Transcript Defense against disease!

Defense against disease!
Immunity
Diseases can be caused by a variety of organisms.
• Bacteria or single cell organisms invade cells or tissues. Some
produce a toxin. This post is probably full of bacteria!
• This may cause a staph infection – caused by the bacteria
staphylococcus aureus which invades cuts and breaks in the skin
Viruses! use a host cell to
duplicate (this is the lytic
cycle)
Ebola, AIDS and the Bird
Flu are all examples of
viruses.
Worms and Parasites!
 Worms and parasites invade the body and
take away tissue or other nutrients
• Note that many very gory pictures were omitted…
most of them involved an anus and roundworms
Heart worms in a dog can
grow 14” long.
• Roundworms can cause Trichinosis – a food
borne illness that involves eating
undercooked pork infested with the worm.
• Flatworms – most common to you is the
tapeworm – YUCK!
Fungi!
• Causes Ringworm….
• Ringworm is caused by several
different fungus organisms that
all belong to a group called
"Dermatophytes”
• Can be transferred through direct
or indirect contact.
ProtozoaAmoebic dysentery
1st line of defense: Barriers
against microbes
 Skin is slightly acidic- pH
of 3-5, and relatively dry
• Skin covers the body
 Mucous membranes trap
foreign material –wet and
sticky!
 Cilia of the trachea will
beat the ‘crap’ back up to
the oral cavity where the
trapped material meets its
doom in the digestive
system.
Don’t Eat your boogers! Flick
them!
How do pathogens get in?
• Inhaled – respiratory tract
• Food, water and other things – digestive
tract.
• External invasion route – cuts and abrasions
in skin.
• Point of entry may determine disease.
What happens when something
gets inside the body?
Trypanosomes – African Sleeping Sickness – Transmitted by the
Tsetse Fly
2nd line of defense is usually
Phagocytosis – eating by the cell

‘phago’ = eat.

‘cyto’ = of the cell.

‘leuco’ = ‘white’

‘phagocytosis is the
process where a leucocyte
recognizes a foreign body
and engulfs it.
ANTIGEN?
• Antigen is a bad or
foreign thing in the
body
3rd line of defense:
ANTIBODIES!
Antibodies are
globular ‘Y’ shaped
proteins.
– 1. The body makes
antibodies to fight
antigens.
– 2. Specific antibodies
bond to specific
antigens.
The ‘Y’ Shaped antibodies attach to an
antigen and make a clump. The clump
gets filtered out at the lymph nodes.
B-cells vs. T-cells
• Find a partner to work with.
• Determine the difference between B-cells and Tcells.
• Know the difference between them for tomorrow.
We will collaborate our findings.
– Where do they come from?
– What do they do?
– Interesting info
(write, define, draw pictures, etc)
Tuesday, March
th
20 ,
2007.
• Syllabus Notes or presentations 1st ?
• Protein synthesis presentations due by
Wed.
• Transcription/Translation/Mutation
worksheets also due on Wed.
• Mid-term questions on Immune,
Circulatory, and Respiratory systems for
you on Thursday or Friday.
Syllabus Notes:
• 5.4.1. Explain how skin and mucous
membranes act as barriers against
pathogens.
– Skin almost impossible for
microorganisms to penetrate
– Mucus : traps and prevents organisms
from entering
– Eyes: tears contain lysozymes which
destroy bacterial walls
– Stomach: very acidic; difficult for
survival
What your stomach would do to
most bacteria!
Syllabus Notes:
• 5.4.2. Outline how phagocytic
leucocytes ingest pathogens in
the blood and in body tissue.
Leucocytes or white blood
cells are our body’s
defense against
pathogens!
They are found in the
blood and in tissue.
Phagocytic Leucocytes
recognize foreign “codes”
on the outside of cell
membranes!
Syllabus Notes:
5.4.3. State the difference between antigens
and antibodies
ANTIBODY:
Globular protein that
recognizes an antigen.
ANTIGEN
Molecule recognized as
foreign by the immune
system.
How do phagocytes and antibodies
work together?
Phagocytes stimulate
B Cells
T Cells
B cells mature in the bone marrow
T cells mature in the thymus
B cell make antibodies to get
T cells work on cells that
antigens which are ‘loose in the body’ have been invaded by antigen
B and T cell review:
• Antigen is loose in the
body? What is going to
kill it?
•Antibodies are needed?
Where do they come from?
•What patrols the body and
looks for body cells that have
been invaded by a foreign
body?
• B Cells!
•B Cell!
•T Cells!
Illustration, Robin Hotchkiss
Leucocytes
ingest the
antigen
Majority are
plasma cells;
secrete large
amounts of
specific
antibodies.
Few cloned
cells remain
as memory
cells.
Travel to B-cell in
lymph nodes.
Phago. Leuco.
Will present
antigen to B-cell
Drain into
blood stream.
Helper T-cell will
then cause B-cell
to clone its self
5.4.4. Explain antibody
production.
How does bonding to an antibody
get rid of the antigen?
1. Phagocytes to come and eat the antibody-bonded-to-theantigen usually in the lymph
OR, if the antigen is a cell, the
antibody can make it lyse
How else does an antibody stop
an antigen?
• A big clog or glob of antigen-antibodies
drop out or precipitate of the area and get
trapped in the lymph nodes
• Bonding to the antigen neutralizes it.
Matching Review:
1. Make antibodies
a. B cell
2. Residence in Thymus
b. Pathogen
3. Disease causing agent
c. Antigen
4. Mature in bone marrow
d. T cell
5. Elicits an immune
response
e. Plasma cell
Today and Tomorrow’s Relaxing yet
Educating Experience
• Draw a diagram of the heart showing all 4
chambers, associated blood vessels and
valves.
– Include the direction of blood flow!
– Include arteries vs. veins, structure and function.
• Tell me about blood, what is it composed of, what
does it transport – through pictures or words.
• Draw a diagram of the ventilation system – trachea,
bronchi, bronchioles, and lungs.
– Use this diagram to explain the mechanism of ventilation…
how does it work?
THIS IS AN ASSIGNMENT TO BE TURNED IN! (2-3 pages)
- more notes to come on heart and lungs 