The lymphatic system Flashcards
what is The lymphatic system?
it is a network of tissues and organs
* It plays a key role in the immune system, fluid balance, and absorption of fats and fat-soluble nutrients
what The lymphatic drainage
- It is the second vascular system
- Capillaries are very permeable so fluid leaks out
- Whole blood never leaks the capillaries
- Leukocytes, water and nutrients do
- Fluid collects in the surrounding tissue
- Interstitial fluid
- Some fluid returns back to the capillaries
- The rest is picked up by lymphatic capillaries
what is Lymphatic capillaries
- Have larger pores in their walls than blood capillaries
- Pressure inside is lower
- Excess tissue fluid drains into them
- Fluid known as lymph * Lymph is filtered by lymph nodes
- Collected by lymphatic ducts
- Enters the left and right subclavian veins
- Returns to blood stream
Structure of The lymphatic system includes
- Lymphatic capillaries
- Lymphatic vessels
- Lymphatic nodes
- Lymphatic ducts
what is Lymph
-Lymph is derived from interstitial fluid
-Composition continually changes as the blood and surrounding cells continue exchanging substances
-Mixture of fats and lymph is called chyle
-Lymph contains less proteins than plasma
-96% water, 4% solids
where is the thoracic duct located
near the left subclavian vein
what is the thoracic duct
Largest lymphatic vessel.
40cm long.
Extends from the 2nd lumbar vertebra to the root of the neck. Empties into the subclavian vein .
Collects and drains lymph from the left side of the head, neck, both lower limbs, left side of the trunk and left arm.
where is the right lymphatic duct located
near the right subclavian vein
what is the right lymphatic duct
Only 1.5cm long. Located at the root
of the neck. Empties into the right
subclavian vein. Receives all the
drained lymph from the right side of
the ehad, chest, neck and right arm
what is Lymph circulation
Through the contraction of skeletal muscle which collapses the vessels
* Valves prevent backflow
* A slight oncoming pressure from the tissue fluids
* Movement of the lymph towards the thorax during inspiration
* Negative pressure helps pull the lymph upwards into the lymphatic ducts
what is Oedema
- Obstruction of lymph flow
- Swelling of tissues due to the collection of excess fluid
what is Lymphatic capillaries structure
- Vessels which work with blood to collect excess tissue fluid
- Unite to form lymphatic vessels
- Fine, blind-ended permeable tubes
- Composed of a single layer of endothelial cells
- Less firmly attached to one another than capillaries
- Occur in all spaces between tissues
- More variable in diameter than blood capillaries
- Not found in the neural tissue of the central nervous system, in cartilage or in the cortex of the thymus gland
structure of Lymphatic vessels
- Have valves to keep moving in the direction toward the heart
- Valves consist of a double layer of lining membrane and:
- An outer later of fibrous tissue
- A middle layer of muscular and elastic tissue
- An inner layer of endothelial cells
- Collect lymph from lymphatic capillaries and convey the lymph towards the heart
- All lymph vessels pass through one or more lymph nodes
what are Lymph nodes
- All small and medium sized lymph vessels open into lymph nodes
- Located throughout the body
- An afferent vessel transports lymph to the node
- An efferent vessel transports the filtered lymph back to the system
Lymph nodes structure
- Nodes are made of lymphatic tissue
- Lymphatic tissue is surrounded by a wall of tough white fibrous tissue
- Trabeculae are inward strands of fibrous tissue which offer support
- Lymph nodes vary in size
