A person entering an empty room suddenly finds a snake right in front on opening the door. Which one of the following is likely to happen in his neuro-hormonal control system?
- Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal medulla.
- Neurotransmitters diffuse rapidly across the cleft and transmit a nerve impulse.
- Hypothalamus activates the parasympathetic division of brain.
- Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal cortex.
Answer
(1) Sympathetic nervous system is activated releasing epinephrine and norepinephrine from adrenal medulla.
Solution
Sudden fear is an emergency (stress) situation.
As per NCERT, the adrenal medulla secretes adrenaline (epinephrine) and noradrenaline (norepinephrine), commonly called catecholamines; they are secreted rapidly in response to stress of any kind and during emergency situations, and are called emergency hormones or hormones of fight or flight.
The adrenal medulla is stimulated by the sympathetic nervous system, while the adrenal cortex secretes corticoids, not catecholamines.
∴ The sympathetic nervous system is activated, releasing epinephrine and norepinephrine from the adrenal medulla.
Answer: (1)