Lymphatic system Flashcards
What is the role of hydrostatic pressure?
While blood circulates through the body, wastes, gases, and nutrients are exchanged between the blood and interstitial fluid. Different pressures (hydrostatic and colloid osmotic pressure) operating at capillary beds (at the very tip of where arteries and veins meet) cause most of the fluid to be reabsorbed at the vein end.
What are the three main parts of the Lymphatic system?
Lymph
Lymph nodes
Lymphatic vessels
What two systems are supported by the lymphatic system?
immune system and cardiovascular system
How is lymph formed?
The fluid that remains behind in the tissue spaces between the capillary beds (as much as 3 litres a day) becomes part of the interstitial fluid.
This leaked fluid, along with plasma proteins that have escaped from the bloodstream, must be returned, to make sure the cardiovascular system continues to operate properly. The problem of circulatory dynamics is resolved by lymphatic vessels, also known as lymphatics.
Lymphatic vessels are drainage vessels that collect the excess interstitial fluid and return it to the bloodstream. Once interstitial fluid enters the lymphatic vessels, it is called lymph. Lymphatic vessels form a one-way system in which lymph only flows toward the heart.
What is the role of the lymphatic vessels?
to help reabsorb the fluid
What are lymph nodes and what do they do?
essentially checkpoints that monitor and cleanse the lymph as it filters through
What are some of the main lymphoid organs?
spleen, thymus, adenoid’s and tonsils
some of these have defensive cells of the immune system to fight bacteria
others such as the thymus and the spleen provide a nursery for lymphocytes and mature them
Where does the transfer of nutrients/waste take place?
at capillary beds, blood is carried from the arterioles to the venules
What are lymphatic capillaries made up of?
loosely overlapping endothelial cells and these flaps means there are mini valves which ensures that the lymph does not leak back into the interstitial space no matter how high the pressure
These capillaries weave in between blood capillaries
What happens when the pressure in the interstitial space is greater than that of the inner lymphatic capillary?
the flaps of the capillary push open and take in interstitial fluid to relieve the pressure, where it becomes lymph
Collagen filaments anchor the endothelial cells to surrounding structures so that any increase in interstitial fluid volume opens the minivalves, rather than causing the lymphatic capillaries to collapse.
What does the lymphatic system essentially do?
The lymphatic system returns fluids that have leaked from the blood (vascular system) back to the blood. Without it, our cardiovascular and immune systems would begin to shut down.
What happens with proteins and large particles?
Proteins in the interstitial space are unable to enter blood capillaries, (they’re too big) but they can enter lymphatic capillaries easily. In addition, when tissues become inflamed, lymphatic capillaries develop openings that permit the uptake of even larger particles such as cell debris, pathogens, and cancer cells. The pathogens can then use the lymphatics to travel throughout the body. This threat is partly neutralized because lymph travels through lymph nodes, where it’s cleansed and examined by cells of the immune system.
Where does lymph go after it has travelled through the lymphatic capillaries?
From the lymphatic capillaries lymph flows through larger and thicker-walled channels – first, collecting vessels, then trunks, and finally the largest vessels, the ducts. The collecting lymphatic vessels have the same three tunics as veins, but the collecting vessels have thinner walls and more internal valves. Generally lymphatic vessels in the skin travel along with superficial veins, while the deep lymphatic vessels travel with deep arteries.
What are the two main ducts and where do they drain lymph from?
The right lymphatic duct drains lymph from the right upper limb and the right side of the head and thorax. The thoracic duct (which is much larger) receives lymph from the rest of the body. It arises as enlarged sac called the cisterna chyli, that collects lymph from the two large lumbar trunks that drain the lower limbs and from the intestinal trunk that drains the digestive organs
what sort of pressure do lymphatic vessels work under?
low pressure, they have valves and smooth muscle in vessel walls to keep it all moving
