D2-3: The Lymphatic SystemSeptember 8, 2010

The Lymphatic System•This system is a collection of organs

whose primary function is to collect extracellular fluid and return it to the blood.

•The main organs in this system include:▫Bone Marrow▫Lymph nodes▫Thymus▫Spleen▫Tonsils

I. Vessels of the Lymphatic System•Lymphatic capillaries are similar to blood

vessels except they absorb:

▫Some of the fluid lost by the blood vessels▫Dead cells▫Pathogens

•These fluids and particles are known as lymph.

I. Vessels of the Lymphatic System• Lymphatic vessels carry

lymph throughout the body and eventually drain into the large neck veins of the cardiovascular system.

• Both the lymphatic and the cardiovascular systems work together to return fluids to the body as well as fight against pathogens with WBCs.

II. Other Parts of the Lymphatic System

•God also designed our bodies to have specialized Lymphatic organs.

•These again include:▫Bone Marrow▫Lymph Nodes▫Thymus▫Spleen▫Tonsils

A. Bone Marrow• As we talked about in our

previous chapter, marrow is very important in the formation of red blood cells and white blood cells.

• Lymphocytes are a type of white blood cells that can help your body to fight pathogens and other viruses.

B. Lymph Nodes•As lymph travels through its vessels they

stop at lymph nodes.▫These are small, bean-shaped masses of tissue

that remove pathogens and dead cells from the lymph.

▫They contain two types of lymphocytes: Killer T cells: Surround and destroy pathogens B cells: Produce antibodies that attach to

pathogens that clump up and are destroyed by other cells.

B. Lymph Nodes• When bacteria or pathogens

cause an infection, WBCs make their “rallying battle cry.”

• WBCs will multiply to fight off the infection in your body.

• The result it that your lymph nodes will often swell up and ache.▫ You, your parent, and your

doctor can actually feel the result of this if you are sick.

C. Thymus• The main gland of the

lymphatic system.

• It produces mature T lymphocytes, which are ready to fight off infection.

• It is located behind the breastbone, just above the heart.

D. Spleen• This is the largest lymphatic

organ.

• As blood flows through it, lymphocytes attack and mark pathogens in the blood.

• It also produces, monitors, stores, and destroys blood cells.

• As RBCs are squeezed through the spleen the old cells are destroyed and can often be “recycled” into new blood cells.

D. Spleen• The spleen has two

important functions:1. White Pulp

Produces WBCs to fight infection.

2. Red Pulp Removal of damaged

or defective RBCs

• Is it possible to live a healthy life without your spleen?

• Answer:

▫ Yes▫ The spleen can

sometimes be damaged or removed.

▫ Other organs inside our bodies will take over the functions of the spleen.

▫ An amazing gift from God!!!

E. Tonsils• Small, rounded masses of

lymphatic tissue located in the pharynx (throat)and in the passage from the mouth to the pharynx.

• Lymphocytes found in the tonsils can fight pathogens that enter the throat and lungs.

E. Tonsils• Conditions that may result

from tonsils:▫ Swelling

May swell with fight infection

Difficulty swallowing▫ Strep throat

Tonsils that are infected and covered with patches of white.

▫ Tonsillitis Infected tonsils Difficulty breathing Surgery may be needed

with frequent infections

E. Tonsils