Renal Physiology Flashcards
1
Q
concentration
A
the amount of a specified solute in a unit amount of solvent
Can be expressed as percentage, molarity, molality, or electrochemical equivalence
2
Q
What can’t cross the lipid bilayer by diffusion?
A
charged particles and polar molecules
3
Q
What can diffuse through the lipid bilayer?
A
lipid soluble molecules and small polar molecules
4
Q
diffusion
A
movement of particles between two regions from an area of high concentration to an area of low concentration.
Passive: requires no energy
5
Q
determinants of rate of diffussion
A
size of gradient and permeability of membrane
Sometimes temperature. Faster at higher temperatures
6
Q
facilitated diffusion
A
Similar to diffusion as it is passive and requires no energy, but it is for particles that can’t normally cross membrane (like charged or polar molecules) and require pores, channels, or carrier proteins
7
Q
electrochemical gradient
A
concentration gradient and electrical gradient
8
Q
Which is true about potassium transport by facilitated diffusion?
a. K moves against electrochemical gradient
b. This K transport requires energy
c. Cell membranes in kidney are freely permeable to K
d. This K is transported via transmembrane protein
A
d. This K is transported via transmembrane protein
9
Q
Active transport
A
movement of particles between two regions from area of low concentration against electrochemical gradient
Requires energy: transporter molecule hydrolyses ATP to ADP
10
Q
co-transport
A
secondary active transport, movement of molecules across biological membrane against gradient
Requires energy acquired not be direct ATP hydrolysis, but uses potential energy created by active transport elsewhere
11
Q
symport via symporter
A
co-transport in same direction. ie. sodium glucose symporter
12
Q
antiport via antiporter
A
co-transport in opposite directions. ie sodium proton exchanger
13
Q
Sodium potassium ATPase moves sodium by active transport. Which of these is correct?
a. Na K ATPase required hydrolysis of ATP to move Na
b. Na K ATPase moves Na down its concentration gradient
c. Na transport continues until equilibrium is met
d. Na K ATPase is located in the cytosol
A
a. Na K ATPase required hydrolysis of ATP to move Na
14
Q
Osmosis
A
movement of water across a selectively permeable membrane from a dilute to a concentrated solution
Diffusion of water
15
Q
effective osmole
A
molecule that can’t cross a membrane and generates osmosis
16
Q
ineffective osmole
A
when membrane is permeable to a molecule and moves by diffusion down its concentration gradient
17
Q
osmolarity/osmolality
A
concentration of osmotically active atoms (osmoles/L or osmoles/kg)
18
Q
How does osmolarity impact osmosis?
A
During osmosis, water moves from low osmolarity to high osmolarity.
19
Q
A neuron in the brain of a healthy dog has an osmolarity of 300 mOsm/L. The dog becomes sick and acute vomit/diarrhea causes significant water loss from extracellular space, increasing extracellular osmolarity to 350 mOsm/L. What will happen to the nerve cell?
A
Shrink
20
Q
Tonicity
A
the overall concentration of effective osmoles in a solution
21
Q
hypotonic
A
a solution with a lower effective osmolarity than another
Cell swells
22
Q
hypertonic
A
a solution with a higher effective osmolarity than another, cell shrinks
23
Q
isotonic
A
a solution with the same effective osmolarity as another
24
Q
Function of renal system
A
- cleans the blood
- Regulates important extracellular fluid components
- endocrine tissue
25
How does the kidney "clean" the blood?
removes waste products by filtering blood then selectively reabsorbing desirable components and passing undesirable components in urine
26
What percentage of the cardiac output do the kidneys receive?
25%
27
What hormones does the kidney produce?
renin to regulate blood pressure and erythropoietin for red blood cell production
28
location of kidneys
just posterior to 13 rib, left kidney is more ventral and caudal
This is conserved across all mammals
29
capsule
layer of mostly collagen with some smooth muscle surrounding the kidney
30
hilum
cleft where ureter and vein leave and artery enters
31
cortex
darker because more organelles in the cytoplasm and more vasculature
32
medulla
lighter portion, fluid has higher osmolarity
33
renal papilla
apex of renal pyramid, fuse to become renal crest
34
renal pelvis
extension of ureter. Sits in the renal sinus, contacts renal papilla. Collects urine and funnels it to ureter.
