PAT 20 Week 6: Hypertension
Non-objective notes:
-The continuous elevation of blood pressure (bp) occurring with hypertension contributes to premature
death because of its impact on the heart, blood vessels, and kidneys.
-Hypertension is a risk factor for coronary artery disease and cardiovascular disease. It is the
most influential cause of stroke, heart failure, kidney failure, and peripheral vascular disease.
-The higher the bp the greater the chance of developing cardiovascular disease.
-Systemic arterial blood pressure = pressure of blood leaving the left ventricle and into the aorta as
measured by baroreceptors in the aorta. The drop in this pressure during diastole is reflective of the
ventricles filling during relaxation.
-70% of the blood leaving the left ventricle is ejected during the first one third of systole.
Arterial blood pressure: The force that distributes blood throughout the body and into the capillaries.
Systolic blood pressure: The amount of blood ejected from the heart with each beat AKA the stroke
volume. It is also a reflection of the compliance of the aorta and large arteries.
Diastolic blood pressure: Reflects closure of the aortic valves and the recoil of elastic fibres when the
heart is not pumping.
-Characteristic circadian pattern: Bp falls 10-20% below the set point at night reaching its lowest
between 2:00am and 5:00am. Blood pressure is highest shortly after waking and decreases throughout
the day.
NSE 13 reminder: When performing manual auscultation deflate the cuff at a rate of 2 mm Hg per
second.
-If the cuff is too small you will obtain a false high bp
-If the cuff is too big you will obtain a false low bp
Intra-arterial methods of bp measurement: A catheter connected to a pressure transducer is inserted
into a peripheral artery. This type of measurement is usually limited to critical care units.
Mechanisms of blood pressure regulation (not an objective but covered in the PowerPoint):
-Short term regulation: Describes homeostatic mechanisms occurring in seconds to hours. Most
commonly short term regulation is activated in fight or flight scenarios. Two types of regulation:
-Neural mechanisms: Occurring in the reticular formation of the medulla and lower third of the
pons where integration and modulation of the autonomic nervous system occur. This area is
, home to vasomotor and cardiac control centres (AKA the cardiovascular centre) which have the
ability to transmit:
-Parasympathetic impulses to the heart via the vagus nerve. Stimulation decreases heart
rate and decreases vascular resistance.
-Sympathetic impulses to the heart and blood vessels via the spinal cord and peripheral
sympathetic nerves. Stimulation results in an increase in heart rate, cardiac
contractility, and constriction of blood vessels.
-Autonomic nervous system (ANS) is mediated through intrinsic circulatory reflexes,
extrinsic reflexes, and higher neuronal control centres.
-Intrinsic reflexes: Baroreceptors and chemoreceptors which are located in the
circulatory system.
-Baroreceptors: Pressure sensitive receptors situated in blood vessels walls
and in the heart (i.e., carotid and aortic baroreceptors). These
receptors communicate the stretch of blood vessels to the
cardiovascular centres in the brain to regulate heart rate, contractility, and
smooth muscle tone. Decrease in stretch causes an increase in heart
rate, contractility, and vasoconstriction (i.e., orthostatic hypertension).
-Chemoreceptors: Chemical sensitive cells which monitor levels of oxygen,
carbon dioxide, and hydrogen within the blood. Chemoreceptors are
located within carotid bodies in the carotid arteries, and within the aortic bodies
of the aorta. The main function of the chemoreceptors is to regulate
ventilation however they also send impulses to the cardiovascular centre to
influence bp. When arterial pressure drops the chemoreceptors recognize a
decrease in oxygen and a build-up of carbon dioxide. The chemoreceptors
send impulses which cause us to increase our rate of respiration to increase
oxygen and expel carbon dioxide.
-Extrinsic reflexes: Existing outside the circulatory system and in response to sensory
stimuli such as pain and cold. Often regulated by the hypothalamus.
-Humoral mechanisms:
-Renin-angiotensin-aldosterone system: Renin is an enzyme which is created and released by
the juxtaglomerular cells of the kidneys which functions to convert angiotensinogen to
angiotensin I. It is released in response to an increase in sympathetic nervous system
stimulation, a decrease in blood pressure, a decrease in extracellular fluid, or a decrease in
extracellular sodium concentration. It is activated into angiotensin 2 in the lungs after circulating
in the blood stream to function as a short term and long term regulator of bp.
