RENAL and ACID-BASE Flashcards
1
Q
Total body wayer is approximately ___________
A
60% of body weight
2
Q
The percentate of TBW is higherst in ___________
A
newborns and adult males
- Lowest in adult females
3
Q
2/3 of TBW
A
Intracellular Fluid
4
Q
Major cations of ICF are _______
A
Potassium and Magnessium
5
Q
The major anions of ICF are
A
Protein and organic phosphates
6
Q
1/3 of TBW
A
Extracellular fluid
7
Q
The major cation of ECF is ________
A
sodium
8
Q
The major anions of ECF are ______ and _________
A
Chloride and HCO3
9
Q
______ is 1/4 of ECF
A
Plasma
(the major plasma proteins are albumins and globulins)
10
Q
_________fluid is 3/4 of the ECF
A
Intestitial fluid
- The composition is the same as that of plasma except that it has little protein
- Ultrafiltrate of plasma
11
Q
A known amount of a substance is given whose volume of distribution is the body of fluid compartment of interest
The substance is allowed to equilibriate
The conentration is measured an the volme of distribution is calculated
A
Dilution method
12
Q
______ marker for TBW that distributes wherever water is found
A
titrated water
13
Q
_______marker for ECF because it is a large molecule that cannot cross cell membranes and is therefore excluded from the ICF
A
Mannitol
14
Q
Marker for plasma volume because it is a dye that inds to albumin and is therefore confined to the plasma compatment
A
Evans blue
15
Q
Body water and ody fluid Compartments
A
16
Q
Concentration of solute particles
A
Osmolarity
Plasma osmolarity is estimated as :
2 x Na + glucose/18 + BUN/2.8
17
Q
At steady state, ECF osmolarity and ICF osmolarity are _____________
A
equal
18
Q
To achieve osmolarity equality ________ shifts between ECF and ICF
A
water
19
Q
Infusion of isotonic NaCl (addition of isotonic fluid)
A
also called as isosmotic volume expansion
- ECF volume increase, but bo change occurs in the osmolarity of ECF or ICF
- Plasma protein concentration and heamtocrit decreases
- Arterial blood pressure increases due to ECF volume increases
20
Q
Diarrhea - loss of isotonic fluid
A
also called as isosmotic volume contraction
- ECF volume decreases, but no change occurs in the osmolarity
- Plasma portein concentraion and hematocrit increases because of loss of ECF concentrates the portein and RBCs
- Arterial blood pressure decrease because ECF volume decreases
21
Q
Excessive NaCl intake - addition of NaCl
A
Also caled hyperosmotic volume expansion
- Theosmolarity of ECF increases because osmoles (NaCl) hace been added to the ECF
- Water shifts from ICF to ECF. As a result of this shift, ICF osmolarity increases until equals that of ECF
- ECF volume increases and ICF volume decreases
- Plasma protein concentration and hematocrit decrease because of theincrease in ECF volume
22
Q
Changes in voume and Osmolarity of body fluids
A
23
Q
Sweating in a desert - loss of water
A
Also called as hyperosmotic volume contraction
- The osmolarity of ECF increases because swert is hyposmotic (relatively more water than salt is lost)
- ECF volume decreases because of the loss of volume in the sweat. Water shits oit of the ICF, ICF osmolarity increases and ICF volume decreases
- Plasma protein concnetration increases because of the decrease in ECF volume. Although Hematocrit might alsobe expected o increase, it remains unchanged because water shifts out of the RBCs
