Unit 6: Lymphatics and Immunity - Biology 2402 Lab

Overview of the Lymphatic System

Part of the circulatory system, alongside the cardiovascular system.
Function: Circulates interstitial fluid (that leaks out from blood vessels) back to the cardiovascular system.
Components:
- Collecting vessels or lymphatic vessels.
- Lymph nodes: Major filtering sites with many white blood cells.

Lymph Nodes:
- Few hundred in the body.
- Connect with afferent (towards) and efferent (away) vessels for lymph circulation.
- Contain germinal centers for B cell proliferation (antibody production) and T cell activation.
- Composed of an outer cortex and inner medulla.
Thymus:
- Located above the heart.
- Essential for T lymphocyte (T cell) maturation.
Spleen:
- Located under the stomach on the left side.
- Contains white pulp (lymphoid tissue with B and T cells) and red pulp (blood storage and filtering).
- Splenic cords provide structural support.
Tonsils:
- Positioned at the entrance to the digestive system.
- Rich in B and T cells, and macrophages, to prevent bacterial infections.
Appendix:
- Houses lymphoid tissue and beneficial gut bacteria.
Lacteals:
- Located in the small intestine.
- Specialized in absorbing lipids.

Spleen:
- Dark purple areas: White pulp (rich in white blood cells).
- Surrounding areas: Red pulp (blood storage).
Lymph Nodes:
- Germinal centers: Sites of B cell proliferation.
- Cortex: Contains lymphatic follicles.
- Medulla: Concentration area for T and B cells.
- Afferent vessels bring in pathogens, targeting by B/T cells and macrophages.
Peyer's Patches:
- Located in the ileum of the small intestine.
- Work with villi to absorb nutrients and fats through lacteals.

Immunity:
- B cells produce antibodies targeting antigens.
- T cells and macrophages facilitate pathogen destruction.