Topic 6: Human Physiology (20 hours) 6.3 Defence against infectious disease: The human body has structures and processes that resist the continuous threat of invasion by pathogens. Nature of science: Risks associated with scientific research—Florey and Chain’s tests on the safety of penicillin would not be compliant with current protocol on testing. Understandings: The skin and mucous membranes form a primary defence against pathogens that cause infectious disease. Cuts in the skin are sealed by blood clotting. Clotting factors are released from platelets. The cascade results in the rapid conversion of fibrinogen to fibrin by thrombin. Ingestion of pathogens by phagocytic white blood cells gives non-specific immunity to diseases. Production of antibodies by lymphocytes in response to particular pathogens gives specific immunity. 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. Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells. 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. Applications and skills: Application: Causes and consequences of blood clot formation in coronary arteries. Application: Florey and Chain’s experiments to test penicillin on bacterial infections in mice. Application: An understanding of immunity has led to the development of vaccinations. Application: Effects of HIV on the immune system (a reduction in the number of active lymphocytes and a loss of the ability to produce antibodies, leading to the development of AIDS) and methods of transmission. International-mindedness: The spread and containment of diseases such as bird flu require international coordination and communication. Aims: The social as well as the economic benefits of the control of bacterial diseases around the world should be stressed. Science has limited means in the fight against pathogens, as shown by the spread of new diseases and antibiotic-resistant bacteria. Biology Journal 1/8/2014 What’s the difference between a prokaryote and an eukaryote? Biology Journal 2/23/2015 ________ is an enzyme that converts fibrinogen, which is ________ (meaning it is dissolved in the blood) into to ________ , which is ________ (meaning it can’t be dissolved in blood). These fibers of ________ mesh together and harden if exposed to air, forming a ________ or scab. Biology Journal 2/23/2015 Thrombin is an enzyme that converts fibrinogen, which is soluble (meaning it is dissolved in the blood) into to fibrin, which is insoluble (meaning it can’t be dissolved in blood). These fibers of fibrin mesh together and harden if exposed to air, forming a blood clot or scab. Biology Journal 2/20/2015 Are viruses cells? How are they structured? How does a virus get into your cells? Biology Journal 2/24/2015 What kind of things are in a vaccine? How is it supposed to work? Why do some last for 10 years, and some last for less than a year? You may revise your exploration IA... Turn in both the original and the revisions! Revisions to the exploration part are due Thursday, March 5th. Youtube Videos Flu Attack! How a virus infects your body. Has terrific computer generated graphics and narration about how viruses spread in the lytic cycle. http://www.youtube.com/watch?v=Rpj0emEGShQ Antibiotic Resistance. Cartoon about antibiotic resistance in bacteria and natural selection http://www.youtube.com/watch?v=zjR6L38yReE MRSA. Official hospital video about MRSA. Nicely visual cartoon with narration. 5 minutes. http://www.youtube.com/watch?v=gU7hrtxBWmA Crawling Neutrophil chasing Bacterium. A White blood cell chases a bacterium to do phagocytosis. https://www.youtube.com/watch?v=MgVPLNu_S-w&feature=player_embedded Blood Clotting. Detailed cartoonish animation with narration. 2.5 minutes. https://www.youtube.com/watch?v=G_J0zEsOOfE&feature=player_embedded Eukaryotes Both Prokaryotes Eukaryotes Both Prokaryotes •Large and more complex •Have a cell membrane and cytoplasm •Small and simple •Has a nucleus and organelles •Reproduce through asexual cell division •Lacks a nucleus and lacks organelles •DNA is linear and in many pieces (chromosomes) Have ribosomes (but they •DNA is circular and in are different) one piece (usually) •Cells divide through mitosis •Cells divide through binary fission •Have 80s ribosomes •Have 70s ribosomes •Attaches and transfers DNA through pili Biology Journal 2/19/2015 What does AIDS stand for? What does HIV stand for? What could be some ways that the perception of AIDS/HIV has changed over time? How do you think perceptions of AIDS have changed over time? Why? The Grim Reaper. (1987) PSA video. 1 minute. https://www.youtube.com/watch?v=U219eUIZ7Qo HIV/AIDS Prevention, Awareness, and Testing. (2012) PSA video. 