Download 6.3 Defense Against Infectious Disease

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