The action of the sympathetic system in the walls of airways is called as:

ESIC Nursing Officer -2019 (Shift -1)

Applied Physiology

Easy

Appeared in: ESIC Nursing Officer -2019 (Shift -1)

Explanation

The sympathetic nervous system is responsible for the body's 'fight or flight' response, which requires increased oxygen intake.
To meet this demand, sympathetic stimulation causes the smooth muscles in the walls of the bronchioles to relax.
This relaxation leads to a widening of the airways, a process known as bronchodilation.
Bronchodilation decreases airway resistance, allowing for a greater volume of air to move into the lungs with each breath.
This action is primarily mediated by hormones like epinephrine and norepinephrine acting on beta-2 (β₂) adrenergic receptors in the bronchial tree.

Option A: Bronchoconstriction is the narrowing of the airways, which is the opposite of the sympathetic system's effect. It restricts airflow.
Option B: The sympathetic system does not primarily cause increased secretion in the airways. This action is mainly attributed to the parasympathetic system.
Option D: Increased gas exchange is a consequence or outcome of bronchodilation, not the direct action on the airway walls. The direct action is the muscular relaxation that allows for better airflow.

Visual 1: Diagram - An illustration comparing the effects of the sympathetic (bronchodilation) and parasympathetic (bronchoconstriction) nervous systems on the bronchial airways. This helps visualize the change in airway diameter.
Visual 2: Flowchart - A flowchart showing the pathway from sympathetic stimulation -> release of epinephrine/norepinephrine -> binding to β₂ receptors -> smooth muscle relaxation -> bronchodilation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Autonomic Nervous System Control of the Respiratory System as background academic context rather than a clinical decision trigger.
Understanding bronchodilation is crucial for treating respiratory conditions like asthma and Chronic Obstructive Pulmonary Disease (COPD).
Medications known as beta-2 agonists (e.g., Albuterol, Salbutamol) are widely used as 'rescue inhalers'. They mimic the action of the sympathetic nervous system to rapidly open constricted airways and relieve symptoms like wheezing and shortness of breath.
What if? - If a patient with asthma is mistakenly given a non-selective beta-blocker (a drug that blocks beta-receptors), it can block the bronchodilatory effects needed to maintain open airways and may even trigger a severe asthma attack. This is why cardioselective beta-blockers are preferred in patients with respiratory conditions.

How to Approach the Question

First, identify the key components of the question: 'sympathetic system' and 'action... in the walls of airways'.
Recall the two main branches of the autonomic nervous system: sympathetic ('fight or flight') and parasympathetic ('rest and digest').
Think about the physiological needs during a 'fight or flight' situation. The body needs more oxygen, so the airways must open to allow more air in.
Evaluate the options based on this logic. 'Bronchodilation' means widening of the airways, which matches the body's need for more air.
Eliminate the other options. 'Bronchoconstriction' is the opposite effect. 'Increased secretion' is a parasympathetic function. 'Increased gas exchange' is a result of bronchodilation, not the direct action itself.

Concept Tested & Keywords

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