Blood pressure is an integrative parameter of cardiac function. This parameter takes into consideration the state of the peripheral vessels in addition to cardiac function. The concept of blood pressure and the factors affecting it will be discussed. The body has developed an intricate mechanism to detect and correct changes in blood pressure. These systems may be broadly divided into short-term and long-term mechanisms. These systems will be discussed in the lectures, with illustrative examples of how these systems function in various circumstances when the blood pressure changes. This series ends with a consideration of exercise and the circulatory system. Exercise poses a challenge to the circulatory system to increase cardiac output, while maintaining blood pressure relatively constant. How does the circulatory system cope with this challenge?
Prelecture reading – Blood pressure 1
- Arterial pressure is the pressure in the arterial system distal to the aortic valve and proximal to the arteriole.
- Systolic arterial pressure is the pressure in the arterial system when the left ventricle contracts.
- Diastolic arterial pressure is the pressure in the arterial system when the left ventricle relaxes. The pressure is caused by the recoil of the arterial wall.
- Mean arterial pressure is the diastolic pressure + 1/3 pulse pressure.
- Pulse pressure is the difference between systolic and diastolic pressures.
- The 2 determinants of arterial pressure are cardiac output and total peripheral resistance.
- Blood pressure is tightly regulated within a narrow range to ensure adequate tissue perfusion to the vital organs – heart and brain.
- Acute (moment to moment) changes in blood pressure are “sensed” by baroreceptors located in the aortic and carotid sinuses and corrected by the autonomic nervous system.