Question

Explain the interactions among components of the nervous system in mediating the stress response.

Answer 1

Nervous system

Cerebral cortex

It evaluats the psychological event/ emotional event /stressor in the light of past experiences and future consequences and based on that develop a plan of action. These functions are involved in the percetion of a stressor

Limbic system

Limbic system lies in the inner midportion of the brain near to the base of the brain. The limbic system is an important mediator of emotions and behaviour. When the limbic system is stimualted, emotions,feelings and behaviours can occur that ensure survival and self-preservation

Reticular formation

It is located between the lower end of brain stem and thalamus. It contains reticular activating system (RAS), which sends impulses contributig to alertness to the limbic system and to the cerebral cortex. When the RAS is stimulated, it increases its output of impulses, leading to wakefulness. Stress usually increases the degree of wakefulness and can lead to sleep disturbances

Hypothalamus

It lies at the base of the brain just above the pituitary gland has many functions that assist in adaptation to stress. Stress activates the limbic system, which inturn stimulates the hypothalamus. Because the hypothalamus secretes neuropeptides that regulate the hormones by anterior pituitary, it is central to the connection between nervous and endocrine responses to stress

Effect on Sympathetic and parasympathetic nervous system

Hypothalamus plays a primary role in the stress response by regualating the functions of both smpathetic and parasympathetic nervous sytstem. When a stressor is perceived by an individual, the hypothalamus sends signals that initiate both nervous and endocrine responses to the stressor. it does this primarily by sending impulses to sympathetic nervous system (SNS) and by relesing Corticotropin -releasing hormone(CRH) which stimulates anterior pituitary to release adrenocorticotropin hormone(ACTH)

Once the hypothalamus get activated , the SNS system gets involved . The SNS stimulates adrenal medulla to release norepinephrine and epinephrine (catecholamines). The effect of catecholamines and SNS including the response of adrenal medulla is referred as sympathoadrenal response. Epinephrine or norepinephrine prepares the body for fight or flight response that leads to increased heart rate and respiratory rate, increased blood pressure, muscle tension, increased brain activity and dcreased skin temperature