24
Q
SIADH - gain of water
A
Hyposmotic volume expansion
- the osmolarity of ECF decreases because excess water is retained
- ECF volume increases. Water shidts in to thecells, ICF osmolarity decreases until it equals ECF. ICF volume increases
- Plasma protein concentration decreasesbecause of the increase in ECF volume. Hematocrit remains unchanged because water shifts into theRBCs
25
Adrenocortical insufficiency - loss of NaCl
also called hyposmotic volume contraction
* The osmolarity of ECF decreases. asa result of the lackof aldosteron, theere is decreased NaCl reabsorption. Kidney excrete more NaCl than water
* ECF volume decreases. water shifts into the cells; asaresult of this, ICF osmolarity decreases until it equals ECF osmolarity and ICF volume increases
* Plasma protein concentration increases because of the decrease inECF volume. HCT increases
* Arterial blood pressure decrease because of the decrease in ECF volume
26
Indicates the volume of plasma cleared of substance per unit time
Clearance
27
RBF is \_\_\_\_\_\_% of the cardiac output
25%
28
RBF is _______ proportional to the pressure difference between the renal arter and the renal vein
Directly propotional
* inversely proportional to the resistance of the renal vasculature
29
\_\_\_\_\_\_\_\_\_\_of arterioles leads to decrease in RBF
Vasoconstriction
* produced by the activation of the sympathetic nervou system and angiotensin II
* at low concentration, ATII preferentially constricts efferent
30
\_\_\_\_\_\_\_\_\_\_\_\_ dilate efferent arterioles and produce decrease in GFR
Angiotensin converting enzyme inhibitors
31
\_\_\_\_\_\_\_\_\_of renal arteriole leads to an increase in RBF produced by prostaglandin E2 and I2, bradykinin ,nitric oxide, and dopamine
Vasodialtion
32
causes vasodialtion of the afferent arterioles and to a lesser extent, vasoconstriction of efferent arterioles
Atrial natriuretic peptide
overall, ANP increases RBF
33
Autoregulation of RBF is accomplished by \_\_\_\_\_\_\_\_\_
changing renal vascular resistance
34
RBF remains constant over the range of arterial pressure from \_\_\_\_\_\_\_\_\_\_\_
80 to 200 mmHg
35
Mechanisms for Autoregulation of RBF
Myogenic
Tubuloglomerular feedback
36
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_in wich the renal afferent arterioles contract in response to stretch. Thus increased renal arterial pressure stretches the arterioles, which cobtract and increase resistance to maintain constant blood flow
Myogenic mechanism
37
\_\_\_\_\_\_\_\_\_\_\_\_\_in which, inreased renal arterial pressure leads to increased delivery of fluid to the macula densa. The macula densa senses the increased load and causes constriction of the nearby afferent arteriole, increasing resistance to maintain constant blood flow
Tubuloglomerular feedback
38
Clearance of _______ is used to measure Renal Plasma flow
para-aminohippuric acid (PAH)
* Meaures effective PAH and understiamtes true RPFby 10%
* Clearance of PAH does not measure renal plasma flow to regions pf the kidney that do not filter and secrete PAH, such as adipose tissue
39
Measurement of RBF
40
\_\_\_\_\_\_\_\_ isused to measure GFR
filtered but not reabsorbed or secreted by renal tubules.
