A. Return fluids (and proteins) in interstitial space to vascular space.

B. Delivers fats from small intestines to vascular space. 

C. Delivers pathogens, foreign cells/materials, cell debris from tissue to lymph nodes. 

- Most of the system is a serious of capillaries and vessels located throughout the body. 

- Lymph capillaries are near blood capillaries and have overlapping cells that allow fluid in (osmotic pressure)

- Lymph vessels have one way valves for one way flow. 

- The organs of the lymphatic system include nodes, spleen, and thymus.

- Nodes are found especially in the neck, arm pits, mid trunk. Nodes filter blood before it returns to the vascular space. 

- the nodes have organized formations of lymphocytes that recognize, multiply, then attack foreign substances. 

1- filters pathogens and old red blood cells. 

2- produces antibodies

3- stores red blood cells in red pulp. White pulp contains many lymphocytes with many same functions as in nodes. 

1) protect from invaders. 

2) Recognize invaders and retain memory

3) "Mount Assault" on invaders

- To protect there are three lines of defense

* surface barriers

* Non-specific responses

* Immune responses

- directed against any "non self" targets

- Complementary proteins (about 20 in blood)

*when one is activated it triggers a cascade response and is exponential in growth.

*Bind to bacteria and make pores in surface, leading to cell lysis.

* Attract phagocytes(chemotaxis), which engulf. 

1) due to irritation, get vasodilation and permeability. This leads to hit redness and swelling. Fibrinogen exits blood and forms clot/ capsule. 

2) Phagocyte migration 

1) bacteria invade and attack cells or release toxins.

2) Mass cells release histamine

3) Fluid and plasma leak out edema

4)Complement proteins attack bacteria.

5) Neutrophils and macrophages engulf. May also send out chemoattractants to get more lymphocytes and promote fever. 

-Neutrophils:most abundant, kill bacteria by phagocytizing and digesting. 

- Eosinophils: secrete enzymes to destroy worm parasite 

- Basophils: secrete enzymes and chemicals to start and continue inflammation. 

-Mast cells: also secrete histamine in inflammation. 

1) Recognition of Antigen ( a molecular configuration that leads to lymphocytes formation and is there target; immunogen )

2) Increased cell division of lymphocytes. 

3) Differentiation of subpopulations of a)effector cells and b) memory cells with receptors for only one type of antigen 

MHC: Major Histocompatibility complex

- There are markers on the outside of the cell membrane, MHC markers that are recognition proteins. When these are bound to an antigen, it is a signal for the immune response to "upregulate".