Hormones Function to Maintain Blood Pressure

Describe how hormones function to maintain blood pressure and how they respond to both a decrease and increase in blood pressure.

Blood pressure is a measurement of blood pressing against the walls of the arteries while the heart is pumping blood around the body.

The pressure of blood flowing through the arteries is lower when the heart relaxes than when it contracts. For example a blood pressure reading shows two measurements, usually the top number is systolic pressure which measures the pressure of when the heart contracts and the blood is forced around the body. The bottom measurement is the diastolic pressure, which represents the heart at rest; this measurement is lower than the systolic pressure.

Hormones are chemical messengers of the body that transport a signal from a cell to another, this then release a chemical to a cell that affects the cells in other parts of the organisms.

As hormones serve as messengers they are responsible for the maintenance and the coordinating activities throughout the body for example the control of blood pressure.

Hormones such as antidiuretic; a hormone produced in the pituitary gland causes the kidneys to keep hold of water and aldosterone which helps in the control of blood pressure, another example is renin found in the kidneys, renin plays a part in the control of blood pressure.

The body has many systems that directly control blood pressure, many factors other than the force and rate of the pumping heart help to maintain or to regulate blood pressure. Regulating systems include the nervous endocrine, cardiovascular and urinary system.

These hormones include the adrenal modularly hormones epinephrine and norepinphrine, which generally reinforce the sympathetic nervous system in most organs as well as vasopressin and angiotensin II which are important in controlling fluid balance.

For example, noradrenaline is a hormone secreted by the adrenal medulla that raises blood pressure during stressful situation.

Hormones can react to increase blood pressure when it becomes low, the sympathetic division of the autonomic nervous system uses several ways to temporarily increase blood pressure when it has dropped for example during the fight or flight response. During the response, the sympathetic division is needed to stimulate the adrenal glands to release the hormones epinephrine and norepineprine which stimulate the heart to beat faster and for blood to flow more forcefully, this effect makes most of the arterioles to constrict and some arterioles dilate, which leads to an increase blood supply where needed.

In order to increase blood it is vital for the sympathetic division to get the kidneys to decrease their secretion of salt and water; this will mean an increase in blood volume and blood pressure then returns to normal.

However if the causes leading to low blood pressure remain then other regulating systems are then activated such as the secretion pressure-controlling hormones. The kidneys can in respond in increasing blood pressure. The kidneys will secrete the enzyme rennin that leads in the production of the hormone angiotensin II being produced.

The kidneys release an enzyme called rennin when blood pressure is really low. Rennin works to increase blood pressure by releasing angiotensin I; a mild vasoconstriction that enters the blood circulation.

Angiotensin I enzymatically processed becomes angiotensin II which is a vasoconstrictor and acts on the small arterioles. This leads to arteriolar constriction increasing the total vascular peripheral resistant which raises blood pressure in the arteries and the venal constriction that then helps return the blood back to the heart.

Angiotensin II also works to eliminate sodium ad water in the kidneys as stated before a small decrease in volume of any extra cellular fluid can cause blood pressure to increase.

When blood pressure is raised which can be caused by a number of things.

Most people with high blood pressure have primary or essential hypertension, so there isn't a single clear cause, there are some contributing factors which are linked with lifestyle and they include smoking, being over weight and diet.

There is also another form; secondary hypertension, this means the condition can be linked to the following conditions, kidney disease, narrowing of the aorta or the arteries leading to the kidneys or endocrine disease.

Blood pressure can be lowered by the actions of arterial natriutretic peptide (ANP) hormone. Artrial natrriuretic hormones are a protein and a vasodilator, which is released by heart muscle cells.

The hormone in involved in maintaining the homeostatic control of water and sodium a constant.

Cells in artia chamber of the heart release arterial natriuretic when the body senses high blood pressure.

The hormone acts to lower blood pressure by reducing the water and sodium levels in the circulatory system. This results in blood pressure being lowered.

There are hormones which help maintain blood pressure at constant and between the normal levels at or below 120 over 80 -120/80.

Cortisol is one, which helps maintains blood pressure and cardiovascular function.

Cortisol belongs to a group of hormones called glucocorticoids that affect most organs and tissues in the body.

The amount of cortisol produced in the adrenal balanced, and is regulated by the hypothalamus and pituitary gland. Once the hypothalamus releases a trigger, hormone called corticotrophin- releasing hormone, which, signals the pituitary glands. The pituitary gland acts by sending out ACTH, which is left to stimulate the adrenal glands that respond by producing cortisol. Cortisol then acts back by sending signals back to decrease the trigger hormone. By keeping everything balance, blood pressure remains within its normal level and doesn't gets raised or lowered leading to problems.

Another example is, aldosterone, which belongs to a class of hormones called mineral corticoids, produced in the adrenal glands.

Role of aldosterone is to help maintain blood pressure, water and salt levels balanced in the body. This done by helping the kidneys keep sodium and get rid of potassium, when aldosterone levels drop to a low level, kidneys then are not able to keep a balance of salt and water, this then results in a drop in both blood volume and blood pressure.

Kidneys are not able to regulate water and salt balance, leading to a drop in both blood volume and blood pressure. By keeping everything functioning correctly, like kidneys; blood pressure is kept maintained.

References:

Hormones involved in maintaining blood pressure

http://www.blood-pressure-hypertension.com/special-cases/high-blood-pressure-hormones.shtml (accessed on 13th February 2010)

Hormones

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/K/KidneyHormones.html (accessed on 13th February 2010)

Blood Pressure http://www.patient.co.uk/showdoc/23068761/ (accessed on 11th February 2010)

What are hormones? http://resources.schoolscience.co.uk/abpi/new/resources/hormones/index.asp (accessed on 15th February 2010)

Journal of Human Hypertension (2008) 22, 743-744; doi:10.1038/jhh.2008.58; published online 5 June 2008 http://www.nature.com/jhh/journal/v22/n11/full/jhh200858a.html (accessed on 16th February 2010)

Alan L. Rubin (2007) High blood pressure for dummies, 2nd ed. For Dummies

Elitham B Turya. (2004). Living with Hypertension and Diabetes. Edukom

William J Marshall, Stephen K Bangert. (2008). Clinical Chemistry. 6th ed. Mosby Elsevier

Please be aware that the free essay that you were just reading was not written by us. This essay, and all of the others available to view on the website, were provided to us by students in exchange for services that we offer. This relationship helps our students to get an even better deal while also contributing to the biggest free essay resource in the UK!