Inulin
41
Both BUN and serum creatinine ______ when GFR decreases
Increase
42
\_\_\_\_\_\_\_ azotemia, BUN increase more than serum creatinine and there is an Increased BUN/creatinine ration (\>20:1)
Prerenal
43
GFR ____ with age
Decreases
44
The fraction of RPF filtered across the glomerular capilalries
Filtration fraction
FF = GRR/RPF
* normally about 0.20
* the remaining 80% leaves the glomerular capillaries by the efferent arterioles and becomes the peritubular capillary circulation
45
\_\_\_\_\_\_in the filtration fraction increases the protein concentraion of peritubilar capillary blood, which leadds to increased reabsorption in the proximal tubule
Increases
46
\_\_\_\_\_\_\_\_in the filtratin fraction produce decrease in the protein concentration of peritublar capillary blood and decreased reabsortpion in the proximal tubule
Decrease
47
The driving force for glomerular filtration is \_\_\_\_\_\_\_across the glomerular capillaries
net-ultrafiltration pressure
48
\_\_\_\_\_\_\_is always favored in glomerular capillaries because the net ultafiltration pressure always favor the movement of fluid out of the capillary
Filtration
49
GFR can be expressed by the \_\_\_\_\_\_\_\_\_\_
Starling equation
50
\_\_\_\_ is filtration across the glomerular capillaries
GFR
51
Kf is the\_\_\_\_\_\_\_\_ of the glomerular capillaries
filtration coefficient
* The glomerular barrier consists of
* capilalry endothelium
* basement membrane
* filtation slits of the podocytes
* Normally, anionic glycoproteins line the filtration barrier and restrict the filtration of plasma proteins, which are also negatively charged
52
PGC is _____________ which is constat along the length of the capillary
Glomerular capillary hydrostatic pressure
* Increased by dialtion of the afferent arteriole or constriction of the efferent arteriole
* Increase cause increase in net ultrafiltration pressure and GFR
53
πGC is \_\_\_\_\_\_\_\_\_\_\_\_. It is usually zero, and therefore ignored,
bowman space oncotic pressure
54
Effects of changes in Starling forces on GFR, RPF, and Filtration Fraction
55
the difference between the aamount filtered across the glmerular capilalried and the amount excreted in urine
Reabsirption or secretion rate
56
If filtered load is greater than the extretion rate, then ___________ has occured
net reabsorption
57
If the filtered load is less than the excretion rate, then _______ has occured
net secretion
58
Filtered load of glucose ____________ in direct proportion to the plasma glucose concentration
Increases
| (filtered load = GFR x P )
59
Na-glucose cotransport in the ___________ reabsorbs glucose from tubular fluid into the blood.
Proxximal tubule
60
The reabsorptive rate at which the carriers are saturated is the \_\_\_\_\_\_\_
Tm
61
Defined as the plasma concentration at which glucose first appears in the urine
Threshold
| (Approximately 250 mg/dL)
62
The region of the glucose curves between the threshold and Tm
Occurs between plasma glucose of approximately 250 and 350 mg/dL
Splay
63
Represents the excretion of glucose in urine before saturation of reabsorption is fully achieved
Splay
64
filtered load of PAH __________ in direct proportion to the plasma PAH concentration
Increases
65
Secretion of PAH occurs from peritubular capillary blood into tubular fluid (urine) via carriers in the \_\_\_\_\_\_\_\_\_
Proximal tubule
66
Excretion of PAH is the _________ across the glomerular capillaries plus __________ from peritubular capillary blood
Sum of filtration
Secretion
67
RPF is measure by the clearance of PAH at plasma concentrations of PAH that are _________ than at Tm
lower
68
Substances with the _________ clearances are those that are both filtered across the glomerular capillaries and secreted from the peritubular capillaries into urine
highest
69
Subsances with ______ clearances are those that either not filtered or are filtered and subsequently reabsorbed into peritubular capillary blood
Lowest
70
Substance with clearances equal to GFR
glomerular markers
71
Have an HA form and A form
weak acids
* The HA form which is uncharged and lipid soluble can "back-diffuse" from urine to blood
* the A form, which is charged and not lipid soluble cannot "back diffuse"
72
Weak acids at \_\_\_\_\_\_\_\_, the HA form predominates. there is more back diffsuion, and there is increased excretion of the weak acid.
