The lymphatic and immune system Flashcards
What is the lymphatic system?
A network of tubes that drain fluid (lymph) that has leaked from the blood vessels into the tissue.
[the lymph is then emptied back into the bloodstream via lymph nodes]
The lymphatic system contributes to homeostasis by performing three key functions.
- drains excess interstitial fluid
- transports dietary lipids
- carries out immune responses
What are the 4 main components of the lymphatic system?
- Lymph - the fluid (note: the major difference between lymph and interstitial fluid is location)
- Lymphatic vessels
- Lymphatic organs and tissues
- Red bone marrow (the site of lymphocyte production)
What are the 4 lymphatic vessels?
- Lymphatic capillaries - located in the space between cells, closed at one end, greater permeability than blood capillaries
- Lymphatic vessels - capillaries merge to form vessels which move lymph in and out of lymph nodes
- Lymphatic trunks - vessels exit nodes in particular regions of the body where they unite to form trunks (i.e. merging point)
- Lymphatic ducts - lymph passes from trunks into two main channels: the thoracic duct and right lymphatic duct before being drained into venous blood
Lymphatic capillaries are tiny thin-walled vessels that collect lymph fluid from the tissues. This allows them to regulate what?
Pressure of the interstitial fluid
What are lacteals?
Specialised lymphatic capillaries in the small intestine that absorb and transport digested fats from the small intestine into the blood
What helps fluid to enter lymphatic capillaries when tissue pressure is high, working as one-way valves? (what type of cell)
Overlapping endothelial cells
A number of lymph trunks drain lymph into different areas of the body. Name the areas that the following trunks drain into…
1) Lumbar trunk
2) Intestinal trunk
3) Broncho mediastinal trunk
4) Subclavian trunk
5) Jugular trunk
1) from the lower limbs, pelvis, kidneys, adrenal glands, abdominal wall
2) stomach, intestines, pancreas, spleen, part of the liver
3) thoracic wall, lung, heart
4) upper limbs
5) head and neck
A key function of lymphatic vessels is to return WHAT to the bloodstream?
Lost plasma proteins and plasma
What is the main collecting duct in the lymphatic system?
The thoracic duct
What are the main two functions of the thoracic duct?
1) receives lymph from the left side of the head, neck and chest, left upper extremity, and the entire body below the ribs
2) drains lymph into venous blood via the left subclavian vein
What are the main two functions of the right lymphatic duct?
1) receives lymph from the upper right side of the body
2) drains lymph into venous blood via the right subclavian vein
Put the following steps into the right order of flow
> lymphatic ducts
lymph capillaries
interstitial fluid
junction of the internal jugular and subclavian veins
lymphatic vessels
1) interstitial fluid
2) lymph capillaries
3) lymphatic vessels
4) lymphatic ducts
5) junction of the internal jugular and subclavian veins
What are the main classifications of lymphatic organs and tissues?
Primary and secondary
Primary lymphatic organs provide an environment for stem cells to divide and mature into B and T lymphocytes.
Name the primary lymphatic organs.
Red bone marrow - B cells continue to mature here
Thymus - Pre-T cells migrate from red bone marrow and mature in the thymus
Secondary lymphatic organs and tissues provide a site for most immune responses to occur.
Name the secondary lymphatic organs.
Lymph nodes
Spleen
Lymphatic nodules (follicles)
Which primary lymphatic organ gives rise to pre-T cells and mature, immunocompetent B cells?
Red bone marrow
The thymus is structured into a cortex and medulla. The cortex is responsible for the proliferation and maturation of immature T cells (pre-T cells) which have migrated from the red bone marrow. What is the medulla responsible for?
Release of mature and immunocompetent T cells into the blood to migrate to lymph organs
The spleen works as part of the lymphatic system to filter blood. There is red and white pulp.
Red pulp consists of venous sinuses filled with blood and splenic tissue and is responsible for the removal of ruptured/worn-out red blood cells, and the storage of platelets.
What is the function of the white pulp?
Lymphatic tissue responsible for the performance of B cells, T cells and macrophages which are involved in immune functions.
Lymphatic nodules are egg-shaped masses of lymphatic tissue that are NOT surrounded by a capsule. Large aggregations in specific parts of lymph nodes include…
1) Peyer’s patch (small intestines)
2) Tonsils
3) Adenoids
4) Palatine tonsils
5) Lingual tonsil (base of tongue)
6) Appendix
Lymph nodes are bean-shaped and often occur in groups, scattered throughout the body. They slow the flow of lymph and function as a type of filter, trapping foreign substances. Lymph flows only in one direction within a node entering through a WHAT lymphatic vessel?
Afferent lymphatic vessel
(contains valves)
What is the route of lymph through a node? (5 steps)
1) Afferent lymphatic vessels
2) Subcapsular sinus
3) Trabecular sinus
4) Medullary sinus
5) Efferent lymphatic
Name the cells of the medulla of a lymph node
B cells
Plasma cells
Macrophages
Name the cells of the inner cortex of a lymph node
T cells
Dendritic cells
Name the cells AROUND the germinal centre of the outer cortex of a lymph node
B cells
Name the cells IN a germinal centre of the outer cortex of a lymph node
B cells
Follicular dendritic cells
Macrophages
Where do B cells mature?
Red bone marrow
Where do T cells mature?
Thymus
T cells kill by…?
Lysis
Antigen presenting cells in lymph nodes include…?
Dendritic cells and follicular cells
B cells give rise to what?
Plasma cells
Plasma cells make what?
Antibodies
What are the two types of immunity?
Innate (non-specific) and adaptive (specific)
Innate immunity acts as the first line of defence by supporting external physical and chemical barriers. Give some examples of physical and chemical factors.
PHYSICAL
- epidermis of skin
- mucous
- hairs
- saliva
- vomiting
- lacrimal apparatus
- defecation
CHEMICAL
- sebum
- gastric juices
- vaginal secretions
The return of lymph is maintained by two pumps…
Skeletal muscle and respiratory pumps
The main duct for the return of lymph to the blood is the…?
Thoracic duct
Which organ removes worn-out red blood cells?
Spleen
Tears contain an enzyme that break down certain bacteria called…?
Lysozymes
