Topic 6 Flashcards
How does the body respond to an antigen?
Immune response
What is a Non-specific immune response
Body’s response to pathogens that works on a wide range of pathogens.
Doesn’t recognise antigens
Not particular for any one pathogen
What are the 3 systems in place as part of the non-specific immune response?
Inflammation
Interferons
Phagocytosis
What is a Specific immune response?
Body’s response to particular antigens on a pathogen’s surface
What happens during an inflammatory response?
The damaged cells (mast cells) release chemicals including histamine if damaged or if pathogens/allergens are detected.
Tissue becomes red, swollen and feels warm.
Blood vessels dilate; Increased blood flow to area; Redness
Increased permeability of capillaries; Fluid enters the tissue; Swelling
White blood cells engulf pathogens
What does histamine do in inflammation?
Histamine causes blood vessels to dilate, which increases vascular permeability
Histamine binds to receptors on local cells, causing them to produce proinflammatory cytokines, which promotes an immune response.
More white blood cells ‘delivered’
What are Interferons?
Anti-viral proteins
Released by cells infected by viruses
Inhibit the production of viral proteins
They signal to neighboring cells to activate defense mechanisms
What are Phagocytes?
Phagocytes are a type of non-specific white blood cell that can engulf and digest foreign material, microorganisms, and dead cells.
They squeeze through capillary walls to enter tissue fluid.
During infection, the number of phagocytes increases
They are attracted by:
Chemicals released by pathogens
Chemicals released by damaged cells; histamine and cytokines
What are the mechanisms of Phagocytosis leading up to digestion of pathogen?
Attracted to area via pathogenic chemicals, cytokines or histamines
Recognise antigens as non-self
plasma membrane extends out to form pseudopodia
Pseudopodia surround and engulf pathogen
Pathogen internalised in a vacuole (endocytosis)
Vesicle fuses with lysosome
Digestive enzymes (protease) breakdown pathogen
What are the mechanisms of phagocytosis after digestion?
After digestion, phagocyte presents the pathogens on it’s surface
Now called an antigen-presenting cell
Antigen is visible to lymphocytes without the pathogen itself, therefore it initiates the specific immune response.
Describe the structure of a virus.
Linear genetic material (RNA or DNA) and viral enzymes such as reverse transcriptase
Surrounded by capsid (proteins coat made out of capsomeres)
No cytoplasm
Describe the structure of an enveloped virus.
simple virus surrounded by matrix protein
matrix protein surrounded by envelope derived from cell membrane of host
attachment proteins on surface
