CVS - Blood Pressure Flashcards
What are the typical values for systematic blood pressure?
120/80 mmHg (Systolic/Diastolic)
What are the typical values for pulmonary blood pressure?
25/8 mmHg
What are the typical values for venous pressure?
6-8 mmHg
How do you calculate BP?
Blood Pressure (BP)=Cardiac Output × Peripheral Resistance
What factors affect BP?
*Cardiac Output
*Peripheral Resistance
What is autoregulation and its function?
*Mechanism: Changes in blood flow are detected by local receptors during microperfusion.
*Function: Ensures that tissues receive adequate blood flow based on their metabolic needs
What is neural regulation and its function?
Function: Provides short-term regulation of blood pressure.
*Mechanism: Responds to transient changes in arterial pressure via baroreflex mechanisms, involving sensors like baroreceptors that quickly adjust heart rate and vessel diameter.
What falls under hormonal regulation?
*Renin-Angiotensin-Aldosterone System (RAAS)
*Anti-Diuretic Hormone (ADH; Arginine Vasopressin)
*Atrial Natriuretic Peptide (ANP)
*Erythropoietin
*Adrenaline/Noradrenaline
What is the function and mechanism of RAAS?
- Function: Increases blood pressure by promoting sodium
and water retention, and vasoconstriction. - Mechanism: Activated by low blood pressure or low blood volume
What is the mechanism and function of ADH?
- Function: Promotes water reabsorption in the kidneys,
reducing urine output and increasing blood volume. - Mechanism: Released in response to high blood osmolarity or low blood volume
What is the mechanism and function of the ANP?
- Function: Reduces blood pressure by promoting sodium
excretion and vasodilation. - Mechanism: Released from the atria of the heart in
response to high blood volume
What is the mechanism and function of the erythropoietin?
- Function: Increases red blood cell production, which can
increase blood viscosity and volume. - Mechanism: Released by the kidneys in response to hypoxia
What is the mechanism and function of adrenaline?
- Function: Enhances the body’s “fight-or-flight” response,
increasing heart rate, the force of contraction, and vasoconstriction. - Mechanism: Released by the adrenal medulla in response
to stress or sympathetic nervous system activation
What are baroreceptors and where are they found?
Baroreceptors are specialised (stretch-sensitive mechanoreceptors) nerve endings
located primarily in the carotid sinus and aortic arch that detect changes in blood pressure and help regulate it through reflex mechanisms.
What do bareorecptors do?
Baroreceptors send afferent signals via the glossopharyngeal nerve (from the carotid sinus) and the vagus nerve (from the aortic arch) to the cardiovascular centres in the medulla oblongata of the brainstem.
What are the two cardiovascular centres?
*vasomotor centre
*cardiac centre
What does vasomotor centre do?
The Vasomotor Center controls sympathetic vasoconstrictor neurons
What does cardiac centre do?
The Cardiac Center modulates heart rate through sympathetic and
parasympathetic neurons.
What is the sympathetic nervous systems role in BP?
Function: Increases heart rate, contractility, and vasoconstriction,
leading to an increase in blood pressure
What is the sympathetic nervous system mechanism in BP?
Baroreceptors: Located in the carotid sinus and aortic arch,
baroreceptors detect changes in blood pressure and send
signals to the brainstem.
Response to Low BP: When blood pressure drops,
baroreceptors decrease their firing rate, leading to increased
sympathetic activity. This results in:
Increased heart rate (tachycardia)
Increased force of cardiac contractions
Vasoconstriction of blood vessels
What is the role of the parasympathetic nervous system in BP?
Function: Decreases heart rate and promotes vasodilation,
leading to a decrease in blood pressure
What is the parasympathetic nervous system mechanism in BP?
Baroreceptor: Detects increases in blood pressure and send
signals to the brainstem.
Response to High BP: When blood pressure rises,
baroreceptors increase their firing rate, leading to increased
parasympathetic activity. This results in:
Decreased heart rate (bradycardia)
Vasodilation of blood vessels
Describe the process of neural regulation of high blood pressure?
- The baroreceptors detect an increase in blood pressure.
- Baroreceptors send signals to the cardiovascular center.
- The cardiovascular center inhibits the sympathetic nervous system and
activates the parasympathetic nervous system. - Sympathetic nervous system inhibition reduces:
a. Cardiac contractility.
b. Peripheral vasoconstriction. - Parasympathetic nervous system stimulation causes: a Decreased heart rate
(negative chronotropic effect). - These responses lead to a decrease in cardiac output
- Vasomotor centre activation leads to vasodilation and reduces systemic
vascular resistance. - The net effect is a decrease in blood pressure to a normal or homeostatic
level.
What are the effects of the neural response on high blood pressure?
- Decreased Heart Rate (Bradycardia): Reduces cardiac
output. - Vasodilation: Decreases peripheral resistance.
- Result: Blood pressure decreases back to normal levels.
