Lylymphatic System Revision - Tutorial Flashcards
Function of lymphatic system
- Fluid management/ recovery
a.Gathering excess interstitial fluid - Lipid absorption
- Immunity
a. Contains immune cell- particularly lymphocytic
Lymph
Usually clear, colorless fluid like blood plasma but low in protein
Lymphatic capillaries closed off at one end. They kind of act like little valves. So once there’s high enough pressure inside the lymphatic capillaries lumen inside of it. Then they close so that the fluid can’t make its way out
Lymphatic vessels
So we go. Lymphatic capillaries make our way up to collecting vessels, and then up to lymphatic trunks and then out collecting ducts.
This is all happening alongside the circulatory system at the same time.
Lymphatic vessels
Origin: begin as lymphatic capillaries
Structure: thin wall, valves
Function: carry lymph toward heart
Capillaries: one sided/ closed ended
Pressure: low
Veins
Origin: venules/ blood capillaries
Structure: thin wall and valves
Function: carry blood towards heart
Capillaries: open ended
Pressure: low
Arteries
Origin: aorta
Structure: thick wall/ muscular, no valves
Function: Carrie’s blood away from heart
Capillaries: open ended
Pressure: high
Major organs of the lymphatic system
Primary (Production or maturation of lymphocytes)
• Red bone marrow
-Produce T and B cells
• Thymus
-T-Cells mature
Secondary (Location of lymphocyte action)
Spleen
Lymph nodes (-450)
• Filters lymph
• Slows the flow of lymph
Tonsils
• Patches of lymphatic tissues
Spleen
Red pulp consists of sinuses gorged with concentrated erythrocytes
White pulp consists of
lymphocytes and macrophages aggregated like sleeves along small branches of the splenic artery.
Lines of defense
1st line of defense
External barrier
- skin
- mucus membrane
- subepithelial aeorlar tissue
2nd line of defense
Non specific line of defense
- inflammation
- fever
- leukocytes and macrophages
- antimicrobial proteins
- immune surveillance ( NK cells)
3rd line of defense
Adaptive immune system
- memory
Innate vs adaptive
Innate:
Characteristics:
- local ( apart from fever)
- non specific
- no memory
Functions: non specific threats
Leukocytes:
- monocytes
- macrophages
- neutrophils
- NK cells
Key mechanisms:
- physical barriers (skin mucus membranes)
• protective proteins/cells
• fever
• inflammation
• phagocytosis
Adaptive
Characteristics:
- systemic
- specific
- memory
Functions: specific threats
Leukocytes:
- B cells
- T cells( helper, cytotoxic)
Key mechanisms:
- humeral immunity ( antibodies)
- cellular immunity
- memory cell formation
Cellular vs Humoral
Cellular
Where does it occur?
Within the cell ( intracellular)
Lymphocytes:
T cells
Stages:
1. Recognition
- antigen presentation
- T cell activation
2. Attack
- helper and cytotoxic T cells
3. Clean up/ memory
- tm cells
Humoral
Where does it occur?
Outside the cell ( extracellular)
Lymphocytes:
B cells (mostly)
Stages:
1. Recognition
- Immunocompetent B cells
2. Attack
- antibodies bind to antigen and tag it for destruction
3. Clean up/ memory
- some b cells become memory cells
Innate Immunity - External Barriers
°3 P’s:
1. Protective proteins
2. Protective cells
3. Protective processes
- Fever, inflammation etc
The three (3) key external barriers:
1. Skin
2. Mucus membrane
3. Sub-epithelial areolar tissue
Leukocytes
Leukocytes 5 types
1. Neutrophils
- wander in connective tissue
- kill bacteria
2. Basophils
- secrete chemicals that assist other leukocytes
3. Eosinophils
- useful for getting rid of parasites
4. Monocytes
- turn into macrophages
5. Lymphocytes
- 80% T cells
- 15 % b cells
- 5% NK cells
Innate immunity - antimicrobial proteins
