Renal physiology Flashcards
1
Q
what does renal mean?
A
Renal refers to the term kidney
2
Q
what is the kidneys main function?
A
Removal of waste from the blood and urine
3
Q
what do kidneys regulate?
A
-Blood volume and pressure
*[water] and fluid volume
**inorganic ion composition
-Acid / base balance
4
Q
what do kidneys excrete?
A
-Urea, uric acid, creatinine, bilirubin
-foreign chemicals (drugs, food additives, pesticides)
5
Q
what do kidneys synthesize?
A
Glucose through gluconeogenesis
-synthesis of glucose from non-carb sources
https://youtu.be/ydhr0QAyxYg?si=oPWH9CkrKcg2L0n8
6
Q
what do kidneys secrete?
A
Hormones / enzymes
-erythropoietin
-1,25-dihydroxy vit D
-renin
7
Q
what percent of the body’s weight is water?
A
60%
8
Q
what makes up the bodily fluid compartments?
A
intracellular fluid - 40%
extracellular fluid - 20%
-plasma
-interstitial fluid (larger)
9
Q
what is the volume of total body water?
A
42L
10
Q
what ions are in greater [ ] in the ECF compared to ICF?
A
140mM Na+ , 100mM Cl-, 24mM HCO3-
11
Q
what ions are in greater [ ] in the ICF compared to ECF?
A
150mM K+, 12mM Mg+, 40mM Pi, 4mM protein
12
Q
inside the ECF where is protein found? why?
A
in the plasma
- plasma proteins are too large to cross the capillary membrane into the interstitial fluid
13
Q
what factors play a role in diffusion across the the fluid compartments?
A
-distance
-chemical properties of cell membrane
-chemical nature of molecules (polar vs non-polar)
-channels and transporters
14
Q
what does osmolarity measure?
A
the number of solutes per unit volume of solution (mol/ L)
15
Q
what is 1 osmole equal to?
A
1 mole of solute particles
16
Q
what are aquaporins?
A
water channels that influence the rate of diffusion
-diffusion is guided by [water]
17
Q
If osmolarity is high, is the [solution] high or low?
A
high osmolarity indicates low [water] and high [solute]
low osmolarity indicates high [water] and low [solute]
18
Q
how does diffusional Eq occur?
A
19
Q
what is osmosis?
A
the diffusion of water across a selectively permeable membrane
- high [water] to low [water]
20
Q
what is osmotic pressure?
A
the pressure needed to prevent solvent movement
-prevent osmosis
21
Q
what is the difference between osmosis and the diffusion of water across a cell membrane?
A
in osmosis, the membrane is only permeable to water; not solutes
22
Q
what is tonicity?
A
the ability for a solution to modify the volume of it’s cells by altering water content
23
Q
what determines tonicity?
A
the [non-penetrating solutes] (NPS) of an extracellular solution relative to intracellular environment of the cell
24
Q
what determines cell volume in regards to tonicity?
A
[solute]
25
what is isotonic (isoosmotic)? what happens to the cell?
same [non-penetrating solutes] inside and outside the cell
-same cell volume
26
what is hypertonic (hyperosmotic)? what happens to the cell?
higher [non-penetrating solutes] outside than inside the cell
-cells shrink
27
what is hypotonic (hypoosmotic)? what happens to the cell?
lower [non-penetrating solutes] outside than inside the cell
-cell swells
28
what direction does water flow in osmosis?
from lower osmolarity to higher osmolarity
*high osmolarity = high [solute] low [water]
29
what is normal osmolarity inside the cell?
300 mOsm/L
30
how does osmolarity values change in relation to changes in tonicity?
300 isotonic (normal)
400 hypertonic
200 hypotonic
31
what is movement of solutes and water out of the blood (plasma) called?
filtration
32
what is movement of solutes and water into the blood (plasma) called?
absorption
33
what factors influence fluid movement along capillaries? what direction does it push fluid?