Describe the neural response to a low BP?
- The baroreceptors detect a decrease in blood pressure.
- Baroreceptors send signals to the cardiovascular center.
- The cardiovascular center inhibits the parasympathetic nervous system and
activates the sympathetic nervous system. - Sympathetic nervous system activation leads to:
a. Increased heart rate (positive chronotropy).
b. Increased contraction of the heart (positive inotropy) - Parasympathetic nervous system inhibition causes: an increased heart rate
- These responses lead to an increase in cardiac output
- Vasomotor centre activation leads to vasoconstriction and increases
peripheral vascular resistance. - The net effect is increased blood pressure to a normal or homeostatic level.
What are the effects to neural regulation of low BP?
- Increased Heart Rate (Tachycardia): Increases cardiac
output. - Vasoconstriction: Increases peripheral resistance.
- Result: Blood pressure increases back to normal levels
What is step 1 in the RAAS? (Low BP)
Renin Release: When blood pressure decreases or when there is reduced blood flow to the kidneys,
specialised cells in the kidneys called juxtaglomerular cells release an enzyme called renin into the bloodstream
What is step 2 in the RAAS? (Low BP)
Angiotensinogen Conversion: Renin acts on a plasma protein called angiotensinogen, converting it into
angiotensin I
What is step 3 in the RAAS? (LowBP)
Angiotensin-Converting Enzyme (ACE):Angiotensin I is then converted into angiotensin II by an enzyme called angiotensin-converting enzyme (ACE). This conversion primarily takes place in the lungs.
What is step 4 in the RAAS? (LowBP)
Angiotensin II Effects:
a. It causes vasoconstriction, narrowing blood vessels, which increases peripheral vascular
resistance.
b.It stimulates the release of aldosterone from the adrenal cortex.
what is step 5 in the RAAS? (LowBP)
Aldosterone Action: Aldosterone, a hormone released from the adrenal glands, acts on the distal tubules and
collecting ducts of the kidneys, promoting the reabsorption
of sodium and water, leading to increased blood volume
These actions collectively increase cardiac output,
peripheral vascular resistance, and blood pressure, helping
to restore blood pressure to a normal range.
What is the effects of angiotensen 2?
Vasoconstriction: Narrows blood vessels, increasing blood pressure.
Stimulates Aldosterone Secretion: Promotes sodium and water reabsorption in the kidneys, increasing blood volume and pressure.
Stimulates ADH Release: Antidiuretic hormone (ADH) from the posterior pituitary gland enhances water reabsorption in the kidneys, further increasing blood volume.
Stimulates Thirst: Increases fluid intake to boost blood volume
What is role of aldersterone?
*Increases reabsorption of sodium and water in the renal tubules.
*Promotes excretion of potassium.
*Enhances blood volume and pressure
What is step 1 in RAAS (high BP)?
Reduced Renin Release:When blood pressure is high, the juxtaglomerular
cells in the kidneys sense this and reduce the
release of renin into the bloodstream
What is step 2 in RAAS (high BP)?
Reduced Angiotensin II Production: With less
renin available, there is a reduction in the conversion of
angiotensinogen into angiotensin I and, subsequently angiotensin II.
What is step 3 in RAAS (high BP)?
Decreased Angiotensin II Effects:
* With reduced angiotensin II levels, the
vasoconstrictive effects and stimulation of
aldosterone release
As a result, the body decreases fluid retention and
vascular resistance, which helps to lower blood pressure.
What does RAAS do when BP is high to normal?
*reduced renin release
*decreased angiotension II formation
*reduced aldosterone secretion
What does antidioretic hormone do? +more
- ADH is secreted by the cells in the
hypothalamus, transported to the posterior
pituitary and stored until nervous stimuli. - ADH signals kidneys to reabsorb more water
- Prevent the loss of fluids in the urine.
- Increase overall fluid levels
- ADH constricts peripheral vessels.
- Restore blood volume and pressure
What does ANP do and more?
- Secreted by cells in the atria of the heart (B-type ANH by
ventricle) - Natriuretic hormones are antagonists to angiotensin II.
- Prevent aldosterone release
- Promotes loss of sodium and water from the kidneys.
- Suppress renin, aldosterone, and ADH production and release.
- Promotes loss of fluid from the body
- Blood volume and blood pressure drop.
- Restore blood volume
Where is adrenaline secreted from + effects?
Released by the adrenal medulla
Enhance and extend the body’s sympathetic activity
(“fight-or-flight” response)
Increases
Heart rate
Force of contraction
Vasoconstriction (non essential organs)
Energy mobilisation to liver, muscle and heart
Where is erythropoietin secreted from + effects?
Blood flow and/or oxygen levels decrease (Hypoxia).
EPO is released by the kidneys
EPO stimulates the production of erythrocytes within
the bone marrow. It is a vasoconstrictor.
