Immunity and reproduction Flashcards
Outline the innate/non-specific defences
There are 2 lines of innate defence:
- Skin and mucous membranes - skin, sweat, sebaceous glands, mucous membranes, tears, saliva, gastric acid, acidic urine and normal flora (bacteria).
- Internal defences - phagocytes (neutrophils and macrophages), natural killer cells, interferons, complement proteins, inflammation and fever.
What is innate immunity?
Innate immunity refers to a wide variety of body responses that serve to protect us against invasion of a wide variety of pathogens and their toxins.
We are born with this kind of immunity.
List the different types of white blood cells and state their functions.
> Neutrophils - short-lived cells that phagocytose bacteria.
> Lymphocytes (T & B) - mostly found in lymphoid tissues - part of the specific immune response
> Monocytes (become macrophages in tissues) - less abundant than neutrophils but longer-lived
> Eosinophils - attack parasitic worms, involved in allergy & asthma
> Basophils - release histamine & heparin, involved in inflammatory response, not phagocytic
State 4 signs & symptoms of inflammation and describe the reasons for these symptoms
- Redness - due to vasodilation and increased blood supply to the area.
- Swelling - due to increased vascular permeability and accumulation of exudate (mass of cells and fluid that have seeped out of the blood vessels or organ)
- Heat - due to increased blood supply to the area.
- Pain - due to increased pressure on nerve endings from swelling and the prostaglandins which also trigger inflammation which activate sensory/pain neurones.
- Loss of function - sometimes described as the 5th symptom but is variable depending on the cause.
Define adaptive/specific immunity
Adaptive immunity is the ability of the body to defend itself against specific invading agents.
What is an antigen?
Antigens are substances recognised as foreign that provoke immune responses.
Usually a protein displayed on the surface of any cell or surface of a virus, but may also be located inside a cell.
Antigens are targeted by our adaptive immune system.
Describe the specific immune cells that recognise and remember specific antigens
Helper T cells recognise a specific antigen which is often ‘presented’
.
Cytotoxic T cells – stimulated by cytokines, recognise foreign antigens, kill virally infected & foreign cells.
What are the 2 types of adaptive immunity?
- Cell-mediated
2. Antibody-mediated
List all the specific immune cells and their functions.
> B lymphocytes become plasma cells which produce antibodies (humoral immunity) - directed against specific antigens in body fluids.
> T lymphocytes – for cell-mediated immunity, directed against intracellular antigens (e.g. antigens on viruses).
- T Helper cells control humoral immune response of B cells, produce interleukins and promote cell multiplication. - T Cytotoxic cells are effector cells of cell mediated immunity, release lethal lytic chemicals that kill cells on contact. - T Suppressor cells damp down the immune response.
Outline the timeline associated with the specific immune system’s first exposure to an antigen
The primary immune response follows the first exposure to an antigen. It is a slow response that takes about 2 weeks.
- Small quantities of large multivalent IgM antibodies are typically produced.
What are IgM antibodies?
The largest antibody and the first to arrive on the scene after initial exposure to antigen.
Produced in the spleen
What are IgG antibodies?
The most common type of antibody in the circulation. Created and released by plasma B cells, each has two antigen binding sites.
They protect the body from infections in a few ways:
> IgG-mediated binding of pathogens causes their immobilisation and binding together viaagglutination
> IgG coating of pathogen surfaces allows their recognition and ingestion byphagocytic immune cellsleading to the elimination of the pathogen itself
> IgG activates theclassical pathwayof thecomplement system - a cascade of immune protein production that results in pathogen elimination
> IgG also binds andneutralisestoxins
Describe how the specific immune system responds to the second and all subsequent exposures to the same antigen?
The secondary immune response occurs on the second and all subsequent exposures to the same antigen.
It is rapid and efficient, with specialised memory B and T cells becoming activated and generating large quantities of antibodies of the IgG type within 2-3 days of re-exposure.
State how antibodies (immunoglobins) work
The primary role of antibodies is to remove or inactivate the specific antigens by agglutination or clumping.
Explain the differences between active and passive immunity
Active immunity:
>Long lasting immunity
>Memory cells and antibodies are produced (naturally by infection, or by vaccination) and maintained in a latent state
Passive immunity:
>Acquired by the transfer of antibodies from an immune person to a non-immune person
>Short lived as no memory cells develop and antibodies break down with time
>Antibodies are passed to infant via colostrum, and some via placenta