Non-objective notes:
-The continuous elevation of blood pressure (bp) occurring with hypertension contributes to premature
death because of its impact on the heart, blood vessels, and kidneys.
-Hypertension is a risk factor for coronary artery disease and cardiovascular disease. It is the
most influential cause of stroke, heart failure, kidney failure, and peripheral vascular disease.
-The higher the bp the greater the chance of developing cardiovascular disease.
-Systemic arterial blood pressure = pressure of blood leaving the left ventricle and into the aorta as
measured by baroreceptors in the aorta. The drop in this pressure during diastole is reflective of the
ventricles filling during relaxation.
-70% of the blood leaving the left ventricle is ejected during the first one third of systole.
Arterial blood pressure: The force that distributes blood throughout the body and into the capillaries.
Systolic blood pressure: The amount of blood ejected from the heart with each beat AKA the stroke
volume. It is also a reflection of the compliance of the aorta and large arteries.
Diastolic blood pressure: Reflects closure of the aortic valves and the recoil of elastic fibres when the
heart is not pumping.
-Characteristic circadian pattern: Bp falls 10-20% below the set point at night reaching its lowest
between 2:00am and 5:00am. Blood pressure is highest shortly after waking and decreases throughout
the day.
NSE 13 reminder: When performing manual auscultation deflate the cuff at a rate of 2 mm Hg per
second.
-If the cuff is too small you will obtain a false high bp
-If the cuff is too big you will obtain a false low bp
Intra-arterial methods of bp measurement: A catheter connected to a pressure transducer is inserted
into a peripheral artery. This type of measurement is usually limited to critical care units.
Mechanisms of blood pressure regulation (not an objective but covered in the PowerPoint):
-Short term regulation: Describes homeostatic mechanisms occurring in seconds to hours. Most
commonly short term regulation is activated in fight or flight scenarios. Two types of regulation:
-Neural mechanisms: Occurring in the reticular formation of the medulla and lower third of the
pons where integration and modulation of the autonomic nervous system occur. This area is
, home to vasomotor and cardiac control centres (AKA the cardiovascular centre) which have the
ability to transmit:
-Parasympathetic impulses to the heart via the vagus nerve. Stimulation decreases heart
rate and decreases vascular resistance.
-Sympathetic impulses to the heart and blood vessels via the spinal cord and peripheral
sympathetic nerves. Stimulation results in an increase in heart rate, cardiac
contractility, and constriction of blood vessels.
-Autonomic nervous system (ANS) is mediated through intrinsic circulatory reflexes,
extrinsic reflexes, and higher neuronal control centres.
-Intrinsic reflexes: Baroreceptors and chemoreceptors which are located in the
circulatory system.
-Baroreceptors: Pressure sensitive receptors situated in blood vessels walls
and in the heart (i.e., carotid and aortic baroreceptors). These
receptors communicate the stretch of blood vessels to the
cardiovascular centres in the brain to regulate heart rate, contractility, and
smooth muscle tone. Decrease in stretch causes an increase in heart
rate, contractility, and vasoconstriction (i.e., orthostatic hypertension).
-Chemoreceptors: Chemical sensitive cells which monitor levels of oxygen,
carbon dioxide, and hydrogen within the blood. Chemoreceptors are
located within carotid bodies in the carotid arteries, and within the aortic bodies
of the aorta. The main function of the chemoreceptors is to regulate
ventilation however they also send impulses to the cardiovascular centre to
influence bp. When arterial pressure drops the chemoreceptors recognize a
decrease in oxygen and a build-up of carbon dioxide. The chemoreceptors
send impulses which cause us to increase our rate of respiration to increase
oxygen and expel carbon dioxide.
-Extrinsic reflexes: Existing outside the circulatory system and in response to sensory
stimuli such as pain and cold. Often regulated by the hypothalamus.
-Humoral mechanisms:
-Renin-angiotensin-aldosterone system: Renin is an enzyme which is created and released by
the juxtaglomerular cells of the kidneys which functions to convert angiotensinogen to
angiotensin I. It is released in response to an increase in sympathetic nervous system
stimulation, a decrease in blood pressure, a decrease in extracellular fluid, or a decrease in
extracellular sodium concentration. It is activated into angiotensin 2 in the lungs after circulating
in the blood stream to function as a short term and long term regulator of bp.
