CPRS 44: Neuroendocrine Regulation of Fluid Balance

Question 1

Consider the following ions
Na
K
Cl
HCO3
Ca
Mg

Conc Extracellular > Intracellular: (4)
Conc Intracellular > Extracellular: (2)

Answer 1

Consider the following ions
Na
K
Cl
HCO3
Ca
Mg

Conc Extracellular > Intracellular: Na Cl Ca HCO3-
Conc Intracellular > Extracellular: K Mg

Question 2

Compare Neural Responses and Neurohormonal Responses

• Speed of response
• Localized/ global
• Duration of response

Answer 2

Neural Responses VS Neurohormonal Responses

• Speed of response: Immediate VS Slower
• Localized/ global: Localized VS Global
• Duration of response: Disappear immediately VS Long-lasting

Question 3

In Neurohormonal Responses, the components involved are…

Afferent pathway
Blood Circulation
CNS
Effectors
Hormone release
Receptor

Arrange them in order

Answer 3

In Neurohormonal Responses, the components involved are…

Receptor
Afferent pathway
CNS
Hormone release
Blood Circulation
Effectors

Arranged

Question 4

There are 3 Mechanisms in regulation of Renin Release
What are they in specific?

• Sympathetic Nerve Mechanism (Stimulation of _______ receptor promotes renin release)
• Baroreceptor Mechanism
• Macula Densa Mechanism

Answer 4

There are 3 Mechanisms in regulation of Renin Release

• Sympathetic Nerve Mechanism: stimulation of beta-1 receptor promotes renin release
• Baroreceptor Mechanism: Reduction in afferent arteriole pressure promotes renin release
• Macula Densa Mechanism: Reduce in NaCl promotes renin release

Question 5

Conversion process from Angiotensinogen from liver to Aldosterone

Angiotensinogen => Angiotensin I (what is required?)
Angiotensin I => Angiotensin II (what is required?)
Angiotensin II => Aldosterone (angiotensin II acts on where to promote the secretion of aldosterone?)

What are the effects of Angiotensin II?

• It binds to ______ (receptor)
• It increases blood pressure by _________
• It increases the production of a vasoconstrictor _______
• For negative feedback, it act on ____ cells to inhibit _______ release

Answer 5

Conversion process from Angiotensinogen from liver to Aldosterone

Angiotensinogen => Angiotensin I (requires renin)
Angiotensin I => Angiotensin II (requires ACE1)
Angiotensin II => Aldosterone (Angiotensin II acts on Adrenal cortex to promote secretion of aldosterone)

What are the effects of Angiotensin II?

• It binds to AT1R (receptor)
• It increases blood pressure by vasoconstriction
• It increases the production of a vasoconstrictor Endothelin-1
• For negative feedback, it act on JG cells to inhibit renin release

Question 6

Consider Angiotensin II

• It stimulates the ______ (channel) on the apical membrane
• Thus stimulation of ________ and ____________ on basolateral membrane (channels)
• Angiotensin II is degraded by _________

Answer 6

Consider Angiotensin II

• It stimulates the NHE (channel) on the apical membrane
• Thus stimulation of Na/HCO3 co-transporter and Na/K ATPase on basolateral membrane (channels)
• Angiotensin II is degraded by ACE2

Question 7

Consider Aldosterone

Aldosterone is synthesized in __________ on the adrenal _________.

Synthesis of Aldosterone

• _________ secretes CRH
• __________ secretes ACTH
• Synthesis of Aldosterone

Aldosterone binds to _____ receptor to form _________ Complex

• Stimulate __________ on basolateral membrane: Increase _____ ion from cell to capillary, Increase _____ ion from capillary to cell
• Stimulate ________ channels on apical membrane: Increase ______ ion from the cell to filtrate
• Stimulate ________ channels on apical membrane: Increase ______ ion from the filtrate to cell

Answer 7

Consider Aldosterone

Aldosterone is synthesized in Zona glomerulosa on the adrenal cortex.

Synthesis of Aldosterone

• Hypothalamus secretes CRH
• Anterior pituitary secretes ACTH
• Synthesis of Aldosterone

Aldosterone binds to MR receptor to form Aldosterone-MR Complex

• Stimulate Na/K ATPase on basolateral membrane: Increase Na+ ion from cell to capillary, Increase K+ ion from capillary to cell
• Stimulate ROMK channels on apical membrane: Increase K+ ion from the cell to filtrate
• Stimulate ENaC channels on apical membrane: Increase Na+ ion from the filtrate to cell

Question 8

Angiotensin can directly stimulate ______ to increase the vasopressin release

Answer 8

Angiotensin can directly stimulate SON to increase the vasopressin release

Question 9

Consider ANP and BNP
They are for blood pressure reduction
They stimulate __________ (Na+ excretion in urine) and also ___________ (Increased urination)

Answer 9

Consider ANP and BNP
They are for blood pressure reduction
They stimulate Natriuresis (Na+ excretion in urine) and also diuresis (Increased urination)

Question 10

Consider ANP and BNP

• ANP is released by ____________ upon stretching of atria
• BNP is released by ____________ upon stretching
• Stretching means increase in blood pressure and increase in blood volume
• BNP binds to the same receptors as ANP, but (higher/lower) in affinity, so effectiveness of (ANP/BNP) is higher

Answer 10

Consider ANP and BNP

• ANP is released by atrial muscle fibres upon stretching of atria
• BNP is released by cardiac ventricles upon stretching
• Stretching means increase in blood pressure and increase in blood volume
• BNP binds to the same receptors as ANP, but lower in affinity, so effectiveness of ANP is higher

Question 11

Just read

ANP Leads to decrease in blood pressure, in the following ways

• Vasodilation of afferent arterioles, Vasoconstriction of efferent arterioles => Increase GFR => More plasma/ water excreted
• Reduce Na+ reabsorption in capillaries
• Inhibit secretion of renin by JG cells
• Inhibit secretion of vasopressin and inhibit binding of AQP2 channels on the luminal membrane