LYMPHATIC SYSTEMLindsay Martin, AP Biology

INTRODUCTION TO THE LYMPHATIC SYSTEM AND ITS FUNCTIONS

Introduction to the Lymphatic System

FUNCTIONS OF THE SYSTEM

Draining interstitial (between tissue) fluid

Transporting dietary lipids

Protection against infection or disease

LYMPHATIC FLOW

The lymphatic system does not have a pump to help it flow through out the body. It is designed so that lymph can only flow upward through the body from the extremities (feet and hands) toward the neck where the lymph enters the subclavian veins and once again becomes plasma in the bloodstream.

Subclavian veins:Located just under the clavicle where lymph returns to the bloodstream

LYMPHATIC ORGANS• Red bone marrow Primary organs• Thymus gland• Lymph nodes• Lymph nodules Secondary

organs• Spleen

RED BONE MARROW

Bone marrow characterized by meshes of the reticular network that contain the developmental stages of red blood cells, white blood cells, and megakaryocytes.

THYMUS GLAND

The thymus processes a white blood cell known as a T-lymphocytes, which control cellular immunity. Tge thymus helps cells recognize and destroy invading bacteria, virus, etc., abnormal cell growth such as cancer, and foreign tissue.

LYMPH and LYMPH VESSELS

Lymph does not circulate

Lymph originates as plasma, which is the fluid portion of blood

Interstitial fluid drains into lymphatic capillaries, which forms lymph

Lymph capillaries merge, forming lymph vessels

o Lymphatic vessels carry lymph into and out of lymph nodes and back to the vascular system

LYMPHATIC VESSEL

LYMPH NODE LOCATIONS

Neck (cervical) Armpits (axillary) Groin (inguinal)

Test your knowledge about lymph nodes

LYMPH NODESLymph is filtered through lymph

nodes

Found in clusters “Waste water treatment plants”

Vary in size Main areas are cervical, axillary

and inguinal regions.

Provide biological filtration

Site of cancer growth and metastasis

Germinal centers – B cells proliferate

INGUINAL AND AXILLARY NODES

Neck Nodes

also known as cervical

nodes

OTHER NODES

LABEL THE LYMPH NODES

SPLEEN AND ITS FUNCTIONSBlood

for

mation

•All blood cells in fetus•Only lymphocytes and monocytes after birth

Blood filtration

•Removes bacteria, particles, worn out RBCs and platelets (recycles iron)

Blood storage

•Can contain over one pint of blood

B-CELLSo The humoral immune system consists of B-cells which

originate in the Bone marrow and stay there to developo B-cells can produce antibodies, but need exposure to

foreign antigens to do so. These antigens are cell surface oligosaccharides and proteins for identification tags

o Antibodies are proteins in blood plasma and lymph to fight bacteria and viruses in body fluids. All daughter cells of a B-cell will be able to produce the same antibodies as the mother cell

T-CELLSo The cell-mediated immune system consists of T-cells

which originate in the bone marrow, but go to the Thymus to finish their development

o T-cells are highly-specialized cells in the blood and lymph to fight bacteria, viruses, fungi, protozoans, cancer, etc. within host cells and react against foreign matter such as organ transplants

Lymphocytes

SPECIFIC AND NONSPECIFIC DEFENSE(WORKSHEET)

ANTIBODIES (SPECIFICITY AND DIVERSITY)

a. Nuetralization – antibody block sites on antigen to make it ineffective. (i.e. antibodies bind to viral attachment site then viruses cant attach to cell) Eventually phagocytes will engulf invaders

b. Agglutination – clumping, possible because each antibody has at least two binding sites and can cross-link antigens, makes it easy for phagocytes to eat antigen

c. Precipitation – antibodies cross-link antigen molecules (not cells) to form precipitates that are eaten by phagocytes

d. Complement System– group of proteins that band with elements of nonspecific/specific defense systems. Antibodies often combine with complement proteins

ACTIVE AND PASSIVE IMMUNITY There are two kinds of immunity: active immunity, when

the body is stimulated to produce its own antibodies, and passive immunity, where the antibodies come from outside the person’s body. Active immunity is usually permanent, and can be induced due to actual illness or vaccination. Passive immunity is not permanent because the antibodies are introduced from outside the body, thus the B-cells never “learn” how to make them. Some examples of passive immunity include antibodies passed across the placenta and in milk from a mother to her baby, and some travelers’ shots. Because antibodies are only protein, they don’t last very long and must be replaced if the immunity is to continue.

Immunology

IMMUNOLOGICAL MEMORY

Immunity is said to have a memory for most invading agents encountered before, because a second encounter with the same agent prompts a rapid and vigorous response. This is called immunological memory which leads to a perception that an individual is immune to a particular agent.

There are two types of immune response: cell-mediated (CMI) associated with specialized blood cells called T-cells, and antibody mediated associated with specialized blood cells called B-cells. Both immune responses act on substances called antigens.

ANTIGENSAn antigen is a substance capable of inducing a specific immune response. The term is derived from the gen eration of anti bodies to such substances. Specific immune responses require recognition molecules like the T cell receptor or antibodies which recognize the antigen, or parts of it, and stimulate a response by the specific arm of the immune response (T or B cells).

Often antigens are foreign proteins (or parts of them) that enter the body via an infection. Sometimes, however, the body's own proteins, expressed in an inappropriate manner (where or when they are not usually seen), are treated like antigens by the immune system. It is important to recognize that bacteria or viruses are not themselves antigens but they contain antigens both on their surface and inside them. Such antigens can be isolated and used to safely vaccinate against infection with the whole organism.

PHAGOCYTOSISANIMATION

VACCINES

A vaccination is a weakened or inactive form of a pathogen given to enable the immune system to respond and produce immunity to it. The first vaccination was when Edward Jenner purposely gave people cowpox, a mild disease, because he had figured out that could prevent them from getting smallpox, a very serious disease.

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