Hypertension Flashcards
What is the definition of BP?
Pressure inside blood vessels or heart chambers relative to atmospheric pressure (mm Hg).
Measure of the force being exerted on the walls of the ARTERIES as blood is pumped out of the heart.
What are the MAJOR factors that determine BP?
include AGE, SEX, BODY MASS INDEX, and DIET (mainly sodium intake).
(always increase BP b/c water follows Na+)
Blood Pressure =
Cardiac Output X Peripheral Vascular Resistance
Cardiac Output =
Heart Rate X Stroke Volume
What are the normal adult values for CO, HR & SV?
Cardiac Output = Heart Rate X Stroke Volume
4900 ml/min = 70 bts/min X 70 ml/bt
Peripheral (systemic) vascular resistance:
The “squeeze” of blood vessels outside heart resisting blood flow.
Cardiac output:
A measure of how much blood is pumped out of left ventricle.
Stroke volume:
Blood volume ejected with each heart beat
Arterial BP:
The pressure exerted on the artery walls. There are
two measures of blood pressure:
* Systolic BP
* Diastolic BP
Systolic BP:
The pressure in arteries during SYSTOLE (contraction)
Diastolic BP:
The pressure in arteries during DIASTOLE (rest/filling)
Systole:
HIGHEST pressure point in cardiac cycle when ventricles
are contracting.
Diastole:
LOWEST pressure point in cardiac cycle when ventricles
are filling with blood.
Normal BP:
<120 mmHg (systolic); <80 mmHg (diastolic)
Mean arterial pressure:
The average arterial pressure throughout cardiac cycle
Mean Arterial Pressure (MAP)
2/3 diastolic blood pressure (time spent in diastole)
+
1/3 systolic blood pressure (time spent in systole)
basically = 2/3 REST + 1/3 CONTRACTION
Preload:
- The tension in the heart muscle or chamber at the end of diastole before the contraction
- It depends on ventricular end diastolic volume (amount of blood at end of diastolic)
Afterload:
The arterial pressure against which the heart must eject its cardiac output
What is the Frank-Sterling law?
- The STRENGTH of CONTRACTION depends on the INITIAL LENGTH of cardiac muscle fibers before contraction.
- The MORE STRETCHED the muscle BEFORE contraction the STRONGER the contraction.
- The INITIAL LENGTH of the heart muscle before contraction depends on the END DIASTOLE VOLUME.
↑ strength of contraction =
↑ stroke volume
What does the Frank-Sterling curve result in?
↑ end diastolic volume –>
↑ stretch in cardiac
muscle –>
↑ stroke volume
- end diastolic volume = ~140 ml
- stroke volume = ~70 ml
End diastolic volume =
~140 ml
Stroke volume =
~70 ml
What is the Regulation of blood pressure?
- Central Nervous System
* SNS: ↑ heart rate ↑ stroke volume (b/c of ↑ in contractility)
* PSNS:↓ heart rate - Kidney
* renin
* angiotensin II - Hormones
* aldosterone
* cortisol
* epinephrine
* ADH