Question

Cardiac centre can moderate the cardiac functions through (a) Somatic neural system (b) Parasympathetic nervous system only (c) Autonomic nervous system (ANS) (d) Sympathetic nervous system only

Short answer

The autonomic nervous system (ANS) moderates the cardiac functions.

Step-by-step solution

Identify the different options

First, identify the different options given - Somatic neural system, Parasympathetic nervous system only, Autonomic nervous system (ANS), and Sympathetic nervous system only.

Understand the autonomic nervous system's role

Next, delve into understanding what the autonomic nervous system (ANS) does. ANS is a part of the nervous system that controls and regulates the internal organs without any conscious recognition or effort. The Autonomic nervous system has two important components: the Sympathetic and the Parasympathetic nervous systems. Both are responsible for the body's automatic functions like digestion, respiration, and specifically in this context, cardiac function.

Analyze the other options

After having understood the function of ANS, analyze the other given options. The somatic nervous system includes actions that are voluntary, while the only sympathetic or only parasympathetic nervous system would not give a complete control over the heart function, as they both work together in this regulation.

Identify the correct choice

Given the role of both the Sympathetic and Parasympathetic nervous systems in controlling cardiac functions and that they both are parts of the ANS, it is clear that 'Autonomic nervous system (ANS)' is the correct answer.

Key concepts

Cardiac Function

Cardiac function refers to the ability of the heart to pump blood effectively throughout the body. It is crucial for delivering oxygen and nutrients to various tissues and removing waste products. The heart achieves this via a coordinated contraction and relaxation cycle known as the cardiac cycle.
To understand cardiac function, it's important to look at how the heart responds to different needs of the body. The body may require more or less blood flow depending on the activity being performed, such as resting or exercise. Adjustments in cardiac function to meet these needs are regulated by the autonomic nervous system (ANS).
The cardiac cycle includes two main phases:

• Systole: The phase where the heart's ventricles contract and pump blood out to the arteries.
• Diastole: The phase where the heart relaxes after contraction, allowing the chambers to fill with blood.

The heart rate and the force of contraction can change based on signals from the ANS, optimizing the cardiac output, which is the volume of blood the heart pumps per minute.

Sympathetic Nervous System

The sympathetic nervous system is a crucial part of the autonomic nervous system responsible for the 'fight or flight' response. It prepares the body to respond to stress or emergencies by triggering several physiological changes.
In the context of cardiac function, the sympathetic nervous system increases the heart rate and the force of contraction. This ensures that more blood is delivered to muscles and vital organs during periods of high demand.
Key functions include:

• Increased Heart Rate: During stress, the sympathetic nervous system stimulates the heart to beat faster to quickly circulate blood.
• Enhanced Contractility: It enhances the strength of heart muscle contractions, improving blood flow.
• Vasoconstriction: The sympathetic nervous system causes blood vessels to constrict, increasing blood pressure to reach distant tissues efficiently.

These responses are automatic and occur without conscious effort, reflecting the involuntary nature of the autonomic nervous system.

Parasympathetic Nervous System

The parasympathetic nervous system, another key component of the autonomic nervous system, helps balance the body's responses by promoting 'rest and digest' activities. It works to conserve energy and maintain long-term health.
With regards to cardiac function, the parasympathetic nervous system acts to slow down the heart rate and decrease the force of contractions, encouraging the body to return to a relaxed state.
Important roles include:

• Reduced Heart Rate: It reduces the speed at which the heart beats, conserving energy and allowing recovery.
• Decreased Contractile Force: By lessening the heart's contraction strength, it reduces the workload on the heart.
• Promoting Restorative Functions: Encourages digestion and metabolic processes that are inhibited during stress.

By functioning in opposition to the sympathetic nervous system, the parasympathetic system helps maintain homeostasis, ensuring that the body responds appropriately depending on the situation.