Lymphatic System

Question 1

Lymphatic system

Answer 1

Made up of lymph, lymphatic vessels , lymph nodes spleen and thymus, diffuse lymphoid tissue and bone marrow.
Functions:
1. Drainage of tissues - fluid from plasma carrying dissolved substances continually moves out of arterial end of capillaries into tissues. Fluid movement is as much as 21L per day. Most fluid returns to blood stream at venous end of capillary but remaining fluid (3-4L) drained away by lymph vessels. If this system wasn’t in place tissues would become water logged and blood volume would fall so circulation would cease.
2. Absorption of fats and fat soluble substances( vitamins) - takes place in central lacteals ( lymphatic vessels) of villi in small intestine.
3. Protection against infection - lymphatic organs the thymus and spleen involved in production and maturation of lymphocytes. These are responsible for immune response.

Question 2

Lymph

Answer 2

Clear , watery fluid.
Has a similar composition to plasma but without the plasma proteins. Identical in composition to interstitial fluid.
Carries the following:
- plasma proteins that have leaked out of capillaries ie in process of inflammation
- large particles from areas of damaged tissues ie cell debris and bacteria because if bacteria in blood it could cause septicaemia.
- Lymphocytes
- Fats ( small intestine)

Question 3

Lymph nodes

Answer 3

Sit along the chain of lymphatic vessels.
Bean shaped structures. Designed to acts as filters. Particles carried in the lymph ie cell debris and bacteria , cells from tumours are captured in the substance of the node. If it’s bacteria the lymphocytes will start an immune response. Organic matter destroyed by macrophages. Lymph drains through a no. of nodes (8-10) before being returned to circulation. By the time it returns to circulation it has usually been cleared of cell debris and foreign material. Activated lymphocytes also found in mode where they will multiply to fight infection. If tumor cells end up in lymph nodes they can rapidly divide to cause malignancies.

Question 4

Spleen and thymus

Answer 4

Functions of the spleen :
1. Phagocytosis
2. Storage of blood
3. Defence against infection ( lymphocyte activation)
4. Erythropoiesis
5. Storage of thrombocytes
If damage to the spleen there will be a lot of bleeding. Without spleen you may be on lifelo antibiotics.
Function of thymus gland:
- Activation of T lymphocytes as part of the the immune response.