Made of transitional epithelium
35
Which is correct?
a. Cleft in kidney where ureter and vasculature enter/leave is called the capsule
b. paired kidneys are located anteriorly in the body cavity
c. gross external morphology is high conserved across species
d. in most species, the right kidney is more cranial than the left
d. in most species, the right kidney is more cranial than the left
36
renal corpuscle
site of filtration, includes glomerulus and Bowman's capsule. Glomerulus is capillary tuft enveloped by Bowman's capsule
37
proximal tubule
place for majority of reabsorption
38
loop of Henle
used reabsorption of Na, Cl, and water
| Longer in desert animals and shorter in aquatic animals
39
collecting tubule/duct
to fine tune fluid constituents. Place for final reabsorption/ secretion
Derived from uriniferous tubule
40
Structures in the cortex
renal corpuscles, cortical labyrinth and medullary rays
41
components in cortical labyrinth
Proximal convoluted tubules and distal convoluted tubules
42
structures in medullary rays
proximal straight tubules, distal straight tubules, collecting ducts
43
Is the proximal or distal convoluted tubule longer?
proximal
44
structures in outer medulla
loops of Henle, distal straight tubules, collecting ducts
45
structures in inner medula
collecting ducts
46
Which of these is only in the cortex?
a. collecting duct
b. loop of Henle
c. renal corpuscle
d. distal straight tubule
e. renal pelvis
c. renal corpuscle
47
What determines capillary pressure in the glomerulus?
afferent/efferent arteriole structure
48
afferent vs efferent arterioles
Blood leaves through efferent arteriole and enters through afferent arteriole.
Efferent has slightly smaller lumen and is less stretchy than afferent. Builds pressure in glomerulus
49
What percentage of blood enters the bowman's capsule from the glomerulus?
20%
50
macula densa
specialized cells in wall of distal straight tubule touching the glomerulus.
Regulates glomerular filtration. Located at vascular pole of renal corpuscle. Cells are tall and tightly packed. Lack a basement membrane
51
visceral layer of Bowman's space
includes podocytes and pedicels
52
filters in glomerulus
basal lamina and slit diaphragm
53
layers of basal lamina
lamina rara externa, lamina densa, lamina rara interna
54
Which of these is only in the medulla?
a. Proximal tubule
b. Loop of Henle
c. collecting duct
d. distal tubule
e. renal corpuscle
b. Loop of Henle
55
Proximal tubule
found in cortical labyrinth and medullary rays
Luminal membrane has long microvilli (brush border).
Lots of mitochondria for active processes like active transport.
Nucleus is large and centrally located or toward basolateral membrane.
56
Which is most accurate regarding proximal tubule?
a. They lack mitochondria
b. Nuclei are located apically
c. they are inefficient at absorption
d. they have simple squamous epithelium
e. they have an extensive brush border
e. they have an extensive brush border
57
Loop of Henle
starts at corticomedullary boundary. Ascending limb is slightly shorter than descending limb. Used for passive absorption. Descending limb is permeable to water but not solutes. Ascending limb is permeable to solutes and not water.
Consists of simple squamous epithelium and clear lumen
58
Distal tubule
low cuboidal epithelium. oval shaped apical nuclei, few microvilli, fewer mitochondria, not permeable to water
Used for reabsorption but not as much as proximal tubule.
Distal straight has more mitochondria than distal convoluted tubule.
Later distal tubule can be permeable to water with antidiuretic hormone.
