Neurons
What is the approximate resting potential of a neuron?
-70 mV
What is the body's normal temperature set point?
37°C
Which hormone regulates water balance by acting on the kidneys?
ADH (antidiuretic hormone)
Which hormone lowers blood glucose concentration?
Insulin
Name the process that maintains stable internal conditions in the body.
Homeostasis
Which part of a neuron receives information from other neurons or receptor cells?
Dendrites
Which control centre acts as the body's thermostat?
Hypothalamus
Which receptors detect changes in blood osmolarity?
Osmoreceptors
Which cells of the pancreas release insulin?
Beta cells
Which hormone is produced by the pancreas and released when blood glucose is low?
Glucagon
During depolarisation, which ion rapidly enters the neuron?
Sodium (Na⁺)
Name two responses that occur when body temperature increases.
Sweating and vasodilation
What happens to ADH release during dehydration?
ADH release increases.
What storage molecule is produced when excess glucose is stored in the liver and muscles?
Glycogen
What is the name of the fluid filtered from blood into Bowman's capsule?
Filtrate
Explain why the refractory period helps nerve impulses travel in one direction.
The recently activated membrane cannot immediately fire again, so the impulse only moves forwards.
Why does shivering help increase body temperature?
Muscle contractions generate heat through increased metabolic activity.
How does ADH increase water reabsorption in the collecting duct?
It causes aquaporin water channels to be inserted into the collecting duct membrane.
Explain how insulin lowers blood glucose concentration.
It stimulates glucose uptake by cells and promotes conversion of glucose into glycogen for storage.
Why does myelination increase the speed of nerve impulses?
Myelin allows saltatory conduction, so impulses effectively jump between gaps in the sheath.
Compare the sodium-potassium pump and voltage-gated ion channels.
The sodium-potassium pump uses ATP and active transport to maintain resting potential, while voltage-gated channels use passive transport to generate action potentials.
A runner finishes a race on a hot day. Outline the complete negative feedback pathway that lowers their body temperature.
Thermoreceptors detect increased temperature → hypothalamus processes information → sweating and vasodilation occur → heat is lost → body temperature returns to 37°C.
A student drinks 2 litres of water in 10 minutes. Explain the negative feedback response that follows.
Blood osmolarity decreases → osmoreceptors detect the change → less ADH is released → collecting ducts become less permeable → less water is reabsorbed → dilute urine is produced → osmolarity returns to normal.
A person has not eaten for 12 hours. Explain how blood glucose is restored to normal.
Low glucose is detected by islets of Langerhans → alpha cells release glucagon → glucagon stimulates glycogen breakdown in the liver → glucose enters the bloodstream → blood glucose returns to normal.
Compare one similarity and one difference between thermoregulation and water regulation.
Similarity: both use negative feedback and a stimulus-response model. Difference: thermoregulation uses thermoreceptors and effectors like sweat glands, while water regulation uses osmoreceptors and ADH acting on the kidneys.