1. Connective Tissue - Most abundant in the human body. - Embryonic is mesenchyme, not yet specialized -Four general types of tissue: Connective tissue proper, cartilage, osseous, vascular 1. Connective tissue proper – fluid intercellular material and fibroblasts as the most abundant cell type (fibers, syrupy ground substance and cells. (Four types) a. Loose areolar tissue – indicates many air spaces, widespread (mucous membranes, around blood vessels and nerves: subcutaneous) Composed of a variety of fibers, cells, and hyaluronic acid as intercellular material.

2. i. Fibers Collagenous (white) -Tough, resistant to pulling, made of collagen Elastic (yellow) -Smaller, provides strength (skin, blood vessels, lungs) Reticular - Thin, immature collagen fibers, coated with glycoprotein, supports the walls of blood vessels, nerve cells, smooth, framework of spleen and lymph nodes – prevents collapse, yet flexible

3. ii. Cells *Fibroblasts – repair cells, responsible for constantly replacing damaged cells. AGING – when repair cannot keep up with damage *Macrophages – large, function to engulf bacteria and cellular debris by phagocytosis. (Security guards – survey and destroy, cannot take care of all invaders) *Plasma Cells – blood, lymphatic system, provide immunity by secreting antibodies

4. *Melanocytes – pigmented cells below the deepest layer of skin, produce melanin (pigment that protects against sun damage) We all have about the same #, but some are large and produce more melanin, freckles, moles *Mast Cells – produce heparin (anticoagulant) and histamine (dilates small blood vessels during inflammation/allergic reaction – give antihistamines so vessels do not dilate)

5. b. Adipose Tissue -Composed of adipocytes (look like cobblestones or signet ring in shape) – fat storage which is necessary for hormone production, energy reserve, insulation, protects internal organs - Subcutaneous in location

6. c. Dense (collagenous) tissue – more numerous cells and thicker fibers, closely packed, decreased intercellular substance *Located in muscle (stretch), ligaments (stability), tendons (somewhere between – Achilles’ ) d. Elastic tissue – little different from above, freely branching fibers, stretch and snap back like a rubber band, allows for elasticity *Located in muscles, ligaments and tendons

7. 2. Cartilage “soft bone” -No blood vessels or nerves except in the perichondrium (tissue around the cartilage) if damaged, doctors will go in and fix because it doesn’t repair well on its own. OSTEOARTHRITIS – excessive damage to the cartilage, calcifies a. Characteristics: Dense network of collagen and chondroitin sulfate, resilient and strong

8. b. Three types *hyaline – (gristle) bluish-white in color, shiny, most abundant type, embryonic skeleton is exclusively composed of, clavicle is the only completely formed bone at birth – WHY? *fibrocartilage – found in the matirx of bone to give strength and stability, bundle of collagen fibers, between vertebrae *elastic – threadlike network for flexibility

9. 3. Osseous tissue (bone) – skeletal system Basic unit is the OSTEON, composed of: a. Lamellae – concentric rings of hard matrix (calcium) b. Lacunae – spaces between lamellae, have Haversian canals which contain nerves and blood vessels

10. 4. Vascular tissue (blood) a. Plasma – mostly water with dissolved substances such as nutrients, wastes, enzymes, hormones, respiratory gases ( O 2, CO 2 ) b. Cells, etc. *Erythrocytes - RBCs

11. *Leucocytes – WBCs – phagocytosis, immunity, allergic reactions. High leucocyte # = infection, leukemia (radiate to destroy bone marrow, replace) *Platelets - clotting

12. Other Tissues 1. Muscle – highly specialized for contraction a.Smooth *walls of internal organs (hollow), blood vessels, stomach, intestine, gall bladder, urinary bladder *non-striated, involuntary (some control- swallowing, etc)

13. b. Cardiac *bulk of heart *involuntary, one nucleus per cell, striated, intercalated disks, not as dense

14. c. Skeletal *striated, voluntary, fibers are cylindrical (fiber = cell), multiple nuclei

15. 2. Neural tissue – one of the most specialized, largest cell in the body (1 m) a. Neurons – action cells, no mitotic devices, pick up stimulus and converts to impulse (to other nerves, glands, muscles) *Dendrites – branches, stimulus gatherer, takes impulse to cell body, increase connections through stimuli *Axons – long, single, conduct impulses away from cell body

16. b. Neuroglia – cells that protect and support neurons * Do not conduct *Common sites of tumors (gliomas)

17. 3. Membranes a. Mucous – line cavities that open to the outside b. Serous – line cavities that do not open to the outside, cover organs, produce serous fluid c. Synovial – line freely moving joints, not open to the outside