-capillary hydrostatic pressure (Pc); out of cell
-interstitial fluid hydrostatic pressure (Pif); into cell
-osmotic force of [plasma protein]; into cell
-osmotic force of [interstitial fluid protein]; out of cell
34
what organs are associated with the kidneys?
ureter
bladder
urethra
35
what is micturition?
urination
36
what is the function of the ureter?
collects everything and sends it to the bladder
37
what is the function of the bladder?
holds and excretes urine; under ANS control
-para-sym and sym systems
38
what is the function of the urethra?
leads urine out of the body; autonomic control
39
what structures make up the kidney?
capsule, outer cortex, nephron-renal corpuscle and renal tube
40
what is the structures make up a nephron?
glomerulus-filters small solutes from the blood
bowman's capsule-helps filter blood from glomerular capillaries
proximal tubule- reabsorbs ions, water and nutrients. removes toxins and adjusts filtrate pH
descending loop of henle- water passes from filtrate to IF
Ascending loop of henle- reabsorption of Na+ and Cl- from filtrate into IF
Distal tubule- selectively secretes and absorbs different ions to maintain blood pH and electrolyte balance
collecting duct-reabsorbs solutes and water from filtrate
41
what lines the tubule?
a single layer of epithelial cells
-cells in each segment vary in structure and function
42
what does the bowman's space extend to?
It continues as the tubule
43
What do nephrons begin as in stage 1 of development?
They develop as blind-ended tubules composed of single layer epithelium
44
what occurs in stage 2 of renal corpuscle development?
the growing tuft of capillaries penetrate the expanded end of tubules
-basal lamina trapped between endothelial cells of capillaries and epithelial layer
-epithelial cell layer differentiates into parietal (outer) and visceral (inner) layer
45
what occurs in stage 3 of renal corpuscle development?
the parietal layer flattens to become the wall of the bowman's capsule
-visceral layer becomes the podocyte cell layer
46
what structures make up the renal corpuscle?
*inside to out*
Glomerular capillary
Fenestrated endothelial layer
Basement membrane
Podocytes with filtration slits
47
where are renal corpuscles found in the kidney?
In the cortex
48
where are the loops of henle found within the kidney?
The medulla
49
what are the basic functions of the nephrons?
Filtration
reabsorption
secretion
50
What are the 2 types of nephrons?is their function?
cortical - 85%; basic functions (filtration,reabsorption,secretion)
juxtamedullary- 15%; basic functions + [urine] regulation
51
what is the renal fraction?
20%
52
what is the rate of flow of blood supply to kidneys?
1200 mL/min
53
what is cardiac output to kidneys?
5600mL/min - high blood flow
54
what are the 3 types of capillaries in the nephron?
Glomerular-inside corpuscle
Peritubular-around peritubular capillaries
vasa recta-parallel to the loop of henle
55
what are the 3 basic renal processes?
1-filtration
2-secretion
3-reabsorption
56
what processes enter into the lumen?
filtration and secretion
57
what processes exit from the lumen?
reabsorption and excretion of urine
58
what is the general formula for amount of substance excreted?
59
what 3 filtration layers are present in the glomerular capillary?
-fenestrated endothelial layer
-basement membrane (BM)
-Podocytes with filtration slits
60
what three reasons prevent large proteins (albumin) from crossing over the glomerular capillary?
1) pore size- too small for protein to pass through
2) Pores and basement membrane have a (-) charge, which repels (-) charge proteins
3) podocytes have slits that remain covered with fine semi porous membranes
61
what 2 proteins make up podocytes? what happens to the proteins with mutations of the podocyte membrane?
Nephrins and podocins
-mutations will cause the slit in podocytes to allow passage of these proteins
-the proteins will appear in the urine
62
what is filtered through the glomerulus?
small molecules, plasma, waste and water flow are filtered while large proteins and blood cells are held back
63
what is ultrafiltrate?
low molecular weight substances that have gone through the bowman's space
64
what is prteinuria?
the passage of proteins through the bowman's space into the urine
65
what forces are involved in glomerular filtration?
*starling forces*
-Glomerular capillary blood pressure (high)
-Fluid pressure in bowman's space (low)
-Osmotic force due to protein in plasma (higher than fluid pressure lower than glomerular capillary pressure)
66
True or false: Net glomerular filtration pressure is always negative.
False. net glomerular filtration pressure is always positive in order to drive filtration and urine formation
67
what is the percentage of blood volume filtered each turn -filtration fraction?
20%
68
what is the percentage of fluid reabsorbed?
>19%
69
what percentage of fluid volume is excreted into the external environment?
<1%
70
what percentage of the plasma entering the kidney will return back to systemic circulation?
>99%
71
what is GFR? How much is it?
glomerular filtration rate is the volume of fluid filtered from the glomerulus into the bowman's space per unit time
-1.8L/ day or 125mL / minute
-plasma filtration 60x per day
72
what factors influence GFR?
