Blood pressure is the force the blood exerts against the inner walls of the blood vessels. (Elaine N Marieb, 2003).At each heart beat called a systole (what about diastolic does it have nothing to do with blood pressure?), the heart contracts and relaxes, this causes pressure to rise and fall hence providing two pressure readings (so it's the diastolic and systolic right? But not only systolic). The pressure exerted in the arteries when the heart contracts is the systolic pressure while pressure taken in the ventricles when the heart relaxes is the diastolic pressure .Blood pressure is recorded in millimeters of mercury(mm Hg) forexample110/80 with 110 being the systolic pressure and 80 the diastolic pressure. (Good stuff)
Blood pressure is important in that it ensures continuous flow of blood throughout the body since blood flow follows a pressure gradient. Blood flows from areas of high pressure to areas of low pressure (Elaine N Marieb, 2003). When ventricles contract, they push blood in to the arteries, the high pressure in the arteries forces blood to move to where pressure is low. This flow continues to a point where there is no more pressure and the blood enters the vena cava back into the right heart.
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The physiological process involved in the normal control of blood pressure has two mechanisms, the regulation of cardiac output, and the peripheral resistance. Cardiac output is the volume of blood discharged from the left ventricle per minute. Blood volume is the total amount of blood in the cardiovascular system. Changes in blood volume can increase or decrease blood pressure. For example if the volume of blood is reduced by a haemorrhage, blood pressure will drop. On the other hand if the Volume is increased for example by transfusion, the blood pressure will be increased. In other wards this mechanism ensures that the volume of blood discharged from the heart is equal to the volume entering its chambers (Boyle and Senior, 2002) (Good stuff)
The other mechanism is the peripheral resistance.Pressoreceptors also called baro-receptors in the walls of the aorta and the carotid arteries are sensitive to blood pressure changes. If blood pressure rises they send nerve impulses to the cardiac centre of the medulla oblongata which relays parasympathetic impulses to the heart which decreases the heart rate and vasodilation hence reducing blood pressure. On the other hand if blood pressure drops sympathetic impulses are sent to the heart causing it to beat faster as a result cardiac output is increased which raises the blood pressure to the normal level. (Boyle and Senior, 2002) (Same reference again!!! If u can get another one it will be better but it still works)
The normal blood pressure is considered to be 120/80 mm Hg however this may vary slightly from one individual to another therefore a reading of 140/90 will still be considered normal(Blood pressure association, 2008). Any reading above 140/90 mmHg will be considered high in other wards referred to as hypertension. On the other hand a reading of 90/60mm Hg and below is considered to be low blood pressure otherwise called hypotension.
Blood pressure is measured using a sphygmomanometer and inflatable cuff. The cuff is wrapped above the elbow and inflated until the cuff pressure exceeds the systolic blood pressure, blood flow will stop and the brachial pulse will not be heard, the pressure in the cuffs is then gradually reduced while the examiner listens for sounds in the brachial artery with a stethoscope, the pressure read (do u mean Reading instead of read!!)at this point as the blood rushes through the artery is the systolic pressure. As the cuff pressure is reduced further, the sound become louder and distinct until they become constant. The pressure reading taken at this point is the diastolic pressure. (Elaine N Marieb, 2003).
Blood pressure is one the vital sign therefore having it measured is significant in that it can reveal an underlying condition. Hypertension is the major cause of stroke, coronary heart disease, kidney failure and aortic aneurysm (Department of Health, 2010). Measuring blood pressure aids in the early diagnosis of some the above conditions thereby helping in their earlier treatment.
Measuring blood pressure is important in assessing the patients usual range before a major operation is carried out. This helps the health workers to make a quick assessment of the patient's condition during the operation and also how the patient is recovering after the operation.
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Measuring the patient's blood pressure helps in assessing the efficiency of anti hypertensive medication. Patients who are undergoing blood pressure treatment take some medication. Therefore in order to evaluate the effectiveness of the medication taking periodic blood pressure readings is essential.
Blood pressure is one of the vital signs of the body which does not need to be neglected at any one time because it signifies an underlying problem which once acted upon can prevent a major catastrophe. Maintaining blood pressure readings should therefore be taken regularly and the results interpreted correctly and action should be taken if required.
Blood pressure association 2008 Normal blood pressure [on line] available from http://www.bpassoc.org.uk/bloodpressureandyou/The basics/what is normal. Last accessed on 29/03/2010.
Department of health 2010 Blood pressure [on line] Available from http://www.dh.gov.uk/en/Healthcare/Longtermconditions/vascular/Bloodpressure/DH_4066153.last accessed on 29/03/2010.
Elaine N.Marieb R N (2003) Essentials of Human Anatomy &Physiology .Seventh Edition San Francisco. Pearson Education Inc, Benjamin Cummings.
Mike Boyle and Kathryn Senior (2002) Human Biology Second Edition London.