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When you have worked through this you should be able to explain Electrolyte balance Ion channels and pumps where they relate to the kidneys Fluid balance regulation Urine – isomolar (more/less) Countercurrent multiplier RAAS and ADH system Acid-base balance Hormonal regulation (Angiotensin II, ADH, ANP,
Aldosterone)
Fluid Balance
These slides are available with all my other lectures on my website http://www.liv.ac.uk/~dcmt
In the text books:Chapters 25,26, 27 and 28 in Preston and Wilson (2013)Chapter 14 in Naish and Court (2014)
Resources
Formation of urine and its composition
Role of the kidneys: Remove waste products Maintain blood volume/pressure Electrolyte balance
Na+ 142 mM, K+ 5mM, Ca2+ 2mM, Cl- 105 mM Acid-base balance
pH=7.4
Electrolyte balance
Acid-base balance
Ion channels and pumps where they relate to the kidneys
Ch. 26 in Preston and Wilson (2013) Fig. 14.9 in Naish and Court (2014)
Two thirds of the filtered water (and almost all sodium and chloride) is reabsorbed in the proximal convoluted tubule
Sodium is rescued by the Na/K ATPase Some of the water is reabsorbed through
paracellular pathways And some is reabsorbed through
transcellular pathways (Aquaporin I)
Fluid balance regulation
Fig 26.2 in Preston and Wilson (2013) Fig 14.9 in Naish and Court (2014)
The key thing to remember is that the fluid leaving the proximal convoluted tubule is almost iso-osmotic with capillary fluid
But is no longer contains glucose (unless the pump was saturated by high concentrations), or amino acids
Fine tuning of electrolyte concentration occurs in the loop of Henlé.
Urine – isomolar (more/less)
Countercurrent multiplier
Ch. 27 in Preston and Wilson (2013) Fig 14.15 in Naish and Court (2014)
Countercurrent multiplier
Permeable to water,Impermeable to NaCl
Permeable to NaClImpermeable to water
Ch. 27 in Preston and Wilson (2013) Fig 14.15 in Naish and Court (2014)
ADH system
Concentration gradient300mOsm upto 1,200mOsmol
Urea
Tubule and early duct membrane impermeable to Urea
Later part of collecting duct membrane permeable to Urea
Urea
[Urea]In duct
Local Blood Flow (kidney)
Sodium reabsorption
Potassium secretion
Decreased renal blood flow
Monitored by JGA cells
Renin production
Angiotensinogen
Converting enzyme
Angiotensin I
Angiotensin II
Aldosterone
VasoconstrictionChapter 20, p 243 in Preston and Wilson (2013)Chapter 11, p 556 in Naish and Court (2014)
Aldosterone increases Na+ reabsorption and K+ secretion
ADH (anti-diuretic hormone) increases water reabsorption through aquaporin II
ANF decreases sodium reabsorption
Hormones
Chapter 20, p 244 in Preston and Wilson (2013)Chapter 11, p 556 in Naish and Court (2014)
Overview
Fluid loss
Blood volume
Venous return
Cardiac output
Arterial pressure
Local blood flow
Blood volume
Venous return
Cardiac output
Arterial pressure
vol
baro
chemo
kidney renin/angiotensin aldosterone
ADH
CNS
sympathetic
heart rate
contractility
vasoconstriction
capillarypressure
veins
