Blood Pressure

Question 1

What is meant by blood pressure?

Answer 1

The force exerted by the blood on the walls of the blood vessels as it passes through them

Question 2

What is the desired blood pressure for a healthy person?

Answer 2

-needs to be high enough for the efficient formation of tissue fluid, but not so high that blood vessels are damaged, bringing risk of a heart attack (myocardial infarction) or stroke

Question 3

What affects blood pressure through the arterial system?

Answer 3

1. Contraction of ventricles

2. The diameter of the blood vessels themselves

Question 4

What is the systolic blood pressure?

Answer 4

• The higher of the 2 figures

- the pressure in the cuff when blood can pass through at systole when the aorta stretches

Question 5

What is the diastolic blood pressure?

Answer 5

• The smaller of the 2 numbers

- pressure in the cuff when blood can pass through at diastole when the aorta walls are recoiling

Question 6

What does a weak heart do to someone’s blood pressure?

Answer 6

-the heart doesn’t beat as strongly so blood leaves the heart at a much lower pressure

Question 7

What does having damaged blood vessels (that are closing or losing their elastic) do to someone’s blood pressure?

Answer 7

-makes the lumen narrower, therefore increasing the bloods pressure

Question 8

What is atherosclerosis and what effect does it have on blood pressure?

Answer 8

Thickening of the arteries due to a build up of cholesterol plaque. This reduces the volume for blood to flow, therefore increasing blood pressure

Question 9

Describe and explain how the pressure of the blood changes as it makes a complete journey around the circulatory system, from the heart, through the 5 blood vessels.

Answer 9

1) blood is at HIGH pressure when it is pumped out of the left ventricle and into the aorta
2) each time muscle relaxes, the pressure falls momentarily before the ventricle contracts again
3) blood moves through the arteries, elastic wall stretches when blood pressure at its highest, and recoil when at lowest. The recoiling helps INCREASE the blood pressure in between heart contractions, gradually smoothing out the flow of blood
4) blood pressure DROPS rapidly as it passes through the arterioles. This is due to there being more friction between the blood and the vessel walls as they narrow
5) rate of blood flow and blood pressure DECREASES as it flows through the capillaries. This is due to their total cross-sectional area being greater then arterioles, so blood has room to spread out. This slower rate is needed to allow time for gas exchange to take place
6) blood pressure is now VERY LOW when it’s passed through the capillaries, and remains constant as it flows back through the venules veins and back to the right atrium. Pressure is SO LOW that valves are necessary to stop the blood from flowing backwards