Anatomy
What are the two main arterial baroreceptor locations involved in blood pressure sensing?
Carotid sinus and aortic arch
How does the sympathetic nervous system elevate blood pressure?
Increased total peripheral resistance, increased inotropic state of the heart and ejection fraction (rate is less important, since increasing rate without other changes merely reduces stroke volume) and activation of the Renin Angiotensin System.
In the long term (years), there are probably changes in the arterial system and heart.
What percentage of patients achieve satisfactory blood pressure control with a single antihypertensive agent
Less than 50%
What is Pulse pressure?
The difference between the systolic and diastolic pressures
Outline physiological principles underpinning tympanometry. What information can be
deduced from the results?
Tympanometry measures compliance of the TM. Liquid in the middle ear is incompressible
and results in reduced compliance. Changes in pressure in the middle ear from blocked
auditory tubes can be demonstrated, as the compliance peak occurs at an offset from atmospheric pressure. Increased compliance is found if the middle ear ossicles are dislocated.
Which two structures meet at the juxtaglomerular apparatus?
Distal tubule and afferent arteriole
Name three organs which are major targets for tissue damage from uncontrolled hypertension. For each, describe how damage may occur.
The brain: cerebrovascular disease develops as a result of hypertensive effects in small and large vessels;
The heart: is affected by left ventricular hypertrophy as well as accelerated coronary artery disease
The kidneys: are affected by progressive glomerular ischaemia (nephrosclerosis) with ultimate progression to chronic renal failure.
A patient develops a persistent dry cough after starting antihypertensive therapy. What class of drug is responsible, and what is the mechanism?
ACE inhibitors cause accumulation of bradykinin in the lungs due to inhibition of its breakdown, resulting in a dry cough
List three signs of hypertensive retinopathy you would expect to see on fundoscopy.
Arteriolar narrowing (silver wiring), cotton wool spots, and flame haemorrhages
List some of the host factors that help regulate the gastrointestinal microbial population
• gastrointestinal motility,
• gastric acid,
• the antibacterial nature of biliary and pancreatic secretions,
• intestinal immunity,
• the mucous layer.
What is the main anatomical feature that allows the afferent arteriole to regulate blood flow into the glomerulus?
Its smooth muscle wall (for vasoconstriction/dilation)
List the mechanisms involved in blood pressure control.
• Baroceptor reflex,
• Chemoceptor reflex,
• Cerebral ischaemic response,
• Atrial (low pressure baroceptor reflex) giving ANP and vasopressin,
• Stress-relaxation in capacitance vessels,
• RAS giving AII,
• RAS giving aldosterone,
• Starling forces fluid shifts,
• Renal pressure diuresis.
What are the principal sites of action and corresponding effects of Angiotensin II?
1. Vascular smooth muscle of resistance vessels (arterioles): vasoconstriction, so increased TPR
2. Adrenal Cortex, G layer: promotes aldosterone secretion
3. Myocardium: increases force of contraction
4. Brain, hypothalamus: promotes thirst and release of vasopressin (antidiuretic hormone)
5. Renal tubules and renal vasculature: increases salt resorption
In a young adult with persistent hypertension, what features would raise suspicion for secondary hypertension rather than essential hypertension?
Onset before age 30, severe or resistant hypertension, abrupt rise in previously controlled BP, or lack of family history
You have a patient with renal artery stenosis who is terrified of needles. He is very reluctant to have a renal artery angioplasty and asks you if antihypertensive tablets would be just as effective in controlling his high blood pressure. Formulate an answerable clinical (PICO) question based on your patient’s concerns.
In hypertensive male patients with renal artery stenosis is angioplasty or antihypertensive medication more effective in controlling blood pressure?
What is the significance of the location of macula densa cells in relation to the afferent arteriole?
They are positioned to detect filtrate composition just before it returns near the glomerulus
Describe how baroreceptor reflex sensitivity changes in chronic hypertension
Chronic hypertension resets the baroreceptor threshold to a higher MAP, making the reflex less sensitive to pressure increases and contributing to maintenance of elevated BP
Name five categories of antihypertensive drugs, citing a potential adverse effect or complication of therapy in each case.
Diuretics cause a loss of salt (and water) thus reducing the total extracellular fluid volume and hence, by the Starling forces equilibrium, the blood volume. Decreased blood volume gives decreased RAP and EDV, and reduces SV, which tends to reduce CO and therefore BP. A more sophisticated way to understand this is to see that diuretics move the renal function curve to the left (the curve of output of salt on the y axis, versus mean arterial BP on the x axis) so that the intersection of the curve with a constant salt intake moves to a lower BP.
In a patient with malignant hypertension and signs of end-organ damage, what are the clinical priorities in initial management?
Gradual BP reduction to prevent ischemic injury, identification of end-organ damage (retina, kidneys, brain), and urgent antihypertensive therapy initiation
Why is kidney function relatively unaffected in CF?
While there are indeed chloride channels in parts of the renal tubules, they are not the
CFTR gene product. They are a different channel, with a larger unit conductance
and different behaviour, usually known as ORCC – the outwardly rectifying chloride channels.
Explain why the collecting duct plays a critical role in volume regulation even though it receives dilute filtrate.
It responds to aldosterone and ADH, adjusting final Na+ and water reabsorption to fine-tune volume and osmolality.
Why does unilateral renal artery stenosis cause hypertension even though the contralateral kidney is normal?
The affected kidney perceives low perfusion and activates RAAS, driving systemic hypertension. The unaffected kidney experiences this high pressure but cannot suppress the RAAS-driven response, because it’s not the source of the renin stimulus. This leads to inappropriate volume retention and systemic BP elevation
Which combination of drug classes can dangerously reduce renal perfusion and precipitate acute kidney injury in patients with compromised renal blood flow?
ACE inhibitors and NSAIDs.
ACE inhibitors lower glomerular pressure by dilating the efferent arteriole through the inhibition of angiotensin II.
NSAIDs reduce prostaglandin production, which normally promotes dilation of the afferent arteriole.
When both drugs are used together, the kidney loses its ability to regulate blood flow in and out of the glomerulus. This can result in a significant drop in filtration pressure and may lead to acute kidney injury, especially in conditions like renal artery stenosis.
What bedside finding might suggest right-sided heart failure when examining the jugular venous pulse?
Elevated JVP that increases with inspiration (Kussmaul’s sign), or a sustained height >3 cm above the sternal angle
Distinguish the types of cyanosis and explain their relationship with anemia?
Central cyanosis
Peripheral cyanosis
Anemia reduces total Hb, so even low oxygen saturation doesn’t produce enough deoxy-Hb to turn skin blue.