1. Tissue Development and Wound Healing

2. Body Defenses Body defense system includes skin mucous membranes, strong acid in stomach, etc. They work to fight off invaders

3. When Tissue is damaged:  Healing starts almost immediately  Inflammatory Response is triggered  Immune Response is started immediately

6. Inflammatory Response  Non-Specific body response  Occurs whenever the body is injured (no matter where on the body you are hurt)  Prevents further injury

7. Immune Response  Very specific body process  Attacks a recognized invader (bacteria, virus, microbes, foreign substance)  Increased Metabolism  Increases Body Temperature

8. Tissue Repair and Wound Healing  2 methods of tissue repair: 1.) Regeneration 2.) Fibrosis  Healing (structures and time) depends on 2 things: 1.) the type of injury 2.) the severity of the injury

10. Regeneration  Replacement of destroyed and damaged tissues by the same kind and type of cells  Good blood supply is essential to healing  Cleaner incisions repair better and heal more successfully than jagged lacerations

11. Fibrosis (scar)  Repair of tissue and a scar is the result  Dense fibrous connective tissue replaces the original tissue

12. Healing Process  Step 1: Capillaries allow clotting proteins into injured area  Step 2: --Clot is constructed to stop blood loss which holds edges of wound together, and forms barrier (so bacteria can’t seep into surrounding tissue) --When exposed to air the clot dries to form a scab

13.  Step 3: Granulation Tissue Forms (delicate pink tissue with many capillaries, stemming from nearby intact areas) Granulation Tissue contains: 1.) Phagocytes to get rid of the clot 2.) Connective tissue cells that could produce a scar

14.  Step 4: Surface epithelium regenerates beneath scab, and then later on the scab falls off *Epidermis, Mucus membranes, Fibrous connective tissue and bone regenerate well *Skeletal muscle regenerates poorly *Cardiac and Nerve Tissue is replaced by scar

15. Scar Tissue  Scar tissue is strong but less flexible  Scar tissue can’t perform the normal functions of that tissue  Scar tissue in muscles or muscular organs such as the heart or bladder hinder the function of that organ

17. Development  Life begins as a single cell that divides thousands of times to form specialized tissues  Mitosis continues in almost all cells until the end of puberty (full grown)

18. Development  After puberty only certain cells routinely divide ex.) skin, intestinal lining  Some cells stop dividing, like liver, but can replace themselves if injured  Heart muscle and nervous tissue cannot replace itself (amitotic)

20. The Aging Process  thinner epithelium – easily damaged, less elastic  “dry out” – less oil, mucus, sweat  fewer hormones that control metabolism & reproduction  less collagen  bones become porous and weaken  Atrophy (wasting away) of nervous and muscle tissue

21. Contributions to Aging Causes and Various Possibilities of Aging:  Chemicals? Toxins, drugs, carbon monoxide  Physical factors? X rays, UV light  Genetic clock? Biological Clock?  Poor circulation (decreased nutrients and oxygen to cells) One question for you: Can you prevent aging?