1) net glomerular filtration pressure
2) permeability of the corpuscular
3) SA available for filtration
4) neural and endocrine control
73
What is the role of mesangial cells on GFR?
they are not part of the filtration layers
-contraction of these cells reduces SA of the glomerular capillaries causing a decrease in GFR
74
what does resistance changes in renal arterials cause?
causes alteration to renal blood flow and GFR
75
what occurs when resistance in AFFERENT arterioles is increased?
increased resistance decreases blood flow to that area
---->decreases capillary blood pressure ---> decreases GFR
76
what occurs when EFFERENT arteriole pressure is increased?
increased resistance decreases blood flow to capillary ---> pressure is increased due to build up of RBC ---> GFR increases
77
explain the effects of modulation of arteriolar resistance on GFR
78
what happens to GFR following large and sudden changes in arterial pressure/renal blood flow? How does this occur?
GFR remains fairly constant due to autoregulation and the adaptation of renal blood vessel resistance
-this allows for compensation in blood flow
79
what 2 ways do renal blood vessels change resistance?
Myogenic response -quick
Tubuloglomerular feedback effect
80
how do blood vessels respond to increased tubular flow through autoregulation on GFR?
causes constriction of afferent arterioles in order to reduce GFR
81
how does neuronal and hormonal control impact autoregulation of GFR?
there is no effect; it is independent of neuronal and hormonal control
82
what regulates auto regulation of GFR?
paracrine control and tubule factors of arterial resistance
83
what is a healthy range of MAP
80-180mmHg
84
what is the juxtaglomerular apparatus (JGA)
a structure involved in the feedback control of renal blood flow and glomerular filtration
85
what is the macula densa?
cells on the wall of the distal tubule that sense increased fluid flow (Na+/Cl-) and responds by secreting vasoactive compounds (adenosine)
-this changes afferent arterial resistance which sends signal to juxtaglomerular cells
86
what are juxtaglomerular cells?
also known as granular cells, these are located on the wall of the afferent arterial
-controls renin release based on [Na+]
87
explain the tubuloglomerular feedback
88
what is filter load?
the total amount of non-protein / non-protein bound substance filtered into Bowman's space
filtered load = GFR x [substance in plasma]
89
what is the filtered load of glucose?
180g/day
90
what occurs when substance excreted in urine < filtered load?
reabsorption
91
what has occured when substance excreted in the urine > filtered load?
secretion
92
what occurs in filtration and secretion?
complete secretion- no substances are needed by the body
93
what occurs in filtration and partial reabsabsorption?
majority of the substance is kept by the body; some filtration
94
what occurs in filtration and complete reabsorption?
all of the substance is taken back by the body- complete reabsorption
95
what type of substances go through filtration only?
inulin and creatinine
96
what substance goes through filtration and partial reabsorption?
electrolytes
97
what substances go through filtration and complete reabsorption?
glucose and amino acids
98
what substances go through filtration and complete secretion?
organic acids and bases (PAH, para-amino hippuric acid)
99
what percentage of water is reabsorbed?
99%
100
what percentage of Na+ is reabsorbed?
99.5%
101
what percentage of glucose is reabsorbed?
100%
102
what percentage of urea is reabsorbed?
44%
103
what 2 types of transport are reabsorption mediated by?
mediated transport (transepithelial) -major
diffusion across tight junctions (paracellular)- minor
104
what is the pathway of substances using transepithelial /mediated transport?
1) across luminal / apical membrane
2) across basolateral membrane
105
what side of the membrane does active transport occur?
active transport of Na+/K+ ATPase occurs on the basolateral membrane side
106
explain the process of reabsorption of Na+
1) Na+/K+ ATPase drives Na+ out of the cell creating a low [Na+] inside the cell
2) low [Na+] in the cell drives Na+ in though secondary active transport
-diffusion
107
How much of glucose is filtered out by the body?
none in a healthy person
108
what tubule is responsible for majority of reabsorption?
the proximal tubule
109
what side of the membrane is responsible for secondary active transport? what protein is involved?
the luminal side by SGLT protein
110
what side of the membrane is responsible for facilitated diffusion? what protein is involved?
baso-lateral side using GLUT carrier protein
111
what is the process of glucose reabsorption?