Acidic urine
73
Have an BH form and a B form
weak bases
* the B form, which is uncharged and lipid soluble, can back-diffuse from urine to the blood
* The BH form is charged and not lipid soluble cannot back diffuse
74
\_\_\_\_\_\_\_ is urine at any point along the nephron
Tubular fluid
75
Plasma is systemic Plasma . It is considered \_\_\_\_\_\_
constant
76
comapres the concentration of a substance in tubular fluid at any point along the nephron with the concentration in plasma
TF/P ratio
77
if Tf/P = \_\_\_\_.then either there has been no reabsorption of the substance or reabsoprtion of the substance has been exactly proportional to the reaborption of water
1.0
78
IF TF/P is __________ then reabsorption of the substance has been greater than the reabsorption of water and the concentration in tubular fluid is less than that in plasma
\<1
79
If TF/P is _______ then eeither reabsorption of the substance has been less than the reabsorption of water or there has been secretion of the substance
\>1.0
80
used as amarker for water reabsorption along the nephron
Increases as water is reabsorbed
TF/Pinulin
* The following equation shows hw to calculate the fraction of the filtered water that has been reabsorbed
81
Corrects the TF/Px ratio for water reabsorption. this double ratio gives the fraction of filtered load remaining at any point along the nephron.
[TF/Px] / [TF/Pinulin] ratio
82
Sodium is \_\_\_\_\_\_along the entire nephron, and very little is excreted
Urine
83
Sodium handling along the nephron
84
Reabsorbs 2/3 or67% of the filtered sodium and water
Site fo glomerulotubuluar balance
Proximal tubule
85
Mechanism of sodium reabsorption of sodium
The process is isosmotic. the reabsorption of sodium and water in the PCT is exactly proportionl. therefore TF/PNa and TF/Posm =1
86
Sodium is reabsorbed by __________ with glucose, amino acids, phosphates and lactate
Cotransport
87
Sodium is also reabsorbed by _________ via Na-H exchange. which is linked directly to the reabsorption of filtred HCO3
Countertrasnport
88
diuretics that act in the early proximal tubule by inhibiting the reabsorption of filtered HCO3
Carbonic anhydrase inhibitors
89
In the late proximal tubule, sodium is reabsorbed with \_\_\_\_\_\_\_\_
Chloride
90
Maintains constant fractional reabsorption )2/3 or 67%)of th filtered sodium and water
Glomerulotubular balance in the proximal tubule
91
Mechanism of Glomerulotubular balance
* based on starling forces in the peritubualr capillaries
* Fluid reabsorption is increased by increase in πc of the peritubilar capillary blood and
92
ECF volume contraction ____________ absorption
Increases
* increases peritubular capillary protein concentraion and πc and decreases peritubular capillary Pc.
93
ECF volume expansion ________ reabsorption
Decreases
* decreases periubular capillary protein concentration and πc and increases Pc
94
TF/ ratios along the proximal tubule
* at the beginning of the proximal tubule, TF/P for freely filtered substance is **1**
* Moving along the PCT, TF/P for sodium and osmolarity remain at 1 because sodium and total solute are reabsorbed proportionately with water
* Glucose, amino acids and HCO3 are reabsorbed proprotionately more than water, so their TF/P values below 1
* In the early PCT, Cl is reabsorbed proportionately less than water so its TF/P valueis greater than 1.0
* Inulin is not reabsorbed so its TF/P value increases steadily avove 1.0 as water is reabsorbed and inulin is left behind
95
Reabsorbs 25% if the filtered Na
contains Na-K-2Cl contransporter
site of action of the loop diuretics
impermeable towater
diluting segment
Thick asccending limb of the loop of henle
* has a lumen positive potential difference
* some K diffuses back in to the lumen, making the lumen electrically positive
96
togeter rabsorbs 8% of the filtered sodium
Distal and collecting duct
97
Reabsobs NaCl by Na-Cl conductance
site of action of thiazide diuretics
impermeabe to water
