Which hormone increases blood pressure by constricting arterioles during severe hemorrhage?

RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Applied Physiology

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Explanation

Anti-diuretic hormone (ADH), also known as vasopressin, is released from the posterior pituitary gland in response to severe blood loss and a drop in blood pressure.
At the high concentrations seen during hemorrhage, ADH binds to V1a receptors on the smooth muscle of arterioles, causing potent vasoconstriction.
This vasoconstriction increases total peripheral resistance, which is a primary mechanism for acutely raising arterial blood pressure to compensate for volume loss.
The name 'vasopressin' itself refers to this function: 'vaso' for vessel and 'pressin' for pressing or constricting.

Option A: Follicle-stimulating hormone (FSH) is a gonadotropin from the anterior pituitary gland. Its main role is to stimulate the growth of ovarian follicles in females and spermatogenesis in males.
Option B: Oxytocin is released from the posterior pituitary, but its primary functions are stimulating uterine contractions during labor and milk ejection during lactation. It has only very weak vasopressor effects.
Option D: Luteinizing hormone (LH) is another gonadotropin from the anterior pituitary. It triggers ovulation and stimulates the production of testosterone. It is not involved in the acute management of blood pressure.

Visual 1: Diagram: A flowchart showing the physiological response to hemorrhage. It should depict decreased blood volume/pressure triggering baroreceptors, leading to ADH release from the posterior pituitary, and ADH acting on arterioles (vasoconstriction) and kidneys (water retention) to restore blood pressure.

Clinical Relevance

Nursing practice connection: Knowing Hormonal regulation of blood pressure during hemorrhage helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses must understand that in a patient with hemorrhage, the body's compensatory mechanisms, like ADH-induced vasoconstriction, can temporarily maintain a normal blood pressure, masking the true extent of volume loss. A sudden drop in BP may indicate these mechanisms are failing.
What if the patient had Diabetes Insipidus? A patient with central diabetes insipidus cannot produce or release ADH. In a hemorrhage, they would lack this critical vasoconstrictive response, leading to a more rapid and severe drop in blood pressure, making them extremely vulnerable to hypovolemic shock.
Synthetic vasopressin is used clinically in hypotensive emergencies, such as vasodilatory shock (e.g., septic shock) and during cardiac arrest, precisely for its potent vasoconstrictive properties.

How to Approach the Question

Analyze the question's core concept: a hormone that responds to 'severe hemorrhage' by 'constricting arterioles' to 'increase blood pressure'.
Recall the major endocrine glands and their hormones. The pituitary gland is a key regulator of many body systems.
Evaluate the options. Recognize that FSH and LH are primarily gonadotropins involved in reproduction, making them unlikely candidates for an acute hemodynamic response.
Differentiate between the two posterior pituitary hormones: Oxytocin and ADH. While structurally similar, recall that Oxytocin's main roles are in childbirth and lactation.
Identify ADH (also known as Vasopressin, a name that literally means 'vessel presser') as the hormone specifically responsible for both water retention (antidiuretic effect) and, crucially in this context, vasoconstriction (pressor effect) to manage blood pressure.

Concept Tested & Keywords

Concept Tested: Hormonal regulation of blood pressure during hemorrhage
Stem keywords: hormone, increases blood pressure, constricting arterioles, severe hemorrhage
Lead-in keywords: Which
Negative lead-in flag: false

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