Hypertension Flashcards
The cardiovascular system comprises __ circulations in series
2 circulations in series
Left heart pumps to the body, blood from the body returns to the right heart
The right heart pumps to the lungs, and blood from the lungs return to the left heart
The site in the circulatory system where nutrient and waste metabolic products is exchanged
Capillaries
Define perfusion
Rate of flow of blood through tissue
Arterial Pressure refers to pressure in that compartment of the circulation between __ and __
Aortic valves and arterioles
Mean arterial pressure (blood pressure) = ?
Cardiac Output (CO) X Peripheral Resistance (TPR)
What is pulse pressure?
It is the difference between systolic and diastolic pressures
Which receptors are responsible for detecting acute changes in blood pressure? And where are they located respectively?
Carotid and aortic baroreceptors
Aortic baroreceptors: in the walls of the aorta
Carotid: in one of the major arteries supplying the brain
How are acute changes in blood pressure corrected in the body?
Via the autonomic nervous system (has 2 arms- sympathetic and parasympathetic)
Sympathetic nervous system acts to increase BP, contractility etc.
Which organ in the body plays a key role in the longer-term regulation of BP?
Kidney
How is blood pressure regulated in the long term?
Through volume regulation via the renin-angiotensin-aldosterone system
Which of the following produced by the juxtaglomerular apparatus plays a key role in regulating blood pressure?
Renin
What is the key component of the Renin-Angiotensin-Aldosterone System?
Juxtaglomerular apparatus
When does circulatory shock occur?
When arterial pressure is insufficient to maintain perfusion
- usually systolic BP < 80mmHg or mean BP < 60mmHg
What are the components of the juxtaglomerular apparatus?
JG Apparatus:
- JG cells
- Macula Densa
Sensors:
- JG cells
-Macula Densa
Effector:
- Renin in JG cells
What are juxtaglomerular (JG) cells and what is their role?
Modified cells of afferent arterioles
Role: Sense pressure in afferent arterioles; contains renin which is released when BP decreases
Where is the Macula Densa located and what is their role?
Location: next to JG cells
Role:
1) signals to the JG cells when there is not enough filtrate for JG cells to release renin
2) Sense Na and Cl presence in the filtrate to determine if there is a sufficient amount
What is primary hypertension?
Hypertension that has no known cause; also known as essential hypertension
What predisposes to primary hypertension?
Involves a dysregulation of BP:
1) Heart: sympathetic overdrive
2) Blood vessels: sympathetic overdrive, dysregulation of vascular smooth muscle tone (smoking, age), smooth muscle hypertrophy due to insulin resistance
3) Kidneys: insensitivity of the RAAS; with age, balance in RAAS is no longer sensitive, kidneys keep reabsorbing Na even though the body does not need it -> volume expansion -> HTN
4) Obesity:
- angiotensinogen released from adipocytes -> increased angiotensin II -> increased resistance -> increased BP;
- increased blood volume
- increased blood viscosity due to dysregulation of the clotting system
Define isolated systolic hypertension
Wide pulse pressure (SBP - DBP > 80 mmHg) + SBP >/= 140mmHg and DBP </= 90 mmHg
Function of aging and arteriolar stiffness
When treating ISH, may lead to orthostatic hypotension. Start low, go slow
What is the definition of orthostatic hypotension?
Defined as a decrease in systolic blood pressure of 20 mmHg or a decrease in diastolic BP of 10 mmHg within 3 minutes of standing when compared to BP from sitting/ supine position
List 2 classes of medications that could lead to secondary causes of hypertension
1) Corticosteroids (cortisone, dexamethasone, hydrocortisone, prednisolone etc.)
2) NSAIDs: Cox-2 selective (celecoxib) and non-selective
- as inhibition of COX in kidneys leads to constriction of afferent arterioles
Other classes:
- Calcineurin inhibitors (e.g. tacrolimus, cyclosporine)
- Decongestants (e.g. pseudoephedrine, oculr phenylephrine)
- Testosterone
- Anti-depressants: desvenlafaxine, venlafaxine, buproprion
- Erythropoiesis-stimulating agents (erythropoietin, darbepoetin)
- Estrogen-containing oral contraceptives
Increased sympathetic activation of beta-1 adrenergic receptors of heart leads to?
Increased cardiac output -> increased preload
Increased sympathetic activation of alpha-1 adrenergic receptors in the smooth muscles leads to?
increased peripheral resistance -> increased afterload
Explain the RAAS cascade in the event of decreased blood pressure
1) Reduced BP -> reduced renal blood flow. This leads to increased secretion of renin which converts angiotensinogen to angiotensin I, which leads to increased production of angiotensin II. Increased angiotensin II leads to increased secretion of aldosterone, leading to increased Na and water retention, leading to increased blood volume
2) Reduced renal blood flow also leads to reduced glomerular filtration rate, which also contributes to increased Na and water retention, hence increasing blood volume