The Immune System Flashcards
____ is the ability to resist damage from pathogens and disease
immunity
____ immunity has both external and internal defenses and is also nonspecific
innate
___ immunity has internal defenses involving the recognition and memory of pathogens and is specific to the type of pathogen
adaptive
___ and ___ are physical barriers that function for external innate immunity
skin and mucous membranes
___ is an anti-microbial peptide released by sweat glands
dermicidin
___ contains anti-microbial fatty acids
sebum
Mucous membrane cells secrete mucus to _____
trap pathogens and debris
Skin secretions are ___ and __ to bacteria
acidic and toxic
____ have lysozymes within lacrimal fluid to damage bacterial cell walls
tears
The digestive tract has what 3 things to provide external innate immunity?
1-lysozymes in saliva
2-HCl in stomach
3- normal flora from intestines
How does the respiratory tract provide external innate immunity?
It secretes mucous which traps pathogens and has cilia in the epithelium that moves the mucus to the throat
____ is a glycoprotein within milk, saliva, tears, and nasal secretions that iron can bind to
lactoferrin
How does lactoferrin inhibit pathogen activity?
Lactoferrin binds to iron and oxidizes microbes
How does the urogenital tract provide external innate immunity? 2 ways
1-The pH of urine (~4.0) kills pathogens
2-the lactic acid within the vagina kills pathogens
What are the 2 phagocytic cells of internal innate immunity?
neutrophils and macrophages
What are the 4 (non-phagocytic) cells of internal innate immunity?
natural killer cells, basophils, eosinophils, mast cells
Hematopoiesis occurs in the ____
bone marrow
Lymphocytes are what 3 cells?
T, B, natural killer cells
Megakaryocytes supply what cells?
platelets
Which white blood cell is normally the first to arrive at the site of infection?
neutrophils
Neutrophils release chemical signals, ____ and ____, to recruit other immune cells
cytokines and chemokines
Neutrophils also release _____, which are antimicrobial peptides active against many bacteria, fungi, and viruses
alpha defensins
__ is a collection of dead neutrophils and microorganisms, dead tissue, and fluid
pus
Neutrophils release lysozymal enzymes into the _____ to kill microorganisms, but it also kills surrounding tissue
extracellular space
____ is the process where neutrophils follow chemical trial to the infection site
chemotaxis
In ____, the inflamed capillary endothelial cells develop cell adhesion molecules for neutrophils to attach (prompted by chemotaxis)
margination
Vasodilation and increased permeability of capillaries allows for _____, where neutrophils flatten and squeeze out of capillaries between endothelial cells
diapedesis
When monocytes leave the blood they become ___ or ___
macrophages or dendritic cells
Macrophages usually arrive after neutrophils and perform what function?
they phagocytose neutrophil remains, microorganisms, and fragments of the damaged tissue
What are the 3 places macrophages are normally located?
1-beneath skin and mucous membranes
2-around blood and lymphatic vessels
3-within the tonsils, lymph nodes, spleen, liver, lungs, and CNS
Macrophages release ____ (antimicrobial peptides), ___ (toxic to many bacteria), ____ (signaling molecules), ____ (actors in the inflammatory process) and ____ (induce fever)
alpha defensins; NO; interferons; complement proteins; pyrogens
____ are plasma proteins synthesized by the liver hepatocytes and monocytes/macrophages and found normally within the blood in an inactive form until they are activated
complement proteins
___ is a process that coats substances or cells to increase adherence of phagocytes
opsonization
The complement system activates MAC which does what?
MAC is a multiunit protein that attaches to a foreign cell and creates a large pore in the cell membrane to allow the free diffusion of water and solutes into and out of the cell, destroying the cell
The complement system increases the inflammatory response by stimulating ___ and ___ to release histamine
mast cells and basophils
____ causes vasodilation and increased permeability of capillaries
histamine
___ is a complement protein normally found in the blood that binds to carbohydrates in bacteria when it is activated and labels it for phagocytosis
C3b
____ are proteins released by cells during a viral infection
interferons
___ and ___ _____ are released by cells infected with virus
alpha and beta interferon
What is the autocrine function of alpha and beta interferon?
it causes the infected cell to upregulate antigen presentation
What is the paracrine function of alpha and beta interferon?
it stimulates other cells to produce antiviral proteins
How does production of antiviral proteins aid cells?
a virus can enter the cell but it can’t replicate within the cell
____ is produced by macrophages and lymphocytes to attract other macrophages and lymphocytes to site of infection
gamma interferon
___ are chemicals released by WBCs that cause a fever
pyrogens
How do pyrogens cause a fever?
