Topic 4 and 5 Flashcards
Define reactivity
This is the ability of an organism to change its actions in response to a change of activity this can be normal or pathogenic influence
Define nonspecific (Secondary/passive) reactivity
This is an innate process whereby it is universal and it is not specific to one particular etiological factor.
Examples of this to day-to-day life changes in temperature, vasodilation, tachycardia…
Examples of this -
External barriers are skin, mucous membrane, digestive and urogenital tract this contains bactericidal factors on its surface
Internal barriers prevent foreign and poisonous material from the blood into organs and tissues
Example- Capillaries, endothelium, blood-brain barrier, placental barrier, Phagocytosis. These are highly selective semipermeable
infection are a mucous membrane, phagocytic cells, enzymes in secretions and interferon
Define specific (primary) reactivity
This is acquired, as a result of the exposure to a variety of agents such as pathogens. This can only be related to immunity.
Examples of this is Cell-mediated response ( T lymphocytes) and humoral response (B lymphocytes)
naturally acquired such as the exposure to certain disease and artificially whereby the administration of vaccination
Define resistance
Resistance is dependent on the reactivity
This is the ability of the organism to overcome fully or partly pathogenic factors. This is subdivided into primary and secondary . It is further divided into passive (biological barriers) and active (formation of antibodies)
What organ systems are involved in reactivity
The nervous and endocrine system as well as the connective tissue( immune system) highlights changes surrounded the body and thus enabling an action to occur
What is the role of phagocytosis and how does it work
- Phagocytes are attracted to chemical products of pathogens or dead, damaged and abnormal cells act as attractants, causing phagocytes to move towards the pathogen
- The receptors on the pathogen attaches to the pathogens cell-surface
- Lysosomes within the phagocyte migrate towards the phagosome formed by engulfing the bacterium
- The lysosmes releases its enzyme lysozymes into the phagosome, where they hydrolyse
the bacterium - The broken down product of the pathogen are absorbed into the cytoplasm of the phagocyte.
What factors can affect Phagocytosis activity
Leukopenia= reduction of phagocyte level
Etiology= factors can be physical or chemical or ionising which affect the leukocyte formation in the bone marrow
What is the difference between T and B lymphocytes
B lymphocytes (B cells) arc so called because they mature in the bone marrow. They are associated with humoral immunity, that is, immunity involving antibodies that arc present in body fluids, or ‘humour’ such as blood plasma.
• T lymphocytes (T cells) are so called because they mature in the thymus gland. They are associated with cell-mediated immunity, that is immunity involving body cells.
Describe the pathway of T lymphocytes
l Pathogens invade body cells or are taken in by phagocytes.
2 The phagocyte places antigens from the pathogen on its cell
surface membrane.
3 Receptors on a specific helper T cell (TH cell) fit exactly onto
these antigens
.
4 This attachment activates the T cell to divide rapidly by mitosis and
form a clone of genetically identical cells.
5 The cloned T cells:
a develop into memory cells that enable a rapid response to future infections by the same pathogen
b stimulate phagocytes to engulf pathogens by phagocytosis
c stimulate B cells to divide and secrete their antibody
d activate cytotoxic T cells (Tc cells). This kills abnormal cells
Describe the process of B lymphocytes
- Helper T cells (activated in the process described in Topic 5.3) attach to the processed antigens on the B cell thereby activating the B cell.
- The B cell is now activated to divide by mitosis to give a clone of plasma cells ( Plasma cells are the primary immune response, they are secreted into the blood plasma. They secrete antibodies immediately to kill the pathogens )
- The cloned plasma cells produce and secrete the specific antibody that exactly tits the antigen on the pathogen’s surface.
- The antibody attaches to antigens on the pathogen and destroys them
- Some B cells develop into memory cells. These can respond to future infections by the same pathogen by dividing rapidly and developing into plasma cells that produce antibodies. This is the secondary immune response.
Define Monoclonal antibodies
Bacteria or other pathogens normally have different antigens on its cell surface. . So B-lymphoctes will multiply to form a specific antibody
What are the different types of immunity
Passive immunity= This is when antibodies are introduced to the person from an external source. As no memory cell are being produced this immunity will not last. An example of this is anti-venom given to the victims of snake bites and the immunity acquired by the fetus when antibodies pass across the placenta from the mother.
Active immunity= This is produced by stimulating the production of antibodies by the individual’s own immune system. Direct contact with pathogens is mandatory, immunity takes a longer time, however it last longer
There are two types of active immunity:
Natural active immunity= This is when an individual becomes infected by the pathogen i.e flu and they will not get it again
Artificial active immunity= This is in the form of a vaccination
Define immunological tolerance
This is when the immune system does not react to the antigen, this may be due to previous exposure to the antigen. Central tolerance is the main way the immune system learns to discriminate self from non-self. Peripheral tolerance is key to preventing over-reactivity of the immune system to various environmental entities (allergens, gut microbes, etc.)
Deficits in central or peripheral tolerance also cause autoimmune disease,
The blood brain barrier prevents organisms undergoing autoimmune disease
Define Immunological reactivity
This is how the organism reacts to an antigen. There are 3 subgroups:
Hypo-function= immunodeficiency and Immunodeppression
Hyperfunction= Allergy
Loss of physiological immunological tolerance= Auto allergy
Define Immunosuppression/ Immunodepression
Immunodepression are such etiological factors, which inhibit multiplication and differentiation of lymphocytes or disturb their functional activity. This is caused by radiation, mutagens, carcinogens, various toxins infectious agents (AIDS virus affects T-helper). Malnutrition conditions promoting immunodepression. Emotional stress may depress may also play a factor
