Neuronal Communication Flashcards
(30 cards)
What is neuronal communication?
The process of transmitting electrical and chemical signals between neurons and effectors.
What are the main types of neurons?
Sensory neurons, relay neurons, and motor neurons.
What is the role of sensory neurons?
Transmit impulses from receptors to the CNS.
What is the role of motor neurons?
Transmit impulses from the CNS to effectors (muscles or glands).
What is the role of relay neurons?
Connect sensory and motor neurons within the CNS.
What is a receptor?
A cell or protein that detects stimuli and initiates a nerve impulse.
What is a generator potential?
A small depolarisation in a receptor cell caused by a stimulus, leading to an action potential if threshold is reached.
What is resting potential?
The difference in charge across the membrane of a neuron at rest (~-70 mV).
How is resting potential maintained?
By the sodium-potassium pump (3 Na⁺ out, 2 K⁺ in) and potassium ion channels.
What is an action potential?
A rapid, temporary change in membrane potential when a neuron is stimulated (~+40 mV).
What is the threshold potential?
The minimum depolarisation needed to trigger an action potential (usually around -55 mV).
What happens during depolarisation?
Voltage-gated sodium channels open, Na⁺ enters, making the inside of the cell more positive.
What happens during repolarisation?
Voltage-gated sodium channels close, potassium channels open, K⁺ leaves the cell.
What is hyperpolarisation?
When the membrane potential becomes more negative than resting due to excess K⁺ leaving.
What is the refractory period?
A short period after an action potential where the neuron cannot fire again.
What is saltatory conduction?
In myelinated axons, the action potential jumps between nodes of Ranvier, increasing speed.
How does myelination affect conduction?
Myelin insulates the axon, allowing faster transmission of impulses.
What is a synapse?
A junction between two neurons where neurotransmitters transmit signals across a synaptic cleft.
What is the synaptic cleft?
The gap between the pre- and postsynaptic neurons.
What happens when an action potential reaches the synaptic knob?
Calcium channels open, Ca²⁺ enters, vesicles release neurotransmitter into synaptic cleft.
What is the role of acetylcholine?
It binds to receptors on the postsynaptic membrane, triggering a new action potential.
What enzyme breaks down acetylcholine?
Acetylcholinesterase, breaking it into ethanoic acid and choline.
What happens to the breakdown products of acetylcholine?
They are reabsorbed into the presynaptic neuron and recycled.
What is temporal summation?
Multiple impulses in quick succession from one presynaptic neuron to reach threshold.