cortical diluting segment
Early distal tubule
98
2 cell types in the late distal tubule and collcting ducts
Principal cells
a-intercalated cells
99
Reabsorbs Na and water
Secretes K
Aldoseterone increases sodium reabsorption and increases Potassium secretion
Principal cells
100
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_increases water permeability by directing insertion of water channels in the luminal membrane potential
Antidiuetic hormone
* in the absence of ADH, the principal cells are virtually impermeable to water
101
Examples of K sparing diuretics
Spironolactone
triamterene
Amiloride
102
secretes H aby an H-ATPase, which is stimulated by aldosterone
Reabsorb Potassium by an H, K ATPase
a-intercalated cells
103
Most of the body's K is locaed in the
ICF
104
Potassium is \_\_\_\_\_\_, \_\_\_\_\_, and _______ by the nephron
Filtered
Reabsobed
Secreted
105
TF/PK in the Bowman space is \_\_\_\_\_\_\_\_
1.0
Filtration occrs freely across the glomerular capillaries
106
Reabsorbs 67% of te filtered K along with Na and water
Proximal tubule
107
Reabsorbs 20% of the filtered K
Reabsorption involves Na-K-2Cl transporter in the luminal membrane of cells
Thick ascending limb of the loop of Henle
108
Either reabsobr or secrete K
Depends on dietary K intake
Distal tubule and collecting duct
109
Causes of Shift of K out cells (hyperkalemia)
* Insulin deficiency
* B-adrenergic antagonist
* Acidosis
* Hyperosmolarity
* Inhibitors of Na-K pump (difitalis)
* Excercise
* Cell lysis
110
Causes of shift of K into the cells (hypokalemia)
* Insulin
* B-adrenergic agonists
* alkalosis
* Hyposmolarity
111
Reabsorption of K involves ___________ in the uminal membrane of the alpha intercalated cells
H-K-ATPase
* occurs only on low K diet (potassium depletion)
112
Secretion of potassium occurs in the \_\_\_\_\_\_\_\_\_\_
Principal cells
* variable and accounts for the wide range of urinary K excretion.
* Depends on factors such as dietary K,aldosterone levels, acid-base status, and urine flow rate
113
Potassium handling of nephrons
114
Mechanis of distal K seretion
* At the basolateral membrane, K is acively transported into the cell by NA-K pump
* At the luminal side, K is passively secreted into the lumen through K channels. The agnitude of this passive secretion is determined by chemical and electrical driving forces on K across the luminal membrane
115
Changes in distal Potassium Secretion
116
Mechanism of aldosteron in K secretion
Involves inreased sodium entry into the cell across the luminal membrane and increased pumping of sodium out of the cells by the Na-K pump. Stimuation of the Na-K pump simulataneously increases K uptake into the principal cells, increaseing the intacellular K concentration andn driving force for K secretion
117
Hyperaldoseronism causes\_\_\_\_\_\_\_\_\_\_\_\_\_
hypokalemia
118
Acidosis \_\_\_\_\_\_K secretion
Decreases
119
Urea is reabsorbed, secreed in the nephron by \_\_\_\_\_\_\_\_\_\_\_
Diffusion
* either simple or facilitated
* 50% of the filtered urea is reabsorbed in the **PCT**
* Urea is secreted into the **thin descending limb of LOH**
120
Urea cannot pass through the \_\_\_\_\_\_, \_\_\_\_\_\_\_, and \_\_\_\_\_\_\_\_\_
distal tubule, cortical collecting ducts, and outer medullary collecting ducts
121
Stimulates a facilitated diffusion for urea (UT1) in the inner medullar collectin ducts
ADH
122
Urea excretion varies with \_\_\_\_\_\_\_\_\_\_\_
Urine flow rate
* at high levels of water reabsoption, there is greater urea reabsorption
123
85% of filtered phosphate is reabsobred in the\_\_\_\_\_\_\_\_\_\_\_\_\_ by \_\_\_\_\_\_
proximal tubule by sodium -phosphate co transport
124
Inhibits phosphate reabsorption in the PCT
PTH
* Activates adenylate cyclase, generating cyclic AM and inhibiting N-Phosphate co transport
* causes phosphaturia and increasesd urinary cAMP
125
60% of the plasma Ca is filtered acrosss \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
