Biology 2017-2018 Name: Noble efforts change lives. Excellence. Tenacity. Community. Reflection.

Topic #6: Human Physiology6.3: Defense Against Infectious Disease

Skeleton NotesSyllabus Statement Guidance6.3.U1 The skin and mucous

membranes form a primary defense against pathogens that cause infectious disease.

Diagrams of skin are not required.

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

6.3.U3 Clotting factors are released from platelets.

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

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

Subgroups of phagocyte are not required.

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

Subgroups of lymphocytes are not required but students should be aware that some lymphocytes act as memory cells and can quickly reproduce to form a clone of plasma cells if a pathogen carrying a specific antigen is re-encountered.

6.3.U7 Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells.

6.3.U8 Viruses lack a metabolism and cannot therefore be treated with antibiotics. Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have multiple resistance.

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

6.3.A2 Florey and Chain’s experiment to test penicillin on bacterial infections in mice.

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

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.

Recommended resources: Allott, Andrew. Biology: Course Companion. S.I.: Oxford UP, 2014. Print.

1. What is a pathogen?

Type of pathogen

Example/Characteristics Can Cause

Bacteria

Virus

Fungi

Protozoa

2. What are some methods of transmission?

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

Physical barriers against pathogens:

MUCOUS MEMBRANES SKIN

6.3.U2: Cuts in the skin are sealed by blood clotting. AND 6.3.U3: Clotting factors are released from platelets.

- Wounds such as to the skin causes through which can potentially enter the body.

- Blood clots at the site of a wound to prevent blood loss and the entry of pathogens.

- (small cell fragments) along with release clotting factors in to a wound.

- Clotting factors cause a series of which end with (a protein) fibers forming a mesh across the wound site.

- The fibrin fibers capture cells and platelets forming a . In the presence of a the clot dries to form a scab which shields the healing tissues underneath.

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

- Blood clotting is an example of a metabolic pathway: a chain of biochemical reactions.

- Outline each stage of the process in this link: http://www.footprints-science.com/flash/Blood%clotting.swf

6.3.A1: Causes and consequences of blood clot formation in coronary arteries AND Review: 6.2.A3: Causes and consequences of occlusion of the coronary arteries.

Atherosclerosis

- areas of the artery wall become damaged.

- release encouraging growth of fibrous tissue.

- builds up in damaged areas. This eventually forms and the artery eventually loses its elasticity.

Activity: http://www.hhmi.org/biointeractive/obesity/heart_attack.html

- Atherosclerosis can lead to blood clots and if these occur in the myocardial tissue, we call it coronary heart disease.

- A myocardial infarction (HEART ATTACK) occurs if a coronary artery becomes completely blocked.

- Coronary muscle tissue dies as a result of a lack of blood and oxygen.

Watch the video and take notes: https://www.youtube.com/watch?v=n8P3n6GKBSY

Risk factors in Coronary Heart Disease

Genetic

Age

Sex

Smoking

Diet

Exercise

Obesity

Stress

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

- If a pathogen enters the body, the first line of defense are:

“eating cell white blood cell”

Watch and take notes on the following videos: http://www.mydr.com/au/health-images/animation-phagocytosishttp://youtube.com/watch?v=MgVPLNu_S-whttp://www.kscience.co.uk/animations/phagocyte.htmhttp://216c.sl.pt/http://216d.sl.pt/

- (movement in response to chemicals) attracts the phagocytes to the area of invasion as response to:

- produced by the pathogen

- released by cells

- The phagocyte attaches to the pathogen’s cell surface proteins and then it. The nature of the plasma membrane allows this to happen.

- A forms. This is a vesicle that contains the pathogen.

- : vesicles of digestive enzymes – deposit the enzymes into the phagosome.

The digestive enzymes break down the pathogen and the waste products are expelled from the cell by exocytosis.

Big Key Point: Phagocytes provide the body with NON-SPECIFIC IMMUNITY, meaning they will attack any material judged to be foreign.

- if the infection becomes too widespread, additional support is called in.

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

ANTIGEN: a substance of molecule often found on a cell of and to it as part of an

- produced by white blood cells called lymphocytes

- helps fight pathogens using 2 methods: Making it more recognizable to phagocytes so they can be engulfed Preventing viruses from docking to host cells so they cannot enter cells

Antibodies are specific to certain antigens. (Review: ABO blood groups)

- Immune response is triggered by non-self cells.

- Hence why matches are crucial in transplants and blood transfusions and why stem cell technology are so promising

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

PRODUCTION OF ANTIBODIES – Circle the right response

- Many different OR similar lymphocytes exists.

- Each type recognizes many OR one specific antigen.

- When the immune system is challenged by the invasion of pathogen OR On regulated occurrences as a precautionary measure, the corresponding lymphocyte responds.

- It makes one clone OR many clones, each which produce antibodies to the pathogen.

CLONAL SELECTION = right lymphocyte is selected and then cloned.

- some cloned cells remain as MEMORY CELLS, ready for a second invasion, hence, IMMUNITY

6.5.U7: Antibodies block processes that occur in prokaryotic cells but not in eukaryotic cells. AND 6.3.U8: Viruses lack a metabolism and cannot therefore be treated with antibiotics.

Antibiotics are used in the and of bacteria.

Block process that occur in prokaryotic cells but not eukaryotic cells as eukaryotes are very different in structure and function.

Which processes are targeted by antibiotics:

o DNA o -

o - o - o - formation

6.3.U8: Viruses lack a metabolism and cannot therefore be treated with antibiotics. Some strains of bacteria have evolved with genes that confer resistance to antibiotics and some strains of bacteria have multiple resistance.

Why should we not take antibiotics for viral infections?

What are the effects of overusing antibiotics? (Hint: Review for 5.2.A2)

6.3.A2: Florey and Chain’s experiments to test penicillin on bacterial infections in mice. AND 6.3.NOS: Risks associated with scientific research – Florey and Chain’s tests on the safety of penicillin would not be compliant with current protocols on testing.

Why were Florey and Chain’s test with penicillin not be compliant with current protocols on testing?

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

What are the effects of HIV on the immune system and what are some methods of transmission?