IMMUNE/LYMPHATIC SYSTEM http://www.youtube.com/watch?v=DStwXsmZ3OE

What is an infectious disease? Pathogens = disease-producing agents Not all microorganisms are pathogenic Microorganisms live on skin, in the intestines, upper respiratory tract, lower urinary tract, reproductive tract, etc… Some have symbiotic relationships with our bodies, help maintain equilibrium

In order for pathogens to enter… they must first penetrate your skin They will encounter the body’s secretions (sweat, oil, mucus, tears, saliva) Main function of mucus is to prevent areas from drying out. It also traps microorganisms

Mucus is continually swallowed and passed to the stomach where acidic gastric juice destroys it Sweat, tears, saliva all have the enzyme lysozyme (breaks down cell walls of some bacteria)

Your skin is a part of your first line of defense against pathogens Your skin is a part of your first line of defense against pathogens. It is included in the category titled “non-specific defense mechanisms” The first line of nonspecific defense = external The second line of nonspecific defense = internal. They indiscriminately attack invaders that penetrate the body’s outer barriers. The third line of defense (the immune system) responds in a specific way to particular substances marked by foreign molecules.

Inflammation of body tissue Inflammation is an example of a second line of defense kicking in. Redness, swelling, pain, and heat Cells damaged by invading microbes release chemical signals that attract white blood cells called phagocytes A neurotransmitter generated by white blood cells, histamine, is released and causes blood vessels to dilate in that area

The steps taken by white blood cells (phagocytosis) The pus that accumulates at the site of some infections consists mostly of dead phagocytic cells, fluid, and proteins that leaked from capillaries during the inflammatory response.

Phagocytosis of pathogens Phagocytes take action. They are white blood cells that destroy pathogens by surrounding and engulfing them Specific examples = monocytes, macrophages, neutrophils

Some macrophages (phagocytes) migrate throughout the body, while others reside permanently in certain tissues.

Lymphatic system Helps body defend itself against disease & maintains homeostasis by keeping body fluids at a constant level

Glands of the lymphatic system Lymphocyte = type of white blood cell that defends the body against foreign substances B lymphocytes (B cells)- make antibodies against antigens. Memory cells. T lymphocytes (T cells)- play a role in cell mediated immunity (no antibodies). Killer T, Helper T, ect. Made in Thymus. Both types of lymphocytes circulate throughout the blood and lymph and are concentrated in the spleen, lymph nodes, and other lymphatic tissue.

Glands of the lymphatic system Lymph nodes = small mass of tissue that contains lymphocytes and filters pathogens from the lymph Made of interlaced network of connective tissue fibers that hold lymphocytes

Antigens (foreign molecules) are identified by B cells Antigens (foreign molecules) are identified by B cells. The B cell with the correct antibody receptor on its antibody then duplicates.

More Glands of the lymphatic system Tonsils are larger clusters of lymph tissue located at the back of the mouth cavity and throat They produce lymphocytes & protect the throat from potential infections normal swollen

Glands of the lymphatic system Spleen = another organ that stores lymphocytes It filters out and destroys bacteria & worn-out red blood cells

Glands of the lymphatic system Thymus gland = stores immature lymphocytes until the are ready to be released into the body’s defense system Spleen

Endocrine Disorders Turner Syndrome http://www.youtube.com/watch?v=ldjb-FR- PKo Pituitary Gigantism http://www.youtube.com/watch?v=Ebhf1qKV A9A