The Immune System

Question 1

What is immunity ?

Answer 1

Body has a wide range of defence mechanisms against bacteria, viruses, foreign cells and parasites.
The body has a specific defence mechanism and non-specific defence mechanism

Question 2

What is non-specific defence mechanisms

Answer 2

Present when born, they are mechanism that protect the body against a white range of dangers,

Question 3

What is specific defence mechanisms

Answer 3

Targeted on specific invader.
Body learns and remembers specific antigens building a immunological memory

Question 4

What is an antigen

Answer 4

Anything that stimulates an immune response

Question 5

Name the 3 main Non- specific defence mechanisms and their roles

Answer 5

Prevents entry of microbes and other foreign materials
Epithelial barrier
Phagocytosis
The inflammatory response.

Question 6

Describe the first line-non specific defence mechanisms- epithelial barriers

Answer 6

Consists of skin and mucous membranes
Healthy skin is a barrier against pathogens
E.g nose hair: filter system to stop foreign bodies entering our respiratory tract
Cilia:moves mucus and inhaled foreign materials towards the throats so its coughed up or swallowed
Epithelial secretion: one way flow of urine from the bladder minimises the risk of infection

Question 7

Describe the 2nd line of non specific defence mechanisms phagocytosis

Answer 7

Phagocytosis is cell eating
Phagocytes migrates to the sites of inflammation and infection as they are attracted to the chemicals that are released by invading microbes
Phagocytes attacks, digests, and destroys foreign cells and may release chemicals which is toxic to the invading microbes , chemicals released alert the immune system the presences of a threat.
Two types of phagocytic cells: Neutrophils and macrophages
Neutrophils are short lived as they destroy themselves with their toxic chemicals and macrophages live longer and link the non specific defence with specific immunity

Question 8

Describe the role of the 2nd non specific defence mechanism: inflammatory response

Answer 8

It’s a physiological response to tissue damage ,
Purpose to isolate, inactivate and remove both the causing agent and damaged tissue so healing takes place
Signs of inflammation =redness, heat, swelling , pain
Inflammation helps body heal and fight problems
Inflammatory response triggered by extreme temperature, ph , trauma and foreign bodies
Increased blood flow: arterioles dilates,capillaries expand, provides more oxygen to the area.Responsible for increased temperature, swelling and redness
Pain: encourages protection
Increased core temperature: inhibit growth and division of microbes while promoting the activity of phagocytes

Question 9

Describe specific immunity

Answer 9

Occurs if non-specific defence are overwhelmed the immune system is actived
Targeted to one antigen
A memory is created of each immuno-response so if encounter again the response is faster and more powerful
Does not attack its owns cells

Question 10

How is lymphocytes linked to specific defence mechanisms

Answer 10

Lymphocytes make up 30 percent of white blood cells
Lymphocytes includes T- cells and B-cells which are both produced in the bone marrow and lymphatic tissue
T and B cells carries antigen recognition molecules allowing to respond to specific antigens
Health immune system can respond to millions of antigens

Question 11

Role of T cells in specific immunity

Answer 11

Immature T cells are produced in the bone marrow
They migrate in the thymus gland and mature under the influence of hormone where they become specialised
T cells become fully active when they encounter infective connective tissue.
Mature T cells only recognise one type of antigen
When T-cells meet their antigen for their first time they become sensitised to it.
T cells can’t recognise free antigens in body fluids must be presented with it on the membrane of another cell

Question 12

Role of B cells in specific immunity

Answer 12

Immature b-cells are produced in the bone marrow and matured in the bone marrow
They produce antibodies which are proteins that bind to and destroy antigens
Each target one antigen
Can recognises and bind to antigens directly

Question 13

What are 4 types of T-cells

Answer 13

Cytotoxic (cd8) -releases powerful toxins,destroys abnormal cells which are infected or cancerous
Helper- supports and promotes cd8 cells and stimulates b cells to produces antibodies which
Regulatory- acts as breaks turning off activated T and b cells. Limits damaging the effects of the immune response . Regulatory T cells protect the fetus in pregnancy
Memory- remember antigens they met before so they can be more stronger and powerful

Question 14

Two types are b cells

Answer 14

Memory b cells = provide long term immunity for the antigen
Plasma cells= produces the antibodies that bind to and destroy antigens Each target

Question 15

What are the 5 types of antibodies and their function

Answer 15

IgA = found in breast milk and saliva prevents antigens invading deeper tissues, some monomers in plasma
IgD = made by B cells . Antigens bind here to activate B-cells ,always attached to b-cells
IgE = this antibody is found in access in allergy , secreted by plasma in skin and tonsils
IgG= largest longed lived and most common antibody type. Crosses the placenta to protect fetus. Effective against viruses
IgM= sign of recent invasion as they are short lived and appear first. Effective against viruses. Attached to b cells

Question 16

What is the classification of antibodies

Answer 16

They are classified according to the structure and location of their heavy chains . They have two heavy chains made of amino acids . Two light chains made from polypeptide

Question 17

Describe the complement system

Answer 17

System of about 20 proteins found in the blood and tissues . Activated by the presence of immune complexes (antigens and antibodies bound together) and by foreign sugars on bacterial cell walls.
Complements binds to and damages bacterial cell walls destroying microbes and bind to bacteria cells walls to simulate phagocytosis by neutrophils and magcrophils

Question 18

What is acquired immunity

Answer 18

The immune response to an antigen following the first exposure is called the primary response.
There is a slow delayed rise in antibodies levels. Antibodies produced is mainly IgM . Delayed response due to activating T-cells which the stimulates b cells
Antibody level falls when infection clears.
Immune system responds well= generates a population of long lived memory b cells making the individual immune to future infections.
Second expose= secondary response= due to memory b cells =faster response 10-15 times more powerful . Antigens produced is mainly IgG= more effective than IgM

Question 19

What are the 4 different types of acquired immunity

Answer 19

Active= individual responded to the antigen and produced own antibodies, lymphocytes and memory cells formed= long lasting resistance
Passive=individual given antibodies. It breaks down with time
Natural= body is stimulated to produced antibodies by disease or infection. Aquired before birth by maternal antibodies and through breast milk
Artificial = ready made anti bodies are injected to individual

Question 20

Describe anti D IMMUNOGLOBULIN

Answer 20

Mother is rhesus negative and fetus rhesus positive and their blood mixes , mother will create an immune response to foreign bodies. Theses antibodies pass through the placenta and kill fetal red blood cells and mothers
This causes fetal anaemia and other diseases to the newborn .
Anti d immunoglobulin mops up the circulating fetal red blood cells prevents mother from making access antibodies.

Question 21

Describe the lymphatic system and immunity

Answer 21

Maintains fluid balance by returning tissue fluids into the venous blood stream
Contains lymphoid structure which contains lymphocytes
Lymphoid structures includes tonsils thymus and bone marrows , spleen
Cancer may travel to over parts of the body via lymphatic system

Question 22

What are the three Lymphoid tissues

Answer 22

Tonsils: located in protective ring under mucous in mouth at the back of the throat . Ring protects against bacteria that may invade tissues .
Thymus : immature lymphocytes are matured in fetal thymus. It secretes hormones to help it develop into mature T cells
Spleen: as blood passes through the vessel of spleen, macrophages removes microorganisms from the blood and destroys them by phagocytosis.