BiologyCBSE Class 11 · Neural Control and Coordination

Synaptic Transmission and the Parts of the Human Brain

Updated 17 October 2026 · Fact-checked

A synapse is the junction between a neuron and another cell. Chemical synapses transmit impulses by neurotransmitters such as acetylcholine across a synaptic cleft; electrical synapses pass current directly. The human brain, protected by three meninges, has a forebrain (cerebrum, thalamus, hypothalamus), midbrain and hindbrain (pons, cerebellum and medulla).

Understand Synaptic Transmission and the Human Brain

Synapse. The junction between a presynaptic neuron and a postsynaptic neuron.

Electrical synapse: membranes of the pre- and postsynaptic neurons are in very close proximity; current flows directly; faster, rare in our system.
Chemical synapse: the membranes are separated by a fluid-filled space, the synaptic cleft. Impulse arrival at the axon terminal causes synaptic vesicles to fuse with the membrane and release neurotransmitters (for example acetylcholine) into the cleft; they bind specific receptors on the postsynaptic membrane, opening ion channels, which generate a new potential (excitatory or inhibitory). Transmission is one-way. The neurotransmitter is removed (broken down by enzymes, e.g. acetylcholinesterase, or taken up).

Human brain. The central neural system comprises the brain and the spinal cord. The brain is protected by the skull and covered by three layers of cranial meninges: dura mater (outer), arachnoid (middle) and pia mater (inner, in contact with the brain tissue). The brain has three major parts.

Forebrain.

Cerebrum: the largest part, divided into left and right cerebral hemispheres by a deep longitudinal fissure, connected by the corpus callosum. The cerebral cortex (grey matter) has folds (gyri) and grooves (sulci); the inner white matter has myelinated fibres. Three regions: motor areas, sensory areas, association areas (for memory, communication, intersensory associations). Lobes: frontal, parietal, temporal, occipital.
Thalamus: a major coordinating centre for sensory and motor signalling.
Hypothalamus: contains centres for control of body temperature, hunger and thirst, and releases hormones that regulate the pituitary.
Limbic system (inner parts of cerebral hemispheres with the amygdala and hippocampus): regulates sexual behaviour, expression of emotional reactions (excitement, pleasure, rage, fear), motivation and memory.

Midbrain. Between hypothalamus of the forebrain and the pons of the hindbrain; has corpora quadrigemina (four lobes) for reflex vision and hearing.

Hindbrain. Pons (fibre tracts linking different regions; respiratory regulation with pneumotaxic centre), cerebellum (coordination of movement, balance and posture) and medulla oblongata (contains centres for respiration, cardiovascular reflexes and gastric secretion). The midbrain, pons and medulla together form the brain stem; the medulla continues as the spinal cord.

Reflex action. An involuntary response to a stimulus: stimulus → receptor → sensory neuron → spinal cord (interneuron) → motor neuron → effector; the knee jerk is an example.

Draw and label: sagittal section of the human brain with cerebrum, corpus callosum, thalamus, hypothalamus, midbrain, pons, cerebellum, medulla.

Synaptic Transmission and the Human Brain: key facts

Synapse types: Electrical (direct current) | Chemical (neurotransmitter across cleft); One-way in chemical
Meninges: Dura mater
arachnoid
pia mater; Outer to inner
Forebrain: $C er e b r u m ∣ t ha l am u s ∣ h y p o t ha l am u s$; Plus limbic system
Hindbrain: Pons
cerebellum
medulla oblongata; Brain stem includes midbrain

How to answer Synaptic Transmission and the Human Brain questions

Questions ask for brain part functions or synaptic transmission steps.

1Match the function to the part: balance cerebellum; respiration medulla; temperature hypothalamus.
2Write synapse steps in order: arrival, vesicle fusion, release, binding, new potential, removal.
3Name the layers of meninges from outside in.
4Distinguish chemical and electrical synapse by cleft presence.
5Add examples of neurotransmitters.

Synaptic Transmission and the Human Brain in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Walking on a narrow beam

Suppose a gymnast walks steadily along a narrow beam and a stumble is corrected at once.

Which brain part coordinates balance?

Try it first, then show the solutionSolution

The cerebellum coordinates movement and balance.
It receives sensory information and adjusts muscle action.
Damage would lead to clumsy, unsteady movement.

Answer: Cerebellum.

Memory hook: Cerebellum keeps balance.

Tricks to remember Synaptic Transmission and the Human Brain

Short memory aids. Say each one aloud once, then use it on a question the same day.

DAP
Dura, Arachnoid, Pia: outside to inside.
Use it when: Meninges
C-T-H
Cerebrum, Thalamus, Hypothalamus.
Use it when: Forebrain
PCM
Pons, Cerebellum, Medulla.
Use it when: Hindbrain

Synaptic Transmission and the Human Brain: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Chemical synapse · 4 marks · Short answerBoard level

Describe the transmission of an impulse across a chemical synapse.

Try it first, then show the solutionSolution

Impulse reaches the axon terminal and synaptic vesicles fuse with the membrane (1 mark).
Neurotransmitter is released into the synaptic cleft (1 mark).
It binds receptors on the postsynaptic membrane and opens ion channels, creating a new potential (1 mark).
The neurotransmitter is broken down or taken up (1 mark).

