Hypertension Flashcards
Describe systolic arterial blood pressure.
The pressure of the arteries during systole (contraction of the heart)
Describe diastolic arterial blood pressure.
The pressure of the arteries during diastole (rest/filling of the heart)
Describe the Mean Arterial Pressure (MAP)
Represents the average pressure throughout the cardiac cycle
MAP = 2/3 diastole + 1/3 systole
(66% of the time the heart is in rest and 33% of the time the heart is in contraction
Define hypertension
High blood pressure
Explain the difference between essential and secondary hypertension
Essential - cause is unknown (90% of cases)
Secondary - comorbid diseases or drug causing elevated BP (10% of cases)
What is the mathematical formula for blood pressure?
BP = total peripheral resistance (TPR) X cardiac output (CO)
What is the formula for cardiac output?
heart rate X stroke volume
What is TPR?
The amount of resistance in the periphery or the blood vessels.
When TPR increases this is called?
Vasoconstriction
What happens when TPR increases? (vasoconstriction)
BP increases
Define: cardiac output
Remember cardiac output = heart rate X stroke volume
How much the heart is pumping
Define: heart rate
How fast the heart is pumping
Define: stroke volume
How much blood the heart is pumping
There are 5 Mechanisms of BP Regulation: List them.
- Renal (RAAS)
- Electrolytes (Na, K, Ca)
- Neuronal
- Vascular
- Hormonal
Describe the Renal Mechanism (RAAS)
- Juxtaglomerular cells (which are baroreceptors) sense a decrease in blood pressure.
- Renin is secreted which converts angiotensinogen that is circulating in the blood into angiotensin I.
- Angiotensin I is then converted into Angiotensin II by a converting enzyme.
- Angiotensin II then affects all areas including adrenal cortex, kidneys, intestines, CNS, peripheral nervous system, vascular smooth muscle and the heart.
Explain how adrenal cortex is affected by angiotensin II.
There is an increase in aldosterone synthesis which increases sodium/water reabsorption which increases the blood volume and increases the TPR and increases BP.
Explain how the kidneys and intestines are affected by angiotensin II.
There is an increase in sodium/water reabsorption which increases the blood volume and increases the TPR and increases BP.
Explain how CNS is affected by angiotensin II.
Causes a release of Vasopressin (an antidiuretic hormone) which causes water (urine) to stay in the body and increase blood volume which increases the TPR and increases BP
Explain how the PNS is affected by angiotensin II.
It causes sympathetic discharge (fight or flight system) which increases the TPR and increases BP.
Explain how vascular smooth muscle is affected by angiotensin II.
Causes vasoconstriction which increases the TPR and increases BP.
Explain how the heart is affected by angiotensin II.
Causes increased contractility (the heart pumps harder) which increases CO and increases BP.
What does RAAS stand for?
Renin Angiotensin Aldosterone System
Explain the Electrolyte Mechanism.
Wherever sodium goes, water follows. Patients with higher sodium levels, have increased water retention which increases blood volume which increases TPR which increases BP.
Lower Ca and Lower K levels can increases TPR which would also cause increased BP.
The Neuronal Mechanism has 3 parts to it: Explain extrinsic reflexes.
Outside circulatory system through hypothalamus (ex. pain or cold temp: You want to increase BP to warm someone up or get rid of pain)
