Lymphatic
→ It is the body’s ’sewerage system’.
→ A network of tissues, organs & vessels that help to maintain the body’s fluid balance & protect it from pathogens.
→ It is important for the optimal functioning of our general & specific immune responses.
FUNCTIONS:
→ The lymphatic system has 3 main functions:
↳ Maintains the balance of fluid between the blood & tissues (homeostasis).
↳ Forms part of the body’s immune system & helps defend against bacteria & other pathogens.
↳ Facilitates absorption of fats & fat soluble nutrients in the digestive system.
STRUCTURES:
→ Lymph: → A clear watery fluid that resembles blood plasma but has fewer proteins.
→ The lymphatic system handles 125 mL/hr (2500-2800 mL of lymph/day).
→ Lymph flows upward towards the neck, through the subclavian veins.
↳ It is created from any fluid that doesn’t return to the heart via the veins.
→ Lymphatic capillaries: → Originate in tissues and lie side by side with blood capillaries.
↳ They have a single layer of endothelial cells like blood capillaries but are much more permeable to solvents, large solutes & whole cells.
→ Lymphatic vessels: → These small lymphatic capillaries merge with others to form larger lymphatic vessels.
↳ They resemble veins in structure.
↳ They have 1-way valves - but many more than veins (every few mm or so).
↳ They also have lymph nodes at intervals along it’s course.
↳ They become larger & larger as they continue toward the chest.
FLOW OF LYMPH:
→ Fluid pressure in the lymphatic system is very low.
→ Vessels contract rythmically and the direction of flow is maintained by 1-way valves.
→ Body movements & pulsing of arteries help to move the lymph along through the lymph vessels.
→ Vessels are wrapped in connective tissue with arteries: the pulsing of the arteries also helps move lymph.
STRUCTURES - LYMPH NODES:
→ AKA lymph glands; are widespread in body but most occur in groups or clusters (600-700 in body).
→ Functions of lymph nodes: 1. Cleanse lymph - as lymph flows through sinuses of node, it slows down & microorganisms & foreign matter are removed.
2. Alert immune system to pathogens.
3. Important in haemopoiesis - lymphocytes & monocytes are made here.
SPLEEN:
→ The spleen is the largest of the lymphatic organs, and is located below the diaphragm to the left.
→ The spleen has several functions:
→ Defence: → helps screen the blood and removes pathogens & bacteria.
→ Haemopoiesis: → monocytes and lymphocytes are made here (before birth, RBC’s are also made here).
→ Erythrocyte & platelet destruction: → the removal of old blood cells & platelets occurs in the spleen, iron is salvaged from these RBC’s.
→ Blood reservoir: → the spleen is able to store blood. Approx. 350 mL of blood can be released into the circulatory system if required.
* Humans can live without the spleen, but are more prone to injury & infection without it.
→ It is the body’s ’sewerage system’.
→ A network of tissues, organs & vessels that help to maintain the body’s fluid balance & protect it from pathogens.
→ It is important for the optimal functioning of our general & specific immune responses.
FUNCTIONS:
→ The lymphatic system has 3 main functions:
↳ Maintains the balance of fluid between the blood & tissues (homeostasis).
↳ Forms part of the body’s immune system & helps defend against bacteria & other pathogens.
↳ Facilitates absorption of fats & fat soluble nutrients in the digestive system.
STRUCTURES:
→ Lymph: → A clear watery fluid that resembles blood plasma but has fewer proteins.
→ The lymphatic system handles 125 mL/hr (2500-2800 mL of lymph/day).
→ Lymph flows upward towards the neck, through the subclavian veins.
↳ It is created from any fluid that doesn’t return to the heart via the veins.
→ Lymphatic capillaries: → Originate in tissues and lie side by side with blood capillaries.
↳ They have a single layer of endothelial cells like blood capillaries but are much more permeable to solvents, large solutes & whole cells.
→ Lymphatic vessels: → These small lymphatic capillaries merge with others to form larger lymphatic vessels.
↳ They resemble veins in structure.
↳ They have 1-way valves - but many more than veins (every few mm or so).
↳ They also have lymph nodes at intervals along it’s course.
↳ They become larger & larger as they continue toward the chest.
FLOW OF LYMPH:
→ Fluid pressure in the lymphatic system is very low.
→ Vessels contract rythmically and the direction of flow is maintained by 1-way valves.
→ Body movements & pulsing of arteries help to move the lymph along through the lymph vessels.
→ Vessels are wrapped in connective tissue with arteries: the pulsing of the arteries also helps move lymph.
STRUCTURES - LYMPH NODES:
→ AKA lymph glands; are widespread in body but most occur in groups or clusters (600-700 in body).
→ Functions of lymph nodes: 1. Cleanse lymph - as lymph flows through sinuses of node, it slows down & microorganisms & foreign matter are removed.
2. Alert immune system to pathogens.
3. Important in haemopoiesis - lymphocytes & monocytes are made here.
SPLEEN:
→ The spleen is the largest of the lymphatic organs, and is located below the diaphragm to the left.
→ The spleen has several functions:
→ Defence: → helps screen the blood and removes pathogens & bacteria.
→ Haemopoiesis: → monocytes and lymphocytes are made here (before birth, RBC’s are also made here).
→ Erythrocyte & platelet destruction: → the removal of old blood cells & platelets occurs in the spleen, iron is salvaged from these RBC’s.
→ Blood reservoir: → the spleen is able to store blood. Approx. 350 mL of blood can be released into the circulatory system if required.
* Humans can live without the spleen, but are more prone to injury & infection without it.
