What does the lymphatic system consist of? (5)
Lymph, lymphatic vessels, lymphois tissue, lymphoid organs and lymphocytes
What are the three main functions of the lymphatics?
- Body defense/immunity
- Draining excess interstitial fluid
- Transporting dietary fat
What are the different lymph vessel types? (from peripheral to the venous network)
- Lymph capillary
- Lymph vessel
- Lymph trunk
- Lymph duct (to the venous network)
What is the structure of a lymphatic capillary? How do they differ from blood capillaries?
- they originate as pockets
- they have larger diameters than blood capillaries
- they have thinner walls, and no basal lamina
- they have overlapping endothelial cells that act as a one way valve
Lymphatic vessels tend to be split into two groups, what are they? Where are they located?
- Superficial lymphatics and deep lymphatics
- Superficial lymphatics are in the subcutaneous layer and areolar tissue
- Deep lymphatics accompany deep arteries and veins.
- What do lymph vessels empty into?
- What two structures do these in turn empty into?
- Describe these two structures - where do they collect lymph from?
- Lymph vessels empty into lymphatic trunks
- These in turn empty into the Thoracic Duct and the Right Lymphatic Duct
- The Thoracic Duct collects lymph from the body inferior to the diaphragm, and the left side of the body superior to the diaphragm. It begins at level L2 as a sac like chamber called the cysterna (Kylie) chyli. It empties into the left subclavian vein
- The Right Lymphatic Duct collects from the body superior to the diaphragm on the right side. It empties into the right subclavian vein.
What is MALT and where is it found? What is MALT populated by?
MALT is mucousa-associated lymphois tissue, and it is found in small concentrations in the GI tract, Thyroid, Breast, Lungs, Salivary Glands, Eye and Skin. MALT is populated by T cells, B cells, plasma cells and macrophages.
- What are tonsils? What general structures are they located in?
- What are the 4 tonsils called?
- Tonsils are non-encapsulated areas of lymphoid tissue - they are located within the nasopharynx and oropharynx.
- The 4 tonsils are the Palatine, Pharyngeal, Lingual and Tubal.
Which tonsils are these?
The Palatine tonsils
Describe the pharageal tonsil and its location
The pharageal tonsil can also be called the adenoid when enlarged, or the nasopharageal tonsil. It is situated posterior to the nasal cavity in the roof of the nasopharynx, inferior to the sphenoidal sinus.
Where are the tubal tonsils?
The tubal tonsils are posterior to the opening of the Eustachian tube into the nasopharynx (tube to the ear)
Name the groups of lymph nodes in the body
- cervical nodes in the neck
- para-aortic nodes in front of the lumbar vertebrae
- axilliary nodes
- mediastinal nodes (mediastinum around the heart)
- inguinal nodes
- popliteal nodes (back of the knee)
- mesenteric nodes (at the fan structure that ‘feeds’ the ilium)
describe the passage of lymph through a node
- lymph enters through the afferent lymphatics
- first enters the subcapsular space: contains macrophages
- then flows to the outer cortex: contains B cells
- then flows to the deep cortex: contains T cells
- then enters the core/medulla
- then exits via the efferent lymphatics