1) Na+/K+ ATPase created low [Na+] within the cell
2) This drived Na+ into the cell along with glucose through the SGLT carrier protein (secondary active transport)
3) glucose diffuses out of the basolateral side using the GLUT protein (facilitated diffusion)
112
what is transport maximum? what is the normal range?
the capacity of how much can be transported
-normal range 100-200 mg/100mL of plasma
113
what is renal threshold? what is its value for glucose?
the maximum at which the kidney tubular cells can't do anymore reabsorption
-300mg
114
what does diabetes mellitus affect?
filtered load is greatly increased and is beyond threshold level to reabsorb glucose by tubules
-glucose shows in urine
-transporters are still able to properly do their job
115
what does renal glucosuria affect?
a genetic mutation of the Na+/glucose cotransporter affects ability for it to mediate active reabsorption of glucose in proximal tubules
-normal glucose levels
-glucose shows in urine
116
where does water reabsorption occur?
proximal tubule
117
what is urea absorption dependent on?
water reabsorption
118
explain the steps in urea reabsorption
119
what causes [urea] to be increased in the tubule lumen?
the loss of water through the increase in osmolarity causes an increase in [urea] in the lumen
120
what substances are secreted during tubular secretion?
H+, K+, choline, creatinine and penicillin
121
what is tubular secretion coupled with?
reabsorption of Na+
-involves active transport
122
where do solutions come from and to in the process of secretion?
from the blood to the lumen and out with urine
123
what is renal clearance?
The renal clearance of any substance is the volume of plasma containing that amount of the substance that is removed by the kidney in unit time (e.g., in one minute).
-every substance has its own clearance value
124
what is the renal clearance formula?
S = UsV / Ps
clearance of "S" = [substance S] in the urine x the volume of urine passed (mL/min) / [substance S] in the plasma
125
what is Us in the renal clearance formula?
[S] in urine
126
what is Ps in renal clearance formula?
[S] in the plasma
127
what is V in the renal clearance formula?
the volume of urine passed mL/minute
128
what does renal clearance tell pharmacists?
provides the rate that a drug will exit the body
129
what is the clearance of inulin?
inulin is only filtered so it's filtered load = clearance
GFR = Uin V / Pin
130
why is creatinine used to measure renal clearance? Is it reabsorbed or secreted?
It may be an easier measure of GFR and renal clearance due to it's natural production by the body
-it is filtered, not absorbed and slightly secreted
-it slightly overestimates GFR
131
what must occur if clearance of substance > GFR?
secretion
132
what must occur if clearance of substance < GFR?
reabsorption
133
what % of reabsorption occurs in distal tubules?
12-15%
134
what % of reabsorption occurs in proximal tubules?
80%
135
what are sources of water to the body?
water from food and liquid
136
what are avenues of water loss in the body?
-skin, respiratory airways
-sweat
-GI tract, urinary tract and menstrual flow
137
how does water move across water channels? what are these water channels called?
water moves by diffusion through aquaporins
138
what percentage of water is reabsorbed in the proximal tubules?
~70%
139
when do aquaporins open in proximal tubules?
aquaporins are always open in proximal tubules
140
what 2 things is water reabsorption dependent on?
1) Na+ reabsorption
2) osmotic gradient set up by Na+
141
what hormone regulates water reabsorption?
ADH or vasopressin
142
what does ADH specifically regulate?
a specific type of aquaporin
143
In what segment of the tubule does water regulation take place?
in the cells of the collecting ducts
144
what hormones regulate water absorption in the proximal/distal tubule and the loop of henle?
NONE; water reabsorption is passive in these areas, no hormone is released to regulate water
*except the distal tubule
145
what is the mechanism for water reabsorption in the distal tubule?
water is not reabsorbed in the distal tubule
146
what is the mechanism for water reabsorption in the proximal tubule?
passive reabsorption through AQP-1
147
what is the mechanism for water reabsorption in the loop of henle?
~15% absorption in the descending thin limb
-passive absorption through AQP-1
148
what is the mechanism for water reabsorption in the large distal tubule and collecting duct?
~8-17% absorption through AQP-2,-3 and -4
-passive reabsorption regulated by ADH / vasopressin
149
explain the process of water absorption in the proximal tubule
150
explain the process of water absorption in the loop of henle
water reabsorption in the descending loop and salt reabsorption in the ascending loop
151
what is the importance of countercurrent multiplication?
Countercurrent multiplication is the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine.
*different transport capabilities on each side of the tubule
152
what kind of transport is needed in the ascending loop of henle?
active transport to move Na+
153
explain the process of countercurrent multiplication
https://youtu.be/cYyJF_aSC6o?si=1XibVO5kHaCADYLc
154
what is the gradient difference created between the interstitial space and the ascending limb?
