U7 Physiology Flashcards
What is the basic functional unit of the nervous system?
The neurone.
What is the role of dendritic spines?
They increase the surface area for synapses.
What is the function of the cell membrane in a neurone?
Separates the inside of the cell from the exterior environment and controls ion flow.
How are nerve impulses regenerated?
They are regenerated at each point along the axon to maintain strength.
What are ions?
Electrically charged particles formed when electrolytes dissolve in water.
What is the resting potential of a neurone?
Approximately -70 millivolts.
What are the two main forces acting on ions in a neurone?
Electrostatic pressure and diffusion.
What maintains the resting potential of a neurone?
Sodium-potassium pumps.
What happens during depolarisation?
The membrane potential becomes more positive.
What is the ‘threshold of excitation’?
The voltage needed to trigger an action potential.
What is the all-or-none law?
A neurone either fires completely or does not fire at all.
What causes repolarisation in a neurone?
Efflux of potassium (K+) ions out of the cell.
What is hyperpolarisation?
When the membrane potential becomes more negative than the resting potential.
What is the refractory period?
The period during which a neurone cannot or is less likely to fire again.
What is action potential propagation?
The movement of the action potential along the axon.
What role do myelin sheaths play in action potentials?
They insulate axons and increase conduction efficiency.
What is saltatory conduction?
Action potentials jumping from one node of Ranvier to the next.
What causes multiple sclerosis?
The immune system attacks myelin sheaths, disrupting nerve conduction.
What is a synapse?
The gap between neurones where communication occurs.
What is an EPSP?
Excitatory postsynaptic potential caused by depolarisation.
What is an IPSP?
Inhibitory postsynaptic potential caused by hyperpolarisation.
What is temporal summation?
The additive effect of multiple EPSPs in rapid succession.
What is spatial summation?
The additive effect of EPSPs from multiple presynaptic neurones.
What did Loewi’s 1920 experiment demonstrate?
Neurotransmitters communicate messages between neurones.
How are neurotransmitters removed from the synapse?
Through breakdown by enzymes or reuptake by the presynaptic neurone.
What enzyme breaks down acetylcholine?
Acetylcholinesterase.
What is reuptake?
The process by which neurotransmitters are reabsorbed into the presynaptic neurone.
What are autoreceptors?
Presynaptic receptors that regulate neurotransmitter release.
What is the role of nitric oxide in neurotransmission?
Provides negative feedback to inhibit neurotransmitter release.
What is the role of calcium (Ca2+) in synaptic transmission?
Triggers neurotransmitter release from the presynaptic terminal.
