Chapter 7

Question 1

What are the 7 natural barriers of the body?

Answer 1

• Skin
• Mucosal Secretions
• Mucus
• Gastric Juices
• Vaginal secretions and semen
• Sweat
• Non-pathogenic bacteria

Question 2

Signs of Inflammation / Inflammatory Response

Answer 2

• Redness
• Swelling
• Heat
• Pain

Question 3

Define cytokines and their role

Answer 3

Cytokines are chemical messengers/small soluble molecules that act on different target cells and have local and systemic effects.

Question 4

What are the effects of cytokines?

Answer 4

Cytokines induce local enlargement of the blood vessels’ diameter, leading to an increase in blood flow to the inflammation site.

Cytokines also induce an increase in vascular permeability and leakage of plasma from blood vessels to the surrounding inflamed tissue.

Question 5

Explain Diapedesis in cytokines

Answer 5

Leukocytes mainly phagocytes cross the permeable blood vessels and migrate into the inflamed tissue

Question 6

Explain the steps of phagocytosis

Answer 6

1- Adhesion: The phagocyte adheres to the bacterium.
2- Absorption: The phagocyte absorbs it
3- Digestion: The phagocyte digests it and forms a phagosome

Question 7

State 3 cases of phagocytosis

Answer 7

1st Case: Bacterial wastes are rejected.
2nd case: The bacterium stays intact, it can later multiply.
3rd case: The granulocyte dies

Question 8

Reasons for cases 2 and 3 in phagocytosis

Answer 8

Enzymatic deficiency or resistant bacterium

Question 9

How long does a specific immune response take to form

Answer 9

one or two weeks following contact with a foreign body

Question 10

Describe what happens when a macrophage phagocytoses a cell

Answer 10

The resulting peptides are attached to HLA classes II molecules and presented on the cell surface.

Then, the macrophage migrates to the closest lymph node, where it becomes an antigen-presenting cell (APC)

TH cells circulate continuously between lymph nodes, inspecting APCs’ HLA-peptide complexes.

Only TH cells specific to the peptides presented by the APC remain attached to it. They are then activated and they proliferate. The others leave the lymph node and recirculate.

Question 11

Explain Clonal selection

Answer 11

Activated TH proliferates and gives rise to a clone made of a large number of daughter cells, all identical to mother cells

Question 12

two different kinds of clones and their lifespan

Answer 12

memory cells that survive for many years.
interleukine-secreting cells that survive for only a few years