Test 2: Wk8: 2 Integrated control of the cardiovascular-renal system - Puri Flashcards
ECF Na concentration doesn’t change if
ADH work and water access is available
Na retention =
water retention
Na intake affects plasma Na
only briefly
Osmolarity and Na are rapidly restored to normal values if
the pt has free access to water
excess dietary Na will lead to
water gain
Na deficient diet will lead to
water excretion
at steady state Na intake =
Na excretion
— to — hrs for kidney to recognize change in Na
48-96hrs
Na balance influence (3 things)
ECF Vol
CO
BP
— signals adequacy of Na balance
Effective Circulating Volume
effective circulating volume cannot be identified anatomically. Rather, it is a — that reflects the extent of tissue perfusion in specific regions
functional blood volume
patients with congestive heart failure, nephrotic syndrome, or liver
cirrhosis, total ECF volume is grossly expanded (e.g., edema or ascites). In
contrast, the effective circulating volume is low, resulting in —
Na+ retention
Low Circulation ➡ — ➡ — Repeat
Low circulation ➡ More Na ➡ More ECF ➡ repeat
Four systems act in concert to regulate Na+ balance
1.Renin Angiotensin Aldosterone System 2.Sympathetic Nervous System 3.Arginine Vasopressin (ADH) 4.Atrial Natriuretic Peptide
ANP responds to
lack of Na
Juxtaglomerular Apparatus
has two components
- Macula Densa in TAL
2. AA Juxtaglomerular cells that secrete renin
Renin Synthesis is a Balance of Four Systems
- NKCC2 in TAL
- SNS in AA on Beta1 Receptors
- Ca release from stretching of AA
- AT1-R on AA
↑ Renin Synthesis NKCC2 (5)
- ↓Blood pressure→ ↓RBF→ ↓GFR→ ↓ Na filtration
- ↓Dietary Na→ ↓ECF volume→ ↓Renal flow
- ↓Cardiac output→ ↓RBF→ ↓GFR
- ↓RBF→ ↓GFR
- ↑Na resorption in the PCT
↑ Renin Synthesis Beta1 Receptor (3)
1.↓Blood pressure→ ↑SNS activity
2.↓Dietary Na→ ↓ECF volume→
↓Blood pressure
3.↓Cardiac output→ ↓Blood pressure
↑ Renin Synthesis Ca (1)
1.↓Blood pressure→ ↓Stretch of the
AA
— is the rate limiting step in synthesis of ANG II
Renin
5 things increase Renin secretion
⬇ Na ⬇ ECF ⬇ MAP ⬇ RPF ⬇ GFR
Short Feedback loop
ANG II feedback inhibition on ANGII
Long Loop Feedback
increased GFR and NaCl at MD prevent reabsorption of NaCl at MD
Renin is released from the A.A in response to a — diet:
reduced Na
Reduced Na has reduced— that reduces the stretch on the
—
perfusion pressure; A.A
Reduced Na has reduced — and the filtered load, which then translates to reduced Na reaching the — as the proximal tubule stills absorbs a constant fraction of N %
GFR; macula densa; 66%
Reduced Na and ECF volume has also reduced — thus
increasing filtration fraction. This leads to increased Na reabsorption in the PT and less Na reaching the —. This stimulates — release.
renal perfusion, MD, renin
Reduced Na has reduced the MAP, which then activates the — and the — which then stimulates — release
baroreflex; SNS; renin
Alters TPR (7)
- Vasoconstriction
- Increased SNS Activity
- Reduced NE reuptake
- Increased peripheral responsiveness
- Increased CNS discharge
- Epinephrine from AM
- Releases AVP (ADH)
Alters CV structure (3)
1.Increased proto-oncogenes
2.Increased growth factors and inflammatory
cytokines
3.Increased collagen production
Alters Renal Fn. (5)
1.Increased NHE in PT
2.Aldosterone release
3.Altered renal hemodynamics
4. Preferential EA constriction = ↑ FF
5 .ADH-mediated water reabsorption
RAAS Regulates Na+ in —, — & —
Proximal Tubule, TAL, Cortical Ducts
3 Effects of ANGII on kidney
increase resistance of EA and AA
increase NHE and NKCC2
increase Aldosterone
Atrial natriuretic peptide is
synthesized in the cardiac
myocyte (L. Atria) in response to
an —.
increase in blood volume
Kidneys make dopamine in response to —
volume expansion
— is the true long term
regulator of arterial pressure
ECF
two pathways are directly affected by change in blood pressure
1 Renin angiotensin system
2 Pressure-natriuresis mechanism
Increased MAP leads to ↑ — in the peritubular capillaries
and ↓ —
Hydrostatic pressure, solute and water reabsorption
to maintain the MAP and to accommodate diet, the P-N is modulated by
by the AngII and ANP
