APH CH 14 lymphatic system and immunity

Lymphatic system

Network of vessels that…

• transport excess fluids

• absorbs fats

• helps protect against disease

Function

filtering potentially harmful particles from lymph before returning to the blood stream

Function

immune surveillance (occur singly or in groups)

Lymphocytes:

attack viruses and bacteria

Macrophages:

engulf and destroy foreign substances, damaged cells, cellular debris

Thymus and Spleen

functions similar to lymph nodes

Thymus

◦ larger during early childhood

◦ shrinks around puberty

◦ produce T cells that provide immunity

Spleen

◦ largest lymphatic organ

◦ filters blood (not lymph)

Pathogen:

disease-causing agent or infection.

Ex: virus, bacteria, fungi, protozoans

Mechanisms to protect the body are

a) nonspecific defenses or

b) specific defense (immunity)

Species resistance -

the fact that a given kind of organism or species develops a set of diseases that is unique to it

Ex: measles, mumps, gonorrhea, syphilis

infect humans, but not other animal species

Mechanical Barriers

First line of defense

ex: skin, respiratory pathway, digestive, mucous membrane, etc…

Chemical Barriers

enzymes in body fluid

ex: gastic juices (low pH), tears (lysozyme), perspiration (salt)

Fever

Elevated body temperature (average, is 98.6 F;

100 F or higher = fever)

Fever

Hypothalamus controls body temperature. Fever

caused by the actual resetting of the

hypothalamus's thermostat

Fever

High temp causes the liver and spleen to

remove iron from the blood. Bacteria and fungi

require more iron as temperature rises in order

to grow and reproduce

Fever

Phagocytic cells attack more vigorously the pathegen

Inflammation

tissue response to injury or infection

Inflammation

increased blood flow

Inflammation

results in ‘walling off’ the infected area so it won’t spread, attack and kill any invaders, dispose of dead and damaged tissue, and begin the process of repair

Inflammation

infected cells release chemical that attracts WBC (pus)

neutrophils-

engulfs and digest smaller particles

monocytes-

engulfs and digest larger particles

Antigen-

a chemical on the cell membrane of ALL cells

Foreign antigens stimulate the body to produce

antibodies

Lymphocyte -

Type of white blood cell that provides immunity. B cells or T cells

Lymphocyte

Originate in red bone marrow and are released into the blood before they differentiate

B Cells -

Produce and secretes antibodies to fight foreign substances in the body

B Cells mature in

red bone marrow

T Cells-

Interacts directly with antigens and

provides a cellular response (interacts directly

by cell-to-cell contact)

T Cells mature in

thymus

Lymphocytes must be activated before it can respond to an antigen

1. Antigen is present

2. Helper T cell contacts the foreign antigen (HIV attacks T cells- blue box p. 382)

3. If antigen fits and combines with the helper T cell than helper T becomes active

4. Once active, helper T cells stimulate the B cells to produce antibodies

5. Once B cells are active, they start to produce antibodies

HIV

Human Immunodeficiency Virus

HIV causes

AIDS

Reproduction

1) HIV attaches to cells with CD4 receptors on the cell membrane

2) Once in the host cell, HIV reproduces

3) Replicated HIV cells attack T-cell (AIDS)

(T-cells- Recognize cells with foreign antigens)

What do I need to know about HIV?

 The first cases of AIDS were identified in the United States in 1981. In 1984 scientists proved that HIV causes AIDS.

 Anyone can get HIV. The most important thing to know is how you can get the virus.

You can get HIV:

 By having unprotected sex- sex without a condom- with someone who has HIV.

 By sharing a needle and syringe to inject drugs or sharing drug equipment used to prepare drugs for injection with someone who has HIV.

 From a blood transfusion or blood clotting factor that you got before 1985.

(But today it is unlikely you could get infected that way because all blood in the United States has been tested for HIV since 1985.)

 Babies born to women with HIV also can become infected during pregnancy, birth, or breast-feeding.

You can NOT get HIV:

 By working with or being around someone who has HIV.

 From sweat, spit, tears, clothes, drinking fountains, phones, toilet seats, or through everyday things like sharing a meal.

 From insect bites or stings.

 From donating blood.

 From a closed-mouth kiss (but there is a very small chance of getting it from open-mouthed or "French" kissing with an infected person because of possible blood contact).

Antibodies- reacts with specific foreign antigens (5 types)

◦Causes antigens (pathogen) to clump together in

order for phagocytic cells to engulf them

or

◦Covers antigen and neutralizes their effect

Immune Response

Primary response-

Release of antibodies into lymph, which is then transferred into the blood

Immune Response

Secondary Response -

forming new antibodies

Vaccine -

consists of killed or weakened bacteria or viruses that stimulates a response but doesn’t produce the disease

Allergen -

Antigen that triggers and allergic response

Lymphedema