General Biology lab Lab 10 Blood Pressure

Blood pressure – is the force that blood exerts against the wall of a blood vessel. It results from the force the heart applies to the blood at any given time.

Pressure is highest in arteries when the ventricles contract. Pressure drops in arteries when the ventricles relax so there are two components to blood pressure :

Components of Blood Pressure Systolic pressure : –the pressure in the artery during the ventricular contraction phase of the heart cycle. The pressure in the vessel is highest at this time. Diastolic pressure : –the pressure in the artery when the ventricles are relaxed

Blood pressure values are universally stated in millimeters of mercury (mm.Hg) Typical values for a resting, healthy adult human are approximately 120 mm.Hg systolic pressure to 80 mm.Hg diastolic pressure ( written as 120/80 mm.Hg ).

This is called SYSTOLIC pressure This is called DIASTOLIC pressure. mm.Hg

Pulse pressure : – The differences between diastolic and systolic blood pressure (120-80= 40 mm.Hg )

These measures of blood pressure are not static, but undergo natural variations from one heartbeat to another or throughout the day ( in a circadian rhythm), they also change in response to – Stress. – Nutritional factors. – Drugs. – Disease.

Normal values of blood pressure Normal ranges for blood pressure in adult humans are : – Systolic between 90 and 135 mm.Hg – Diastolic between 50 and 90 mm.Hg Diastolic Systolic – 135 Normal ranges

High blood pressure Blood pressure exceeding normal values is called hypertension. Hypertension –is defined a persistent systolic blood pressure reading (SBP) of 140 mm.Hg or greater and or a diastolic blood pressure reading (DBP) of 90 mm.Hg or greater.

High blood pressure usually has no symptoms. Many people have high blood pressure for years without knowing it. It's called the "silent killer." It doesn't refer to being tense, nervous or hyperactive. You can still have high blood pressure even if you are a calm, relaxed person.

High blood pressure can have many different causes. Atherosclerosis –produces hypertension because the heart works harder moving blood through restricted arteries. Being overweight can lead to hypertension. –The heart pumps harder to move blood through additional capillaries in adipose tissue.

Persistent hypertension is one of risk factors for : 1.Strokes. 2.Heart attacks. 3.Heart failure. 4.Kidney failure.

Control the high blood pressure: – Weight loss – Low salt diets – Medication – Eat Healthy Foods

Low blood pressure Blood pressure that is too low is known as hypotension. People with a reading of around 90/60, or less, are commonly regarded as having low blood pressure. Low blood pressure may be a sign of severe disease and requires urgent medical attention.

When blood pressure and blood flow decrease beyond a certain point, the perfusion of the brain becomes critically decreased (i.e., the blood supply is not sufficient), causing Lightheadedness. Dizziness. Weakness. Fainting.

Factors maintained blood pressure 1.Peripheral Resistance : –blood vessel diameter. –blood viscosity. –total vessel length. 2.Vessel Elasticity. 3.Blood Volume. 4.Cardiac Output.