Regulation of Blood Pressure Flashcards
Describe the renin - angiotensin - aldosterone system in the context of a person who is hemmorhaging.
Hemmorhage –> decreased blood volume –> decreased blood pressure –> not enough blood reaching kidneys –> juxtaglomerular cells release renin –> renin converts angiotensinogen to angiotensin 1 –> ACE secreted by lungs converts angiotensin 1 to angiotensin 2 which has many systemic effects. Notably, it can directly increase vasoconstriction leading to increased blood pressure and it stimulates the adrenal glands to relese aldosterone which is going to promote Na+ reabsorption which pulls water with it to increase blood volume. It will also simulate the posterior pituitary to secrete vasopressin (ADH) which will increase water absorption in the kidneys thus also increasing blood volume and it will promote thirst.
Under what cirumstances do the kidneys secrete renin?
When there is a loss of volume in circulation (hemmorhage)
In the parasympathetic division of the NS, the receptors that act at the end organ are […]
Muscarinic GPCRs (inhibitory or excitatory)
For each of the following types of adrenergic GPCRs, explain whether the receptor is inhibitory or excitatory and what type of signaling it uses:
- Alpha 1
- Alpha 2
- Beta 1
- Beta 2
This graph shows that if the baseline HR is around 160bpm and the sympathetic nerves are stimulated, there will be a gradual increase in HR that is drawn out over a longer duration. Why is that the case?
Propanolol is a beta blocker that blocks sympathetic activation of the heart while atropine is a parasympathetic agonist and blocks PSNS activation of the heart. What does this graph tell you about the regulation of the heart with regards to NS?
What is the bainbridge reflex?
Increase in HR due to increase in atrial stretch and activation of sympathetic NS
For a normal person, MAP is around 100mmHg. If a person has HTN, their MAP will be higher. Does this mean their baroreceptors are firing constantly to try and correct their BP?
NO - baroreceptors can adapt to new MAPs in about 2 days
This graph shows that if the baseline HR is around 120bpm and the vagus nerve is stimulated, there will be an abrupt decrease in HR that lasts only a short period of time. Why is that the case?
Complete this table as it pertains to the sympathetic NS.
What is atrial natriuretic peptide?
When is it released?
What does it do?
Peptide released from atrial myocardium
In response to increased stretch
Increases sympathetic formation of filtrate to decrease blood volume and promote sodium excretion from kidney (water follows sodium –> decreases volume)
Complete this table as it pertains to the parasympathetic NS.
Why don’t capillaries respond to sympathetic innervation?
They don’t have a tunica media ergo they aren’t innervated by the SympNS
The RAAS system is [faster or slower] than baroreceptors?
Slower
What would occur at the level of the CNS in response to ischemia to try and increase MAP?
Central chemoreceptors in the medulla sense an increase in H+ due to ischemia. Those chemoreceptors then stimulate cardiac accelerator nerve to increase sympathetic discharge and increase HR and contractility. They also stimulate the vasomotor nerve to cause vasoconstriction and in increase in total peripheral resistance which increases MAP.
Unlike the heart, the vasculature is under largely […] control. As such, its mean arterial pressure is around […] mmHg. What functional purpose does this serve?
Sympathetic
100
Allows smaller changes in simulation to achieve more or less constriction
What is the atrial volume reflex?
This all occurs in response to release of ANP from atrium due to stretching
