The push on the walls
Blood pressure.
Water in a hose
Water pushes against the wall of a hose. A strong push can make the hose bulge.
Where do you think blood pushes harder on the wall, in the arteries or in the veins?
What this lesson covers
The idea
Blood pressure is the force blood exerts against a vessel wall, much greater in arteries than veins; arterial pressure is systolic during ventricular contraction (normally about 120 mm Hg) and diastolic during relaxation (80 mm Hg).
Water in a hose
Water pushes against the wall of a hose. A strong push can make the hose bulge.
Where do you think blood pushes harder on the wall, in the arteries or in the veins?
- In the arteries
- In the veins
- The same in both
Squeeze and relax
Choose what the ventricle is doing and read the pressure in the artery.
Two readings
The force that blood exerts against the wall of a vessel is called blood pressure. It is much greater in arteries than in veins. In an artery the pressure goes up and down with the beat. During ventricular contraction it is the systolic pressure, normally about 120 mm Hg. During relaxation it is the diastolic pressure, 80 mm Hg.
Blood pressure is the force blood exerts against a vessel wall, much greater in arteries than veins; arterial pressure is systolic during ventricular contraction (normally about 120 mm Hg) and diastolic during relaxation (80 mm Hg).
Notes
Blood pressure: the force blood exerts on a vessel wall, much greater in arteries than veins; systolic (ventricle contracts, about 120 mm Hg), diastolic (relaxes, 80 mm Hg).
Check yourself
Where is blood pressure much greater?
What is the normal systolic pressure? (in mm Hg)
Answer: 120 mm Hg
The normal systolic pressure is about 120 mm Hg, during ventricular contraction.
Diastolic pressure is the pressure in the artery during ...
By how many mm Hg is the normal systolic pressure higher than the diastolic pressure?
Answer: 40 mm Hg
120 − 80 = 40 mm Hg.
- In arteries — correct. Yes!
- In veins. The pressure is much greater in arteries than in veins.
- It is the same everywhere. The pressure is much greater in arteries than in veins.
- ventricular contraction. The pressure during ventricular contraction is the systolic pressure.
- ventricular relaxation — correct. Yes!
- breathing in. Systolic and diastolic pressures are named for the contraction and relaxation of the ventricles.