Question

a)Explain how the blood pressure is regulated if the pressure is dropping. b) What happens to the secretion of aldosterone, ADH and atrial natriuretic peptide when the pressure is dropping? c)There are four groups of hormone receptors (membrane bound, etc.). Name one hormone for each receptor type.

Answer 1

Ans a. A decrease in blood pressure causes a decrease in action potentials sent to the cardio regulatory center of the medulla. Therefore, to raise blood pressure, the body will first cause an increase in sympathetic nerve activity to the SA node, causing it to fire more frequently, which increases the hear rate.

Low blood pressure that either doesn't cause signs or symptoms or causes only mild symptoms rarely requires treatment.

If you have symptoms, treatment depends on the cause. For instance, when medication causes low blood pressure, treatment usually involves changing or stopping the medication or lowering the dose.

If it's not clear what's causing low blood pressure or no treatment exists, the goal is to raise your blood pressure and reduce signs and symptoms. Depending on your age, health and the type of low blood pressure you have, you can do this in several ways:

Use more salt. Experts usually recommend limiting salt in your diet because sodium can raise blood pressure, sometimes dramatically. For people with low blood pressure, that can be a good thing.

But because excess sodium can lead to heart failure, especially in older adults, it's important to check with your doctor before increasing the salt in your diet.

Drink more water. Fluids increase blood volume and help prevent dehydration, both of which are important in treating hypotension.

Wear compression stockings. The elastic stockings commonly used to relieve the pain and swelling of varicose veins can help reduce the pooling of blood in your legs.

Medications. Several medications can be used to treat low blood pressure that occurs when you stand up (orthostatic hypotension). For example, the drug fludrocortisone, which boosts your blood volume, is often used to treat this form of low blood pressure.

Doctors often use the drug midodrine (Orvaten) to raise standing blood pressure levels in people with chronic orthostatic hypotension. It works by restricting the ability of your blood vessels to expand, which raises blood pressure.

Exercise regularly.

Eat a healthy diet.

Reduce sodium in your diet.

Limit the amount of alcohol you drink.

Quit smoking.

Cut back on caffeine.

Reduce your stress

Ans b.   If decreased blood pressure is detected, the adrenal gland is stimulated by these stretch receptors to release aldosterone, which increases sodium reabsorption from the urine, sweat, and the gut. This causes increased osmolarity in the extracellular fluid, which will eventually return blood pressure toward normal.Many patients with symptoms of fatigue and often salt-craving, “cognitive fuzziness”, dizziness or lightheadedness on standing, or palpitations have low blood levels of aldosterone.

Lowered osmolarity decreases ADH secretion, causing loss of water over salt in the kidney and the blood osmolarity returns toward normal. Increased osmolarity increases ADH secretion, leading to reabsorption of water

Atrial Natriuretic Hormone

They promote loss of sodium and water from the kidneys, and suppress renin, aldosterone, and ADH production and release. All of these actions promote loss of fluid from the body, so blood volume and blood pressure drop

Reduction of blood volume by ANP can result in secondary effects such as reduction of extracellular fluid (ECF) volume (edema), improved cardiac ejection fraction with resultant improved organ perfusion, decreased blood pressure, and increased serum potassium. These effects may be blunted or negated by various counter-regulatory mechanisms operating concurrently on each of these secondary effects.

Ans c. A hormone receptor is a molecule that binds to a specific hormone. Receptors for peptide hormones tend to be found on the plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm.

the stretch receptors located in the atria of the heart. If decreased blood pressure is detected, the adrenal gland is stimulated by these stretch receptors to release aldosterone, which increases sodium reabsorption from the urine, sweat, and the gut.

ADH is also called arginine vasopressin or vasopressin. ADH is a small peptide hormone produced by the hypothalamus that binds to the vasopressin 1 and 2 receptors (V1 and V2). Vasopressin release is regulated by osmoreceptors in the hypothalamus, which are exquisitely sensitive to changes in plasma osmolality.

Atrial natriuretic peptide (ANP) or atrial natriuretic factor (ANF) is a natriuretic peptide hormone secreted from the cardiac atria that in humans is encoded by the NPPA gene. ... These cells contain volume receptors which respond to increased stretching of the atrial wall due to increased atrial blood volume.