lymphatic system Flashcards
What is the primary function of the immune system?
To protect the host from pathogenic microbes including bacteria, viruses, fungi, and parasites
Also helps to protect against cancerous cells and contributes to tissue homeostasis and repair.
What are the two types of immunity?
Innate Immunity and Adaptive Immunity
Innate immunity is always ‘on’ while adaptive immunity requires priming by antigens.
List four cellular mediators of the immune response.
- Macrophages
- Neutrophils
- Dendritic cells
- T cells
- B cells
These cells play crucial roles in recognizing and responding to pathogens.
What is an antigen?
A molecule, usually a protein or peptide, that can be recognized by T and B cells, stimulating an immune response
Antigens are recognized by specific receptors on T and B cells.
What distinguishes innate immunity from adaptive immunity?
Innate immunity is non-specific and always active, while adaptive immunity is highly specific and has a memory response
Adaptive immunity becomes more effective with repeated exposures.
Where do T cells develop?
In the thymus
T cells are crucial for helping B cells and killing infected cells.
What is the role of B cells in the immune response?
B cells produce antibodies that bind to and neutralize pathogens
Antibodies enhance uptake by phagocytes and activate complement.
What are the primary lymphoid organs?
- Thymus
- Bone marrow
These organs provide an environment for the formation and maturation of immune cells.
What are secondary lymphoid organs responsible for?
Monitoring the contents of bodily fluids and activating the adaptive immune response
Examples include lymph nodes and the spleen.
What is lymphedema?
Swelling resulting from the accumulation of excess fluid in tissues due to damage to the lymphatic system
It highlights the importance of the lymphatic system in fluid balance.
What are lymphatic capillaries?
Blind-ended, thin-walled vessels that transport lymph, immune cells, and pathogens
They allow fluid and larger molecules to enter through overlapping endothelial cells.
How do dendritic cells function in the lymphatic system?
They bring antigens from tissues to lymph nodes and display them to T cells
Dendritic cells are essential for initiating adaptive immune responses.
What is the flow sequence of lymph?
Blood capillaries → interstitial spaces → lymphatic capillaries → lymphatic vessels → lymphatic trunks → lymphatic ducts → junction of the internal jugular and subclavian veins
This sequence illustrates how lymph is transported back to the bloodstream.
What are the two types of lymphatic vessels?
- Afferent lymphatics
- Efferent lymphatics
Afferent vessels carry lymph into lymph nodes, while efferent vessels carry lymph away.
What role do macrophages play in lymph nodes?
They capture particulate antigens, immune complexes, and pathogenic microbes from lymph
Macrophages help prevent the spread of pathogens from lymph to the bloodstream.
True or False: T cells can directly recognize free antigens.
False
T cells require antigens to be presented by Major Histocompatibility Complex (MHC) molecules.
What is the function of lymph nodes?
To filter harmful particles from lymph and provide an environment for immune cell interactions
They are crucial for generating adaptive immune responses.
Fill in the blank: Lymphatic vessels transport _______ and lipid-soluble vitamins from the intestine.
lipids
This process is important for nutrient absorption.
What is filtered by the immune system as it passes through the lymph node sinuses?
Lymph
Lymph is monitored for pathogens and other particles.
What types of cells are resident in the SCS and medullary sinuses of lymph nodes?
Macrophages
These cells capture antigens, immune complexes, and pathogens.
What is the primary function of macrophages in the lymph node?
Prevent spread of pathogens from lymph to bloodstream.
What type of connective tissue makes up the lymph node parenchyma?
Reticular connective tissue.
What do fibroblastic reticular cells produce in the lymph node?
A 3D network of reticular fibers.
Where do conduits in the lymph node terminate?
Near high endothelial venules.
What are the two key functions of the reticular network in lymph nodes?
- Provides structural support
- Allows passage of fluid while excluding large particles.
What is excluded from the conduits in the lymph node?
Large particles and molecules >70kDa.
What type of antigens can pass through the conduits?
Low molecular weight antigens.
What role do chemokines play in the lymph node?
They attract blood leukocytes into the lymph node.
How do lymph node resident dendritic cells interact with antigens?
They extend processes across the fibroblastic reticular cell layer to sample antigens.
How do T cells enter the lymph node?
Through high endothelial venules (HEV).
What happens to T cells in an inflamed lymph node?
They remain longer and scan dendritic cells for cognate antigen.
What is the role of the spleen in the immune system?
Traps and filters blood-borne antigens and microbes.
What is the primary role of the thymus?
Maturation of T lymphocytes.
What happens to immature T lymphocytes in the thymus?
They generate unique T cell antigen receptors.
What is the significance of deleting T cells that recognize self antigens in the thymus?
Prevents autoimmune disease.
What imaging technique indicated abnormal lymphatic flow in the case study?
Lymphangiography.
What symptom did John present with in the case study?
Persistent cough and shortness of breath.
What was revealed by John’s chest X-ray?
Areas of opacity in the right lung.
Fill in the blank: The lymphatic system contributes to _______ and immune function in the body.
[fluid balance]
