Health Unit 6 Test Prep

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White Blood Cells-

Also known as leukocytes search out and destroy any organism or substance they do not recognize as part of the body

Immunology-

The study of the immune system

Phagocytes-

They kill pathogens engulfing and disposing them. Some can also destroy the pathogens by secreting germ-killing chemicals

Lymphocytes-

They travel through body killing infected cells or directing other leukocytes in battle. Some stay behind and secrete germ-killing antibodies into the lymph and bloodstream

Other Leukocytes-

Some serve as sentinels to warn the body of invaders. Some travel to the lymph nodes to show suspicious particles to the lymphocytes. Others secrete chemical alarm

signals into the bloodstream when they detect an invasion

Leukocytes-

Can travel from place to place at free will not restricted to blood-stream

When infection is detected leukocytes from all over body enter bloodstream and crawl out of blood vessel and through tissue to reach the invaders

Don't operate independently- constantly

Communicate with body cells and each other over short distances by docking with another

cell and exchanging info through surface sensors

Also communicate over long distances with chemical sensors called interleukins

Some release an alarm signal called histamine when an invasion is detected

Histamine-

This chemical released by leukocytes causes inflammation in nearby tissue

Inflammation-

A condition in which capillaries become larger to allow more blood to an affected area. The dilated blood vessels cause the tissue to become red, swollen, and tender. This allows the leukocytes to get to the infected site more quickly

Refer back to pg.143 for phagocytes and lymphocytes cell types/functions

Antibodies-

Some of the immune system's most important weapons against pathogens

They are Y-shaped and produced by B cells (important lymphocytes often found in the lymph nodes)

They circulate through the body and attach to foreign substances

They inactivate pathogens until they can be destroyed

They "mark" pathogens to be destroyed by other defense mechanisms

Cannot affect viruses already inside a cell

Can also protest against protein poisons (like tetanus or snake venom) by attacking the poisonous molecules as if they were bacteria or viruses

Lymphatic System-

A complex network of fluid-filled vessels and chambers to transport the white blood cells (refer to pg.1) body and aids them in cleansing the body of pathogens. It also serves as a drainage and sanitation system for the body's tissues.

As it flows through the tissue, it picks up invading bacteria, viruses, and cellular debris.

Tissue Fluid-

All of the body's tissue contains this liquid, which is supplied by the blood. It surrounds the cells and helps them maintain a proper water balance. Excess fluid leaves through lymph capillaries

Lymph Capillaries-

Tiny, thin-walled tubes used to transport tissue fluid

Lymph-

Tissue fluid in the lymph capillaries is called lymph

Lymph Vessels-

Larger tubes that the lymph flows through after it goes through the lymph

capillaries

Relies on the bodies movement to move it along because it does not have a pump (like the heart)

One-way valves ensure the lymph flows forward, not backwards

The lymph vessels continue to merge together, eventually emptying into two large lymph ducts

Lymph Ducts-

The two lymph ducts return lymph from its side of the body into the bloodstream

Refer back to pg.145 for structure of a lymph node/Lymphatic system diagram/organ placement

White Blood Cells

Antibodies/Lymphatic system