The Lymphatic System

FUNCTION

Drains tissue spaces of escaped protein and fluid and returns to cardio-vascular system 

• Transports fats from intestines to blood 
• Produces Lymphocytes to protect body from foreign bodies, and disease 
• Acts as a filter to prevent spread of pathogens from blood stream 

Two types of Lymphocytes:

• T-Cells – destroy foreign cells/viruses/cancer cells  
• B-Cells – secrete anti-bodies against foreign substances 

ANATOMY

• Lymph (fluid derived from plasma) 
• Lymph Vessels/Capillaries
  • Have valves. Run alongside arteries and veins
  • Very thin permeable walls that large particles including bacteria can permeate
  • Some contain involuntary muscles 
  • Found throughout body except C-N-S, cartilage, teeth
• Lymph Nodes 
  • Bean shaped 1-25mm in length
  • Produce lymphocytes in outer cortex 
  • Filter lymph  
  • Found around major arteries 

Lymphatic Tissue

• Found in mucous membranes of gastro-intestinal tract, respiratory passageways, urinary tract, reproductive tract, and organs of body 

Tonsils

• Collection of lymphatic tissue in a mucous membrane
• Protect against invasion of foreign substances 

Spleen 12cm

• Largest mass of lymphatic tissue 
• Stores and releases blood in emergency 
• Produces activated lymphocytes 
• Ingests bacteria and worn out erythrocytes and thrombocytes 

Peyer’s Patches 

•  A collection of lymphatic tissue found in the small intestines, mainly in the ileum 

Thymus Gland between lungs

• Conspicuous in Infant  
• Atrophied but still functional in adult 
• Activates T Cells and distributes to other lymphoid tissue around the body

Thoracic duct and right lymphatic duct

• Collects lymph from all lymph vessels 
• Drains into left and right jugular veins

LYMPHATIC SYSTEM QUIZ 

1.  What is the lymphatic system?

a. A network of tubes throughout the body that drains fluid from tissues and returns it to the bloodstream
b. A transport system for carrying nutrients around the body
c. A series of glands that secrete chemicals called hormones into the blood 
 
2.  What are the main functions of the lymphatic system?
a. Managing fluid levels in the body, making hormones that regulate metabolism, and filtering out bacteria
b. Managing fluid levels, maintaining the sense of balance, and housing types of white blood cells
c. Managing fluid levels, filtering out bacteria, and housing types of white blood cells 
 
3.  What are lymph nodes?
a. Glands made of lymph tissue that are found at various sites around the body
b. Abnormal scar tissue that prevents the free flow of lymph through the vessels
c. Special clusters of nerve cells that allow the lymphatic system to communicate directly with the brain. 
 
4.  Which organs belong to the lymphatic system?
a. The spleen and thymus
b. The pancreas and the liver
c. The kidneys and bladder 
 
5.  What happens to the excess fluid that the lymphatic system removes from the tissues?
a. Fluid that the body needs is returned to the bloodstream but excess fluid is piped directly to the bladder for excretion
b. Fluid that the body needs is returned to the bloodstream but excess fluid is directed to the mouth to aid in saliva production
c. All collected fluid is returned to the bloodstream 
 
6. What is oedema?
a. A type of cancer that affects the lymphatic system
b. Temporary swelling of certain parts of the body
c. The collective name for the largest lymph vessels 

Anatomy and Physiology On-Line
Gill Tree Training

View all messages