1.5 minutes. https://www.youtube.com/watch?v=0RS9khOEbd8 HIV Abundance World Map Number of HIV pos. individuals HIV Concentration World Map A pathogen is any disease causing organism. Types of pathogens Bacteria •Prokaryotes •Can divide very fast! Can cause: •Food poisoning •Ear, eye infections •Digestive infections (diarrhea, cholera) Types of pathogens Viruses •Acellular (they are not cells!) •Do have DNA or RNA •Need a host cell to infect and reproduce •Reproduce and evolve fast! Can cause: •Flu •Cold •Herpes •HIV/AIDS •new ones? … A bit of background on viruses Viruses are not cells They are not considered alive They can be many shapes A bit of background on viruses Structure of a typical Virus DNA/RNA: Has all of the information to make the virus Capsid: A protein coat that protects the DNA/RNA; may serve other functions Receptors: Interact with your cells to gain entry! Oftentimes are glycoproteins. Envelope: made out of phospholipids -just like a cell membrane A bit of background on viruses Viruses are extremely diverse and evolve quickly. How long is a flu shot good for? Why? Zoonosis is the transfer of a pathogen from one species to another. The introduced pathogen can have unexpected and deadly effectiveness. Viruses are best at this! What could be some pathogens that may have originated from zoonosis? Types of pathogens Fungi •Eukaryotes •Reproduce with spores Can cause: •Ringworm •Athlete’s foot •Some respiratory infections Above: ringworm. It’s not a worm at all, but a fungus, growing in a ring, just like mushrooms do. Below: a severe case of athlete’s foot in a person with AIDS, who can’t fight it off. Types of pathogens Protoza (aka “protists” aka “protista”) •Eukaryotic, single-celled parasites Can cause: •Malaria •Leishmaniasis •Toxoplasmosis All of these are pictures of leishmania, and its consequences. What could be some ways that you can “catch” pathogens? What could be some barriers that your body has that prevent us from “catching” pathogens? Above: a poster from the 1940’s warning women about contracting the STD syphilis from men returning form World War II. Physical barriers against Pathogens Skin • Few openings • Low pH that can kill some pathogens • Naturally occurring bacteria outcompete some pathogens Physical barriers against Pathogens Mucous Membranes • Sticky mucus traps pathogens • Low pH • Naturally occurring bacteria Viruses vs. Bacteria Viruses Size Structure DNA? Surface Antibiotics Tiny! (about 0.1µm) Not a cell Has DNA or RNA Has spikes and receptors for infection Do nothing! Bacteria Larger (about 1µm) Prokaryote cell DNA in a loop Has flagella for movement and pili for recognition Kills them Antibiotics block specific metabolic pathways that bacteria need to survive. • Most are 70s ribosome blockers Which means that the bacteria won’t be able to do what? Antibiotics block metabolic pathways such as… What could be some reasons that antibiotics don’t work against viruses? Viruses use the host cells’ metabolism for almost everything. Aid workers disposing of the corpse of a person infected with Ebola virus. Some strains of bacteria have evolved genes that confer resistance to antibiotics. Some strains of bacteria have multiple drug resistances. Antibiotic resistant bacteria is a dangerous lesson in natural selection Antibiotic resistant bacteria is a dangerous lesson in natural selection Antibiotic resistant bacteria is a dangerous lesson in natural selection Antibiotic resistant bacteria is a dangerous lesson in natural selection Antibiotic resistant bacteria is a dangerous lesson in natural selection Danger! Cuts in the skin are sealed by blood clotting. Q: In numbered steps, explain how clotting occurs. 1. Clotting factors are released from platelets. 2. An enzyme called thrombin is produced. 3. Thrombin converts soluble fibrinogen to insoluble fibrin. 4. Fibrin forms a mesh that traps red blood cells. 5. The gel, if exposed to air, hardens into a scab. Blood clotting can happen “accidentally” in many parts of the body. What are some names for this? Coronary heart disease or arthrosclerosis is the build up of cholesterol that can clog arteries, leading to clots. Heart attack – clot in coronary artery Stroke – clot in brain artery Blood clot – clot elsewhere in body Rate of Discovery of Approved Antibiotics Chemical Class of Antibiotic 1. 2. 3. 4. 5. Describe a trend shown in the graph. Which chemical class of antibiotic was approved of the most from 1980 to 2007? What has happened to the diversity of antibiotics approved over time? Suggest a reason for the trend. (there are many possible answers for this one!) What could be the consequences of this trend on the health care field? Immune System Products 1. Phagocytes. Do phagocytosis (eating other cells) to pathogens or damaged cells. 2. Lymphocytes. Designed to attack a particular pathogen. They stay around as “memory cells” and will multiply rapidly when encountering the specific pathogen again. 3. Antibodies. Proteins that stick to pathogens to target them. HIV infects and destroys lymphocytes. What would be some consequences of this? AIDS is the loss of immune system memory and antibody production. An “opportunistic” pathogen can grow to the point that it kills the patient. Youtube Videos Flu Attack! How a virus infects your body. Has terrific computer generated graphics and narration about how viruses spread in the lytic cycle. http://www.youtube.com/watch?v=Rpj0emEGShQ Antibiotic Resistance. Cartoon about antibiotic resistance in bacteria and natural selection http://www.youtube.com/watch?v=zjR6L38yReE MRSA. Official hospital video about MRSA. Nicely visual cartoon with narration. 5 minutes. http://www.youtube.com/watch?v=gU7hrtxBWmA Crawling Neutrophil chasing Bacterium. A White blood cell chases a bacterium to do phagocytosis. https://www.youtube.com/watch?v=MgVPLNu_S-w&feature=player_embedded Blood Clotting. Detailed cartoonish animation with narration. 2.5 minutes. https://www.youtube.com/watch?v=G_J0zEsOOfE&feature=player_embedded Youtube Videos