Lymphatic System

Lymphatic system related to blood vessels

One way series of valved vessels that collects interstitial fluid from tissues and returns it to the circulatory system, no pump

Tunica intima

forms valves, these valves prevent retrograde flow

Lymphocytes

generic name for leucocytes of white blood cells

Lymphatic system

interstitial fluid leaks from blood capillaries

Trapdoor of lymphatic capillaries

overlapping cells create doors that are pushed open by pressure of interstitial fluid

Why do lymph nodes swell when sick

1. Large number of viruses trapped in the node. 2.Large number of lymphocytes traveling to the site to fight a virus. 3.Excess of fluid trying to dilute the concentration of viruses.

Lymphatic system functions

1.Transports lymph that has collected in tissues back to the blood stream 2.Transports fat from small intestine to blood 3.Transports immune cells between lymph nodes and circulatory system

Lymph node

500 lymph nodes collect/remove pathogens, filters through multiple nodes

Lymph Trunk

Drain large regions of body

Lymphatic collecting vessels

Drain lymph capillaries, same layers as veins but thinner, low pressure

Thoracic Duct

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

Right Lymphatic Duct

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

Lymph Ducts

Final tube that drains lymph back into major blood veins. Only 2, each draining into a different vein

Capillary Thin walls

Gas and substrate diffusion in and out of tissues

Lymphatic capillary connection to blood vessel function

Recycle fluid, fats, microorganisms, ect. that have collected within tissues of body

Capillary Endothelium

Simple squamous epithelium

Capillary Basement membrane

Subendothelial layer= loose areolar CT

Layers of lymphatic collecting vessels

Tunica intima = epithelium Tunica media = smooth muscle Tunica externa = CT

Lymphocytes found..

along reticular matrix

Interstitial fluid

called lymph when in lymph vessels, fluid leaks out of blood capillaries into surrounding tissue

Types of Cappilaries

continuous, fenestrated, sinusoidal

Efferent lymphatic vesesl

drain away from node

afferent lymphatic vessels

drain into node

Lymphatic cappilaries

entrances to blood vessel system

Lacteal

lymph capillaries of small intestine transport absorbed fat molecules/globules that are too big to enter blood capillaries

Primary structures

lymph ducts, lymph trunks, lymph nodes, lymphatic collecting vessels

Lymphatic capillary closed end tubes

walls are simple squamous epithelium