Dr Gawad Physiology Course - Lecture 1 (Synaptic Transmission) Online Exam

1.

About synaptic transmission, which is true:

A.

It is initiated by closure of the Ca voltage gated channels.
B.

It is only inhibitory.
C.

Central excitation means that the post synaptic neurons receives equal number of stimulatory and inhibitory neurons.
D.

None of the above.

Correct Answer
D. None of the above.

Explanation
The given answer states that none of the statements about synaptic transmission are true. This means that the closure of Ca voltage gated channels does not initiate synaptic transmission, synaptic transmission is not only inhibitory, and central excitation does not mean that the post synaptic neuron receives an equal number of stimulatory and inhibitory neurons.

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2.

About synaptic transmission, which of the following is false:

A.

The direction of conduction is unidirectional.
B.

It can be summated.
C.

Post-tetanic facilitation can be observed after repetitive stimulation of the presynatpic neuron.
D.

Acidosis increases neural activity.

Correct Answer
D. Acidosis increases neural activity.

Explanation
Acidosis refers to a condition where there is an increase in acidity in the body. In this condition, neural activity is actually decreased rather than increased. Acidosis can disrupt the normal functioning of neurons and impair their ability to transmit signals effectively. This can lead to a decrease in neural activity and potentially cause various neurological symptoms. Therefore, the statement that acidosis increases neural activity is false.

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3.

About synaptic transmission, which of the following is true:

A.

Electrical synapse conduction is slower than chemical synapse conduction of impulse
B.

Exocytosis of chemical transmitter in synapse is directly proportional to the Ca influx to the knob
C.

Central inhibitory state means that post synaptic neuron has more presynaptic excitatory neurons
D.

There is no synaptic delay in chemical synapse

Correct Answer
B. Exocytosis of chemical transmitter in synapse is directly proportional to the Ca influx to the knob

4.

About synaptic chemical transmitters, which of the following is true:

A.

Acetyl choline is an inhibitory transmitter
B.

GABA is a stimulatory transmitter
C.

Noradrenaline is a stimulatory transmitter
D.

Serotonin is inhibitory transmitter, while glycine is a stimulatory one

Correct Answer
C. Noradrenaline is a stimulatory transmitter

Explanation
Noradrenaline is a stimulatory transmitter because it is involved in the fight or flight response, which activates the sympathetic nervous system and increases heart rate, blood pressure, and alertness. It acts on adrenergic receptors to stimulate the target cells and promote excitatory effects in the body.

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5.

Regarding excitatory post synaptic potential (EPSP), which of the following is true:

A.

It is a propagated potential
B.

It lasts for more than 15 milliseconds
C.

It leads to complete depolarization
D.

It increases the neuronal potential and reach the threshold (firing) level
E.

It increases the excitability of the post synaptic neuron

Correct Answer
E. It increases the excitability of the post synaptic neuron

Explanation
The correct answer is that an excitatory post synaptic potential (EPSP) increases the excitability of the post synaptic neuron. EPSPs are small, localized changes in the membrane potential of a neuron that are caused by the release of excitatory neurotransmitters from the presynaptic neuron. These EPSPs can summate and reach the threshold level, leading to the generation of an action potential in the post synaptic neuron. Therefore, EPSPs increase the likelihood of the post synaptic neuron firing an action potential and are responsible for the transmission of excitatory signals in the nervous system.

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6.

Pre-synaptic inhibition is mainly through:

A.

Release of GABA inhibitory transmitter from the interneuron to inhibit the postsynaptic neuron
B.

It is mainly by neurotransmitter serotonin
C.

Inhibitory synaptic knob (of the interneuron) release GABA to inhibit the presynaptic neuron
D.

None of the above

Correct Answer
C. Inhibitory synaptic knob (of the interneuron) release GABA to inhibit the presynaptic neuron

Explanation
The correct answer is that inhibitory synaptic knobs of the interneuron release GABA to inhibit the presynaptic neuron. GABA is an inhibitory neurotransmitter that helps regulate the activity of neurons in the brain. When GABA is released from the inhibitory synaptic knobs, it binds to receptors on the presynaptic neuron, reducing the release of neurotransmitters and inhibiting the transmission of signals between neurons. This process is known as pre-synaptic inhibition.

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7.

Inhibitory post synaptic potential (IPSP) is through:

A.

Increase the permeability of Na ion in the post synaptic membrane
B.

Increase the influx of K ion and the outflux (efflux) of Cl ion in the post synaptic membrane
C.

Produces a hyperpolarization state at the post synaptic potential (i.e. more intracellular negativity and more extracellular positivity)
D.

Acetyl choline is the main neurotransmitter

Correct Answer
C. Produces a hyperpolarization state at the post synaptic potential (i.e. more intracellular negativity and more extracellular positivity)

Explanation
IPSP, or inhibitory post synaptic potential, refers to a change in the membrane potential of a postsynaptic neuron that makes it less likely to generate an action potential. It is achieved by increasing the permeability of the postsynaptic membrane to potassium (K+) ions and the outflux (efflux) of chloride (Cl-) ions. This increased permeability leads to a hyperpolarization state, where the intracellular environment becomes more negative and the extracellular environment becomes more positive. This inhibitory effect is crucial for maintaining the balance between excitatory and inhibitory signals in the nervous system. Acetylcholine is not specifically mentioned as the main neurotransmitter in this context.

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