Topic 6.3:  Defense Against Infectious Disease

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

At SHS, Topic 6.3 is taught in the following class unit(s):

• Prokaryotic Cells (unit 3)
• Evidence for Evolution (unit 20)
• The Circulatory System (unit 45)
• Innate Immunity (unit 47A)
• Acquired Immunity (unit 47B)​

Statements & Objectives:

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

• Define pathogen.
• State that skin and mucous membranes form the first line of defense against pathogens.
• Outline the role of skin, sebaceous glands and mucous membranes in the defense against pathogens.​

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

• State two benefits of blood clotting when skin is cut.​

6.3.U3  Clotting factors are released from platelets.

• Outline two roles of platelets in the blood clotting cascade.​

6.3.U4  The cascade results in the rapid conversion of fibrinogen to fibrin by thrombrin.

• Describe the blood clotting cascade, including the role of platelets, clotting factors, thrombin, fibrinogen and fibrin.

6.3.U5  Ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases.

• State the white blood cells are the second line of defence against pathogens.
• Outline the function of phagocytic white blood cells in defense against pathogens.​

6.3.U6  Production of antibodies by lymphocytes in response to particular pathogens gives specific immunity.

• Define “specific immune response.”
• Contrast antigen and antibody.
• Describe the structure and function of antibodies.
• State the function of plasma cells and memory cells.​

6.3.U7  Antibiotic blocks processes that occur in prokaryotic cells but not in eukaryotic cells

• Define antibiotic.
• Outline the mechanisms by which antibiotics kill bacteria.
• Explain why antibiotics are ineffective against viruses.​

6.3.U8  Viruses lack a metabolism and cannot therefore be treated with antibiotics.

• Explain why antibiotics are ineffective against viruses.

6.3.U9  Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have multiple resistance.​

• List five measures that can be taken to avoid the development of antibiotic resistance.
• Explain why multiple drug antibiotic resistance is especially dangerous.
• State an example of a multidrug resistant bacteria.

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

• State the function of the coronary arteries.
• Define coronary thrombosis.
• List sources of arterial damage that increase the risk of coronary thrombosis.
• List factors that are correlated with an increased risk of coronary thrombosis and heart attack.

6.3.A2  Effects of HIV on the immune system and methods of transmission.

• Describe the consequences of the HIV on the immune system.
• Outline the relationship between HIV and AIDS.
• List ways the HIV virus is spread.

6.3.A3  Florey and Chain’s experiments to test penicillin on bacterial infections in mice.

• Explain methods and results of Florey and Chain’s experiments.​

6.3.NOS  Risks associated with scientific research- Florey and Chain’s tests on the safety of penicillin would not be compliant with current protocol on testing.

• Compare allowable research risks of the past with those of the present.​

In the News:

• ​Protect the skin, build barriers: Old acquaintance in a new role (20174-11-08)
• New antibiotic resistance genes found (2017-10-16)
• Skin microbes trigger specific immune responses (2015-01-05)
• Unraveling the mechanism of skin barrier formation (2017-04-14)
• ​To stop the bleeding, the platelet have to 'die' (2016-08-09)
• ​Understanding how the 'police' of the cell world deal with 'intruders' and the 'injured' (2016-08-30)
• ​Building An Antibiotic To Kill Bad Microbes While Sparing Good Ones (2016-05-23)