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Animal defences against infection

30 important questions on Animal defences against infection

Which defenses has the innate immunity?

Barrier defenses and internal defenses

What kind of barrier defenses do we have?

skin, mucous membranes, secretions

What kind of internal defenses do we have?

phagocytic cells
natural killer cells
antimicrobial proteins
inflammatory response

What is the adaptive immunity?

The acquired ability to recognize and destroy a particular pathogen or its products; dependent on previous exposure to the pathogen or its products.

What is the function of antimicrobial petides and proteins?

functions in the innate defense by attacking pathogens or impeding their reproduction.

Which proteins provide innate defense?

interferon: interfering with viruses and helping activate macrophages.

How many proteins make up the complement system?

What does the proteins of the complement system?

causes lysis of invading cells and helps trigger inflammation

How works cellular innate defenses?

phagocytic cells can recognize groups of pathogens by using TLRs, toll- like receptors, that recognize fragments of molecules characteristic of a set of pathogens.

Which two main types and additional types of phagocytic cells do we have?

neutropohils : they engulf and destroy pathogens
macrophages: are found throughout the body.
dendritic cells: stimulate development of adaptive immunity
eosinophils: discharge destructive enzymes

What do the natural killer cells?

circulate through the body and detect abnormal cells.
release chemicals leading to cell death, inhibiting the spread of virally infected or cancerous cells.

How works the inflammatory response?

pathogen entering the body trough damaged cells.
Mast cells and macrophages release histamines and cytokines.
capillaries dilate.
antimicrobial peptides enter tissue and neutrophils are recruited.
neutrophils digest the pathogens and cell debris and the tissue heals.

On which two types of lymphocytes is the adaptive response rely?

Mature B-cells and Mature T-cells

How does a B-cell antigen receptor looks like?

two heavy chain and two light chain. the heavy chain is embedded in to the plasma membrane.
the chains have a constant part ( can not move) and a variable part ( that can move).
the chains are connected by disulfide bridges.
the variable region can move and bind an antigen.

What is the process antigen presentation?

in infected cells, MHC molecules bind and transport antigen fragments to the cell surface.

What are the four major characteristics of the adaptive immune system?

immense DIVERSITY of lymphocytes and receptors
SELF-TOLERANCE; lack of reactivity against an animal's own molecules.
b and t cells PROLIFERATE after activation.
immunological MEMORY.

How works the gene rearrangement?

1 DNA of undifferentiated B cell is:recombination deletes DNA between randomly selected V segment and J segment. into DNA of differentiated B-cell
2 transcription of permanently rearranged, functional gene (into pre-mRNA).
3 pre -mRNA is processed into mRNA
4 mRNA is translated into a antigen receptor.

Where are antigen exposed to a steady stream of lymphocytes until a match is made?

in the lymph nodes

What is immunological memory responsible for?

long-term protection against diseases.

What represents the primary immune response?

the first exposure to a specif antigen.
(selected B and T cells give rise to their effector forms)

How works the secondary immune response?

memory cells facilitate a faster and more efficient response.

How works the humoral immune response?

antibodies help neutralize or eliminate toxins and pathogens in the blood and lymph.

How works the cell-mediated immune response?

specialized T cells destroy affected host cells.

Which of type of cell triggers both the humoral immune response and cell-mediated immune response?

T-helper cell

What do cytotoxic T cells?

uses toxic proteins to kill cells infected by viruses or other intracellular pahtogens.

How works the killing action of a cytotoxic T cells on an infected host cell ?

1 an activated cytotoxic t cells binds to a clas I MHC-antigen fragment complex on an infected cell via its antigen receptor and an accessory protein (called CD8)
2 the T cell releases perforin molecules, which form pores in the infected cell membrane, and granzymes, enzymes that breakdowns proteins. granzymes enters the cell by endocytosis.
3 granzymes initiate apoptosis within the effected cell, leading to fragmentations of the nucleus and cytoplasm and eventuall cell death. the released cytotoxic T cell can attack other infected cells.

Which three types of antibody binding to an antigen in a pathogen.

neutralization
opsonization
activation of complement system and pore formation.

How works the activation of complement system and pore formation?

binding of antibodies to antigens on the surface of a foreign cell activates the complement system. Following activation of the complement system, the membrane attack complex forms pores in the foreign cell’s membrane, allowing water and ions to rush in. the cell swells and eventually lyses.

What is active immunity?

develops naturally a pathogen invades the body and elicits a primary or secondary immune response.

What is passive immunity?

provides immediate, short-term protection.

The question on the page originate from the summary of the following study material:

Biology: A Global Approach, Global Edition | 9781292008653 | Jane B Reece, et al

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