B1 Infection Defence (Innate Immunity)

Question 1

What is innate immunity?

Answer 1

Innate immunity is present from birth and includes first line and second line defences.

Question 2

Examples of physical defences

Answer 2

Skin, scabs, goblet and ciliated cells, nasal hairs and eyelashes

Question 3

How does skin act as a physical barrier?

Answer 3

Skin blocks pathogens from entering the rest of the body and bacteria protects the body from colonisation from harmful bacteria.

Question 4

How do scabs act as a physical barrier?

Answer 4

Scabs form using the body’s blood clotting pathway and stops pathogens from getting in.

Question 5

How do goblet and ciliated cells act as a physical barrier?

Answer 5

Goblet and ciliated cells trap and sweep out bacteria in the airways.

Question 6

How do nasal hairs act as a physical barrier?

Answer 6

Nasal hairs act as filters to dust and pathogens out of the air we inhale during respiration before they can enter the lungs.

Question 7

How do eyelashes act as physical barriers?

Answer 7

They trap dirt and pathogens

Question 8

Examples of chemical defences

Answer 8

Sweat, sebum, mucus, stomach acid (HCI), lysozyme, vaginal acidity, saliva, tears

Question 9

How does mucus act as a chemical barrier?

Answer 9

Muscus, which is made by goblet cells, prevents bacteria from infecting the walls of the trachea and digestive tract

Question 10

How does stomach acid act as a chemical barrier?

Answer 10

Stomach acid has a low pH to kill pathogens

Question 11

How does lysozyme act as a chemical barrier?

Answer 11

Lysozyme is able to hydrolyse bacteria cells walls and destroy microorganisms

Question 12

How do tears act as a chemical barrier?

Answer 12

Tears continuously lubricate and cleanse the eyes, they also contain lysozyme.

Question 13

How do skin secretions act as a chemical barrier?

Answer 13

Sweat + sebum make the epidermal surface acidic which inhibits bacterial growth

Question 14

How does the acidity of the vagina act as a chemical barrier?

Answer 14

Vaginal acidity inhibits the growth of bacteria and fungi in the reproductive tract

Question 15

How does saliva act as a chemical barrier?

Answer 15

Saliva lubricates and cleanses the mouth, contains lysozyme

Question 16

Describe the inflammation response

Answer 16

Inflammation is protective response by the body against something harmful. Symptoms of swelling, heat, redness and pain. Chemicals like histamines are released by mast cells and basophils as a response to an allergen. Histamines causes arterioles to dilate, and increases permeability of capillary walls which lets fluid through and makes the tissues swell. White blood cells can move in and act on antigen.

Question 17

Examples of biological defences

Answer 17

White blood cells, also known as leukocytes act as the biological defence against pathogens if they have bypassed physical and chemical barriers in place.

Question 18

What are phagocytes?

Answer 18

A type of white blood cell that engulfs and ingests pathogens, dead cells, and other foreign materials that have entered the body e.g neutrophils

Question 19

What is a macrophage?

Answer 19

Another type of phagocyte. They do antigen presentation and turn into antigen presenting cells.

Question 20

What are basophils?

Answer 20

Biological defence in the body, a white blood cell that releases histamine to an allergen, heparin to prevent unnecessary blood clotting and serotonin which makes capillary walls more leaky

Question 21

What are mast cells?

Answer 21

Biological defence, a white blood cell that releases histamine in response to an allergen

Question 22

What are eosinophils?

Answer 22

Biological defence, white blood cell that can carry out phagocytosis, specialises in the destruction of parasites, involved in counteracting the inflammation response

Question 23

What are natural killer cells?

Answer 23

Biological defence, white blood cell that detects and attacks virus infected an tumour cells. They are the first to be deployed.