vertebrate immune systems

who has an innate immune system

all animals

who has an acquired or adaptive immune system

all vertebrate animals

what are the two major parts of an innate immune system

the barrier to entry and the inflammatory response

what does the barrier to entry in the innate immune system do

prevent pathogens from contacting cells and tissues that they can infectw

what does the inflammatory response do

marks and destroys invading pathogens that are able to breach the barriers to entry, often through a wound.

what are the entry ways to your body (nose, mouth, eyes etc) protected by

they are protected by dense mats of hair or cilia, antibiotic-containing liquids like tears and nasal secretions, and sticky wax or mucous or saliva.

what do cilia and saliva help you do in terms of pathogens

Cilia and saliva help you cough pathogens out or swallow them, so they can be digested in the acidic environment of the stomach.

what do hair and mucous do in terms of pathogens and what follows it

it helps you trap the pathogens  and the protein called lysozyme that is found in tears and nasal secretions can kill them outright

what is one the skins major functions

to prevent pathogen entry.  Its surface comprises tightly bound cells with a dry, acidic surface that is not conducive to bacterial growth.

what is lysozyme

an enzyme that breaks bonds in the structural carbohydrate called peptidoglycan.

why is lysozyme so effective in breaking down pathogens

because it breaks down peptidoglycan and peptidoglycan is abundant in bacterial cell walls, but is not found in other organisms or in viruses. Thus lysozyme harms the bacteria without harming host cells

what are leukocytes

white blood cells

what are the leukocytes that act as a primary agent of the innate immune response and play a role in the inflammatory response

macrophages, mast cells at the cite of the wound, mast cells located near blood vessels, and neutrophils

where are macrophages located and what do they do during the inflammatory response

location: in the skin at the wound site

function: patrol tissues throughout the body and can crawl by extending their cell membrane and cytoplasm. When a wound occurs, macrophages in the skin secrete signaling molecules that act like a siren blast, alerting nearby cells to the danger. they later recognize and engulf invading. bacteria

what do mast cells located at the site of the wound do during the inflammatory response

 secrete compounds that constrict blood vessels and reduce blood loss.

what do mast cells located near blood vessels do during the inflammatory response

secrete compounds that make blood vessels in the area expand and become more permeable.
 

where are neutrophils located during the inflammatory response

located in blood that is circulating past the wound site, then migrate to site of infection by crawling towards signals

what do neutrophils do during the inflammatory response

recognize invading bacteria and engulf them

Why does the LPS-recognition-then-destruction system work well as a defense mechanism?

lipopolysaccharides (LPS) do not exist on self cells

what compound do many bacteria have that the innate immune system uses to identify them

lipopolysaccharides (LPS)

what are the two ways the innate immune system responds to lipopolysaccharides

Some leukocytes have membrane proteins that stick directly to the LPS on bacteria and create cell-cell contact that triggers destruction of the bacterial cell. Other innate system cells produce and secrete proteins that bind to LPS and thus mark them for destruction by neutrophils.

when does the acquired immune system spring into action

when a pathogen breaches the body’s innate defenses and begins multiplying

if the adaptive immune system is able to recognize the invader what two things do the cells in this system do

• They secrete proteins that bind to the invader and mark them for destruction; and
   

• They recognize cells in the body that have been infected by viruses and other types of pathogens that enter the interior of cells, then destroy the infected cell before the virus can reproduce.

what is the adaptive immune systems “mark and destroy” activity analogous too?

 to the way that proteins and cells in the innate immune system recognize and eliminate pathogens at the site of a wound. 

when does the mark and destroy response activate

when the pathogen does not enter a host cells but has gotten passed the innate immune response

what antigens activate the adaptive immune system and which activate the innate immune system

adaptive: proteins on the surfaces of virus or bacteria

innate: LPS

what is needed to match for a binding to occur

Binding occurs because the size, shape, and charge on specific R-groups in antibodies match up with the size, shape and charge on specific R-groups in antigens.

what happens once an antibody binds to en epitope on an antigen

other proteins and cells in the adaptive immune system recognize the virus particle or bacterium as non-self and destroy it.

what is the difference in how the innate system binds to antigens and how the adaptive system binds to antigens

Instead of binding in a generic way, for example to any type of lipopolysaccharide (LPS), antibodies bind to specific locations (epitopes) on specific antigens.

does the innate immune system produce antibodies

no

what kind of cell are B cells

leukocytes

what are B cells

they are adaptive immune systems antibody producing cells

B cell receptors

membrane proteins that are essentially antibodies with a stalk-like transmembrane domain that allows them to reside in the membrane of B cells,

describe the shape of the B cell receptor

it is shaped like a Y and the two tips of those Y’s can bind to the same epitope (or identical epitope) For example, a BCR that binds to an epitope on the SARS-CoV-2 spike protein would stick to two separate (and identical) virus particles at the same time.

are every B cell receptor the same?

no every B cell has a unique B cell receptor. with unique amino acid sequences at the tips

How can each B cell in your body have a unique receptor?

when a B cell begins to mature: the DNA sequences that comprise the genes for that cell's BCR protein are cut and pasted to create a new gene, meaning that they are mixed-and-matched.

The outcome of this DNA recombination sequence differs in every cell. As a result, each B cell has a unique DNA sequence that codes for its BCRs. The unique DNA sequence is transcribed to create a unique mRNA and translated to produce a unique protein. The process is called gene recombination 

what happens when a B cell binds to an antigen

it becomes activated and starts synthesizing and secreting massive numbers of antibodies—essentially, proteins that are identical to the Y-shaped region of the BCR that projects from the cell to the exterior. The antibodies produced by activated B cells are key to your body's ability to fight off infections.

what happens if a B cell does not bind to an antigen

it dies and gets recycles

what kind of cells are T cells

leukocytes

what are the two major leukocytes essential to the adaptive immune system

T cells and B cells

How are T cells similar to B cells

they both have transmembrane receptors that bind to antigens

how do B cells and T cells differ

Unlike B cells, T cells do not bind antigens directly on a pathogen. Instead, they only bind antigens that are presented on another cell. 

what do antigen presenting cells in the innate immune system do

they engulf antigens, attach them to a molecule called an MHC protein, and then transport the MHC-antigen complex to the cell surface

what happens if a T cell receptor binds to the antigen being displayed by antigen presenting cells

If a TCR binds to the antigen being displayed, the T cell is transformed into one of two types of mature, specialized cells: either a helper T cell or a cytotoxic T cell. 

what do helper T cells do

Helper T cells help activate B cells and cytotoxic T cells that respond to the same antigen. 

what has the nickname “cell poison”

cytotoxic T cells

what do cytotoxic T cells do

kill self cells that have become infected with a virus or other intracellular pathogen

what do T cells bind to

an innate self cell that has been infected and presents antigens on its surface

what makes it possible for B cells and T cells to attack one specific invader/ illness

activated B cells and T cells undergo a long and rapid series of mitoses, meaning that they clone themselves. The result is a large population of identical cells specialized for identifying and destroying a particular invader.

memory cells

specialized versions of B and T cells that stay in the body after the initial infection is cleared. this is incase the same pathogen invades the body twice

is the first or second response faster and larger?

the second response