59
Juxtaglomerular cells
Specialized muscle cells in the afferent arteriole, trigger renin-angiotensin system
60
Juxtaglomerular apparatus
includes macula densa, extraglomerular mesangial cells, and juxtaglomerular cells
stretch receptors in afferent arterioles, initiates renin-angiotensin system to increase a low ECF volume in a process separate to renal autoregulation that regulates GFR and control of Na reabsorption
61
collecting tubules
located all the way from the outer cortex to the renal crest.
Clear lumen with clear halo around cell nuclei
62
principal cells
found in cortical collecting tubules, for reabsorption. Cuboidal epithelium. Nuclei oval shaped and centrally located or toward the lumen. Lightly staining, no brush border
63
intercalated cells
in the cortical collecting tubules. Used for secretion, protrude past the principal cells, fewer going deep into medulla
64
ureter
conveys urine from kidney to bladder.
Mucosa: transitional epithelium overlying lamina propria (loose connective tissue, protective and immune functions)
Tunica muscularis: 2/3 layers of smooth muscle
Outer coat (adventitia): connective tissue
65
Bladder
Mucosa: transitional epithelium overlying 2 layers of lamina propria
Tunica muscularis: 3 layers of smooth muscle (detrusor muscle)
Outer coat (adventitia): connective tissue
66
internal sphincter muscle of urinary bladder
involuntary control of urination. Opens with bladder is full
67
external sphincter muscle of urinary bladder
voluntary control of voiding the bladder
68
micturition
filling and voiding of bladder
69
urethra
Mucosa; transitional epithelium overlying large porous lamina propria
Tunica muscularis: 2 irregular layers of smooth muscle
Outer coat (adventitia): connective tissue
Dominant layer is circular muscle with deeper longitudinal layer.
70
Which epithelial type is in the Loop of Henle?
a. cuboidal
b. simple squamous
c. transitional
d. low cuboidal
b. simple squamous`
71
fenestrated epithelium of glomerulus
large pores filter cells, antibodies and large proteins
| Polyanionic glycoprotein glycocalyx with heparin sulfate repels negative charges
72
Filtration by lamina rara interna and externa
in glomerulus, has polyanionic non-collagenous proteins
73
filtration by lamina rara densa
in glomerulus, collagenous proteins form a mesh that filters based on size
74
filtration by slit diaphragm
in glomerulus, perforated with small pores, not an effective filter
podocytes with polyanionic glycoprotein glycocalyx repels negative charges and neighboring podocytes
75
equation for glomerular filtration rate
Kf((Pc-Pbs)-(pi c - pi bs))
76
Kf
= permeability of capillary multiplied by filtration surface area
77
Do diseases increase or decrease filtration surface area?
decrease
78
How does capillary hydrostatic pressure (Pc) change when the efferent arteriole contracts?
it increases
79
How does liver failure impact GFR?
Hypoproteinemia, pi c decreases and GFR increases
80
How can blockage in urethra or ureter impact GFR?
increases Bowman's space oncotic pressure and GFR decreases
81
Which is correct?
a. Normal afferent arteriole and constricted afferent arteriole decreases GFR
b. constricted afferent arteriole and normal efferent arteriole increases GFR
c. normal afferent arteriole and dilated efferent arteriole increases GFR
d. dilated afferent arteriole and normal efferent arteriole increases GFR
d. dilated afferent arteriole and normal efferent arteriole increases GFR
82
Goals of renal autoregulation
1. Prevent damage to glomeruli caused by spiking blood pressure (maintain flow)
2. prevent fluctuations in blood pressure from changing delivery of filtrate to tubules (maintain GFR)
83
myogenic mechanism of renal autoregulation
triggered by fluctuations blood pressure in afferent arteriole
Increased BP causes vasoconstriction. Decreased BP causes vasodilation.
Rapid changes in 1-2 seconds
84
Which is true about the myogenic mechanism?
a. it helps to protect the glomerulus
b. it is triggered in the efferent arteriole wall
c. it will reduce GFR in response to low blood pressure
d. it is a slow acting response
e. the main effect is to constrict the efferent arteriole
a. it helps to protect the glomerulus
85
Tubuloglomerular feedback mechanism of autoregulation.
triggered by fluctuation in BP changing GFR and composition of distal tubule fluid.
