Human Anatomy and Physiology : Neural Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

Example Question #21 : Help With Neurotransmitter And Receptor Physiology

What is saturability?

Possible Answers:

There is a finite number of neurotransmitter molecules, and excess receptors for binding will not be able to saturate the neurotransmitter molecules, resulting in excess signaling.

None of the answers are correct.

There are a finite number of action potentials that can be concurrently occurring in the CNS, and this is referred to as saturability.

There is a finite number of receptors in a given tissue, and excess neurotransmitters will saturate these receptors.

Saturability refers to the finite amount of neurotransmitter receptors that can be embedded into the neuronal membrane before there is no more space.

Correct answer:

There is a finite number of receptors in a given tissue, and excess neurotransmitters will saturate these receptors.

Explanation:

There are a finite number of receptors for a neurotransmitter in a neuron. When neurotransmitter molecules are released, they will bind these receptors. Since the number of neurotransmitters is greater than the number of neurotransmitter receptors, there will be a saturation of receptors with neurotransmitter. This is the term 'saturability.'

Example Question #22 : Help With Neurotransmitter And Receptor Physiology

A neurotransmitter with high affinity for its receptor will have a __________ association constant (Ka) and __________ dissociation constant (Kd).

Possible Answers:

high association constant; high dissociation constant

low association constant; low dissociation constant

variable association constant; low dissociation constant

high association constant; low dissociation constant

low association constant; High dissociation constant

Correct answer:

high association constant; low dissociation constant

Explanation:

The affinity of a neurotransmitter for its receptor is governed by its association and dissociation constants. The association constant describes how readily it associates with the receptor. Therefore, a higher association constant means more ready association with the receptor, and higher affinity. On the other hand, the dissociation constant describes how readily it dissociates from the receptor. Therefore, a higher dissociation constant means more ready dissociation from the receptor, and lower affinity. Therefore, a high association constant and low dissociation constant means the neurotransmitter readily binds but does not readily unbind from the receptor, meaning it has a high affinity.

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