Question

In response to the increased returns of venous blood in the heart, which hormone is secreted and from which part of the human body?
a. ADH from kidney
b. ANF from heart
c. Epinephrine from adrenal medulla
d. Nor- adrenaline from adrenal medulla

Answer 1

Hint: Venous blood is the deoxygenated blood. It travels from the peripheral blood vessels, through the venous system into the right atrium of the heart. The atrial natriuretic factor is a hormone, which is secreted mainly in response to atrial stretch by the heart atria. Antidiuretic hormone(ADH) helps to control blood pressure by acting on the kidneys and the blood vessels.

Complete answer:
> Role of epinephrine and noradrenaline - They create the flight or fright response, whip up metabolism to face special conditions created by physical stress such as fall in BP or blood sugar, anger, fear, etc. All of these conditions require more energy. It is provided by increasing heart rate, blood pressure, the sugar level of blood.

> Sympathetic activation of veins has various impacts like decreased venous compliance, increases central venous pressure. It promotes venous return indirectly by augmenting cardiac output, which increases the total blood flow through the circulatory system.

> Venous blood return to the right atrium is the most important factor. It helps in determining cardiac output, provided both ventricles and the pulmonary circulation are normal. From the systemic venous reservoir, venous return to the right atrium occurs along the venous pressure gradient.

> The heart needs to pump more blood; it leads to stretch in heart walls when there is increased venous return to the heart. In response to the stretch in heart walls, the heart walls release Atrial natriuretic factor(ANF) into the blood circulation. ANF binds to ANF Receptor -Antagonist. Binding leads to the increase in renal sodium excretion, which in turn results in a decreased ECF and blood volume.

Hence, the correct answer is option (B).

Note: When the venous blood flows into the heart, it leads to the stretching of the heart walls. In response to the stretching of the walls, hormone ANF is released. The hormone further binds to the antagonistic receptor which leads to the excretion of renal sodium leading to decreased ECF and blood volume. Hence, ANF is released from the heart in response to the venous blood.