Chapter 8: The Immune System Flashcards
________ immunity is composed of defenses that are always active against infection, but lack the ability to target specific invaders.
innate
Innate immunity is also known as ____________ immunity.
nonspecific
____________ or ____________ immunity refers to the defenses that target a specific pathogen.
adaptive, specific
Which type of immunity is slower to act but maintains immunological memory to mount a faster attack in subsequent infections?
Adaptive immunity
What produces all of the leukocytes? What is this process called?
bone marrow; hematopoiesis
The spleen is a location of blood storage and activation of ____-________, which turn into ____________ cells to produce antibodies as part of adaptive immunity.
B-cells; plasma
When B-cells leave the bone marrow, they are considered mature but naive. Why?
They have not yet been exposed to an antigen.
Because B-cells dissolve and act in the blood (rather than within cells), this division of adaptive immunity is called ____________ immunity.
humoral
____-________, another class of adaptive immune cells, mature in the thymus, a small gland just in front of the pericardium, the sac that protects the heart.
T-cells
T-cells are the agents of ________-____________ immunity, because they coordinate the immune system and directly kill virally infected cells.
cell-mediated
________ ________, a major component of the lymphatic system, provide a place for immune cells to communicate and mount an attack. B-cells can be activated here as well.
lymph nodes
____-________ ________ tissue, which are found in close proximity to the digestive system, can be a site of potential invasion by pathogens. This could include the ________ and ____________ in the head, ________ ________ in the small intestine, and lymphoid aggregates in the ____________.
gut-associated lymphoid tissue (GALT); tonsils/adenoids, Peyer’s patches, appendix
________ ________ is the site of immune cell production.
Bone marrow
The ________ is the site of T-cell maturation.
thymus
The ________ acts as a storage area for WBCs and platelets, a recycling center for RBCs, and a filter of blood and lymph for the immune system.
spleen
Granulocytes and agranulocystes are the 2 groups of leukocytes. What is their precursor?
hematopoietic stem cells
What are the 3 types of granulocytes?
- neutrophils
- eosinophils
- basophils
What are the 2 types of leukocytes?
granulocytes and agranulocytes
Agranulocytes include the ____________, which are responsible for antibody production, immune system modulation, and targeted killing of infected cells, as well as ____________, which are phagocytic cells in the bloodstream.
lymphocytes, monocytes
Monocytes become ____________ in tissues.
macrophages
What are macrophages in the CNS called?
microglia
1
What are macrophages in the skin called?
Langerhans cells
What are macrophages in bone called?
osteoclasts
The specific immune system can be divided into what two types of immunity?
humoral and cell-mediated immunity
What drives humoral immunity? Cell-mediated immunity?
B-cells and antibodies; T-cells
What is innate immunity also known as?
nonspecific immune response
What is adaptive immunity known as ?
specific immune response
The ____________ system consists of a number of proteins in the blood that act as a nonspecific defense against bacteria.
complement
Complement can be activated through what 2 pathways?
classical or alternative
What is the classical pathway for the complement system?
Requires the binding of an antibody to a pathogen
What is the alternative pathway to the complement system?
does not require antibodies; punches holes in bacterial cell walls
Cells that have been infected with viruses also produce ____________, which are proteins that prevent viral replication and dispersion.
interferons
Interferons upregulate which molecules? What does this cause?
MHC class I and class II molecules; results in increased antigen presentation and better detection of the infected cells by the immune system
What do interferons do to nearby cells?
Cause them to decrease production of both viral and cellular proteins; decreases permeability
What is responsible for many flu-like symptoms during viral infection?
interferons
Where are macrophages derived from?
blood-borne monocytes
Macrophages can become a ____________ population within a tissue.
resident
When a bacterial invader enters a tissue, the macrophages become activated. What 3 things does an activated macrophage do?
- Phagocytizes the invader
- Digests the invader with enzymes
- Presents pieces of the invader (mostly peptides) to other cells
What protein does a macrophage use to present the invader to other cells?
It uses the major histocompatibility complex (MHC).
MHC binds to a pathogenic peptide, known as an ____________, and carries it to the cell surface, where it can be recognized by cells of the adaptive immune system.
antigen
Macrophages also release ____________, which are chemical substances that stimulate inflammation and recruit additional immune cells to the area.
cytokines
All nucleated cells in the body display MHC Class ____ molecules. Any protein produced within a cell can be loaded onto MHC-I and presented on the ________ of a cell.
I; surface
The MHC-I pathway is often called the ____________ pathway because it binds antigens that come from inside the cell.
endogenous
Cells that have been invaded by intracellular pathogens can then be killed by a certain group of ____-________ to prevent infection of other cells.
