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