IPHY 3410 LYMPHATIC SYSTEM

What is the purpose of the lymphatic system?

-Transports interstitial fluid (lymph) that has collected in tissues back to the bloodstream

-transports absorbed fats from the small intestine to blood

-transports immune cells to and from the lymph nodes to the blood

What fluid can leak from the blood capillaries:

This fluid is called LYMPH when it is within lymph vessels

Primary structure of the lymphatic system:

•Lymphatic collecting vessels

•Lymph nodes

•Lymph trunks

•Lymph ducts

Lymphedema is what?

Swelling in a region of the body due to an obstruction within the lymphatic structures

-removal or enlargement of the lymph nodes mostcommon cause in US

-Obstruction (such as by a parasite) more common in 3rd world countries

Elephantiasis is what?

A case of lymphedema that cause been caused by a parasite

•Most common parasitic nematode to cause elephantiasis •Larva carried by mosquitoes, but an adult thrives in the human lymphatic system blocking lymph nodes and collecting vessels

The relationship of the lymphatic vessels and blood vessels

The cardiovascular system is a series of vessels that transports blood within a closed circuit, but when fluid leaks out of the blood capillaries it is known as interstitial fluid

interstitial fluid

The fluid found in the spaces between cells. It provides nutrients to cells, removes waste, and becomes lymph once it enters the lymphatic vessels

Lymphatic system:

is a ONE WAY series of vessels that collects interstitial fluid from tissues of body and returns it to the blood

Lymph

The fluid formed when interstitial fluid enters the lymphatic system. It moves through the lymphatic system to be filtered before returning to the bloodstream.

Lymphatic Capilaries

They are the entry to the lymphatic system, and consist of closed end tubes that are made of a SIMPLE SQUAMOUS epith. They work to recapture fluid, fats, microorganisms, and things that have collected within the bodies tissues

How does interstitial fluid enter lymphatic capillaries?

Rising interstitial fluid pressure forces open the minivalve flaps between overlapping endothelial cells, allowing the fluid to enter. Once inside, it is called lymph.

Lacteals

specialized lymph vessels, lymph capillary of the small intestine that picks up absorbed fats that are unable to enter blood capilaries

Lymphatic collecting vessels (drain capillaries)

Made up of the same layers as the blood vessels but are much thinner:

Tunica intima: epithelium

Tunica media: smooth muscle

Tunica externa: connective tissue

The tunica intima forms what?

It forms VALVES where lymph is under low pressures, and the valves keep it moving forward though the vessels

Lymph Nodes

Approximately 500 lymph nodes in our body that cleanse lymph of pathogens, they can occur alone or in clusters that filter lymph through multiple nodes

Afferent lymphatic vessels:

drain INTO node

Efferent lymphatic vessels:

drain AWAY from node

What does each node consist of?

have an outer cortex and inner medulla, they are also seeded within lymphocytes and found along the reticular matrix

Reticular tissues found in the lymph node

Macrophages, lymphocytes, medullary sinus, and reticular fibers

What causes lymph nodes to swell when you are sick?

There are a large number of lymphocytes that travel to the site to fight the virus

Lymph Trunks:

drain large regions of the body

Lymph ducts:

drain lymph BACK into the blood, ONLY TWO lymph ducts, and each drain into different veins

1) Right lymphatic duct

Drains right side: head, neck, arm, thoracic cavity INTO right subclavian vein

2) Thoracic duct

Drains most of body: all of left side and right lower limb, abdomen Into left brachiocephalic vein