BM1022 Immune System Flashcards Preview

SEMESTER 2 EXAMS > BM1022 Immune System > Flashcards

Flashcards in BM1022 Immune System Deck (16):

Natural barriers

Natural barrier to infectious diseases
Intact skin
Normal flora in the gastrointestinal tract
And upper respiratory tract as well as on the skin can compete with pathogens and afford some protection



White blood cells
Originate in bone marrow (can develop and mature there)


Where do leukocytes travel?

Originate in one narrow and many develop and mature there
Then migrate to peripheral tissues where some reside
Others circulate in the bloodstream and in the lymphatic system, which drains extracellular fluid and delivers them back into the blood


Examples of cells of the immune system (leukocytes)

Neutrophils (PMNs)
Mast cells
Dendritic cells
Natural killer cells
T lymphocytes (=T cells)
B lymphocytes (=B cells)
Plasma cells



Cytokines are a group of chemical substances that act as messengers within the immune system and between the immune system and other systems of the body
I.e. Cytokines are the language of the immune response
They are protein molecules that are secreted by a range of cells and allow each of these cells to communicate with each other


Cytokines such as interleukin 2 (IL-2) are important as they...

Stimulate the growth of lymphocytes


The group of cytokines known as chemokines are important as they...

Control the movement of cells throughout the body


The cytokines known as the interferons are important for...

Activating macrophages and natural killer cells


Innate immunity

Is non-specific and includes natural, mechanical, chemical and biological barriers to infection

Innate immunity is an extremely active process based around a set of receptors found on cells such as neutrophils and macrophages

These receptors recognise patterns such as sugars in the surface of bacteria as well as components of complement and antibodies that have starch to their respective antigens


Components of innate immunity

Innate immunity consists of cellular and non-cellular defences
Cellular defences include cells like phagocytes and natural killer cells (NK).
Other defences include inflammation and complement


Phagocytes and phagocytosis

Phagocytosis is a process whereby cells such as granulocytes and macrophages will destroy foreign antigens.



Natural killer cells (NK)

NK's are part of the innate lymphoid cells and are capable of destroying a variety of targets such as tumour cells, infected cells and damaged cells. VIA a complex system of receptor cells, they identify changes in the surface of abnormal cells. They insert protein molecules, called perforins, into the cells' membrane, which creates a pore, allowing the NKs to insert toxic substances into the cells and thereby killing them



Inflammation can be acute or chronic. The acute inflammatory response is a non-specific response to tissue injury (e.g. Physical damage, burns, chemical damage or infection)

The major function of inflammation is to clear the injured site of cellular debris and foreign material such as pathogens, thereby repairing the site for the healing process


The four main signs of inflammation are




The complement system is a group of plasma proteins that are present in the blood in an inactive state

When activated, for example by infection, the complement proteins enhance the inflammatory response and can destroy foreign cells (e.g) bacteria and viruses


Mucous membranes

Physical barrier
Sites of secretion of various substances that contribute to the barrier function.
For example, lysozyme in saliva, sweat, tears and other secretions breaks down cell walls of many bacteria, and the acidity of stomach secretions inhibits growth of micro organisms