6.3 Defence against infectious diseases Flashcards
What forms the primary defense against pathogens causing infectious diseases?
The skin and mucous membranes form the primary defense against pathogens.
How are cuts in the skin sealed to prevent infection?
Cuts in the skin are sealed by blood clotting.
What triggers the release of clotting factors?
Clotting factors are released from platelets.
Describe the cascade resulting in the conversion of fibrinogen to fibrin.
The cascade results in the rapid conversion of fibrinogen to fibrin by thrombin.
What are the causes and consequences of blood clot formation in coronary arteries?
Causes include atherosclerosis and hypertension. Consequences can be a heart attack or angina due to restricted blood flow.
How does ingestion of pathogens by phagocytic white blood cells provide immunity?
It gives non-specific immunity to diseases by destroying pathogens.
Explain how antibodies produced by lymphocytes give specific immunity.
Antibodies recognize and neutralize specific pathogens, giving specific immunity.
How do antibiotics work against bacterial infections but not eukaryotic cells?
Antibiotics block processes that occur in prokaryotic cells, but not in eukaryotic cells.
Why can’t viral diseases be treated with antibiotics?
Viruses lack a metabolism and do not respond to antibiotics.
How have some strains of bacteria evolved resistance to antibiotics?
Through genes that confer resistance, often spreading through gene exchange among bacteria.
What are the effects of HIV on the immune system and its methods of transmission?
HIV destroys T helper cells, weakening the immune system. It is transmitted via sexual intercourse, infected blood, shared needles, and from mother to child.
Outline the experiments conducted by Florey and Chain on penicillin.
They infected mice with Streptococcus and treated half with penicillin, noting that the treated mice survived, indicating penicillin’s effectiveness against bacterial infections.
