Chapter 21: The Lymphatic and Immune System Flashcards
What are the functions of the lymphatic system?Wh
- fluid recovery (2-4L/day)
- Immunity
- Lipid absorption (lacteals)
Where do lymphs originate from?
tissue fluid
What does a lymph look like?
like plasma, clear, colourless, but less protein. contain lymphatic capillaries
What do lymphatic vessels look like?
similar to veins, thin-walled, little muscle, but have more valves.
What is the path of flow of lymphatic vessels?
Capillaries–>Collecting vessels through lymph nodes–>6 lymphatic trunks–>2 collecting ducts
What drains the right arm, thorax, head, and into the right subclavian vein?
the right lymphatic duct
What drains all the lower body and into the left subclavian vein?
Thoracic duct
What are the different types of lymphocytes?
T cells, B cells, Natural Killer Cells (NK)
What are the different lymphatic cells?>
lymphocytes(tcells, bcells, nk), macrophages, dendritic cells, and reticular cells
What are T cells?
T Lymphoctyes (T cells)- mature lymphocytes in the thymus, and later depend on thymic hormones. T stands for thymus-dependent
What are B cells?
B lymphocytes (B cells)- lymphocytes that differentiate into plasma cells- connective tissue cells that secrete antibodies.
What are Natural Killer Cells?
large lymphocytes that attack and destroy bacteria, transplanted tissues, and host cells (cells of own body) that have either become infected with viruses or turned cancerous.
What are dendritic cells?
macrophage-like cells localized in the tissue and lymph organs
What are reticular cells?
framework of the lymph organs
What are the 2 main types of lymphatic tissues?
- Diffuse lymphatic tissue- scattered lymphatic cells in passages that are open to the exterior
- Lymphatic nodule tissues- clumps of lymphocytes, transient
What are the different types of lymphatic organs?
red bone marrow, thymus, lymph nodes, tonsils, and the spleen.
What does red bone marrow produce?
lymphocytes and all other formed elements
What lymphatic organ is larger in children than adults?
thymus
The cortex of the thymus is the site of what?
site of lymphocyte maturation
The reticular epithelial cells of the thymus create what and why?
create blood thymus barrier to isolate cortex
What do lymph nodes do?
- cleanses lymph
- signal immune system about pathogens
What do afferent and efferent lymphatic vessels do?
afferent vessels move blood in
efferent vessels move blood out
Where are lymph nodes most concentrated?
groin, axillary, and cervical areas
What is considered the ‘guard entry to pharynx’?
tonsils
The deep tonsillar crypts surrounded by what?
lymphatic capsules
Where and how many tonsils are there?
1 pharyngeal, 2 palatine and numerous lingual
What is red and white pulp in the spleen full of?
red pulp- sinuses full of erythrocytes
white pulp- full of leukocytes
What are the functions of spleen?
- erythrocyte graveyard
- erythropoiesis in fetus and children
- cleanse blood
What are the different types of nonspecific resistance?
- external barrier
- leukocytes and macrophages
- antimicrobial proteins
- immune surveillance
- fever
- inflammation
What are the external barriers of nonspecific resistance?
skin and mucous membranes
How do neutrophils kill bacteria?
through digestion, phagocytosis and respiratory bursts
What eosinophils in the mucous membranes destroys what?
parasites and allergens
What do eosinophils phagocytize and why?
Antigen-antibody complexes to limit the action of histamine
What do eosinophils in the mucous membrane stimulate?
basophils and mast cells to release chemicals (heparin)
What do basophils secrete?
histamine (vasodilator) and heparin (anticoagulant)
What is the percentage of each of the different lymphocytes?
t cells (80%), b cells (15%) and NK (5%) involved in specific immunity and immune surveillance
What are the different types of antimicrobial proteins?
interferons and complement proteins
What do interferons secrete and why?
secrete from host cells infected with virus to:
- attract NK cells and macrophages that will kill the infected cell
- alert other cells about potential viral attack
- inhibit viral replication
What are complement proteins activated by?
-Classical Pathways and alternative pathways(bind directly to a pathogen)
What are the actions of complement proteins?
- Inflammation- CPs activate mast cells and histamine
- Immune clearance-CPs bind Ab-Ag complexes to RBC to go to spleen
- Phagocytosis-CPs mark pathogens to macrophages
- Cytolysis (leaky hole)-CPs form membrane attack complex that forms a hole
NK are the immune surveillance. They patrol the body and attack host cells that are what?
- infected with viruses
- precancerous cells
- cells of transplanted organs/ tissue, etc
- bacteria
NK cells bind to enemy cells and release what? what does this cause?
Releases perforins and granzymes (destroy cellular enzymes) –> death of enemy cells
What are the benefits of a fever?
- promotes interferon secretion
- increases metabolic rate and accelerate tissue repair
- inhibits reproduction of bacteria and viruses
How does a fever occur?
macrophages and neutrophils secrete pyrogens (eg. interleuki-1) –>acts on HYP–> increases temp set point
What is cytokine?
general term for any molecule secreted by one cell to communicate with another
Specific immunity is characterized by what?
specificity and memory of pathogens
What are the different forms of immunity?
-Cellular (cell-mediated) vs.
Humoral (antibody-mediated) AND
-Active (body makes its own antibodies) vs.
Passive (antibodies from outside the body) AND
-Natural vs.
Artificial (injected)
Explain Natural Active immunity.
Ag enters the body naturally;
body develops own Ab and memory cells
Explain Artificial Active immunity.
Ag (antigen) enters the body artificially;
body develops own Ab and memory cells
Explain Natural Passive immunity.
Ab enters the body naturally
eg. breast feeding, placenta
Explain Artificial Passive immunity.
Ab enters the body artificially
eg. anti-venom, rabies vaccine
What are antigens?
(Ag) any molecule that triggers an immune response
Where are t cells made and where do they mature?
born in red bone marrow and mature in the thymus
What happens to T cells that react to themselves?
they die= clonal deletion
Which cells are involved in cellular immunity?
- Cytotoxic T cells (T^c or CD8)= KILL
- Helper T cells (T^h or CD4)= HELP
- Regulatory T cells= BRAKE
- Memory T cells (T^m) from T^c cells
What are the 3 stages of both cellular and humoral immunity?
- recognition
- attack
- memory
What are the 4 mechanisms of the attack stage of humoral immunity>?
- Neutralization- active site of pathogen in covered
- Complement fixation
- inflammation
- immune clearance
- phagocytosis
- cytosis - Aggutination- of Ag-Ab complex
- Precipitation- Ag forms an insoluble globule phagocytized by eosinophils
What is the difference between primary and secondary responses of the memory stage of humoral immunity?
primary- slow to peak (15 days) and not very strong (low Ab titer)
Secondary-faster (3 days) and stronger response
