water and sodium regulation part 2
Post on 30-May-2018
217 Views
Preview:
TRANSCRIPT
-
8/14/2019 Water and Sodium Regulation Part 2
1/17
Physiology Series
WATER & SODIUMREGULATION PART 2
onald E. Pakasi
PHYSIOLOGY SERIES
Ronald E. Pakasi, MDPhysical Medicine & Rehabilitation Specialist
Spinal Cord Injury Rehabilitation UnitFatmawati General Hospital, Jakarta Indonesia
-
8/14/2019 Water and Sodium Regulation Part 2
2/17
Physiology Series
Role of Angiotensin II andAldosterone in Controlling ECF
Osmolarity & Sodium Concentration
Primary: regulates sodium
reabsorption in renal tubules
sodium intake angiotensin II & aldosterone sodium reabsorption
(inverse mechanism w/
sodium
intake)
ECF sodium concentration?
IMPORTANT ROLE ?
Angiotensin II
Aldosterone
-
8/14/2019 Water and Sodium Regulation Part 2
3/17
Physiology Series
Role of Angiotensin II andAldosterone in Controlling ECF
Osmolarity & Sodium Concentration
angiotensin II & aldosterone:
amount of sodium in ECF fluid ECF fluid volume by waterreabsorption (following sodium) Little effect unless extremecondition
Angiotensin II
Aldosterone
-
8/14/2019 Water and Sodium Regulation Part 2
4/17
Physiology Series
Angiotensin II & AldosteroneDo Not Have Major Effect on
Plasma Sodium Concentration
both sodium & water
reabsorption by the renaltubules
(
ECF fluid volume & sodium
quantity)
ADH-thirst mechanismovershadow the angiotensinII-aldosterone system (under normal condition)
Angiotensin II
Aldosterone
-
8/14/2019 Water and Sodium Regulation Part 2
5/17
Physiology Series
Salt-Appetite Mechanism forControlling ECF Sodium
Concentration & Volume
Modern civilization: too
much sodium intake (mayup to 100-200 mEq/day).
Basic functional human
needs = 10-20 mEq/day Salt appetite: behavioraldrive in the event sodium
deficiency
Usually occurs when eating
a low-sodium diet
Salt-Appetite
-
8/14/2019 Water and Sodium Regulation Part 2
6/17
Physiology Series
Salt-Appetite Mechanism forControlling ECF Sodium
Concentration & Volume
2 primary stimuli:
ECF sodium concentration blood volume / blood pressure(associated w/ circulatoryinsufficiency)
Same major stimuli that elicit thirst Neuronal mechanism: analogue tothirst mechanism
AV3V region in brain
Salt-Appetite
Ph i l S i
-
8/14/2019 Water and Sodium Regulation Part 2
7/17
Physiology Series
INTEGRATION OF RENALMECHANISM FOR CONTROLOF BLOOD VOLUME AND ECF
VOLUME; AND RENALREGULATION OF
ELECTROLYTES
Integration
Ph i l S i
-
8/14/2019 Water and Sodium Regulation Part 2
8/17
Physiology Series
Urinary System-Interconnections
Integration
Ph i l S i
-
8/14/2019 Water and Sodium Regulation Part 2
9/17
Physiology Series
Sodium Excretion is PreciselyMatched to Intake Under Steady-
State Conditions
Excretion by kidney is determined byintake
Sodium excretion is almost preciselythe amount of sodium intake If kidney function disturbances are nottoo severe sodium balance:
Intrarenal
adjustments w/ minimal changes
in ECF fluid volume Other systemic adjustments (BP,hormones, alteration of sympathetic
activities)
Sodium Excretion
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
10/17
Physiology Series
Control of Sodium Excretion:Intrarenal Changes
Altering glomerular filtration rate Altering tubular sodium reabsorption rates
Sodium Excretion
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
11/17
Physiology Series
Role of Pressure Natriuresis &Pressure Diuresis in Maintaining
Body Sodium & Fluid Balance
Pressure natriuresis: effect of bloodpressure on sodium Rise of sodium excretion w/ elevatedBP
Pressure diuresis: effect of bloodpressure on water excretion
Increased BP to raise urinary
volume excretion
Pressure Natriuresis
Pressure Diuresis
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
12/17
Physiology Series
Effect of Arterial Pressure on
Urinary Sodium Output
Rise of BP 30-50 mmHg: urinarysodium output 2-3x
Effect is independent fromsympathetic activity or RAA system Chronic increase of BP:effectiveness of pressure natriuresis
is greatly enhanced Because of the suppression on RAAsystem
Pressure Natriuresis
Pressure Diuresis
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
13/17
Physiology Series
Role of Pressure Natriuresis &Pressure Diuresis: Key Components
of a Renal-Body Fluid Feedback
Pressure Natriuresis
Pressure Diuresis
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
14/17
Physiology Series
Basic Renal Body Fluid
Feedback1. fluid intake (w/ sodium) >urine output temporary fluid accumulation 2. Accumulation in blood & interstitialspaces blood volume & ECF fluid
volume (small variables)
3. mean circulatory filling pressure 4. pressure gradient for venous return 5.
cardiac output
6. arterial pressure 7. urine output (pressure diuresis) 8.
fluid excretion
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
15/17
Physiology Series
Prevent continuous accumulation ofsalt and water
If kidney function normal: pressurediuresis mechanism is effective Large change in salt & water intakecan be accomodated with only slightchanges in blood volume, ECF fluid
volume, CO & arterial pressure Opposite sequence occurs whenfluid intake falls below normal
Role of Pressure Natriuresis &Pressure Diuresis: Key Components
of a Renal-Body Fluid Feedback
Pressure Natriuresis
Pressure Diuresis
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
16/17
Physiology Series
Precision of Blood Volume andECF Fluid Volume Regulation
Blood volume remains almostexactly constant despiteextreme changes in daily fluidintake
1. Slight change in BV cause amarked change in CO2.
Slight change in CO cause alarge change in BP
3. Slight change in BP cause alarge change in urine output
Physiology Series
-
8/14/2019 Water and Sodium Regulation Part 2
17/17
y gy
To be continued
Ronald E.Ronald E. PakasiPakasi, MD, MDPhysical Medicine & Rehabilitation Specialist
Spinal Cord Injury Rehabilitation Unit
Fatmawati General Hospital
Jakarta, Indonesia
top related