Module 13 Flashcards
Elevated systemic arterial blood pressure.
HTN
Measurement of the force against the walls of your arteries as the heart pumps blood through the body
BP
BP is measured with this
Sphygmomanometer
When the heart contracts
systole
Period of time when the heart fills after a contractoin
Diastole
BP numbers Normal Pre-hypertension Stage 1 HTN Stage 2 HTN
< 120 and <80
120-139 or 80-89
140-159 or 90-99
>160 or >100
HTN of no known cause
The _____ of cases of HTN
Primary HTN
Majority of HTN cases
HTN with an identifiable cause.
Secondary HTN
What are the different causes of secondary HTN?
Kidney disease Hyperthyroidism Pregnancy Erythropoeitin Pheochromocytoma Sleep apnea Contraceptive use
Tumour on the adrenal gland that causes excess epinephrine release
Pheochromocytoma
What are three major factors that influence BP?
1 - The amount of water and salt in the body
2 - The condition of your kidneys, NS and blood vessels
3 - Hormone levels in the body
What are risk factors for HTN?
Obesity, stress, smoking, high salt, diet, diabetes, African descent
What are certain drugs that are known to cause HTN?
NSAIDs, oral contraceptives, and cold medicines that contain pseudoephedrine
If untreated, HTN can cause these, potentially fatal consequences.
MI, kidney failure, stroke, retinal damage
Why is HTN called a silent killer?
Since many patients may have elevated BP for years before they show any symptoms
How does HTN affect the brain?
The brain swells and has multiple areas of hemorrhage
How does HTN affect the kidneys?
The vasculature of the kidney is dramatically constricted and the urine output is reduced
How does HTN affect the heart?
The heart is dilated (enlarged) and in cardiac failure
What are the determinants of BP?
Cardiac output and Peripheral (vascular) resistance
What is cardiac output determined by?
Heart rate, heart contractility, blood volume and venous return
An increase in what factors increases cardiac output?
HR, heart contractility, blood volume and venous return
Determined by arteriolar constriction.
Peripheral resistance
What are the three systems that our body uses to regulate BP?
1 - Sympathetic nervous system
2 - RAAS - renin-angiotensin-aldosterone system
3 - Renal regulation of BP
The sympathetic nervous system has a reflex circuit called the ______ _____ that helps keep BP at a set level
Baroreceptor reflex
Constantly active to help keep body functions in homeostasis.
Sympathetic nervous system
Consists of the brain stem, receptors on the aortic arch and carotid sinus of the heart, and vascular smooth muscle
Baroreceptor reflex
If BP is too low, describe the action of the baroreceptor reflex.
If BP is perceived to be too low by baroreceptors on the aortic arch and carotid sinus, they relay the information to the brainstem
The brainstem then sends impulses along sympathetic neurons that stimulate the heart to increase CO and cause constriction of smooth muscles on arteries
Blood pressure then increases
If BP is perceived as too high by baroreceptors of the aortic arch and carotid sinus, what occurs?
Sympathetic activity is decreased, causing decreased CO and vasodilation
The activity of baroreceptors can ______ our attempts to lower BP with drugs, since the “set point” in patients with HTN is _____.
oppose
high
Unlike the baroreceptors reflex, activation of the RAAS may take _____ or _____ to influence BP.
hours to days
What is the RAAS pathway?
Angiotensinogen – Renin –> angiotensin I (inactive) – ACE –> angiotensin II (Active) –> aldosterone + ADH
Enzyme that catalyzes the formation of angiotensin I from angiotensinogen
Renin
Rate-limiting step in RAAS.
Renin step
Renin is synthesized and secreted by the __________ cells of the kidney into the blood.
Juxtaglomerular
These all increase renin release.
1 - Decreased blood volume
2 - Low BP
3 - Stimulation of beta 1 receptors on juxtaglomerular cells of the kidney
Converts inactive angiotensin I into the active angiotensin II.
ACE - angiotensin converting enzyme
Activated angiotensin II is a potent ________. It binds to its receptor (the __________ on smooth muscle) to produce _________.
Activated angiotensin II also stimulates the release of ________ from the ________ _______. This in turn acts on the kidneys to increase _______ retention, thereby increasing ______ retention.
vasoconstrictor
AT1 receptor on smooth muscle
vasoconstriction
aldosterone, adrenal cortex
sodium
water
Angiotensin II also acts on the ________ _______ ______ to release ________ ________ (also called _________). This in turn causes ______ retention by the kidneys.
posterior pituitary gland
Antidiuretic hormone (aka vasopressin)
causes water retention by the kidney
Increased retention of water and sodium from the RAAS system causes an increase in ______ ______, which in turn increases ____.
blood volume
CO
If blood pressure decreases for a prolonged period of time, the kidney retains ______. This causes an increase in ______ ____, and thus an increase in ____ and thus BP.
water
blood volume
CO
Decreasing body weight:
There is a _______ relationship between obesity and HTN
Obesity is thought to cause HTN by two mechanisms:
1 - Increased _______ secretion, causing tubular reabsorption of ______ and thus ______ reabsorption and a higher blood volume, higher CO and thus BP
2 - Obese patients also have increased _________ nervous activity
direct
insulin, Na+, water reabsorption
sympathetic
How does salt affect BP?
When salt levels are too high, it causes water to be reabsorbed from the kidney into the blood, causing increased BP.
How does exercise affect BP?
Regular exercise decreases ECF fluid volume and circulating levels of plasma catecholamines (e.g. epinephrine)
The benefits of _______ to BP are seen even in patients that do not restrict their ______ intake or _____ ______ during the training period.
exercise
sodium
lose weight
Total body ________ levels are inversely correlated with BP.
Potassium
High potassium diets decrease BP in what ways?
Increased sodium excretion
Decreased renin release
Vasodilation (think opposite of action potential so less contraction)
Preferred sources of potassium are fresh _____ and ______.
fruits and vegetables
Patients taking ___ ________ should NOT be on a high potassium diet.
Ace inhibitors
For the DASH diet, the best results were seen in patients with _______.
pre-hypertension
How is smoking related to HTN?
Smoking acutely elevates BP, but has not been linked to the causal development of HTN
How does alcohol affect BP?
Excessive alcohol consumption increases BP
Alcohol can decrease responses to anti-hypertensive
