Tissue Development and Wound Healing

Body DefensesBody defense system includes skin

mucous membranes, strong acid

in stomach, etc.

They work to fight off invaders

When Tissue is damaged:

Healing starts almost immediately

Inflammatory Response is triggered

Immune Response is started immediately

Inflammatory ResponseNon-Specific body response

Occurs whenever the body is injured (no matter where on the body you are hurt)

Prevents further injury

Immune ResponseVery specific body process

Attacks a recognized invader (bacteria, virus, microbes, foreign substance)

Increased Metabolism

Increases Body Temperature

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

RegenerationReplacement 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

Fibrosis (scar)Repair of tissue and a scar is the result

Dense fibrous connective tissue replaces the original tissue

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

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

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

Scar TissueScar 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

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)

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)

The Aging Processthinner 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

Contributions to AgingCauses 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?