Alliyah Evangelista-
Define resistance and susceptibility?
Resistance - The body's ability to ward off disease-causing pathogens.
Susceptibility - The body's inability to ward off pathogens; lack of disease resistance.
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Generally, the purpose and design of the human body is to defend itself against disease-causing pathogens. True or false?
True
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Resistance can grouped into two types. Define and give examples of some of them.
Nonspecific Resistance (Innate Immunity) - Defenses which are present at birth and doesn't require a specific response to a microbe. They represent an early warning system and are designed to prevent microbes from even entering the body. For example, the skin you were born with.
Immunity (Adaptive Immunity) - Requires the activation of a specific response (lymphocytes) to a specific microbe. The lymphocytes required T and B cells.
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Where is lymph (a clear fluid) formed from?
It is formed from plasma during capillary exchange.
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What is the difference between interstitial fluid and lymph.
Lymph flows inside lymphatic vessels, whereas interstitial fluid flows outside the vessel.
Otherwise they are the same.
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Interstitial fluid and lymph plasma have less protein than blood plasma. Why is that?
It's because most blood plasma protein molecules are too large to filter through the capillary wall (during formation of interstitial fluid).
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What are the 4 main functions of the lymphatic system?
1. Drains excess interstitial fluid: Lymphatic vessels drain interstitial fluid and then return it to the blood (the remaining 3L from the 17L that was normally returned).
2. Transports dietary fats (lipids): The lipids can't be captured by veins and the capillary bed because of their size so the lymphatic vessels carry them instead from the digestive canal.
3. Carries out immune responses: Initiates by responding through lymphocytes.
4. Return leaked plasma proteins to the blood
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Describe the structures of lymphatic capillaries.
- Overlapping endothelial cells which act like valves: what allows the interstitial fluid to enter.
- Close ended on one end.
- Form lymphatic vessels.
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What are the 5 lymphatic trunks?
- Lumbar
- Intestinal
- Bronchomediastinal
- Subclavian
- Jugular
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Lymphatic ducts are formed from what?
The trunks
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What is the main collecting duct of the lymphatic system?
The thoracic or the left lymphatic duct.
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What areas of the body does the thoracic duct receive lymph from?
Mostly the left side of the body:
- Left side of head
- Neck
- Chest
- Left upper extremity
- Entire body below the ribs
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What areas of the body does the right lymphatic duct receive lymph from?
- Right side of head
- Anything above the right ribs
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Where do the ducts drain lymph into?
Into the right and left subclavian veins.
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What do the primary lymphatic organs do and what are they?
Primary lymphatic organs are where immune cells become immunocompetent (capable of creating an immune response). They are the thymus and the red bone marrow.
Multipotent stem cells in red bone marrow give rise to immunocompetent B cells and pre-T cells which migrate to the thymus. There the T cells mature.
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What do the secondary lymphoid organs do and what are they?
They are where most immune responses occur. They include the lymph nodes, the spleen and nodules.
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What do lymph nodes contain?
- T cells
- B cells
- macrophages
- follicular dendritic (like dendrites) cells
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What separates lymph nodes from lymph nodules?
Lymph nodes are covered by a capsule, while lymph nodules are not.
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What constitutes the stroma of a lymph node?
- The capsule
- Trabeculae
- Reticular fibers
- Fibroblasts
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Where does lymph enter a lymph node and where does it exit?
Enters through the afferent vessels and exits through the efferent lymphatic vessels.
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What is the main purpose of lymph nodes?
It filters and cleanses the lymph that flows through the lymphatic system.
