Download Preventing and fighting disease

Preventing and fighting disease
Learning Objectives
Introduce the barriers to infection entering
the body.
Introduce and describe the non specific
disease prevention system looking at roles
of different organs, cells and chemicals.
Inside the body
The immune system
http://www.youtube.com/watch?v=IWMJIMzs
EMg&feature=related (introduction to how
the body fights disease)
Analogy
How is this city defended?
What are the weak points?
How is each weak point
defendable?
If an attacker gets inside how
does the city defend itself?
Find analogies for each of these
situations in the human system
Three lines of defense
3. Specific internal
defenses or immune
response that fight
specific infections and
then remember the
infection to allow for
more rapid response
next time it is
encountered.
External
barriers
1.
2. Non-specific internal defenses
including white blood cells that
engulf invading particles and
destroy infected cells, and
chemicals released by infected
cells and white blood cells that
induce inflammation and fever
which help to fight the disease.
Mark the barriers to infection on the
outline body
Human immune system
Need to learn:
How do non specific defenses function?
The role of white blood cells in non specific defense
The role of the inflammatory response and fever
The role of white blood cells in the specific immune response
The role of antibodies
The role of cytokinins
This leads on to
Acquiring immunity
Medical help for the immune system
Allergies
Autoimmune diseases
Immuno-deficiency diseases
HIV
Cancer.
Non specific internal response
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If invaders get in they will encounter:
Leukocytes (white blood cells)
These include:
Macrophages and neutrophils that eat bacteria, foreign substances and
dying cells by phagocytosis and subsequent digestion using lysosomes.
http://www.youtube.com/watch?v=UeuL3HPfeQw (live film of
phagocytosis)
http://www.youtube.com/watch?v=7VQU28itVVw (animated
explanation of process of phagocytosis)
Flood to the site of injuries
Can squeeze through capillary walls and onto lung surfaces etc.
http://www.youtube.com/watch?v=cL9KY_ECzfo&feature=related
(how macrophages recognise pathogens)
Natural Killer Cells
Another type of leukocyte
Attack cancerous cells
Attack cells infected by viruses.
Act by boring holes into cells and injecting enzymes that destroy the cells.
http://www.youtube.com/watch?v=HNP1EAYLhOs (natural killer cells)
The inflammatory response
http://www.youtube.com/watch?v=CmbWE3jLUgM (explanation of inflammatory response)
Injured tissues become warm swollen and red.
Inflammatory response attracts phagocytes to site of potential infection.
Damaged cells release substances that stimulate mast cells to release histamine
Histamine makes capillaries leaky and relaxes smooth muscles in arterioles allowing greater blood flow to the
site of infection.
Other chemicals actively attract phagocytes
http://www.youtube.com/watch?v=uNG-jZxvhcg
Write a script for this 2nd video!
Inflammatory response contd.
Phagocytic macrophages and neutrophils squeeze out of leaky capillaries.
Act on invaders and damaged cells.
Pus is a mixture of living and dead white cells, dead bacteria and tissue
debris.
Macrophages release cytokines which help cells coordinate response to
pathogens.
Leaky capillaries lead to clotting – cutting off infected area.
Pain encourages us to protect the damaged area.
Fever
Controlled by
Hypothalamus
Body temperature
is intentionally
raised,
This happens in
response to the
release of the
cytokine
endogenous
pyrogen by some
macrophages.
Raised body
temperature and
warmth seeking
behaviour speeds
up defense
responses, i.e.
activity of white
cells and
multiplication of
immune response
cells.
Less ideal
conditions for
bacterial
reproduction which
reduces their ability
to attack.
Increases
interferon
production by cells
attacked by viruses
which increases the
resistance of
neighbouring cells
to viral attack
Proof fever works
• People with flu were given either aspirin
which brings down fever or a placebo which
does not.
• Those taking aspirin had much higher viral
loads in their sneezes than those taking the
placebo.
Plenary
What is a leukocyte?
How does phagocytosis work?
How does the release of cytokinins help
the
body
to
fight
infection?
http://www.youtube.com/watch?v=JGb5IweiY
G8