http://www.bbc.co.uk/education/clips/zy4c87h
The Immune System
Specification Point 3.4.2
What is a
pathogen?
Each type of cell has specific molecules on its surface
that identify it. These molecules include proteins and
enable the immune system to identify:
•• pathogens
•• cells from other organisms of the same species
•• abnormal body cells
•• toxins.
Definition of antigen. The effect of antigen variability on
disease and disease prevention.
Learning Outcomes:
• Define the term
antigen
• Explain how cells
of the immune
system
distinguish
between self and
non self.
• Describe the likely
process of how
cells are able to
develop and
diferentiate
between self and
non self cells.
Types of Response against Pathogens
• Immediate, non specific responses –
natural barriers and Phagocytosis
• Less Rapid more specific responses –
Lymphocytes
• Cell mediated response (Using T
Lymphocytes)
• Humoral response (Using B Lymphocytes)
Antigen
Learning Outcomes:
• Define the term
antigen
• Explain how cells
of the immune
system
distinguish
between self and
non self.
• Describe the likely
process of how
cells are able to
develop and
diferentiate
between self and
non self cells.
•
•
•
Any chemical substance which can provoke an immune
response.
Chemical marker on the cells surface on the membrane. It
identifies the cell.
White blood cells have the ability to recognise these antigens
and respond appropriately.
Learning Outcomes:
• Define the term
antigen
• Explain how cells
of the immune
system
distinguish
between self and
non self.
• Describe the likely
process of how
cells are able to
develop and
diferentiate
between self and
non self cells.
Distinguishing between you and foreign
particles
Foreign particles have different antigens to your own cells.
•
•
•
Mr Nash cells have Mr Nash Antigens.
Saab cells have Saab antigens.
Bacterial cells have their own bacterial antigens
When your cells come into contact with other bodies, they detect if
the antigens are ‘self’ or ‘non self’.
If the antigens detected are ‘non self’, then an immune response
is initiated.
Q: Why are organ donations/transplants rejected so often?
How cell recognition develops
Learning Outcomes:
• Define the term
antigen
• Explain how cells
of the immune
system
distinguish
between self and
non self.
• Describe the likely
process of how
cells are able to
develop and
diferentiate
between self and
non self cells.
1.
Immature white blood cells are produced by the bone
marrow in the fetus.
2. These cells have different receptors that can detect a
huge variety of different antigens.
3. Whilst developing, they are exposed (only) to plenty of
‘self’ antigens.
4. If they come into contact with one of the ‘self’
antigens, then they interact and both the cell with this
self detecting receptor and the antigen will die. This is
called Apoptosis (programmed cell death)
5. Only cells with receptors that can don’t have self
receptors survive and mature. (These ones can detect
non self antigens)
Immature white blood cells are produced by the bone marrow.
These cells have different receptors that can detect a huge variety of d
Whilst developing, they are exposed to plenty of ‘self’ antigens.
If they come into contact with one of the ‘self’ antigens, then they intera
Only cells with receptors that can don’t have self receptors survive and m
Learning Outcomes:
• Define the term
antigen
• Explain how cells
of the immune
system
distinguish
between self and
non self.
• Describe the likely
process of how
cells are able to
develop and
diferentiate
between self and
non self cells.
Non – Specific - Natural Barriers
Learning Outcomes:
• Define the term
antigen
• Explain how cells
of the immune
system
distinguish
between self and
non self.
• Describe the likely
process of how
cells are able to
develop and
diferentiate
between self and
non self cells.
Non – Specific - Phagocytosis