Homeostasis
What is homeostasis?
The maintenance of stable internal conditions in the body.
Does negative feedback increase or reverse a change in the body's internal conditions?
It reverses the change, helping return conditions towards their normal range.
What is the body's first line of defence against pathogens?
Physical and chemical barriers, such as skin, mucus and stomach acid.
What is a pathogen?
A biological agent that can cause disease.
What is the main purpose of a vaccine?
To prepare the immune system to recognise and respond to a pathogen, reducing the risk of disease.
Name TWO internal conditions regulated through homeostasis.
Including but not limited to: body temperature, blood pressure, blood glucose, water balance, blood pH
What is a stimulus in a negative feedback loop?
A change in an internal or external condition that triggers a response.
Which immune cells produce antibodies: B cells or T cells?
B cells, after developing into plasma cells.
Name THREE types of pathogens.
Any three: viruses, bacteria, fungi and parasites.
How many types of vaccines have we looked at this term?
Six.
What happens to blood vessels near the skin when the body becomes too hot?
They dilate (widen), allowing more heat to be lost through the skin.
Name the THREE main components of a negative feedback loop that detect, coordinate and carry out a response.
Receptor, control centre and effector.
A cut becomes red, swollen and warm. Which line of defence is responsible for this inflammatory response?
The second line of defence (innate immune response).
What are antigens, and why are they important in the immune response?
Antigens are molecules recognised by the immune system as targets. They can trigger a specific immune response, including the production of antibodies.
What is the difference between an inactivated vaccine and a live attenuated vaccine?
An inactivated vaccine contains a killed or inactivated pathogen; a live attenuated vaccine contains a weakened living pathogen.
Why is sweating less effective at cooling the body in very humid conditions?
High humidity slows sweat evaporation, reducing the amount of heat removed from the body.
A person's body temperature drops below normal. Identify TWO responses that help restore their temperature.
Shivering and narrowing of blood vessels near the skin (vasoconstriction).
Explain how memory B cells and memory T cells help the body respond to a pathogen it has encountered before.
Memory B cells enable a faster antibody response, while memory T cells help coordinate the immune response or destroy infected cells more quickly.
A person contracts malaria after being bitten by an infected mosquito. Identify the pathogen type and transmission method.
Pathogen: parasite (Plasmodium).
Transmission: vector transmission through a mosquito.
How do mRNA vaccines help the immune system recognise a pathogen?
They provide instructions for body cells to temporarily produce a pathogen antigen, triggering an immune response.
During exercise, breathing rate and heart rate increase. Explain how BOTH responses help maintain homeostasis.
Faster breathing increases oxygen uptake and carbon dioxide removal. A faster heart rate transports oxygen to working muscles and removes carbon dioxide more quickly.
A person's body temperature rises. Explain the negative feedback process using the terms stimulus, receptor, control centre, effect
Stimulus: Body temperature rises.
Receptor: Temperature receptors detect the change.
Control centre: The hypothalamus processes the information.
Effect: Sweating and vasodilation increase heat loss, returning temperature towards normal.
Explain how B cells and T cells work together to defend the body against a pathogen.
Helper T cells activate B cells, which develop into plasma cells that produce antibodies. Cytotoxic T cells destroy infected body cells, while memory B and T cells provide a faster response to future infections.
Compare how bacteria and viruses, which are living and how do they reproduce?
Bacteria are living cells that can reproduce independently by dividing.
Viruses are non-living and must use host cells to reproduce.
Explain how vaccines prepare the immune system to respond to a pathogen before an infection occurs.
Vaccines introduce safe antigens.
Immune cells detect the antigens as part of the immune response.
Memory B and T cells remember the antigen and remain ready.
When the immune system next encounters the antigen a rapid response can be triggered, lessening the effects of the disease.