Homeostasis - Maintain stability when internal and external environments are changing

I. Dynamic Equilibrium A.Response to correct changes to restore healthy conditions in the body

I. Dynamic Equilibrium B.LOW Body Temperature i.Blood vessels constrict (more blood flow to organs) ii.Body Shivers to generate more heat C.HIGH Body Temperature i.Blood vessels dilate (more blood flow to skin) ii.Skin produces sweat

II. Types of Protection A.Senses detect danger B.Hormones (adrenaline) stimulate emergency responses to danger C.Reflexes can rapidly respond to danger D.Muscles to fight off / flee from danger E.Skin keeps out harmful organisms F.Tears and saliva can trap and/or destroy invaders (bacteria, virus)

III. Immune System A.Body fights invaders (pathogens) and malfunctioning cells B.Pathogens are identified by membrane proteins (antigens) and trigger a response. C.Toxins, poisonous wastes from pathogens, can also make an immune response

III. Immune System D.Pathogens can be: i.Bacteria ii.Fungi iii.Worms iv.Viruses

III. Immune System E.ALL cells have antigens on surface (membrane proteins) but immune system can USUALLY tell “self” from “non-self” F.Lymphocytes make antibodies to bind with antigens and inactivate the pathogen. Phagocytes engulf pathogens and destroy them.

IV. Damage to Immune System A.Immune system can weaken with age, stress or fatigue B.Some diseases attack Immune System (AIDS). Damage from disease leaves person unable to deal with other infections. i.People with AIDS often die from diseases that would make normal people sick

V. Disorders A.Allergies i.Rapid immune response to harmless things (foods, pollen, insect bites) ii.I Sys releases histamines, which make: a)Runny nose b)Sneezing c)Rash d)Swelling e)Swelling is MOST dangerous, if throat swells one cannot breathe.

Disorders (cont) B.Autoimmune diseases i.Immune system cannot recognize “self” and attacks body ii.Type 1 Diabetes – T cells attack pancreas causing dec insulin production iii.Rheumatoid Arthritis – body attacks joint cartilage

Disorders (cont) C.Transplant rejection i.Transplant seen as “non-self” and it is attacked. ii.Patient given drugs to weaken immune response

Disorders (cont) D.Cancer i.Uncontrolled growth / reproduction of cells ii.Caused by genetics or mutagenic agents (asbestos, sunlight, etc) iii.Results in tumors, disrupting homeostasis. Tumors can spread through body.