Lymphatic System and Immunity

Human Anatomy and Physiology II

Oklahoma City Community College

Dennis Anderson

Fluid Leaves Capillary

Cells

Blood

Blood Capillary

Capillaries

Functions of Lymphatic System

• Drain fluid from around cells

• Absorb fat from intestines

• Circulate lymph

• Filter lymph

• Immunity

Right Lymphatic Duct

Thoracic Duct

Lymph

• Fluid of the lymphatic system

• Similar to blood plasma and interstitial fluid

Lymphatic Vessels

• Transport lymph

• Lymph is returned to the circulatory system at either the right or left subclavian veins

Lymph Nodes

• Filter lymph– Microorganisms

– Cancer cells

• Lymphocytes• Monocytes

Thymus

• Programs some lymphocytes to develop into T-cells

Spleen

• Filters blood– Worn out RBC– Bacteria

• Lymphocytes

• Monocytes

Fluid Movement

Edema

• Accumulation of interstitial fluid

Causes of Edema

• Blockage of lymphatic system

• Increased pressure in veins

• Lack of albumin– Decreases fluid returning to blood capillaries

by osmosis

• Inflammation

Nonspecific Body Defenses

• Skin

• Acid– Stomach– Vagina

• Mucus

• Saliva

• Tears

More Nonspecific Defenses

• Phagocytosis

• Complement

• Fever

• Inflammation

Complement

Inflammation

• Bodies response to tissue injury

• Classic signs– Heat– Redness– Swelling– Pain

Skin

Blood

Tissue Damaged

Histamine Released

Capillary More Permeable

Plasma Leaks Out

Capillary More Permeable

Antibodies Leaks Out

Capillary More Permeable

WBCs Leave by Diapedesis

Wall of Fibrin Forms

Pus Forms

Steroid Hormones

• Hydrocortisone, cortisone and others

• Depress inflammation

• Used to treat inflammatory diseases– Rheumatoid arthritis

Antigens

• Molecules often found in the membrane of cells

• Antigens of foreign cells stimulate an immune response

Self Antigens• Antigens of our own cells

• Do not cause an immune response in our body– Usually cause an immune response in another

person

• MHC proteins– Major Histocompatibility Complex

Cells of the Immune System

• APCs– Antigen-presenting cells

• B cells– B lymphocytes

• T cells– T lymphocytes

Antigen-Presenting Cells

• Macrophages• Engulf foreign cells and attach the cells antigens on their

MHC proteins

Lymphocytes

T Cells B Cells

B Cell

Receptor

Foreign Cell

Cytotoxic T Cell = Killer T Cell

Receptor

Body Cell

Helper T Cell

Receptor

APC

Antigen-Presenting CellAPC

• Macrophages and other cells

• Engulfs and digests foreign cells

• Present antigens on MHC proteins to T cells

B Cells

• Lymphocytes that react directly with antigens

• Require stimulation from Helper T Cells

• Offspring become– Plasma cells– Memory B cells

• Humoral Immunity

Plasma Cells

• Produce huge numbers of antibodies– 2000/second

Helper T Cell

• Reacts with antigen from APC

• Stimulates Cytotoxic T Cells and B Cells– Secretes Interleukin II

Cytotoxic T Cells• Activated by antigens

on any body cell• Require stimulation

from Helper T Cells• Destroys body cells

infected with viruses• Destroys cancer cells• Cellular Immunity

Memory Cells

• T Cells and B Cells

• Remember antigen

• React to a second invasion of an antigen more rapidly

Suppressor T Cells

• Stops T cells and B cells after an infection has been conquered

Cytokines

• Chemicals used in cellular immunity• Interleukin I

– Produced by macrophages– Stimulates helper T cells

• Interleukin II– Produced by helper T cells

• Perforin– Causes lysis of target cell

Virus

Protein Coat

DNA or RNA

Virus Attaches to Body Cell

Viral DNA Enters Host

Protein Coats Synthesized

Viral DNA Synthesized

Viruses Exit Cell

Host Cell Killed by Virus

Interferon Produced by Dying Cell

Acquired Immune Deficiency Syndrome

• HIV Virus

• Attacks and destroys Helper T Cells– Depresses humoral and cellular immunity

The End