WEEK 2 (PART 2) Flashcards
What are tonsils?
Masses of lymphoid tissue that protect against pathogens entering the body.
Where are tonsils located?
Form a broken ring around the opening of the throat at the back of the mouth.
What are the different types of tonsils?
Palatine, tubal, pharyngeal (adenoids), and lingual.
Why are tonsils prone to infection?
Their location exposes them frequently to external antigens.
What is the name of a tonsil infection?
Tonsillitis
What is the thymus?
A central organ of the lymphatic system.
Where is the thymus located?
In the mediastinum, behind the sternum and under the thyroid gland.
What is the size of the thymus throughout life?
Largest in infancy (70g), shrinks in puberty (30g), remains around 3g in old age.
What is the main function of the thymus?
Enables immature lymphocytes to develop into T cells.
What hormones does the thymus produce?
Thymosin (peptide) and Thymopoietin (protein), both involved in immune cell development.
Where is the spleen located?
Left upper abdomen, under the diaphragm, behind the stomach.
What is the shape and size of the spleen?
Ovoid, about the size of a fist.
What happens to the spleen during infection?
Hypertrophies (increases in size) due to immune cell division.
What are the main functions of the spleen?
Defense, tissue repair, hematopoiesis, red & platelet destruction, blood reservoir.
How does the spleen defend against pathogens?
Macrophages in the spleen ingest and destroy microorganisms from the blood.
How does the spleen aid in tissue repair?
Monocytes from the spleen migrate to injured tissue to assist in healing.
What is hematopoiesis?
The process of blood cell formation. (Spleen helps differentiate monocytes and lymphocytes)
What is the role of the spleen in red blood cell destruction?
Macrophages remove worn-out red blood cells and salvage iron for reuse.
How does the spleen act as a blood reservoir?
Stores about 350ml of blood that can be released back into circulation during blood loss.
Where is bone marrow located?
Inside the hollow spaces of bones like the femur.
What is the main function of bone marrow?
Houses hematopoietic cells that give rise to all blood cells.
What are hematopoietic cells?
Stem cells that can differentiate into various types of blood cells.
What types of immune cells develop in bone marrow?
Immature B and T cells.
Where do immature B and T cells go after bone marrow?
They migrate to other lymphoid organs to mature into fully functional immune cells.
What are lymph nodes?
Bean-shaped organs distributed throughout the body, connected by lymphatic vessels.
What is the function of lymph nodes?
Filter lymph fluid and present antigens to T and B cells.
How does lymph enter and exit lymph nodes?
Enters through afferent vessels, flows through sinuses, exits through efferent vessels.
What cells are found in lymph nodes?
T and B cells, which can identify foreign particles in the lymph fluid.
What is MALT?
Mucosa-associated lymphoid tissue, found in mucous membranes throughout the body.
Where is MALT located?
Digestive, urinary, respiratory, and reproductive tracts.
How is MALT similar to lymph nodes?
Both filter fluids and contain immune cells (T and B cells).
How is MALT different from lymph nodes?
MALT has a closer connection to the external environment (e.g., gut lumen).
What is the lymphatic system?
A network of vessels that drains fluid, macromolecules, and immune cells from tissues.
What is the main function of the lymphatic system?
To return excess fluid and waste products to the bloodstream.
How does the lymphatic system collect fluid?
Lymphatic vessels begin blindly in tissues and collect fluid as it travels towards the bloodstream.
How does lymph fluid return to the bloodstream?
The right lymphatic duct drains lymph from the upper right body to the right subclavian vein. The thoracic duct drains lymph from the rest of the body to the left subclavian vein.
What helps move lymph fluid?
Skeletal muscle pump, respiratory pump, and one-way valves in the lymphatic vessels.
What is the role of lymph nodes in the lymphatic system?
Filter lymph fluid and house immune cells that identify foreign particles.
How many main mechanisms does the immune system have?
Two: Innate (non-specific) and Adaptive (specific) responses.
What is the role of the innate immune system?
First line of defense, providing general protection against invaders.
What is the role of the adaptive immune system?
Targeted defense against specific pathogens.
How can the innate immune system be further categorized?
External barriers (skin, mucous membranes) and internal defenses (phagocytes, inflammation).
How does the adaptive immune system differ from the innate system?
It is specific to a particular pathogen and develops memory for future encounters.
What is the innate immune system?
The body’s first line of defense, present at birth and doesn’t require specific training.