Ch. 13 Hypertension Flashcards
Name the types of hypertension & their causes.
(1) Essential Hypertension – this is BP of an unknown cause. (2) Secondary Hypertension – this is less common and is due to some definable/known cause.
What are the categories of blood pressure & their values?
There is Normal, Prehypertensive, Hypertension stage I, and Hypertension stage II. Normal < 120/80. Prehypertensive = 120-139/80-89. Hypertension stage I = 140-159/90-99. Hypertension stage II > 160/100.
normal blood pressure range
< 120/80.
prehypertensive range
120-139/80-89
hypertension stage 1 range
140-159/90-99.
hypertension stage II range
> 160/100.
How does cardiac output and total peripheral resistance affect blood pressure
Blood pressure is the total of cardiac output and peripheral resistance, so increases in these can cause increases in BP. Blood from the peripheral system has to completely return which can rely on blood vessel tone and renal components.
What is cardiac output? How does stroke volume & heart rate affect cardiac output
Cardiac Output is the volume of blood (stroke volume) times the heart rate, which makes the total output of blood pumping out and through the vascular system. Increases or decreases in SV or HR can change the CO, for example, if someone has a very low LVEF they will have less volume of blood being pumped out of the ventricle, which will make a low total cardiac output.
CO = SV x HR
What are the four systems that are responsible for BP regulation
(1) Heart (2) Blood vessel tone (3) Kidneys (4) Hormones
What role does renal excretion play in maintaining BP?
Kidneys are very important in maintaining BP. Healthy kidneys respond to an increase in BP with urine volume and Na+ excretion. This is known as pressure natriuresis. Patients that suffer from hypertension have kidneys that are blunted to this process.
In patients with hypertension, what process is hindered & results in higher renal pressures?
Explain this process and the effects it has on the kidneys.
Pressure natriuresis is hindered in patients that have hypertension. This is the process of kidneys responding to high blood pressures and responding by increasing urine volume and sodium excretion, but when this is mechanism is blunted, the kidneys require even higher blood pressures to respond.
Explain when baroreceptors are stimulated. How does this affect BP? How do changes in
BP affect stimulation & transmission rate of baroreceptors?
Baroreceptors are sensitive to the stretching and deformation of arteries. When arterial pressure is high it stimulates baroreceptors, which tells the CNS and signals back to the ANS, which will help the blood pressure to drop back down to baseline. The higher the BP the more baroreceptors are stimulated and causes a greater transmission rate of signals.
Are baroreceptors involved in acute or chronic regulation of BP? Explain
They are mainly involved in acute BP and do not help with long-term regulation of chronic hypertension. The firing rate of baroreceptors will slow back to a control value after a day or two of being exposed to high pressures.
What are some main points when comparing essential vs. secondary hypertension? What
clues & tests provide a diagnosis of secondary hypertension?
Essential HTN is more common, showing in around 90% of HTN patients. It is the label given when a physician rule out Secondary HTN. It could be a genetic disorder involving several loci, or a hereditary issue, or there are links between insulin resistance, obesity, and the metabolic syndrome. Secondary HTN is a smaller percentage of patients but had underlying conditions that can be treated. Ways to observe the possibility of Secondary HTN over essential is by looking at age (before 20 or after 50), severity (dramatic rises in BP), onset (abrupt onset), associated signs and symptoms (renal artery bruit, renal artery stenosis), or having a family history. Lab tests can be done including urinalysis, serum concentration of creatinine and BUN, serum K+, blood glucose, and cholesterol panel.
. What types of renal dysfunction can lead to hypertension? What are their causes? How are
they diagnosed or treated?
Renal parenchymal disease and renal arterial stenosis (renovascular HTN). Renal parenchymal disease is damaged nephrons being unable to excrete normal amounts of sodium and water which leads to a rise in intravascular volume, elevated CO and causes increased blood pressure. Renovascular hypertension is from stenosis of the renal arteries due to atherosclerosis and/or fibromuscular dysplasia. This stenosis reduces renal blood flow and secretion or renin, which reduces angiotensin II and aldosterone and results in vasoconstriction and sodium retention.