T-cells
MHC class ____ molecules are mainly displayed by professional ________-____________ cells like macrophages.
II; antigen-presenting
____________ pick up pathogens from the environment, process them, and then present them on ________-________ cells.
macrophages; MHC-II
An ____________ is a substance that can be targeted by an antibody.
antigen
Because these antigens originate from outside the cell, the MHC-II pathway is often called the ____________ pathway.
exogenous
Professional antigen-presenting cells include macrophages, ________ cells in the skin, some B-cells, and certain activated epithelial cells.
dendritic
Macrophages and dendritic cells also have special receptors known as ________ ____________ receptors. These are capable of recognizing molecules frequently found in pathogens.
pattern recognition
____-____ receptors are a common type of pattern recognition receptors.
toll-like
Pattern recognition receptors allow the production of appropriate ____________ to recruit the right type of immune cells.
cytokines
Some viruses cause downregulation of MHC molecules, what does this do for T-cells?
Makes it harder for them to recognize the presence of infection
____________ ____________ cells are a type of nonspecific lymphocyte that can detect the downregulation of MHC and induce apoptosis in these virally infected cells.
natural killer
____________ are the most populous leukocyte in blood and are short-lived.
neutrophils
Neutrophils are ____________, like macrophages, and target bacteria. They follow bacteria using ____________ - the movement of an organism according to chemical stimuli.
phagocytic; chemotaxis
Neutrophils can also detect bacteria once they have been ____________ (marked with an antibody from a B-cell).
opsonized
Dead neutrophil collections are responsible for the formation of ____ during an infection.
pus
____________ contain bright red-orange granules and are primarily involved in allergic reactions and invasive parasitic infections.
eosinophils
Upon activation, eosinophils release large amounts of ____________, an inflammatory mediator.
histamine
Histamine results in vasodilation and increased leakiness of blood vessels. What does that do?
Allows additional immune cells (especially macrophages and neutrophils) to move out of the bloodstream and into tissue
____________ contain large purple granules and are involved in allergic responses. They are the least populous under normal conditions.
basophils
________ cells are closely related to basophils, but have smaller granules and exist in the tissues, mucosa, and epithelium.
mast cells
What are the two divisions of the adaptive immune system?
humoral immunity and cell-mediated (cytotoxic) immunity
What are the 2 main types of lymphocytes?
B-cells and T-cells
B-cells mature in the ____________ and ________. T-cells mature in the ____________.
bone marrow and spleen; thymus
Humoral immunity involves the production of ____________, and it may take as long as ________ to become fully effective after initial infection.
antibodies; week
Antibodies are specific to the ____________ of the invading microbe. Antibodies are produced by ____-cells, which are lymphocytes that originate and mature in the bone marrow and are activated in the ________ and ________ ________.
antigen; B; spleen and lymph nodes
Antibodies are also called ________________.
immunoglobulins (Ig)
When an antibody binds to an antigen, the response depends on what?
THe location
For antibodies secreted into body fluids, what are the 3 main possibilities?
- Antibody attracts other leukocytes to phagocytize
- May cause pathogens to agglutinate to be phagocytized
- antibodies can block ability of pathogen to invade tissues (neutralize)
For cell-surface antibodies, the binding of antigen to a B-cell causes what?
Activation of the cell, resulting in its proliferation and formation of plasma and memory cells
When an antigen binds to antibodies on the surface of a mast cell, it causes ____________, releasing ____________ and causing an inflammatory allergic reaction.
degranulation; histamine
What is degranulation?
exocytosis of granule contents
Antibodies are Y-shaped molecules that are made up of two identical ________ chains and two identical ________ chains.
heavy; light
What holds heavy and light chains together?
disulfide linkages and non-covalent interactions
Each antibody has an ________-________ region at the end of which is called the ________ region (domain), at the tips of the Y.
antigen-binding; variable
Within the variable region, there are specific polypeptide sequences that will bind how many antigenic sequences?
Only one
Each B-cell undergoes ____________ of its antigen-binding region, trying to find the best match for the antigen.
hypermutation
Only those B-cells that can bind the antigen with high affinity survive, providing a mechanism for generating specificity called ________ ____________.
clonal selection
The remaining part of the antibody molecule is known as the ________ region (domain). This is where receptors are that can initiate the ____________ cascade.
constant; complement
How many different isotypes of antibodies are there?
5
Cells can change which isotype of antibody they produce when stimulated by specific cytokines in a process called what?
isotype switching
________ B-cells that have not yet been exposed to an antigen wait where for their particular antigen to come along?
naive; lymph nodes
Upon exposure to the correct antigen, a B-cell will proliferate and produce two types of daughter cells. What are they?
