circulation and the lymphatic system

the lymphatic system and circulation

The lymphatic system is a network of vessels and tissues that carry a clear fluid called lymph. The lymphatic system ( Figure 1.1) spreads all around the body and filters and cleans the lymph of any debris, abnormal cells, or pathogens. Lymph vessels are tube-shaped, just like blood vessels, with about 500-600 lymph nodes (in an adult) attached. The lymphatic system works with the cardiovascular system to return body fluids to the blood. The lymphatic system and the cardiovascular system are often called the bodys two "circulatory systems." Organs of the lymphatic system include the tonsils, thymus gland and spleen. The thymus gland produces T cells or T-lymphocytes (see below) and the spleen and tonsils help in fighting infections. The spleens main function is to filter the blood, removing unwanted red blood cells. The spleen also detects viruses and bacteria and triggers the release of pathogen fighting cells. The lymphatic system helps return fluid that leaks from the blood vessels back to the cardiovascular system.

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role of the lymphatic system in circulation

You may think that your blood vessels have thick walls without any leaks, but thats not true. Blood vessels can leak just like any other pipe. The lymphatic system makes sure leaked blood returns back to the bloodstream. When a small amount of fluid leaks out from the blood vessels, it collects in the spaces between cells and tissues. Some of the fluid returns to the cardiovascular system, and the rest is collected by the lymph vessels of the lymphatic system ( Figure 1.2). The fluid that collects in the lymph vessels is called lymph. The lymphatic system then returns the lymph to the cardiovascular system. Unlike the cardiovascular system, the lymphatic system is not closed (meaning it is an open circulatory system that releases and collects fluid) and has no central pump (or heart). Lymph moves slowly in lymph vessels. It is moved along in the lymph vessels by the squeezing action of smooth muscles and skeletal muscles. Lymph capillaries collect fluid that leaks out from blood capillaries. The lymphatic vessels return the fluid to the cardiovas- cular system.

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role of the lymphatic system in the bodys defenses

The lymphatic system also plays an important role in the immune system. For example, the lymphatic system makes white blood cells that protect the body from diseases. Cells of the lymphatic system produce two types of white blood cells, T cells and B cells, that are involved in fighting specific pathogens. Lymph nodes, which are scattered throughout the lymphatic system, act as filters or traps for foreign particles and are important in the proper functioning of the immune system. The role of the lymphatic system in the immune response is discussed in additional concepts.

instructional diagrams

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questions

the lymphatic system is a closed circulatory system.

a. true

-->  b. false

the heart pumps lymph throughout the lymphatic system.

a. true

-->  b. false

the lymphatic system works with the ____ system to protect your body.

a) cardiovascular

b) endocrine

-->  c) immune

d) all of the above

what part of the lymphatic system acts as a trap for foreign particles?

-->  a) the lymph

b) the lymph nodes

c) the thymus gland

d) the blood

the lymphatic system helps return fluid to the

a) immune system.

b) endocrine system

-->  c) circulatory system.

d) respiratory system.

about how many lymph nodes are in a typical adult?

-->  a) 50

b) 100

c) 500

d) 1000

what is the role of the spleen?

a) to make t cells

-->  b) to filter the blood

c) to return blood to the circulatory system

d) to fight pathogens

diagram questions

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