4.1.5- Secondary Non Specific Defences

Question 1

What is a neutrophil?

Answer 1

A type of WBC that engulfs foreign matter and traps it in a large vacuole (phagosome) that fused with lysosomes to engulf the foreign matter.

Question 2

What is an opsonin?

Answer 2

Proteins that bind to the antigen on a pathogen and then allows the phagocytes to bind to the pathogen.

Question 3

What is an antigen presenting cell?

Answer 3

A cell that isolated the antigen from a pathogen and places it on the plasma membrane so that it an be recognised by other cells in the immune system.

Question 4

Define what clonal selection?

Answer 4

Selection of a specific B or T cell that is specific to the antigen.

Question 5

What are secondary responses?

Answer 5

They are used to combat pathogens that entered the body already.

Question 6

An _______ is on the surface of a pathogen.

Answer 6

Antigen.

Question 7

When a pathogen enters a body, how is it recognised?

Answer 7

By the antigen (chemical markers) on its membrane.

Question 8

Antigens are…

Answer 8

Specific to the organism.

Question 9

Opsonins are a type of _________.

Answer 9

Antibody.

Question 10

What is the role of an opsonin?

Answer 10

They enhance the ability of the phagocyte to bind to and engulf the pathogen.

Question 11

What is the first line of secondary defence?

Answer 11

Phagocytosis.

Question 12

What is the most common type of phagocyte for phagocytosis?

Answer 12

Neutrophils

Question 13

Neutrophils are manufactured where?

Answer 13

In the bone marrow.

Question 14

What type of nucleus does a neutrophil have?

Answer 14

Multi lobed nucleus.

Question 15

What happens to phagocytes after they engulf a few pathogens?

Answer 15

They die and may collect in an area of infection to form pus.

Question 16

Briefly explain the whole process of phagocytosis.

Answer 16

The neutrophil binds to the opsonin that’s attached to the antigen on the pathogen and the pathogen is engulfed by endocytosis- forming a phagosome. Lysosomes fuse to the phagosome and release hydrolytic enzymes into it and the pathogen is digested. After this, the harmless waste products are absorbed into the cell.

Question 17

List six ways in which phagocytes are specialised for their function.

Answer 17

• many lysosomes w/lysin
• many mitochondria- release energy glucose
• ribosomes- synthesise enzymes needed
• lobed nucleus- can squeeze through narrow gaps
• plasma memb receptors that bind to opsonin or specific pathogen
• well developed cytoskeleton- cell can change shape to engulf pathogen and move organelles around in cell

Question 18

What are macrophages?

Answer 18

Larger cells that are manufactured in the bone marrow and travel in the blood as monocytes m before settling in body tissues.

Question 19

Macrophages and neutrophils are produced where?

Answer 19

In the bone marrow.

Question 20

Macrophages travel in the blood as ____________.

Answer 20

Monocytes.

Question 21

Explain how a macrophage and a pathogen interact.

Answer 21

The macrophage partially digests the pathogen and a special protein complex is formed on the surface of the cell and the macrophage comes an antigen presenting cell.

Question 22

What advantage does the special protein complex of the macrophage have?

Answer 22

It ensures the APC (macrophage) is not mistaken for a foreign cell and is attachments by other phagocytes.

Question 23

What is a cytokine?

Answer 23

A hormone like molecule that is used in cell signalling to stimulate the specific immune response.