6.3: Defence against infectious disease

prior learning & retrieval practice

Essential idea: The human body has structures and processes that resist the continuous threat of invasion by pathogens.

Exercise 1: Chalk-Talk in two phases: 

• What do the words "infectious disease" mean? 

• How do our bodies prevent them?

Exercise 2: Glossary of key terms: pathogen

U1: The skin and mucous membranes form a primary defence against pathogens that cause infectious disease.

Skin and mucous membranes

Exercise 3: Copy and complete this word-cloze exercise, you can fill in the blanks from the following words:  bronchi, cells, mucous, Keratin,  sebaceous, oily, internal, primary, lysozyme ,water,

The skin and mucous membranes form a _______________ defence against pathogens that cause infectious disease.

External skin is composed of several layers of dead                              which act as a physical barrier to pathogens. The outer layers are Keratinised (contain the protein _______________) which makes them tough and impermeable to ________________.

                                                             glands in the skin secrete sebum, an                                    substance which prevents the growth of bacteria and other organisms on the skin.

Mucous membranes are                                                 surfaces found in the human digestive system, respiratory system and reproductive system.

They are composed of thin linings of epithelial cells, protected by copious quantities of sticky                                                       which traps pathogens and contains                                                          , an enzyme that kills and digests pathogens.

Mucus membranes in the respiratory system contain cilia, organelles which waft the mucus out of the system to prevent the sticky mucus from blocking the _____________ and bronchioles.

U2: Cuts in the skin are sealed by blood clotting.

U3: Clotting factors are released from platelets.

U4: The cascade results in the rapid conversion of fibrinogen to fibrin by thrombin.

Blood Clotting

Exercise 4: Find the section of your textbook that explains blood clotting and connect-extend-challenge

Exercise 5: Glossary of key terms: clotting factors, platelets, cascade, fibrinogen, fibrin, thrombin

Exercise 6: Using the table below, create a flow chart that details the sequence of events in blood clotting

A1: Causes and consequences of blood clot formation in coronary arteries. 

Exercise 7:  Revision link to DP Topic 6.2 A3: Causes and consequences of occlusion of the coronary arteries. Review your notes from this section before proceeding.

Exercise 8: Using your textbook, create a table with the headings "causes" and "consequences" and the title "Causes and consequences of blood clot formation in coronary arteries. ". Bullet point your notes under each heading in your own words.

A3: Effects of HIV on the immune system and methods of transmission.

Guidance from the syllabus: :The effects of HIV on the immune system should be limited to a reduction in the number of active lymphocytes and a loss of the ability to produce antibodies, leading to the development of AIDS.

Exercise 14: List the ways that HIV can be transmitted, horizontally and vertically.