*Increase=
Blood viscosity, resistance, and pressure
*Decrease=
Blood flow
What is the cause, mechanism and examples of hypovolemia? LOWBP
*Cause: Significant loss of blood or fluids.
*Mechanism: Reduces blood volume, decreasing cardiac output and blood
pressure.
*Examples: Haemorrhage, severe dehydration, excessive vomiting, or
diarrhoea
What is the cause, mechanism and examples of cardiac conditions? LOWBP
*Cause: Impaired heart function.
*Mechanism: Reduces the heart’s ability to pump blood effectively.
*Examples: Heart failure, myocardial infarction (heart attack), valvular heart
disease
What is the cause, mechanism and examples of endocrine disorders?LOWBP
*Cause: Hormonal imbalances affecting blood pressure regulation.
*Mechanism: Alters fluid balance and vascular resistance.
*Examples: Addison’s disease (adrenal insufficiency), hypothyroidism,
hypoglycaemia
What is the cause,mechanisms and examples of medications (On heart)?LOWBP
*Cause: Side effects of drugs.
*Mechanism: This may cause excessive vasodilation, diuresis, or decreased
cardiac output.
*Examples: Antihypertensives, diuretics, antidepressants, narcotics
What is the cause, mechanism and examples of septic shock?LOWBP
*Cause: Severe infection leading to systemic inflammation.
*Mechanism: Causes widespread vasodilation and capillary leakage, reducing
blood pressure.
*Examples: Bacterial, viral, or fungal infections that lead to sepsis.
What is the cause, mechanism and examples of neurogenic shock?LOWBP
*Cause: Damage to the nervous system.
*Mechanism: Disrupts sympathetic nervous system control over blood vessel
tone.
*Examples: Spinal cord injury, severe brain injury
What is the cause, mechanism and examples of anaphylactic shock?LOWBP
*Cause: Severe allergic reaction.
*Mechanism: Triggers massive histamine release, leading to vasodilation and
fluid leakage.
*Examples: Allergic reactions to foods, insect stings, or medications.
What is the cause, mechanism and examples of orthostatic hypotension?LOWBP
*Cause: Sudden change in body position.
*Mechanism: Blood pools in the lower extremities, reducing venous return to
the heart.
*Examples: Standing up quickly from a sitting or lying position
What is the cause, mechanism and examples of renal disease? HIGHBP
*Cause: Impaired kidney function.
*Mechanism: Reduced ability to excrete sodium and water, leading to
increased blood volume and pressure.
*Examples: Chronic kidney disease, glomerulonephritis, renal artery
stenosis
What is the cause, mechanism and examples of endocrine disorders? HIGHBP
*Cause: Hormonal imbalances affecting blood pressure regulation.
*Mechanism: Excess production of hormones that increase blood
pressure.
*Examples Primary -Aldosteronism
-Cushing’s
-Syndrome
Pheochromocytma
What is the cause, mechanism and examples of cardiovascular conditions? HIGHBP
*Cause: Conditions affecting the heart and blood vessels.
*Mechanism: Increased vascular resistance or cardiac output leading
to higher blood pressure.
*Examples:
* Atherosclerosis: Plaque buildup in arteries increases
vascular resistance.
* Coarctation of the Aorta
What is the cause, mechanism and examples of genetic factors? HIGHBP
*Cause: Hereditary predisposition to hypertension.
*Mechanism: Genetic variations affecting renal sodium handling,
vascular tone, or sympathetic nervous system activity.
*Examples: Familial hyperaldosteronism, Liddle syndrome.
What is the cause, mechanism and examples of obesity HIGHBP
Cause: Excess body weight.
*Mechanism: Increased cardiac output, altered renal sodium handling,
and activation of the sympathetic nervous system.
*Examples: Obesity-related hypertension due to increased adipose
tissue and associated metabolic changes
What is the cause, mechanism and examples of medications on HIGHBP?
Mechanism: Induce hypertension through various pathways,
including fluid retention and sympathetic activation.
*Examples:
* Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): Can
cause sodium retention and increase blood pressure.
* Oral Contraceptives: Can increase blood pressure through
hormonal effects
What is the cause, mechanism and examples of lifestyle factors HIGHBP?
*Cause: Unhealthy lifestyle habits.
*Mechanism: Contribute to vascular stiffness, increased blood
volume, and elevated sympathetic activity.
*Examples:
* High Salt Intake: Increases blood volume and pressure.
* Sedentary Lifestyle: Contributes to obesity and poor
vascular health.
* Excessive Alcohol Consumption: Can raise blood pressure
through various mechanisms, including increased
sympathetic activity.
* Smoking
What is the cause, mechanism and examples of sleep apnoea HIGH BP?
*Cause: Repeated episodes of blocked breathing during sleep.
*Mechanism: Increased sympathetic activity and intermittent hypoxia
lead to sustained hypertension.
*Examples: Hypertension associated with untreated sleep apnoea
