Topic 6.3 - Defence against infectious disease

Question 1

Primary defence

Answer 1

Pathogens are blocked by a physical barrier: skin.

Question 2

Breaching of primary defence

Answer 2

If the primary defence against infection - the skin - is penetrated, then the body will clot the cut. This occurs through the use of fibrinogen and thrombin.

Question 3

Blood clotting

Answer 3

Can only occur if clotting factors are released in the blood. These clotting factors cause reactions that cause fibrinogen (a soluble protein) to react to form fibrin (a non-soluble protein). This reaction is catalysed by the enzyme thrombin.

Question 4

Coronary thrombosis

Answer 4

Formation of blood clots in the coronary arteries. This may cause sufficient materials to not fully reach the heart (like ATP) and fibrillation may occur - the quivering of the heartbeat that makes the pumping of blood less effective.

This is caused by smoking, obesity, high blood pressure, high blood cholesterol pressure, obesity, lack of exercise.

Question 5

HIV

Answer 5

human immunodeficiency virus - destroys helper-T-cells. Leads to long term inability to defend against pathogens,

Question 6

Antibiotics

Answer 6

Blocks processes that are found in prokaryotes but not eukaryotes: bacterial DNA replication, transcription, translation, ribosome function and cell wall formation.

Question 7

Location of antibiotics

Answer 7

Many antibiotics can be found in saprotrophic fungi. Since they decompose organic matter, it is beneficial for them to inhibit the growth of competitive bacteria.