Question

Which of the following statements is correct?
A. Electrical synapses are more common in our neural system than chemical synapses.
B. The new potential in postsynaptic neurons may be either excitatory or inhibitory.
C. Hypothalamus is the major coordination centre for sensory and motor signalling.
D. The tracts of nerve fibres that connect two cerebral hemispheres are called corpora bigemina.

Answer 1

Hint: Synapses are specific junctions formed inside the nervous system, precisely between two neurons. This gap between the two acts as a pathway for the transmission of signals. These are of two types: Electrical and Chemical.

Complete Step by Step Answer:
Electrical synapses have synthetic clefts (gaps) which allow the transmission of ions from one neuron to the other. Its signalling can be bi-directional, that is to say, any of the two neurons can be either pre synaptic neuron or postsynaptic neuron.

Chemical synapses have a fixed presynaptic and postsynaptic neuron. The presynaptic neuron releases neurotransmitter to the postsynaptic neuron. These are more common due to their role played in both secretory and inhibitory and excitatory signalling.
The new potential in postsynaptic neurons may be either excitatory or inhibitory, depending upon which they are named EPSP (Excitatory PostSynaptic Potential) and IPSP (Inhibitory PostSynaptic Potential). EPSPs tend to increase the intensity of action potential while IPSPs tend to decrease it.

Thalamus, surrounded by cerebrum, is the major coordination centre for sensory and motor signalling.
The tracts of nerve fibres that connect two cerebral hemispheres are called corpus callosum. This is an entirely white matter region as it consists of millions of axons or long slender nerve fibres.

Thus, the correct answer is B: The new potential in postsynaptic neurons may be either excitatory or inhibitory.


Note: Electrical synapses can perform transmission in both directions and are specifically present between neurons while in chemical synapses the signalling occurs only in one direction which can occur between one neuron and another non-neuronal cell.
Since the corpus callosum is located between the two hemispheres of the brain, it allows communication between the same.