Lesson C3 - Antihypertensive Drugs Flashcards
hypertension
high blood pressure
lowering of high blood pressure would
lower the possibility of
stroke, heart attack, heart failure and kidney damage.
what is high blood pressure?
The heart is a muscular pump providing pressure for blood to circulate through blood vessels,
allowing blood to provide nutrients and oxygen to all organs. The blood pressure must be kept
within relatively narrow limits and the body has several mechanisms to achieve control of blood
pressure.
Hypertensaion leads to:
increased vascular disease, increase in heart attacks, increase in stroke and an increase in renal
disease
When an individual has a basal diastolic pressure of 90-105 millimetres of mercury and no
detectable kidney, heart or brain problems, she/he is classified as having
mild hypertension
An individual with a basal diastolic pressure of greater than 130 millimetres of mercury is
classified as having
severe hypertension
An individual with blood pressure intermediate in
severity between mild and severe is classified as having
moderate hypertension.
why should high blood pressure be controlled?
The reason high blood pressure should be controlled is that when blood pressure is above normal
for long periods, the possibility of stroke, heart attack, heart failure, and kidney damage is
increased
One way of controlling blood pressure is by instituting
lifestyle changes
It has been clearly
documented that the following lifestyle changes will lower blood pressure: (a) reducing weight,
(b) regular exercise, (c) low salt diet, and (d)
reduced alcohol consumption
How do drugs lower blood pressure?
(a) By dilating (increasing the diameter) of blood vessels, (b) by reducing the force of the heart
beat, and (c) by increasing the removal of salt and water from the body.
What factors control blood pressure?
There are three factors which control blood pressure: (1) volume of fluid in blood vessels, (2)
resistance to blood flow in the circulation, and (3) the renin-angiotensin-aldosterone system.
Volume of fluid in blood vessels:
Increasing the volume of fluid in the blood vessels increases blood pressure, while decreasing the
volume of fluid in blood vessels leads to a decrease in blood pressure. The volume of fluid in the
blood vessels is controlled primarily by the kidney.
Resistance to blood flow in the circulation:
diminished SNS activity will result in
diminished release of noradrenaline, resulting in dilation of arterioles and reduced resistance to
blood flow.
Renin-angiotensin-aldosterone system:
Renin, an enzyme released from the kidney, acts upon a protein present in blood, namely α2-globulin. A small portion of the protein is split off and this small portion is a peptide named
angiotensin I. An enzyme known as angiotensin converting enzyme (abbreviated as
ACE) acts upon angiotensin I, reducing it in size to form the peptide, angiotensin II.
Angiotensin II acts upon blood vessels to cause vasoconstriction and results in elevation of blood
pressure. In addition, angiotensin II acts upon the adrenal cortex, a portion of an organ situated
on top of the kidney, causing the liberation from the adrenal cortex of a hormone known as
aldosterone. Aldosterone acts upon specific aldosterone receptors in a portion of the kidney to
cause increased retention of sodium and water by the kidney. The retention of sodium and water
by the kidney in turn leads to an elevation of blood pressure.