Explain how the immune system responds after primary exposure to a pathogen

Explain how the immune system responds after primary exposure to a pathogen, including innate and acquired immunity

Innate Immune Response:

Inflammation is one of the first responses of the immune system to infection or irritation which is stimulated by chemical factors released by injured cells and serves to establish a physical barrier against the spread of infection, and to promote healing of any damaged tissue following the clearance of pathogens.
The process of acute inflammation is initiated by cells already present in all tissues, mainly resident macrophages, dendritic cells, histiocytes, Kupffer cells, and mast cells.
Neutrophils can trigger other parts of the immune system by releasing factors that summon additional leukocytes and lymphocytes.
The complement system includes several biochemical reactions occurring consecutively and linked to one another which specifically cause death of pathogenic cells.
The cascade is composed of many plasma proteins, synthesized in the liver, primarily by hepatocytes. The functions of proteins include:
- Triggering the recruitment of inflammatory cells
- Selecting pathogens for destruction by other cells by opsonizing, or coating, the surface of the pathogen
- Form holes in the plasma membrane of the pathogen, resulting in cytolysis of the pathogen cell, causing the death of the pathogen
- Remove the “corpse” of neutralised antigen-antibody complexes

Adaptive Immune Response:

Usually triggered when a host has been invaded by a type of pathogen that has attacked before.
Immunological memory plays a vital role here because the cells that remember the pathogen’s earlier attack know possible ways to trigger chain reactions that can excavate the pathogen and reduce its harmful effects.
At first antigen processing occurs where the antigens are enzymatically cleaved into smaller pieces.
T cells that have receptors specific to that antigen bind with the antigens. They can either kill the target cells or regulate the immunological activity and development of a variety of cells, including macrophages and other types of T cells.
B Cells are the major cells involved in the creation of antibodies that circulate in blood plasma and lymph, known as humoral immunity. Similar to T cells, B cells are also antigen specific.
The functions of antibodies include;
- IgM functions in eliminating pathogens in the early stages of B cell-mediated (humoral) immunity.
- IgG can clear pathogens from the blood and can activate complement proteins and is the only antibody capable of crossing the placenta to give passive immunity to the fetus.
- IgA can protect body surfaces and prevents colonization by pathogens.
- IgE protects against parasitic worms.
- IgD functions mainly as an antigen receptor on B cells that have not been exposed to antigens.

EasyBio > Infectious Disease > Immunity > Explain how the immune system responds after primary exposure to a pathogen

Explain how the immune system responds after primary exposure to a pathogen, including innate and acquired immunity

Innate Immune Response:

Inflammation is one of the first responses of the immune system to infection or irritation which is stimulated by chemical factors released by injured cells and serves to establish a physical barrier against the spread of infection, and to promote healing of any damaged tissue following the clearance of pathogens.
The process of acute inflammation is initiated by cells already present in all tissues, mainly resident macrophages, dendritic cells, histiocytes, Kupffer cells, and mast cells.
Neutrophils can trigger other parts of the immune system by releasing factors that summon additional leukocytes and lymphocytes.
The complement system includes several biochemical reactions occurring consecutively and linked to one another which specifically cause death of pathogenic cells.
The cascade is composed of many plasma proteins, synthesized in the liver, primarily by hepatocytes. The functions of proteins include:

Triggering the recruitment of inflammatory cells
Selecting pathogens for destruction by other cells by opsonizing, or coating, the surface of the pathogen
Form holes in the plasma membrane of the pathogen, resulting in cytolysis of the pathogen cell, causing the death of the pathogen
Remove the “corpse” of neutralised antigen-antibody complexes

Adaptive Immune Response:

Usually triggered when a host has been invaded by a type of pathogen that has attacked before.
Immunological memory plays a vital role here because the cells that remember the pathogen’s earlier attack know possible ways to trigger chain reactions that can excavate the pathogen and reduce its harmful effects.
At first antigen processing occurs where the antigens are enzymatically cleaved into smaller pieces.
T cells that have receptors specific to that antigen bind with the antigens. They can either kill the target cells or regulate the immunological activity and development of a variety of cells, including macrophages and other types of T cells.
B Cells are the major cells involved in the creation of antibodies that circulate in blood plasma and lymph, known as humoral immunity. Similar to T cells, B cells are also antigen specific.
The functions of antibodies include;

IgM functions in eliminating pathogens in the early stages of B cell-mediated (humoral) immunity.
IgG can clear pathogens from the blood and can activate complement proteins and is the only antibody capable of crossing the placenta to give passive immunity to the fetus.
IgA can protect body surfaces and prevents colonization by pathogens.
IgE protects against parasitic worms.
IgD functions mainly as an antigen receptor on B cells that have not been exposed to antigens.