Regulation Of Blood Pressure Flashcards
What is blood pressure
The pressure generated on the walls by circulating blood
Name types of blood pressure
•diastolic
•systolic
• pulse
What is systolic blood pressure
The pressure generated when blood is ejected from the ventricles when the contract
What is diastolic blood pressure
Pressure on blood vessels when the heart muscle relaxes
What is pulse pressure
The difference between systolic and diastolic pressure
How do we calculate the mean blood pressure
Either the sum of 2/3 of systolic pressure and 1/3 of diastolic pressure or diastolic pressure + 1/3 pulse pressure
Pressure for systemic circulation
The left ventricle pumps blood at a higher pressure of 80-120 and if above 140 then it’s abnormal
Pressure for pulmonary circulation
The right ventricle pumps blood at a lower pressure of 8-20 and if above 25 then it’s abnormal
Why is blood pressure needed
To drive blood flow
Does the pressure increase or decrease as we move down the vascular system
It decreases
From arteries to arterioles to capillaries to venules to veins
what is Poiseullie’s law
flow is proportional to the pressure gradient divided by resistance to flow
* the blood flow decreases as pressure decreases
* the resistance increases then the blood flow decreases
what are the regulators of blood pressure
- cardiac output (stroke volume x heart rate)
- baro reflex
- ADH (antidiuretic hormone)
- renin angiotensin aldosterone system
how is the heart a regulator of blood pressure
the heart and cardiac output is the main source of blood pressure.
cardiac output can be calculated by stroke volume x heart rate
how can stroke volume be affected
it can be affected by the size of the heart and force of cardiac contraction as stroke volume is the amount of blood pumped out of the heart per contraction
how are blood vessels regulators of blood pressure
- poiseuille’s law linked
- resistance can be changed by altering the diameter of blood vessels.
- eg vasodilators: if diameter increases, resistance decreases, blood flow increases
- vasoconstrictors: if diameter decreases, resistance increases, blood flow decreases
what are the most important resistance vessels
small arteries/ arterioles
state the homeostatic regulators of blood pressure
- negative feedback loop
- diuresis
- natriuresis
how is diuresis a regulator of blood pressure
it’s responsible for the production of urine and the extraction of volume which brings down blood pressure
how is natriuresis a regulator of blood pressure
it extracts sodium in urine
how does renin angiotensin aldosterone system regulate blood pressure
- the liver produces angiotensin and the kidneys produce renin. renin then acts on angiotensin to produce angiotensin 1
- the lungs then produce angiotensin-converting enzyme (ACE) which acts on angiotensin to produce angiotensin 2
- angiotensin 2 is a vasoconstrictor ( decreases diameter of blood vessels) and helps adrenal gland produce aldosterone which reabsorbs salt and water.
what is antidiuretic hormone (ADH)
a vasopressin which is a hormone that promotes the retention of water and increase blood pressure
where is ADH released from and why
released from the posterior pituitary due to decreased volume and blood pressure
How does ADH work on the kidneys
- water is reabsorbed from the distal tubules and collecting duct through increased permeability (via aquaporins)
- increased blood volume
- decreases urine output
- increased sodium reabsorption
- increased osmotic gradient
- fluid retention
- concentrated urine with low volume
name two natriuretic peptides
- atrial natriuretic peptides
- brain natriuretic peptides
what are atrial natriuretic peptides
short lived peptides that are released from atrial myocytes due to increased pressure in the atria
what are brain natriuretic peptides
short lived peptides which are released from ventricular myocytes (mainly left ventricle) due to increased pressure in the ventricles
what do natriuretic peptides inhibit
- inhibit renin and reduce angiotensin 2 to stop vasoconstriction
- inhibit aldosterone and promote salt and water uresis
what are baroreceptors
- they sense pressure in the arteries
- if there’s increased blood pressure then it stimulates baroreceptors to increase their activity
- however if decreased blood pressure then there is decreased baroreceptor activity
what is hypertension
this increases baroreceptor activity which decreases sympathetic drive (fight or flight) and increases parasympathetic drive (rest or digest)
what is hypotension
this decreases baroreceptor activity which increases sympathetic drive and decreases parasympathetic drive
are baroreceptors long-term or short-term controllers of blood pressure
they are short-term acute regulators of blood pressure
describe blood pressure during the day and night
blood pressure decreases at night at rises early morning
describe link between blood pressure and aging
diastolic and systolic blood pressure increases with age
what is autoregulation
it’s the intrinsic ability of an organ to maintain a constant blood flow regardless of the changes to blood pressure
what in the body is autoregulation important
in the brain, heart and kidneys
