BLOOD PRESSURE
What is blood pressure?
When blood is held in blood vessels, its exerts a pressure on the walls, known as hydrostatic pressure. Therefore, it refers to the force exerted by the blood circulation on the walls of the blood pressure.
How is blood pressure measured?
First we will need to know what is being measured:
1) Systolic Pressure- maximum pressure in an artery at the moment when the heart is beating and pumping blood through the body.
2) Diastolic Pressure
- lowest pressure in an artery in the moments between beats when the heart is resting.
Steps to take blood pressure:
1) A cuff that inflates is wrapped around your upper arm and kept in place with Velcro. A tube leads out of the cuff to a rubber bulb.
2) Another tube leads from the cuff to a reservoir of mercury at the bottom of a vertical glass column. Whatever pressure is in the cuff is shown on the mercury column. The mercury is held within a sealed system – only air travels in the rubber tubing and the cuff.
3) Air is then blown into the cuff and increasing pressure and tightening is felt on the upper arm.
4) The doctor puts a stethoscope to your arm and listens to the pulse while the air is slowly let out again.
5) The systolic pressure is measured when the doctor first hears the pulse.
6) This sound will slowly become more distant and finally disappear.
7) The diastolic pressure is measured from the moment the doctor is unable to hear the sound of the pulse.
2) Another tube leads from the cuff to a reservoir of mercury at the bottom of a vertical glass column. Whatever pressure is in the cuff is shown on the mercury column. The mercury is held within a sealed system – only air travels in the rubber tubing and the cuff.
3) Air is then blown into the cuff and increasing pressure and tightening is felt on the upper arm.
4) The doctor puts a stethoscope to your arm and listens to the pulse while the air is slowly let out again.
5) The systolic pressure is measured when the doctor first hears the pulse.
6) This sound will slowly become more distant and finally disappear.
7) The diastolic pressure is measured from the moment the doctor is unable to hear the sound of the pulse.
**Blood pressure is measured in terms of millimetres of mercury(mgHg)
Instruments needed to take blood pressure:
Stethoscope & Sphygmomanometer
Below is a video of how to measure blood pressure:
How does blood pressure change with the pumping of the heart?
Pressure in the Left Side is Higher than the Right Side
The normal pressure in the Left Ventricle is 120 mmHg in an adult. This pressure is needed to transport the blood through the artery from the left side of the heart all the way down to the lower body such as the toes and still have enough energy for the blood to travel back through the vein to the right side of the heart. At the same time, the Right Ventricle have a lower pressure. The normal pressure in the Right Ventricle is about 30 mmHg which is enough to pump the blood a short distance to the lungs and then back to the left side of the heart.
Pressure in the left side of the heart
1) A slight increase in the ventricular pressure due to the contraction of the left atrium, forcing blood into the relaxed ventricle.The ventricle begins to contract, the bicuspid valve closes and the pressure increases.
2) The pressure in the left ventricle becomes higher than that in the aorta. The semi-lunar valve in the aorta opens.
3) The ventricle begins to relax. The aortic valve closes to prevent backflow of blood into the ventricle.
4) The pressure in the ventricle continues to decrease as it relaxes.
5) The bicuspid valve opens as the pressure in the ventricle becomes lower than that in the atrium.
6) The pressure in the ventricle gradually increases as blood continues to enter the ventricle fromt the atrium
7) The cycle repeats.
2) The pressure in the left ventricle becomes higher than that in the aorta. The semi-lunar valve in the aorta opens.
3) The ventricle begins to relax. The aortic valve closes to prevent backflow of blood into the ventricle.
4) The pressure in the ventricle continues to decrease as it relaxes.
5) The bicuspid valve opens as the pressure in the ventricle becomes lower than that in the atrium.
6) The pressure in the ventricle gradually increases as blood continues to enter the ventricle fromt the atrium
7) The cycle repeats.
How does blood pressure differ in differetn blood vessels?
Each blood vessel has it's own blood pressure value, arterial blood pressure, capillary blood pressure, venous blood pressure, left atrial blood pressure, right ventricular blood pressure etc.
Blood pressure in the pulmonary system is considerably lower than that of the systemic system but there is still a pressure gradient from the blood leaving the right ventricle to the left atrium.
There must be a difference in the pressures so that the blood could travel from the site of higher pressure to the site of lower pressure.
We wanna thank:
Done by:
Yan Chong Xi
Jeremy Tan
Lim Shi Quan
Low Wei Yee
No comments:
Post a Comment