Chapter 4 - 2

1. Chapter 4 - 2 Histology Tissues and Membranes

2. Adipose Connective Tissue • Mature cells are specialized for storage of triglycerides and largest cells in body. • Adipocytes are derived from fibroblast cells. • Cells fill up with triglycerides which push cell nuclei to the periphery of the cell. • Most adipose in adults is white adipose tissue. • Brown adipose tissue gets its coloration from rich vascular supply and is less common. • Functions as insulation, energy storage, protects and supports organs. • Usually found with or close to areolar tissue.

3. Adipose Connective Tissue

4. Reticular Connective Tissue • Composed of interlacing reticular fibers with various types of cells interspersed among the fibers. • Forms the stroma of the liver, spleen and lymph nodes and helps to bind smooth muscle cells.

5. Reticular Connective Tissue

6. Dense Regular Connective Tissue • Composed of bundles of collagen fibers regularly arranged in parallel patterns. • Fibroblasts are interspersed between the collagen fibers. • Main component in ligaments, tendons, aponeuroses and fascia. • Has a wavy appearance on slides. • Forms tendons to attach muscles to bone and ligaments to attach bones to bones.

7. Dense Regular Connective Tissue

8. Dense Irregular Connective Tissue • Similar to areolar connective tissue but collagen fibers are much thicker. • Fibers run in different planes making this a very strong tissue and resistant to strong tensions from all directions. • Found in dermis; fibrous capsules surrounding kidneys, bones and lymph nodes; and in the submucosa of the GI tract.

9. Dense Irregular Connective Tissue

10. Dense Irregular Connective Tissue

11. Elastic Connective Tissue • High content of branching elastic fibers. • Very distensible, allows for stretching and returning to original shapes. • Found in lung tissue, large elastic arteries, and suspensory ligaments .

12. Elastic Connective Tissue

13. Cartilage • Three types: • Hyaline cartilage • Fibrocartilage • Elastic cartilage

14. Hyaline Cartilage • Consists of a dense network of collagen fibers embedded in a gel-like ground substance containing chondroitin sulfate with chondrocytes situated in lacunae. • Matrix appears homogeneous and clear of fibers. • The predominant cartilage found in the trachea, bronchi, articular cartilages, nose and ribs.

15. Hyaline Cartilage

16. Elastic Cartilage • Consists of chondrocytes located in lacunae surrounded by a network of elastic fibers. • Found in epiglottis, pinna of the ear and the internal auditory canal (Eustachian tube)

17. Elastic Cartilage

18. Fibrocartilage • Consists of chondrocytes in lacunae scattered among bundles of collagen fibers. • Most predominant in intervertebral discs, pubic symphysis, and menisci of knee joints.

19. Fibro cartilage

20. Bone Two types: Compact and Spongy • Compactbone consists of osteons (Haversian systems) osteocytes in lacunae and lamellae. • Spongy bone is characterized by trabeculae surrounded by spaces filled with red bone marrow

21. Bone • Two types: a) Compact b) Spongy

22. Compact Bone

23. Blood • Consists of liquid portion (plasma) • Erythrocytes (RBC) • Leukocytes (WBC’s = 5 types) • Platelets (Thrombocytes) • Functions to carry nutrients and waste products to and from tissues as well as protect body against foreign invaders and infection. Also active against bleeding maladies and hemorrhage.

24. Blood

25. Erythrocytes • Small anucleated cells in blood • Donut shaped • Most numerous cells in a blood smear

26. Leukocytes • Includes Agranulocytes and Granulocytes. • Agranulocytes: lymphocytes and monocytes • Granulocytes: neutrophils, eosinophils and basophils • Never Let Monkeys Eat Bananas (Most abundant to least abundant) • neutrophils>lymphocytes>monocytes>eosin-ophils>basophils

27. Leukocytes

28. Neutrophils • Medium-sized leukocytes (10-12 um) • Most numerous white blood cells (60-70%) • Granular cytoplasm but granules not easily discernable • Nucleus is multi-lobed and variable shaped Lymphocytes Nucleus is spherical and dark purple inside pale blue cytoplasm (5-17 um) Second most prominent wbc (20-25%)

29. Monocytes • Largest of the wbc’s (14-24 um) • Third most abundant wbc’s (3-8%) • Nucleus is “U” or kidney shaped • Cytoplasm is bluish in color Eosinophils • Nucleus is bi-lobed • Reddish cytoplasmic granules • Similar size to neutrophils (10-14 um) • Fourth most abundant wbc’s (2-4%)

30. Basophils • Nucleus is bilobed; (8-10 um) • Large blue-purple cytoplasmic granules • Least common wbc (0.5-1%)

31. Leukocytes summary

32. Body membranes • Cutaneous membranes = skin (more later) • Mucous membranes = line body cavities that open directly to the exterior (digestive, respiratory, reproductive and urinary tracts). • Serous membranes = line body cavities not directly open to exterior • Synovial membranes = line joint cavities

33. Mucous membranes • Vary considerably throughout the body where they exist. • Are an important barrier to foreign microbes and agents that could invade the body. • Composed of epithelial tissues with underlying connective tissue support. • Contain numerous mucus and goblet cells that keep the membranes moist.

34. Serous Membranes (SM) • Composed of areolar (loose) connective tissue and covered by simple squamous epithelium • Serous membranes line body cavities that are not exposed to the outside and also cover the organs within the cavities. There are 2 layers with a space between them. • Parietal layer = attached to body wall • Visceral layer= covers and attaches to organs • Serous fluid = clear fluid between two layers

35. Specialized Serous Membranes • Pericardium = serous membrane surrounding the heart as a sac and covering the heart. • Pleura = serous membranes lining the thoracic cavity and covering the lungs.

36. Specialized Serous Membranes • Peritoneum = serous membrane lining the abdominal cavity and covering most abdominal organs, except the kidneys, duodenum, and parts of the colon.

37. Synovial membranes • Line joint cavities • Consist of fibrous connective tissue and enclose the joint cavities. • This will be covered in greater detail in the next unit when we talked about joints and articulations.

38. Muscle Three types • Skeletal muscle • Smooth muscle • Cardiac muscle

39. Skeletal Muscle • Most prominent characteristic is parallel large cylindrical cells with multiple nuclei. • Cross-striations are present. • Voluntary muscle; under willful control. • Attached to bones and tendons and skin.

40. Skeletal Muscle

41. Cardiac muscle • Branching cells that interdigitate as a syncytium. • Intercalated discs present at cell junctions. • Generally uni-nucleate • Found in walls of heart only (myocardium) • Characterized by auto-rhythmicity • Involuntary muscle • Cross striations are present.

42. Cardiac muscle

43. Smooth Muscle • Cells are spindle shaped • Single nucleus • DOES NOT HAVE cross striations • Involuntary muscle • Found in walls of most hollow organs (vessel walls, intestinal tract walls, reproductive tract, urinary tract, respiratory tract, etc.).

44. Smooth Muscle

45. Nervous tissue • Two cell type: Neurons and neuroglial cells • Neurons are branching elongated cells, highly specialized for generating nerve impulses. • Neuroglial cells are of multiple shapes and functions and are considered as supporting cells.

46. Nervous tissue • Neurons and neuroglial cells