Answer: Vesicles release transmitter that binds receptors.

Example 2: Meninges · 2 marks · Very short answerBoard level

Name the three meninges from outside to inside and the one in contact with brain tissue.

Try it first, then show the solutionSolution

Dura mater, arachnoid, pia mater (1 mark).
Pia mater touches brain tissue (1 mark).

Answer: Dura, arachnoid, pia.

Example 3: Brain functions · 4 marks · Short answerHarder board level

Name the brain part responsible for: (a) balance (b) heart rate and respiration centres (c) body temperature and hunger (d) linking the two hemispheres.

Try it first, then show the solutionSolution

(a) Cerebellum (1 mark).
(b) Medulla oblongata (1 mark).
(c) Hypothalamus (1 mark).
(d) Corpus callosum (1 mark).

Answer: Cerebellum, medulla, hypothalamus, corpus callosum.

Example 4: Brain stem · 3 marks · Short answerHarder board level

What constitutes the brain stem? Why is damage to it often fatal?

Try it first, then show the solutionSolution

Midbrain, pons and medulla oblongata (1 mark).
Medulla contains centres for respiration and cardiovascular reflexes (1 mark).
Damage can stop breathing and heart control (1 mark).

Answer: Midbrain + pons + medulla; vital centres.

Example 5: Split brain · 5 marks · Long answerHOTS / competency

If the corpus callosum is cut, predict the effect on the exchange of information between hemispheres and what functions still remain intact. Link with association areas and the limbic system.

Try it first, then show the solutionSolution

Hemispheres cannot communicate directly (1 mark).
Information received by one side cannot be fully shared (1 mark).
Each hemisphere still controls its own sensory and motor areas (1 mark).
Association areas for memory and communication may work in isolation (1 mark).
Limbic system and brain stem functions such as breathing continue (1 mark).

Answer: Poor integration but basic function remains.

Where students lose marks in Synaptic Transmission and the Human Brain

The slips examiners see most often, and what to write instead.

Mistake: Meninges order
Order reversed.
Wrong working
Pia mater is outermost.
Right working
Dura mater is outermost.
Do this: Dura outside.
Usually costs: 1 mark.
Mistake: Cerebellum for respiration
Parts mixed.
Wrong working
Cerebellum controls respiration.
Right working
Medulla controls respiration; cerebellum balance.
Do this: Medulla.
Usually costs: 1 mark.
Mistake: Two-way synapse
Direction.
Wrong working
Chemical synapses are two-way.
Right working
They are one-way.
Do this: One-way.
Usually costs: 1 mark.

Exam tips

Learn the functions in a table.
Write synapse steps in sequence.
Draw a labelled brain.
Mention the corpus callosum.

Practice questions on Synaptic Transmission and the Human Brain

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
The centre for respiration and cardiovascular reflexes is in the
(a) cerebellum (b) medulla oblongata (c) thalamus (d) cerebrum
Hint
Brain stem.
Answer
(b).
Q2 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Chemical synapses transmit impulses in one direction.
Reason (R): Neurotransmitter is released only from the presynaptic terminal and receptors are on the postsynaptic membrane.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Polarity.
Answer
(a).
Q3 · 2 marks · Very short answerBoard level
What is the limbic system and two functions?
Hint
Emotion.
Answer
Inner parts of the cerebral hemispheres with amygdala and hippocampus; regulates sexual behaviour, emotional reactions, motivation and memory.
Q4 · 4 marks · Case-basedHarder board level
Read and answer.
Suppose a patient cannot control body temperature or feels extreme hunger without cause and also has unsteady movements.
(a) Name the part for temperature and hunger. (1)
(b) Name the part for movements. (1)
(c) Name the lobes of the cerebrum. (2)
Hint
Hypothalamus; cerebellum.
Answer
(a) Hypothalamus. (b) Cerebellum. (c) Frontal, parietal, temporal and occipital.
Q5 · 3 marks · Short answerHOTS / competency
Suppose an inhibitor of acetylcholinesterase is applied to a synapse. Predict the effect on the postsynaptic cell and explain.
Hint
Transmitter persists.
Answer
Acetylcholine would persist in the cleft, repeatedly binding receptors, giving prolonged stimulation of the postsynaptic cell, which may lead to continuous contraction or paralysis.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Largest brain part?Show answer
Cerebrum.
2.Corpora quadrigemina in?Show answer
Midbrain.
3.Balance centre?Show answer
Cerebellum.
4.Temperature centre?Show answer
Hypothalamus.
5.Link of hemispheres?Show answer
Corpus callosum.
6.A neurotransmitter?Show answer
Acetylcholine.

Synaptic Transmission and the Human Brain: frequently asked questions

What is a synapse?

Junction between neurons.

What is the synaptic cleft?

Space between neurons at a chemical synapse.

What is a reflex?

An involuntary response to a stimulus.

What are gyri?

Folds of the cerebral cortex.

What is the brain stem?

Midbrain, pons and medulla.