Lyphatic System Flashcards
What is the lymphatic system?
A network of vessels and tissues that assist in circulating fluids, help defend the body against diseases and transport of fats and fat soluble vitamins form the gut
Where is the lymph nodes located?
All over the body but primarily in the neck, chest, armpits, abdominal and groin
Describe the formation of lymph
Hydrostatic moves from plasma out of the blood capillaries into the interstitial tissue
Osmotic pressure only reabsorbs some of the lost fluid from the interstitial space that can carry on into the venules
Excess fluid enters through one-way valves that is taken into the lymphatic vessels
Describe lymphatic vessels
Small vessels lead to larger vessels which lead to lymph nodes then to lymphatic trunks
They have similiar, but thinner walls to veins
Composed of 3 layers:
Inner-Endothelial lining
Middle- Smooth muscle
Outer- Connective tissue
What are lacteals?
Lymphatic vessels in the gut that collect lymph from villi that can contain fatty acids from the diet
The lymph collected is cloudy and called CHYLE
What is the hierarchy of the lymphatic system?
Lymphatic capillary
Afferent lymphatic vessels
Lymph node
Efferent lymphatic vessel
Lymphatic trunk
Collecting duct
Subclavian vein
What is lymph accumulation?
When the amount of fluid in the lymph exceeds what’s absorbed in the tissues
Usually caused by inflammation or a blockage
What are lymph nodes?
Found in groups/ chains along the paths of the larger lymphatic vessels throughout the body
They contain lymphocytes and macrophages to fight invading pathogens
Describe primary and secondary lymphoid organs?
Primary- Tissues in which lymphocytes develop and mature
Bone marrow (B cells) and Thymus (T cells)
Secondary- Filter potentially harmful particles form the lymph and provide the environment for lymphocytes to be activated
Lymph nodes
Spleen and various mucosal associated lymphoid tissues
What is the spleen and its role in the lymphatic system?
Largest lymphatic organ, in the upper left abdominal quadrant
Contains 2 types of tissues:
White pulp- Lymphocytes
Red pulp- RBCs, lymphocytes and macrophages
The spleen filters blood and NOT lymph
Describe the thymus and its function
Located just above the heart, decreases in size with age and is replaced by fat and connective tissue in the elderly
Role is to secrete protein hormones called thymosins that stimulate the maturation of T lymphocytes
What is a thymocyte?
Cells that will grow and become a T cell
Describe the body’s innate defences
Barriers (skin, hair etc) that innate cells and proteins that act immediately to prevent pathogen entry and growth
This is the first and the same response to any subsequent infection
Describe the body’s adaptive defences
T and B cells
Immune cells that learn from a primary exposure to a pathogen so that the response the second time round is much faster and more efficient
What is adaptive immunity?
Can fight almost all pathogens
Response is specific to the invader, targeted to antigens
B cells produce antibodies and T cells produce cytokinins t direct the immune response/ directly kill infected cells
