B2 Defending Against Pathogens Flashcards
What type of defences does the human body use?
Non-specific defences, always present
Physical, Chemical, Microbial, the Immune system
List physical defences (3)
Respiratory tract, skin, platelets
What is the respiratory tract?
Nasal passage, trachea, lungs
What are cilia?
Hair like structures that waft the mucus to the back of the throat where it can be swallowed
How does the respiratory tract defend against pathogens?
It is lined with mucus and cilia, the mucus traps particles and the cilia wafts the mucus to the back of the throat where it can be swallowed.
How does the skin defend against pathogens?
The skin acts as a barrier to pathogens
How do platelets act as a defence against pathogens?
Platelets in the blood clump together to plug the wound (blood clotting) this stops you losing blood and prevents microorganisms entering the blood.
List chemical defences(3)
Eyes, saliva, stomach acid
How do the eyes defend against pathogens?
Tears produce an enzyme called lysozyme which breaks down bacteria on the surface of the eyes.
What is the enzyme in tears called?
Lysozyme
How does the mouth defend against pathogens?
Saliva contains molecules that kill pathogens to prevent them reaching the stomach
How does the stomach defend against pathogens?
Produces hydrochloride acid, this kills the pathogens.
What are the body’s microbial defences?
Some pathogens make it past the saliva and the stomach acid in the gut. The have to compete with the Bacteria in the gut to survive.
What is the final defences of the body?
The immune system
Explain a plants physical defences against pathogens
Leaves have a waxy cuticle, which acts as a waterproof barrier.
Plant cells are surrounded by cellulose, this is a physical barrier against pathogens which have made it past the cuticle.
Explain a plants immune system
If a pathogen crosses a plants physical defences, it detects it and responds by producing anti microbial substances as a form of chemical defence.
What are phytoalexins?
Anti microbial substance produced in response to infection by a pathogen
Why is it important for plants to defend themselves against pathogens?
Because they are at the start of most food chains, it is important for the plants and for other organisms.
Example damage to crops by pathogens can threaten human food security.
How do phytoalexins work?
They are thought to disrupt the metabolism and cell structure of some species of fungi and bacteria.
What is the most important part of the immune system?
The white blood cells, they travel around in your blood, patrolling for pathogens.
How do white blood cells identify pathogens?
White blood cells have receptors in their membrane which help them to identify antigens on pathogens.
What part of a cell identifies whether it is a pathogen or not?
Each cell has molecules on its surface called antigens. Each antigen is unique to the specific cell it is found on.
Explain a plants physical defences against pathogens
Leaves have a waxy cuticle, which acts as a waterproof barrier.
Plant cells are surrounded by cellulose, this is a physical barrier against pathogens which have made it past the cuticle.
Explain a plants immune system
If a pathogen crosses a plants physical defences, it detects it and responds by producing anti microbial substances as a form of chemical defence.
What are phytoalexins?
Anti microbial substance produced in response to infection by a pathogen
Why is it important for plants to defend themselves against pathogens?
Because they are at the start of most food chains, it is important for the plants and for other organisms.
Example damage to crops by pathogens can threaten human food security.
How do phytoalexins work?
They are thought to disrupt the metabolism and cell structure of some species of fungi and bacteria.
What is the most important part of the immune system?
The white blood cells, they travel around in your blood, patrolling for pathogens.
How do white blood cells identify pathogens?
White blood cells have receptors in their membrane which help them to identify antigens on pathogens.
What part of a cell identifying whether it is a pathogen or not?
Each cell has molecules on its surface called antigens. Each antigen is unique to the specific cell it is found on.
