Question

A scientist hypothesizes that the pancreas’s hormone production is controlled by neural stimuli. Which observation would support this hypothesis?

a. Insulin is produced in response to sudden stress without a rise in blood glucose.

b. Insulin is produced in response to a rise in glucagon levels.

c. Beta cells express epinephrine receptors.

d. Insulin is produced in response to a rise in blood glucose in the brain.

Short answer

The option a is the correct answer.

Step-by-step solution

Introduction

Neural stimuli are when the neurological system directly causes the release of hormones from the endocrine glands. Remember that the hormones adrenaline and norepinephrine are crucial for supplying the quick bursts of energy needed for the body to react during a short-term stress response. Here, sympathetic nervous system neuronal communication directly activates the adrenal medulla to release the stress-related chemicals adrenaline and norepinephrine.

The explanation for the correct answer

So, in this case, the hormone insulin is produced or released due to sudden stress or disturbance in the body which leads to its secretion without any rise in blood glucose. Therefore, option a i.e., Insulin is produced in response to sudden stress without a rise in blood glucose, directly supports neural stimuli.

The explanation for incorrect options

Generally, the humoral stimulus occurs which is a change in the extracellular fluids, such as blood, or the ion concentration in the blood, which affects the release of hormones. For instance, a spike in blood glucose levels causes the release of insulin from the pancreas. In a negative feedback loop, as blood glucose levels fall as a result of insulin, the pancreas is alerted to stop manufacturing insulin.

The three options namely, Option, c, and d are related to changes in the extracellular fluids such as ionic concentration of blood that affects the release of hormones. Therefore, these three options are hormonal stimuli rather than neural stimuli.