Week 4 - Immune System Flashcards
What is the function of the immune system?
Target and destroy pathogens
What is a pathogen?
Microbes + viruses that cause disease
What is a non-pathogenic microbe called
Commensal microbes
What is the microbiota
Non-pathogenic microbes of the body
What is innate immunity? Name an example
Defense in ALL animals
ex: Barrier defences, NK cells
What is the chitin exoskeleton?
Innate immunity of invertebrate. Protects against intruding microorganisms
What are hemocytes?
Phagocytic cells that recognize pathogens on their cell surface.
Then hemocyte fuses with a vacuole that has enzymes in it. Then it’s exported out by exocytosis
What is an antimicrobial peptide?
Released by some hemocytes. Can poke through plasma membrane of pathogens and cause them to lyse.
What is lyse?
Contents of the cell spill out
Name the two main innate defences of invertebrates
Chitin exoskeleton, hemocytes
What do lymph vessels do?
Link body tissues with organs associated to immune system.
MAMMALS
How do lymphatic vessels work?
Blunt ends pick up the interstitial fluid AND pathogens. One-way valves move everything unidirectionally. Lymph nodes clear the fluid of pathogens and then it drains back into the circulatory system
Where does the fluid from the top right quarter of the body go
Right subclavanian vein
Where does the fluid from the top left and bottom half of the body go
Left subclavanian vein
Name primary tissues of the immune systems. Why are they primary?
Bone marrow, thymus.
This is where cells of the immune system develop and mature
Name secondary tissues of the immune system
Adenoid gland, tonsils, spleen, appendix, large intestine, peyer’s patch
Name barrier defences of vertebrates
Skin, mucus membranes of different tracts, secretions from glands
What is the mucus elevator?
In respiratory tract, beating cillia of cells move up pathogens up to the pharynx to be swallowed. This prevents pathogens from reaching the alveoli
What are TLR (toll-like receptors)?
Recognize the proteins, lipids, etc that are on the cell surface of pathogenetic microbes
What happens after TLR recognizes a pathogen?
They are phagocytized and destroyed
What does toll mean? (TLR)
Amazing
What are leukocytes?
White blood cells
Which cells are leukocytes derived from?
Stem cells in bone marrow
Name the leukocytes
Neutrophils
Monocytes
Basophils
Lymphocytes
Eosinophils
Monocytes derive into what cells?
Macrophages and dendritic cells
What are the phagocytic cells of the innate immunity? (Name)
Neutrophils and the derivitives of monocytes (macrophages and dendritic cells)
What types of cells make up lymphocytes?
B cells
T cells
NK cells
Out of the three types of lymphocytes, which are part of the innate immunity? Which are part of adaptive?
NK -> innate
B and T cells -> adaptive
What do NK cells do
Seek out and kill virus infected and cancer cells
Where do neutrophils circulate?
In the blood. Only gains access to tissues upon infection
What happens after neutrophils engulph a pathogen?
neutrophils die too
What is the important difference between neutrophils and macrophages?
Neutrophils die after they engulph a pathogen, macrophages dont. So- They can eat up more than one
Which is larger: neutrophils or macrophages? Why?
Macrophages. They have larger vacuoles to enable continued phagocytosis
What are cytokines?
Signaling molecules that cause mast cells to degranulate and release histamines.
Explain the inflammatory response
Macrophages phago a pathogen and release cytokines, which causes mast cells to release histamines. This causes blood capillaries nearby to dilate, which allows neutrophils to gain access to the infected tissues
Does blood flow increase during inflammatory response? Why/why not?
No. though the capillaries dilate, the blood is thicker because of the increase in neutrophils in the blood
Where do macrophages stay?
Dermis
Alveoli
Lymph nodes - prevents pathogens from entering the blood
Explain what dendritic cells are
Function like macrophages but interact with B and T cells to activate adaptative immunity
What cell is the link between innate and adaptive immunity?
Dendritic cells
Explain what NK cells do
Release perforin that perforates the plasma membrane of the cell. Then, granzymes go into the pores (holes from perforin) and destroy the cell from the inside.
Then macrophages and dendritic cells respond to the signals of the NK cells and clean up the debris
What are antimicrobial peptides? Name an example
Short polypeptide chains that destroy pathogens, flag them for destruction or prevent them from replicating
SALIVA
What do interferons do?
Travel by diffusion to UNinfected cells and bind to surface proteins. They trigger the production of anti-viral proteins.
When virus infects a cell like this, they are blocked from replicating
What is the compliment system?
30 proteins
Circulate in the blood plasma and perforate the membranes of pathogens. It then recruits phagocytic cells to clean up debris
Name the three things that make up chemical defence
Antimicrobial peptides
Interferons
Compliment system
Where do B cells mature?
Bone marrow
Where do T cells mature?
Thymus
What are antigens?
Proteins or polysaccharides on the surface of pathogens
What do T and B cells do
recognize and bind to specific antigens of specific pathogens
What part of the antigen do B and T cells bind to?
Epitope
What is the epitope
The binding site of B and T cells to antigen. Small cluster of amino acids or sugar molecules
Which cell destroys pathogens circulating in body cells?
T cells.
Cell- mediated immunity
Which cell destroys pathogens circulating in body fluid? What is this called
B cells
Humoral immunity
What shape is the B cell antigen receptor?
Y shaped
What shape are T cell antigen receptors
Straight, stick-like
What types of antigen do B cells attach to?
Intact antigens
What types of antigen do T cells attach to?
Antigens attached on the surface of host cells
How are the chances of self reactivity reduced?
Once T and B cells mature, they are tested for self-reactivity
Explain clonal selection
The proliferation stage
Macrophages/dendritic cells engulph a pathogen, and move the antigens to their surface. All cells in body (not rbc) have receptors on their plasma membrsne.
A helper T cell will try to fit the epitope. Once the right one is found, it secretes cytokines to trigger cloning. The helper T cell also activates the cloning of B cells that recognize the antigen
Clonal selection also produces memory B and T cells. Rapid response upon reinfection (a few days instead of 14)
Explain the proliferation of B cells (after clonal selection)
Produces two types of cells: Memory cells and effector cells
Plasma cells are effector cells. They secrete antibodies (which bind to pathogens and flag them for destruction).
What do antibodies do
Bind to viruses, flagging them for destruction. The viruses are unable to replicate or cause harm when marked by antibodies
What is opsonization?
The increased rate of phagocytosis due to antibodies
Explain cytotoxic T cells
Effector cells of T cells
They destroy virus infected body cells
Recognize antigens on
