Theme 4 - Blood and Immunity - Lecture 1

Question 1

Disease-causing organisms

Answer 1

• There are many millions of bacteria, fungi and viruses but relatively few are pathogenic.
• I.e. relatively few can evade the immune system and cause diseases.
• Mostly our immune system reacts so quickly that we are not aware of the attack.

Question 2

What do we need protection from?

Answer 2

1. Bacteria
2. Virus
3. Fungi
4. Parasites
5. Wide variety of pathogens (cancer)

Question 3

What are the immune cells stationed to detect microbial invasion equipped with?

Answer 3

Pattern Recognition Receptors (PRR)

Question 4

What are the immune cells with PRR part of?

Answer 4

The innate immune system (a rapid response)

Question 5

What is PAMPS?

Answer 5

PAMPS are characteristic of common microbes

• Bacterial and fungal cell wall components
• Viral and bacterial RNA and DNA

Question 6

What do immune cells with PRR include?

Answer 6

• Phagocytes such as neutrophils and macrophages

- Dendtritic cells

Question 7

What is Phagocytosis?

Answer 7

The ingestion of bacteria or other material by phagocytes.

Cells capable of phagocytosis are called phagocytes

Question 8

What is pus?

Answer 8

Dead neutrophils and pathogens

Question 9

Describe the killing mechanism

Answer 9

Neutrophils can eliminate pathogens by intracellular and extracellular ways. Neutrophils encounter microorganisms, they phagocytose them. After they are encapsulated in phagosomes, the cells kill the pathogens using toxic enzymes and proteins. The antibacterial proteins are released from the neutrophil granules either into phagosomes or into the extracellular milieu.

Neutrophils can also set extracellular traps called NETs. They are composed of core DNA elements to which histones, proteins and enzymes that are released from neutrophil granules are attached. NETs immobilize pathogens, thus preventing them from spreading .

Question 10

What are the cells of the Adaptive Immune System?

Answer 10

B and T lymphocytes

Question 11

Function of antibodies

Answer 11

Antibodies attach onto pathogens so that they are picked up and destroyed by other parts of the immune system

Question 12

Describe the Antigen cycle

Answer 12

1. A phagocyte “eats” a bacteria
2. Parts of the bacteria (antigen) goes to the surface of the phagocyte
3. The phagocyte presents the antigen to a helper T cell
4. Activates the T cell

Question 13

What are Effector T cells?

Answer 13

• Helper T cells produce different types of mediator (cytokine) to suit the threat
• Cytotoxic T cells can kill virus-infected cells or tumour cells

Question 14

What are cytokines?

Answer 14

• Are the communication mechanism for cells of the immune system
• Secreted mediators which act locally or at a distance
• Secreted by many cell types especially cells of the immune system to stimulate and shape immune responses
• Secreted in response to microbes or other cytokines
• Powerful molecules, act at nanomolar levels

Question 15

Describe septic shock

Answer 15

• Severe infection by some bacteria (and fungi) in which viable microbes or microbial products present in the blood
• Septic shock is a severe and frequently fatal form of sepsis

Question 16

What is septic shock characterised by?

Answer 16

• The collapse of blood vessels
• Widespread blood clotting
• Metabolic disturbance
• Can lead to multiple organ failure

Question 17

Hypersensitivity to environmental antigens

Answer 17

• Reaction to harmless environmental substances

- Allergic diseases such as asthma, eczema, house dust, pollen, insect stings, etc

Question 18

What is allergy?

Answer 18

• Innate cells designed to respond rapidly to infection (especially to parasites) are triggered by allergen to release mediators, e.g. Histamine causes sneezing and itching