200 mOsm
155
what is the gradient created between the descending limb and the interstitial space?
the interstitial osmolarity is initially the same as the descending limb osmolarity
156
what is the effect of a longer loop of henle on the [urine]?
as the length of the loop increases, there is a larger distance for water reabsorption to occur and the gradient is seen to be higher
-this creates a more concentrated urine
157
where in the loop of henle does fluid become concentrated?
The descending limb
-H2O is reabsorbed into the interstitial space
158
where in the loop of henle is fluid diluted?
up the descending into the distal tubule
158
where does fluid in the collecting duct become isoosmotic with?
fluid in the collecting duct becomes isoosmotic with the interstitial space
159
Where in the collecting duct is ADH activated?
cortical collecting duct
160
what is the importance of the vasa recta in the counter current exchange?
vasa recta form a parallel set of hairpin loops within the medulla; it is vital to prevent gradient from washing away
-MAINTAINS Na+ / Cl- concentration gradient by adding/removing solute and water from the medulla
161
why can't the medulla maintain the [Na+] and [Cl-] on its own?
the blood flow in the medulla is low to prevent solute loss
162
how does the countercurrent exchange work in the vasa recta?
Nacl moves out of the ascending limb into the descending limb as blood enters the descending limb of the vasa recta
water diffuses out of the descending limb into the ascending limb
163
What 4 characteristics describ ADH or vasopressin?
1) fast acting peptide hormone
2) produced by cells of the SON of the hypothalamus
3) secreted from the posterior pituitary
4) osmoreceptors sense increases in plasma osmolarity
164
what is ADH's mechanism of action?
ADH alters water permeability of the luminal membrane of collecting ducts
165
what are aquaporins?
water channels found in renal tubule cells and other cells
166
where is AQP-1 found?
proximal tubules and descending loop of henle
167
where are AQP2,3 and 4 found?
in the collecting ducts
168
what regulates AQP2 insertion on the luminal side? and on the basolateral side?
ADH regulates the luminal side
- it does not regulate the basolateral side
169
what is water diuresis?
extreme loss of fluid volume in the urine
-absence of ADH makes collecting duct cells almost impermeable to water for reabsorption
170
what does increases in ADH cause? what are some causes of an increase?
retention of water; pee less
-shock, pain, warm, hot weather and water deprivation
171
what does decreases in ADH cause?what are some causes of a decrease?
decreased water retention; pee more
-cold, humid environment, alcohol
172
what is diabetes insipidus?
central diabetes insipidus- failure to release ADH
nephrogenic diabetes insipidus- kidney resistance to ADH
173
what is the difference in gradients created between conditions of excess water vs water deprivation?
excess- smaller graident to decreases water absorption
deprived- larger gradient to increases absorption
174
what is water diuresis?
only excess water excreted without excess solute in urine
-diabetes insipidus
175
what is osmotic diuresis?
excess solute in urine is always associated with high levels of water excretion
-diabetes mellitus
176
what is plasma osmolarity mainly determined by?
plasma [Na+]
177
How is Na+ regulated when [Na+] is low?
Short term- baroreceptors regulate GFR
long-term- aldosterone promotes Na+ reabsorption
-renin and angiotensin II needed
178
How is Na+ regulated when [Na+] is high?
Atrial natriuretic peptide (ANP)
-regulates GFR and inhibits Na+ reabsorption
-inhibits aldosterone actions
179
what are baroreceptors? where are they located?
Nerve endings that are sensitive tp stretch
-carotid sinus
-aortic arch
-major veins
-intrarenal (JG cells of JGA)
180
explain how baroreceptors act when [Na+] is low
short term regulation
181
what triggers aldosterone synthesis and secretion?
low [Na+]
182
where is aldosterone secreted from?
adrenal cortex
183
where is the site of action for aldosterone?
late distal tubule and cortical collecting duct
184
what are the 3 actions of aldosterone?
1) induce synthesis of Na+ transport protein
2) stimulate Na+ reabsorption
3) reduce Na+ secretion
185
True or False: Na+ reabsorption is linked to K+ secretion
TRUE
186
what are the steps in aldosterone Na+ regulation?
