muscle. • distinguishing characteristic is the presence of intercalated disks- dark-staining transverse lines that cross the chains of cardiac cells at irregular intervals.

40. EM of cardiac muscle tissue

41. Structure of the Intercalated Disk

42. Long. section of Cardiac Muscle

43. Smooth Muscle Tissue

44. Smooth Muscle Tissue • composed of elongated, nonstriated cells • Cells are enclosed by a basal lamina and network of reticular fibers • these 2 components serve to combine the forces generated by each smooth muscle fiber into a concerted action. • cells are fusiform (largest at midpoint and tapered at the ends) with a single centrally-located nucleus • tight packaging of tissue is achieved by lining up cells with the narrow parts of some cells against the broad parts of neighboring cells. • the cell boarders become scalloped when contracted, and the nucleus becomes folded or has a cork-screw appearance.

45. Smooth Muscle Tissue • composed of elongated, nonstriated, fusiform cells(largest at midpoint and tapered at the ends) • tight packaging of tissue is achieved by lining up cells with the narrow parts of some cells against the broad parts of neighboring cells. • Contain dense bodies for attachment of filaments and propagation of contraction.

46. Nerve Tissue

47. ORGANIZATION OF NERVOUS SYSTEM

48. Peripheral Nervous System Can be divided into: -the somatic nervous system -the autonomic nervous system -sympathetic division -parasympatheic division -enteric division Components include: -cranial nerves -spinal nerves -peripheral nerves -ganglia -somatic or sensory - dorsal root ganglia -autonomic sympathetic, parasympathetic, enteric -specialized nerve endings

49. Types of Neurons Can be classified based on: -morphology -function -neurotransmitters

50. Organization of a Typical Neuron