glomerular capilalries
126
90% og the filtered calcium is reabsorb by passive processes that are coupled to sodium reabsorption in the \_\_\_\_\_\_\_\_\_\_\_\_
Proximal tubule and thick ascending limb
127
cause increased urinary calcium excreton
Loop diuretics
128
PTH ____________ calcium reabsorption by activating adenylate ylace in the distal tubule
increases
129
Thiazide diuretics ________ calcium reabsorption in the early distal tubule
increases
* treatment of idiopathic hyercalciuria
130
Magnesium reabsorb in the \_\_\_\_\_\_\_\_,\_\_\_\_\_\_\_\_\_, and \_\_\_\_\_\_\_\_\_\_\_
PCT, thick ascending limb, and distal tubule
131
in the _________________ magnesium and calcium compete for reabsorption
thick ascending limb
132
Response to water deprivation
133
Response to water intake
134
Gradient of osmolarity from the cortex (300 mOSm/L) to the papilla (1200 mOsm/L) and is composed primarily of NaCl and urea
Corticopapilalry gradient - high ADH
* established by countercurrent multiplication and urea recylcing
* maintained by countercurrent exchange in the vasa recta
135
Countercurrent multiplication in the loop of Henle
* depends on NacCl reabsorption in the thick ascending limb and countercurrent flow in the descending and ascending limbs of the loop of henle
* augmented by ADH
* stimulate NaCl reabsorption in the thick ascending limb.
136
Urea recycling
From the inner medullary collecting ducts into the medullary interstital fluid
Augment by ADH
137
\_\_\_\_\_\_are the capillaries that supply the loop of Henle. They maintain the corticopapillary gradient by serving as osmotic exchanges
Vasa Recta
138
Mechanism for producing hyperosmotic urine
139
Production of concentrated urine
1. Corticopapilalry osmoic gradient -high ADH
* Countercurrent multiplication in the loop og henle
* urea recycling
* vasa recta
2. Proximal tubule -High ADH
* TF/Posm = 1
3. Thick ascending limb - High ADH
* diluting segment
* Na-K-2Cl contransporter
* impermeable to H20
* TF/Posm \<1
4. Early DCT - high ADH
* cortical diluting sergmen
* impermeable to water
5. late DCT - high ADH
* ADH increaes water permeability
* TF/P = 1
6. Colleting ducts - high ADH
* ADH icnreases water permeability
* Tf/P \>1
140
Production of dilute urine
1. Corticopapillary osmotic gradient - no ADH
* smaller
2. PCT -no ADH
* TF/P = 1
3. Thick ascending limb LOH -no ADH
* TF/Posm \<1
4. Early distal tubule - no ADH
* TF/P, \<1
5. Late distal and collecting ducts - no ADH
* Impermeable to water
* TF/P \<1
141
Use to estimate the abilty to concetrate or dilute urine
Free water clearance
142
urine that is isosmotic to plasma (isosthenuric)
CH2O is zero
* Loop diuretic
* inhibits NaCl reabsorption in the thick ascending limb, inhibiting both dilution in the thick ascending limb and production of the corticopapillary osmotic gradient
143
Summary of ADH pathophysiology
144
Urine that is hyposmotic to plasma (low ADH)
CH2O is positve
* high water intake
* central diabetes insipidus
* nephrogenic diabetes insipidus
145
Urine that is hyperosmotic to plasma (High ADH)
CH20 is negative
* Produced in water deprivaton (ADHrelease from the pituitary is stimulated) or SIADH
146
RENAL HORMONES
147
Two types of acid produced in the body
Volatile and nonvolatile acids
148
Volatile acids
* CO2
* produced from aerobic metabolism of cells
149
catalyze the reversible reaction between CO2 and H2O
Carbonic anhydrase
150
Nonvolatile acids
Fixed acids
icnlude sulfuric acids
normally Produced at a rate if 40 to 60 mmoles/day
151
Prevent a change in pH when H ions are added to or removed from a solution
Buffer
152
Buffers are most effective within \_\_\_\_\_pH unit of pK of the buffer
1
153
Major extracellular buffer
HCO3
pK of CO2/HCO3 bufferpair is 6.1
154
minor extracellylar buffer
most important urinary buffer
Phosphate
pK of H2PO4/HPO4 buffer is 6.8
155
Major intracellular buffer
Hemoglobin
156
What is a better buffer, deoxyHgb or oxyhemoglobin?