187
what does decreased [Na+] do to renin and angiotensin concentration?
increases renin secretion which increases angiotensin I, increasing angiotensin II
188
what directly increases aldosterone release?
increased anhgiotensin II concentration
189
what structure does angiotensin II act on?
adrenal cortex
190
what senses low [NaCl] in the renin-angiotensin system?
renin
191
what converts angiotensin I to angiotensin II?
ACE
-angiotensin converting enzyme
192
what is the affect of angiotensin II on blood vessels/ blood pressure?
causes vasoconstriction which increases blood pressure
193
what are juxtaglomeruar cells?
mechanoreceptors loctaed on the wall of afferent arterioles that sense plasma volume associated with low [sodium]
193
what are the macula densa?
chemoreceptors onthe wall of the convulated tubule that sense NaCl load of the filtrate
194
what 3 inputs do the juxtaglomerular cells recieve to promote renin release?
1) sympathetic input from extrenal baroreceptors
2) intrarenal baroreceptors
3) signals from the macula densa
195
explain the steps in barorecptor control for the renin-angiotensin system
196
what stimulates ANP secretion?
1) increased [Na+]
2) increased blood volume
3) atrial distension
197
where is ANP synthesized?
synthesized and secreted by the cardiac atria
198
where is ANP activated?
on cells in several tubular segments
-ANP inhibits aldosterone actions
-Inhibits Na+ reabsorption
-Increases GFR and Na+ excretion
199
where is majority of filtered K+ reabsorbed?
proximal tubule and loop of henle
200
where may K+ be secreted?
collecting ducts secrete a small amount
201
where is [K+] in urine regulated?
cortical collecting duct
202
what is excess K+ in blood cells called?
hyperkalemia
203
what hormone controls homeostasis of K+ in the body?
aldosterone secreting cells
-sensitive to extracellular [K+]
204
what occurs when extracellular [K+] is increased?
aldosterone is produced and more [K+] is excreted in urine
205
what occurs when extracellular [K+] is increased?
aldosterone is not produced and less [k+] is excreted in the urine
206
what is the pH for ECF?
between 7.35 - 7.45
-slightly basic
207
what pH ranges become fatal?
<6.8 and >7.8
208
what are examples of some kinds of acids are produced by our body?
CO2- volatile acid
phosphoric and sulfuric acid- non-volatile acid
209
what are sources of H+ ion gain and loss in the body?
210
what is the role of buffers?
composed of a weak and and its conjugate base in order to decrease rapid changes in pH
211
what is involved in the ECF buffer system?
CO2/HCO3-
212
what is involved in the ICF buffer system?
phosphate ions and hemoglobin
213
what organs are resonsible for balancing hydrogen ion concentration wihtin a narrow range?
kidneys and lungs
214
how do the lungs balance changes in pH?
short term homeostatic regulator that stimulates ventilation changes in order to adjust H+ imbalances
increased [H+] stimulates ventilation-more CO2 leaves
decreased [H+] inhibits ventilation-less CO2 leaves
215
how do kidneys balance H+ changes in the body?
long term regulators that synthesize and excrete bicarbonate ions
decreased [H+] - excretion of HCO3-
increased [H+]- synthesis of HCO3-
216
how is HCO3- reabsorbed?
an active process that depends on H+ secretion
217
where is HCO3- absorbed?
proximal tubule, ascending loop of henle and collecting duct
218
what is the repsonse mechanism to acidosis (NH4+)?
when excess H+ are in the lumen addition of HCO3- occurs by:
1) binding of H+ to HPO4 2-
2) HCO3- generation by tubular cells to diffuse into plasma
3) NET gain of HCO3- in plasma
219
what is the repsonse mechanism to acidosis (HPO4)?
1) only uses cells from proximal tubule
2) uptake of glutamine
3) NH4+ amd HCO3- formed inside the cells
4) NH4+ actively secreted via Na+/NH4+ counter transporter
5) HCO3- added to plasma
220
summarize the renal regulatoin of acids during acidosis and alkalosis
221
what is respiratory acidosis?
a result of decreased ventilation that increases blood Pco2
-kidney compensates by secreting H+ and lowers plasma [H+]
-occurs in emphysema
222
what is respiratory alkalosis?
a result of hyperventilation that causes decreased Pco2
-kidney compensates by excreting HCO3-
-happens at high altitudes
223
TRUE or FALSE: kidneys can excrete either acidic or basic urine?
TRUE
224
what is metabolic acidosis?
results in increased ventilation and H+ secretion from diarrhea, severe excercise and diabetes mellitus (loss of bicarbonate ions)
225
