Immuntity And Antigens

Question 1

What is a pathogen

Answer 1

A disease causing organism or virus

Question 2

What is an antigen? What does it trigger

Answer 2

A molecule recognised as ‘non self’
It triggers an immune response leading to production of an antibody

Question 3

What molecules are usually antigens

Answer 3

Protein, glycolipids or glycoproteins

Question 4

What types of cells and molecules can the immune system identify ? Give examples

Answer 4

Pathogens eg viruses, fungi or bacteria
Cells from other organisms of the same species eg organ transplants
Abnormal body cells eg tumour or virus infected cells
Toxins released by bacteria eg poisons

Question 5

What are the 2 types of defence mechanisms

Answer 5

Non specific immunity and specific immunity

Question 6

What is a non specific immune response

Answer 6

An immediate response which is the same for every pathogen

Question 7

What are some examples of a non immune response

Answer 7

Physical barriers
Phagocytosis and the inflammatory response

Question 8

What are examples of physical barriers

Answer 8

Cilia, stomach acid, skin, scabs, tears

Question 9

What is a specific immune response

Answer 9

A delayed response which is specific for each pathogen
It has a long lasting immunity

Question 10

Give examples of specific immune responses

Answer 10

Cell mediated response - T lymphocytes
Humoral response - B lymphocytes

Question 11

Describe the phagocytosis of pathogens

Answer 11

Phagocyte is attracted by chemicals and recognises foreign antigens on the pathogen
Phagocyte engulfs the pathogen by surrounding it with its cell membrane
The pathogen is then contained in the vesicle in the cytoplasm of the phagocyte
The lysosome fuses with the phagosome and releases lysozymes
Lysozymes hydrolyse and digest the pathogen

Question 12

What does phagocytosis lead to? What is this

Answer 12

Presentation of antigens
This is where antigens are displayed on the phagocyte cell surface membrane stimulating the specific immune response

Question 13

What 2 molecules on the surface identify cells

Answer 13

Glycolipids and glycoproteins

Question 14

What do the cell surface receptors recognise/identify?

Answer 14

Pathogens
Toxins
Abnormal body cells (eg cancerous cells)
Cells from other organisms of the same species (eg organ transplant)

Question 15

Define antibody

Answer 15

A foreign protein released during an immune response

Question 16

Define lymphocyte

Answer 16

A type of WBC that releases antibodies

Question 17

Define phagocytosis

Answer 17

The engulfment and breakdown of pathogens

Question 18

Describe the appearance of phagocytes

Answer 18

Lobed - so that they can move through small spaces and so they can engulf things
Can have antigens - when they become APCS

Question 19

Describe the appearance of lymphocytes

Answer 19

They have antibodies - so that they can attach to antigens

Question 20

Where do phagocytes originate from

Answer 20

Bone marrow

Question 21

Where do lymphocytes originate from

Answer 21

The thymus

Question 22

What is the function of phagocytes

Answer 22

To engulf pathogens

Question 23

What is the function of lymphocytes

Answer 23

To kill pathogens

Question 24

What are the 2 types of phagocyte

Answer 24

Neutrophils and macrophages

Question 25

What are the 2 types of lymphocyte

Answer 25

T and B lymphocytes