Plasma cells and memory B-cells
________ cells produce large amounts of antibodies, whereas ________ ____-________ stay in the lymph node, awaiting reexposure to the same antigen.
plasma; memory B
The initial activation of plasma and memory B-cells takes 7-10 days and is known as the ____________ response.
primary
Plasma cells eventually die, but the memory cells may last the lifetime of the organism. If the same microbe is encountered, the ________ cells proliferate and differentiate into plasma cells to produce specific antibodies. This is known as the ________ response.
memory; secondary
Cell-mediated immunity involves which cells?
T-cells
T-cells mature in the ________, where they undergo both positive and negative selection.
thymus
________ selection refers to allowing only the maturation of cells that can respond to the presentation of antigen on MHC (cells that cannot respond to MHC undergo apoptosis because they will not be able to respond in the periphery).
positive
____________ selection refers to causing apoptosis in cells that are self-reactive (activated by proteins produced by the organism itself).
negative
The maturation of T-cells is facilitated by ____________, a peptide hormone secreted by thymic cells.
thymosin
Once the T-cell has left the thymus, it is mature but naive. When it is exposed to antigen, it will undergo clonal selection so that only those with the highest ____________ for a given antigen proliferate.
affinity
What are the 3 types of T-cells?
- Helper T-cells
- Suppressor T-cells
- Killer (cytotoxic) T-cells
Helper T-cells are also called ________ T-cells, and they coordinate the immune response by secreting chemicals known as ____________.
CD4+; lymphokines
____________ can recruit other immune cells and increase their activity.
Lymphokines
CD4+ T-cells respond to antigens presented on ____________ molecules.
MHC-II
Cytotoxic T-cells, also called ____ T-cells, are capable of directly killing virally infected cells by injecting toxic chemicals that promote ____________ into the infected cell.
CD8+, apoptosis
CD8+ T-cells respond to antigens presented on ________ molecules.
MHC-I
Since MHC-I presents endogenous antigens, Cd8+ T-cells are most effective against what infections?
viral (and intracellular bacterial or fungal)
Suppressor or ________ T-cells also express ____, but can be differentiated from helper T-cells because they also express a protein called ________.
regulatory; CD4; Foxp3
Regulatory T-cells turn off self-reactive lymphocytes to prevent autoimmune diseases; this is called what?
self-tolerance
________ T-cells can also be generated, and they lie in wait until the next exposure to the same antigen.
memory
In bacterial (extracellular) pathogen infections, ____________ will first engulf bacteria and release inflammatory mediators.
macrophages
____________ attract inflammatory cells, which activate ________ cells and cause degranulation, which results in ____________ release and increased leakiness of the capillaries.
cytokines; mast; histamine
____________ cell leave affected tissue and travel to the nearest lymph node, where it presents the antigen to ____-________.
dendritic; B-cells
____________ cells also present the antigen to ____-cells and activate the ________ T-cells.
dendritic, T; CD4+
For virally infected cells, they present intracellualr proteins on their surface in conjunction with ________.
MHC-I
What T-cells recognize the MHC-I?
CD8+
________-________ are the proteins and carbs present on the surface of every cell of the body. They signal to immune cells that a cell is not foreign and should not be attack.
self-antigens
Part of preventing autoimmune reactions involves ____________ of T-cells that respond to self-antigens. This is called ____________ selection.
elimination; neagtive
In ________ immunity, the immune system is stimulated to produce antibodies against a specific pathogen.
active
________ immunity results from the transfer of antibodies to an individual.
passive
e.g. fetal
The lymphatic system is made up of one-way vessels that carry ________ and most join to form a large ____________ duct in the posterior chest, which then delivers fluid into the left ____________ vein near the heart.
lymph; thoracic; subclavian
________ ________ are small, bean-shaped structures along lymphatic vessels. They contain a lymphatic ________, an artery, and vein.
lymph nodes; channel
The ________ pressure of blood draws water back into the vessel at the ________ end, once ____________ pressure has decreased.
oncotic; venule; hydrostatic
Because the net pressure drawing fluid in at the venule end is slightly less than the net pressure pushing fluid out at the arterial end, a small amount of fluid remains in tissues. ________ vessels drain these tissues and return the fluid to the bloodstream.
Lymphatic
____________, small lymphatic vessels, are located at the center of each villus in the small intesetine. ________, packaged into chylomicrons by intestinal mucosal cells, enter the lacteal for transport. Lymphatic fluid carrying many chylomicrons takes on a milky white appearance and is called ________.
Lacteals; fats; chyle
Lymph nodes are a place for which cells to interact? B-cells proliferate and mature in the lymph nodes in collections called ____________ centers.
APC and lymphocytes; germinal