Deoxyhemoglobin
157
Henderson-hasselbach equation
158
describes how the pH of a buffered solution changes as H+ ions are added to it or removed from it
Titration curves
159
A buffer is most effective in the __________ portion of the titration curve, where the addition or removal of H causes little change in pH
linear
160
According to the Henderson-Hasselbach equation, when the pH of the solution is ________ to the pK, the concentrations of HA and A are equal
Equal
161
Reabsorption of filtered HCO3 occurs primarily in the \_\_\_\_\_\_\_\_\_\_
proximal tubule
162
Regulation of filtered load of HCO3
Increaes in the filtered load of HCO3 result in the increasse rates of HCO3 reabsorption However, if the plasma HCO3 concentration becomes very high, the filtered load will exceed the reabsorptive ccapacity and HCO3 will be excreted in the urine
163
Increases in PCO2 result in ___________ rates of HCO3 reabsorption
Increased
164
ECF volume expansion results in \_\_\_\_\_\_\_\_\_\_\_\_HCO3 reabsorption
Decreased
165
Stimulates Na-H exchange thus increases HCO3 reabsorption, contributing to the contraction alkalosis that occurs secondary to ECF volume contraction
Angiotensin II
166
Excretion of fixed H+
* Excretion of H as titatable acid (H2PO4)
* depends on the amount of urinary buffer present and the pK of the buffer
* minimum urinary pH is 4.4
* Excretion of H as NH4
* depends on the amount of NH3 synthesized by renal cells and the urine pH
* diffusing trapping
167
\_\_\_\_\_\_\_inhibits NH4 synthesis, which produces a decrease in H excretion as NH4 (type 4 RTA)
Hyperkalemia
168
Summary of acid -base disorders
169
In chronic metabolic acidosism an adapative increase in\_\_\_\_\_\_\_\_\_\_synthesis aids in the excretion of excess H+
NH3 synthesis
170
Causes of Acid-Base Disorders
171
If metabolic alkalosis is accompanied by ECF volume contraction
the reabsortipn of HCO3 increases (secondary to ECF volume contraction and activationof the RAAS), worsening the metabolic alkalosis (contraction alkalosis)
172
Compensatory response to Acid-Base Disorders
173
Inhibition of carbonic anhydrase
Proximal tubule
Carbonic anhydrase inhibitors (Acetazolamide\_
Increase HCO3 excretion
174
Inhibition of Na-K-2CL cotransport
thick ascending limb of the loop of henle
Loop diuretics (furosemide, ethacrynic acid, bumetanide)
* Increased NaCl excretion
* Increased K excretion (Increase DCT flow rate)
* Increased Ca excretion (treat hypercalcemia)
* Decreased ability to concentrate urine
* Decreased ability ro dilute urine (inhibitin of diluting segment)
175
Inhibition of Na-Cl co transport
Early distal tubule (cortical diluting segment)
Thiazide diuretics
* Increased NaCl excretion
* Increased K excretion
* Decrease Ca excretion (treatment for idiopathic hypercalciuria)
* Decreased ability to dilute urine
* No effect on the ability to concentrate urine
176
Inhibition of Na reabsorption. Inhibition of K secretion, Inhibition of H secretion
Late distal and collecting duct
K-sparing diuretics
* Ibcreased sodium excretion
* Decrease K excretion
* Decreased H excretion
177
Effects of hypoaldosteronism
Decreased sodium reabsorption (ECF volume contraction)
Decreased K secretion (volume contraction)
Decreased H+ secretion (metabolic acidosis)
