Transcript 11.2
The Body’s Line of Defence
Chapter 11
Section 11.2
Blood pressure regulation
Blood pressure is monitors by blood pressure receptors in your
carotid and aortic arteries.
High blood pressure- if detected it sends a signal to medulla
oblongata. Sympathetic nervous system is decreased and
parasympathetic is increased. The main result is that the
arteries DILATE – VASODILATION which will decrease blood
pressure
The opposite happens with low blood pressure and the end
result will be a constriction of the vesselsVASOCONTRICTION to increase the blood pressure
Interesting Video
Show video: microscopic assassins
http://www.youtube.com/watch?v=CeVtPDjJBPU
Terms
Pathogen =Greek for “producer of suffering”
Microscopic
Enters
organism
body
Can be dangerous
What do Pathogens Want With Us?!?!?
Wants to reach inside of body as it is an IDEAL
place for many pathogens to grow and reproduce
Body Has 3 Lines of Defense Against Pathogens
1. Barriers to keep pathogens out.
2. General (non-specific) defenses against many
pathogens.
3. Specific defenses against particular pathogens.
1st Line of Defense: Barrier
The body has the following physical and
chemical barriers.
Eyelashes.
Cilia
in trachea – sweep away.
Tears, mucous, saliva and sweat – lysozyme.
-
Enzyme that destroys the cell walls of bacteria.
Skin
- When intact it can’t usually be penetrated
- Can also produce acidic secretions that make the
pH too low for microbes or bacteria to grow
2nd Line: Non-Specific Defenses (General)
Includes 3 types of WBC
Macrophages
Neutrophils
Monocytes
Destroys invading
organisms
Inflammation
Brings
in defensive cells and speeds healing
Fever
Slows
growth of bacteria; speeds up body defenses
Occurs inside body
2nd Line: Non-specific
Macrophages
Develop from monocytes
Eat foreign bacteria (phagocytosis)
Found all over body
3rd Lind of Defense: The Immune System
Kicks in to assist the body’s 1st and 2nd lines of
defense
FUNCTION: the recognition and destruction of
specific pathogens or foreign molecules
2 characteristics
Is specific
Has a memory
3rd Line: Specific Defenses
Lymphocytes divided into 2 main groups
(depending on where they mature – both
form in bone marrow)
T
lymphocytes (aka T cells)
Mature
B
lymphocytes (aka B Cells)
Mature
in thymus gland (T=T)
in bone marrow (B=B)
http://health.howstuffworks.com/adam-200095.htm
When an antigen is detected…
T cells that have the receptors specific for
that particular invader are stimulated to
divide repeatedly
Forms
2 lines of cells
Effector cells – attack enemy; short life
Memory cells – remember particular
invaders and mount a rapid response if it
should ever appear again; longer life
3rd Line: Two types of Specific Defense
Antibody-mediated Immune Response
Defend primarily against antigens that are free in the body
fluids
Warriors = B cells
Weapons = antibodies
Cell-mediated Immune Response
Protect against body cells that have become infected with
pathogens
Warrior = T cell
First Steps in Immune Response
1.
Pathogen invades cell
2. Macrophage engulfs pathogen
3. Macrophage puts piece of pathogen (ANTIGEN) on
surface
4. This antigen on the surface is presented to a HELPER
T CELL
5. Macrophage then activates helper T Cell
HELPER T CELLS THEN ACTIVATE
BOTH LINES OF DEFENSE TO
FIGHT AGAINST THAT SPECIFIC
ANTIGEN
Cell-Mediated Response Steps
6. Helper T cells stimulates the killer T cell (that is
bound to antigen on macrophage) to begin dividing
7. T Cells divide into two separate populations
- memory cytotoxic T cells
- (killer) effector cytotoxic T
cells
Cell-Mediated Response Steps
7 CONT…. Killer T cells cause the target cell to
burst and die (drills holes)
AND
Memory T cells remain in body and mount a
quick response if the invader is encountered
again!
And now for the Antibody-Mediated Immune
Response!
First steps of the Immune response occur, resulting
in an activated helper T cell
Helper T cell activates B cell to begin dividing into
plasma cells (effector B cells) and
memory B cells
Memory B cells remember attack so next attack with that
pathogen is faster
Plasma cells secrete antibodies specific for that antigen
Antibody-Mediated Immune Responses
Plasma cells secrete antibodies that are
specific for that antigen
Weapons = Antibodies
Y-shaped
proteins that bind to specific antigen
Can only bind to antigens that are free in body
fluids or on the surface of a cell. Cannot bind to
toxins within a cell
Have SAME SHAPE as the antigen receptors
IMMUNE SYSTEM VIDEO (4min)
http://www.youtube.com/watch?v=Hr7jjlZI6N
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