Recap Questions Chapter 7a What is innate immunity? A bacteria has managed to invade a hair follicle on your face describe the process involved in destroying the resulting bacterial colony Explain the difference between primary and secondary immune responses You have been given the chicken pox vaccine is this natural or artificial immunity? (add into your answer whether it is active or passive)

Higher Human Biology Cellular Response in Defence Chapter 7b

Allergy Immune system over-reacts to harmless substance. Common allergens are: pollen (hay fever), dust, feathers, penicillin The above allergens cause an allergic reaction to people hypersensitive to them. Presence of an allergen causes the body to produce antibodies against it. In the case of hay fever the body produces antibodies against pollen. They become bound to specialised mast cells in connective tissue which then produce histamine and the common symptoms of hay fever result. Antihistamines are used to relieve the symptoms of allergies such as hay fever.

Allergy Immune system over-reacts to harmless substance. Common allergens are: pollen (hay fever), dust, feathers, penicillin In the case of hay fever the body produces antibodies against pollen. They become bound to specialised mast cells in connective tissue which then produce histamine and the common symptoms of hay fever result. Antihistamines are used to relieve the symptoms by preventing the action of histamine

Recognition of ‘self’ Human body is able to detect ‘self’ and ‘non-self’ cells. This is determined by antigenic markers on the cell membrane Non-self cells are attacked by antibodies and killer T cells This is of importance when considering people for blood transfusions and transplants

ABO Blood Grouping Four blood groups: A, B, AB and O Blood group O is the universal blood group (can be donated to anybody) Blood transfusions depend on the antigenic markers present on the red blood cells (see table for summary) Giving the wrong blood to somebody e.g. blood group A to blood group B person is extremely dangerous Anti A antibodies in blood plasma would combine with the A antigens on the red blood cells causing the blood cells to clump together (agglutinate). The clumps can block small blood vessels and cause severe pain and tissue damage.

Antigen Signature Antigenic markers on membrane: Human Leukocyte Antigen System (HLA) Controlled by 4 genes with many different alleles coding for different antigens. 8 possible antigens therefore there is a huge number of different combinations making it extremely unlikely that 2 people will have the same antigenic markers (except monozygotic twins) The HLA system is analysed when matching donors to recipients for transplants. As close a match as possible is preferred to reduce chances of rejection (caused by T-lymphocytes) Immunosuppressant drugs are prescribed to the recipient for the rest of their life. Unfortunately these drugs make the person more susceptible to other life threatening infections (e.g. pneumonia)

Autoimmunity When the body’s immune system fails and starts to attack itself i.e. fails to recognise it’s own antigenic markers Examples of autoimmune disease: -rheumatoid arthritis: cartilage is attacked and replaced by fibrous tissue making the joint stiff and painful -multiple sclerosis: immune system attacks myelin sheath surrounding nerve cells. Nerve cells no longer able to transmit nerve impulses leading to more and more disability as the disease progresses