Neurotransmitters, receptors and feedback control
Practice Flashcards
Flip to reveal answersWhat is a neurotransmitter, and where does it act?
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 7 Flashcards — Neurotransmitters, receptors and feedback control
Sign up free to track progress and get spaced-repetition review schedules.
Question
What is a neurotransmitter, and where does it act?
Answer
A **chemical signal** released at a **synapse**; it diffuses across the cleft and **binds receptors** on the postsynaptic membrane.
Question
What actually triggers the response at a synapse?
Answer
The neurotransmitter **binding its receptor** on the postsynaptic membrane — a neurotransmitter in the cleft does nothing until it binds.
Question
What makes a response excitatory?
Answer
The receptor opens channels that let **positive ions (Na⁺) in** → the membrane **depolarises** → the neuron is **more likely to fire**.
Question
What makes a response inhibitory?
Answer
The receptor opens channels that let **Cl⁻ in (or K⁺ out)** → the membrane **hyperpolarises** → the neuron is **less likely to fire**.
Question
How can one neurotransmitter excite one cell and inhibit another?
Answer
The **receptor decides**, not the neurotransmitter — different receptors open different ion channels, so the same signal gives opposite effects.
Question
How is a synaptic signal switched off, and why?
Answer
The neurotransmitter is **removed (re-uptake)** or **broken down by an enzyme**, so the receptors empty and the signal stops — keeping it **brief and controlled**.
Question
How does negative feedback control chemical signalling?
Answer
A **rising response inhibits further signalling**, so the response stops growing and the system **returns to its set point**.
Read the notes
Full study notes for Neurotransmitters, receptors and feedback control
Topic 3.4 hub
Chemical signalling
More from Topic 3.4
All flashcards in this topic
Biology exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free