Pyrogens are released by WBCs, travel to the hypothalamus, and causes hypothalamic neurons to increase the set point for body temperature
Why are mild fevers beneficial?
They inhibit the growth of some microbes by stimulating the liver and spleen to sequester zinc and iron, which bacteria need to multiply and they also increase the metabolism of immune cells
Why are high fevers (what temperature?) dangerous?
Fevers over 107 can denature proteins (104 in kids)
___ are lymphocytes that are nonspecific and part of the innate immune system. They release alpha defensins as well as cytokines and destroy infected, cancer, or foreign cells.
Natural killer cells
How do natural killer cells destroy cells?
NK cells release perforin and granzymes and bind to Fas receptors to cause apoptosis in the infected cell
Natural killer cells are especially important in killing ____
viruses
___ (in blood) and ___ (in body tissues) are similar cells that produce molecules, like histamine, that aid in the inflammatory response
basophils and mast cells
How do basophils and mast cells aid the inflammatory response (4)?
1-local vasodilation
2-local increase in vascular permeability
3- increased mucus and tear production
4-bronchiole constriction
What is the result of increased capillary permeability (2)?
1-allows WBCs, complement proteins, and clotting factors into tissue
2-swelling because plasma proteins also exit the capillary
___ reduce the inflammatory response by secreting enzymes that breakdown molecules released by basophils and mast cells
eosinophils
____ release enzymes that can kill some parasitic worms
eosinophils
What are the 4 signs of inflammation?
redness, heat (both due to vasodilation), swelling (due to the leakage of plasma proteins), and pain (from swelling and cytokines)
How does the inflammatory response begin?
macrophages and epithelial cells have TLRs that recognize specific classes of microbes and once activated, the cells release cytokines to attract the immune cells
What is the protein that forms the clots?
fibrin
Leaked clotting proteins from interstitial clots do wall off an area of inflammation in order to____
prevent injury to surrounding tissue
lymphatic tissue houses ___
immune cells
lymphatic tissue is composed of ___ secreted by reticular cells
reticular tissue
Reticular cells produce reticular fibers, which are ___, where other lymphatic cells attach and form a network that filters lymph or blood and traps pathogens or dysfunctional red blood cells
fine collagen fibers
____ is found throughout the body and within lymphoid organs and contains dispersed immune and reticular cells
diffuse lymphatic tissue
____ are large groups of lymphatic nodules and diffuse lymphatic tissue located deep to mucous membranes within the pharynx
tonsils
___ function to protect against microorganisms and materials entering the body from the nasal and oral cavities
tonsils
____ are small structures that filter lymph before it returns to the venous system
lymph nodes
___ filter microbes and other foreign material out of the lymph
macrophages
What is the order of lymph flow through a lymph node?
afferent vessels –> subcapsular sinuses –> lymphatic nodules –> lymphatic tissue of medulla –> efferent vessels
lymphatic nodules house ___ and ___
dendritic cells and lymphocytes
Lymph capillaries are __ permeable than blood capillaries
more
The __ is the largest lymphoid organ located within the upper left abdominal cavity posterior to the stomach
spleen
The spleen filters blood and does what 2 things?
1-destroys defective RBCs
2-detects and attacks foreign substances and pathogens within the blood
The ___ bring arterial blood into the spleen from the splenic artery
trabecular arteries
Within the spleen, the ___ is lymphatic tissue, where immune cells detect and destroy pathogens
white pulp
Within the spleen, the ___ is venous sinuses
red pulp
What is the flow of blood through the spleen?
From splenic arteries, trabecular arteries bring blood into the spleen –> first into the white pulp –> then into red pulp –>through the venous sinuses and splenic cords of red pulp –> out through trabecular veins –> into splenic vein
The red pulp consists of ___ which are enlarged capillaries that drain blood into trabecular veins, and ___ which are a network of reticular fibers with reticular cells and macrophages
venous sinuses and splenic cords
The ___ is located anterior the heart and great vessels and is the site of the maturation of T lymphocytes where they learn to differentiate self cells from foreign cells
thymus
The ___ of the thymus are connective tissue sheets that extend from the capsule and separate the thymus into lobules
trabeculae
___ selection occurs in the lobule cortex
positive
___ selection occurs in the lobule medulla
negative
The lobule medulla contains ____ which are involved in the development of regulatory T cells
thymic corpuscles
In order to be considered ____, all of the receptors within the plasma membrane of an individual B cell or T cell will bind with only one type of antigen
immunocompetent
____ is when lymphocytes must learn to not attack the body’s own cells
self-tolerance
Positive selection is when lymphocytes are able to ____
recognize MHC
Negative selection is when lymphocytes don’t ____
bind to self-antigens
