infectious diseases unit 5 lesson 3 plan
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Infectious Diseases Unit 5 Lesson 3 plan. Do now. Why might the innate response be unable to control an infection? What happens then ?. Do now. Why might the innate response be unable to control an infection? What happens then ? What is ADAPTIVE IMMUNITY?. Do now. - PowerPoint PPT PresentationTRANSCRIPT
Infectious DiseasesUnit 5 Lesson 3 plan
Do now
• Why might the innate response be unable to control an infection?
• What happens then?
Do now
• Why might the innate response be unable to control an infection?
• What happens then?
• What is ADAPTIVE IMMUNITY?
Do now• What is adaptive immunity?• What happens when innate responses don’t
control the infection?
B lymphocytes are made in the blood– Secrete antibodies
T lymphocytes are made in the thymus– Some help activate immune system responses.– Others attack and kill cells infected with
bacteria or viruses.
Adaptive immune cells are called
Lymphocytes.
• Antigens are:– Not usually found in the host – they are specific to the
pathogen.– They are recognized by a specific receptors on B and T
cells.
The T cell receptor binds antigen that is presented by an innate cell
Adaptive cells ‘see’ Antigens
The B cell receptor can be attached to the cell surface …
….or released from the cell surface as an antibody.
Small group brainstorming:
• At your table, take 10 minutes to complete the worksheet.
Each B and T cell responds to only one antigen
– There are millions of kinds of B cells and T cells
– Each randomly makes one antigen receptor.– They wait in the lymphatic system.– If they ‘see’ their antigen they will respond.
Only the B cells that ‘see’ their antigen respond!
Antigen
How do B cells recognize ‘their’ antigen?
• B cells bind to extracellular antigen.• They cannot ‘see’ an antigen that is inside cells!
• T cells only bind to antigen when it is presented to them by an antigen presenting host cell
• T cells can ‘see’ both extracellular and intracellular antigens!
Extracellular antigen (bacterial infection)
How do T cells recognize ‘their’ antigen?
• T cells only bind to antigen when it is presented to them by an antigen presenting host cell
• T cells can ‘see’ both extracellular and intracellular antigens!
Intracellular antigen (viral infection!)
How do T cells recognize ‘their’ antigen?
How do B and T cells respond?
At your table, discuss the following question:
– Each B and T cell receptor is unique because it was made randomly.
– So, if only one B cell has a receptor that recognizes H1N1, how could this lone cell control the infection?
1. B cells with antigen receptors
2. Bind to a specific antigen
3. Then begin to replicate – clonal expansion increases the pool of B cells available.
Remember, only the antigen specific cells respond.This creates a pool of adaptive recognition specialists!
As soon as B and T cells bind an antigen they begin to replicate – this is called clonal expansion!
Clonal expansion
Homework
• Write one paragraph that summarizes the main points of today’s lesson.