Lymphatic system

Question 1

Lymphatic system

Answer 1

Function:
1. To collect some of the fluid that escapes from the blood capillaries (cap’s) + return it to the circulatory system.
2. Part of the body’s internal defence system against pathogens.
Made up of, lymph capillaries joined to larger lymph vessels and lymph nodes, located along the length of some lymph vessels.

Question 2

Lymphatic system movement of fluid

Answer 2

Not all of the fluid that leaves at the arterial end of the capillary can get back in at the venous end. In 24 hrs 3L of fluid is left behind in the tissue fluid. This can cause huge swelling if not drained away.
- Lymph capillaries drain this excess fluid away.
- Once the fluid enters the lymph capillary is it known as lymph.
- Lymph is a clear yellow liquid that carries WBC’s, especially lymphocytes.

Question 3

Lymph Capillaries and Lymph Vessels

Answer 3

• Lymph capillaries begin in tissues as blind ended tubes.
  They occur in most parts of the body except the brain + spinal cord.
• In the villi of the small intestine there are special lymph capillaries called lacteals. They absorb fat.
• Lymph vessels and large lymph vessels contain valves and nodes along their lengths.
• Flow through the lymph vessels is very slow + skeletal muscle contraction and valves help move the lymph.
• Lymph vessels eventually join into 2 main channels, which open into veins of the neck (circulatory system) known as the subclavian veins via the right lymphatic duct and the thoracic duct.

Question 4

Lymph Nodes (lymph glands)

Answer 4

Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease.

Question 5

Role of Lymphatic System In Defence Against Disease

Answer 5

Lymph entering the nodes may contain cell debris, bacteria, viruses or cancerous cells, Larger particles (bacteria) are trapped in the meshwork + destroyed by macrophages via phagocytosis
- Projections from the macrophage surround the particle and take it into the cell, where it is destroyed by enzymes.
- Bacteria are usually killed within 10-30 minutes.
- When a person has an infection the rate of lymphocyte formation increases + the lymph nodes swell + become sore.

Question 6

Lymphatic Tissue

Answer 6

Structures in the body that contain lymphatic tissue, but are not part of the lymphatic system, include:
- The spleen
- Thymus gland
- Tonsils
- Peyer’s patches in the gut
- The appendix.

Question 7

Phagocytes

Answer 7

Phagocytes are cells that can engulf + digest micro organisms + cell debris via phagocytosis. (Cell eating.)
A type of immune cell that can surround and kill microorganisms, ingest foreign material, and remove dead cells. It can also boost immune responses.