Lymphatic system Flashcards
→ what is it → organs within this system
What are the main functions of the lymphatic system?
- Immune defense.
- Drainage of tissue fluid (prevents swelling due to fluid build-up).
- Absorption of fat through lymphoid vessels in the small intestine.
What is lymph?
A fluid similar to plasma, derived from blood, that moves around the body carrying pathogens to screening areas for immune defense
What are the two categories of lymphoid organs?
- Primary lymphoid organs: Create and mature immune cells.
- Secondary lymphoid organs: Screen blood and lymph for pathogens.
What is the function of lymph vessels?
To transport lymph collected from tissues and organs back into circulation
What is the flow direction of lymph in vessels?
Unidirectional (one way), with muscle cells helping push the fluid
Where does lymph drain into the bloodstream?
It drains into the vena cava via the thoracic duct
What is the function of lymph nodes in the lymphatic system?
They act as screening centers, filtering pathogens before returning lymph to the bloodstream
What are the primary lymphoid organs?
Bone marrow.
Thymus.
Peyer’s patches (also has secondary functions).
What are the two types of bone marrow?
- Red marrow: Produces blood cells (haematopoietic tissue).
- Yellow marrow: Stores fat (replaces red marrow as the animal matures)
How does bone marrow change with age?
- Young animals: Mostly red marrow.
- Mature animals: Red marrow decreases, replaced by yellow marrow
Where is the thymus located?
Cranial to the heart
How does the size of the thymus change with age?
- Largest in immature animals (critical for immune development).
- Shrinks in mature animals but remains functional
What is the function of the thymus?
- Lymphocyte (T cell) production.
- Essential for immune system development in young animals
What happens if the thymus is removed in young vs. mature animals?
- Young animals: Become susceptible to infections and stop growing.
- Mature animals: Can survive but become immunocompromised
Where are Peyer’s patches located?
In the small intestine wall, consisting of lymphoid follicles
What is the function of Peyer’s patches?
- Produce lymphocytes (B cells).
- Provide immune surveillance of the gut.
What are the two groups of Peyer’s patches?
- Group 1: Found mostly in the ileum (important in young animals, regresses with age).
- Group 2: Found in the jejunum and ileum, remains throughout life
How do Peyer’s patches differ in pigs?
B cell production does not require Peyer’s patches (other sites compensate)
What are the secondary lymphoid organs?
Lymph nodes.
Lymph centers.
Spleen
Where are lymph nodes found?
Throughout the body, mainly concentrated in the digestive tract
What is the function of lymph nodes?
- Filter and screen lymph for pathogens.
- Detect and destroy microbes.
What are the three main regions of a lymph node?
- Cortex: Contains B cells.
- Paracortex: Contains T cells and dendritic cells.
- Medulla: Contains plasma cells, macrophages, and memory T cells.
What is the tributary territory of a lymph node?
The specific tissue region a lymph node is responsible for draining
How does lymph enter and exit the lymph nodes?
- Afferent lymph vessels enter at the subcapsular sinus.
- Efferent lymph vessels leave at the hilus.