Low/high ion concentration is sensed by macula densa and juxtaglomerular apparatus changes arteriole resistance.
Slower changes in 10-12 seconds.
86
extraglomerular mesangial cells
part of JGA, promote information transfer between macula densa and juxtaglomerular cells
87
production of angiotensin II
liver produces angiotensinogen that is converted to angiotensin I by renin which is converted to angiotensin II by angiotensin converting enzyme (ACE) produced in the lungs
88
angiotensin II
systemic arteriolar vasoconstriction to increase blood pressure
Increases aldosterone secretion by adrenal cortex.
Promotes ADH secretion in pituitary and thirst
Increases tubular NaCl uptake.
89
Which is correct when high GFR is lowered by tubular glomerular feedback?
a. JG cells release renin
b. macula densa releases PGE2
c. The trigger is low Na, K, and Cl sensed by the macula densa
d. a key intermediate step is decreased intracellular Ca in extraglomerular mesangial cells.
e. afferent arteriole smooth muscle contracts
e. afferent arteriole smooth muscle contracts
90
How do NSAIDs cause acute renal failure?
prevent production of PGE2
91
Captopril is an ACE inhibitor. Which is correct?
a. Captopril increases Angiotensin II and decreases GFR
b. Captopril reduces Angiotensin II and increases GFR
c. Captopril reduces Angiotensin II and decreases GFR
d. Captopril increases Angiotensin II and increases GFR
c. Captopril reduces Angiotensin II and decreases GFR
92
luminal membrane
separates tubular cell from tubular fluid
93
basolateral membrane
separates cell from peritubular interstitium
94
Transepithelial potential difference
the potential difference between tubular lumen and peritubular interstitium
Changes between tubular sections and contributes to electrochemical gradient
95
Transcellular reabsorption or secretion
Reabsorption or secretion through cytoplasm of tubular.
| Both passive and active transport can be transcellular but all active transport must be transcullar
96
paracellular reabsorption or secretion
not crossing the membrane, simple diffusion.
Reabsorption between tubular cells across tight junctions.
Allows reabsorption of ions and nonpolar solutes by passive transport only.
97
Which membrane has Na K ATPase? Which tubular sections?
basolateral membrane of all sections
98
Which is correct regarding Na K ATPase?
a. It transports Na and K at the luminal membrane of nephron epithelia
b. It moves 3 Na into the cells in exchange for 2 K out of the cell
c. Na movement is by facilitated diffusion
d. It requires energy in the form of ATP
e. It moves K paracellularly
d. It requires energy in the form of ATP
99
Reabsorption in 1st half of proximal tubule
1. Na K ATPase generates Na gradient
2. Na enters down electrochemical gradient via passive transport by Na H antiporter and secondary active transport by Na glucose symporter
3. Water follows Na down osmotic gradient
100
How would diabetes impact reabsorption in the proximal tubule?
more glucose in the lumen acts as an osmole sink preventing water reabsorption, Animal become polyureic
101
Reabsorption in 2ns half of proximal tubule
1. Na K ATPase generates Na gradient
2. Na enters down electrochemical gradient via Na H antiporter
3. Cl enters down electrochemical gradient via Cl anion antiporter and pia paracellular route.
4. Lumen +ve PD drives Na down paracellular route. Water follows by osmosis
102
anions used by Cl anion antiporter
hydroxyl, formate, etc
103
protein reabsorption in proximal tubule
some small proteins filtered by glomerulus
These are partially degraded by enzymes in luminal membrane and reabsorbed by endocytosis
Further degraded by enzymes in lysozyme into amino acids and leave via basolateral membrane
Process can be easily saturated because Tmax is low so proteins can appear in the urine (proteinuria)
104
Reabsorption in Loop of Henle
water reabsorption occurs in descending limb only
| NaCl reabsorption si passive and occurs in ascending limb only
105
Which is correct about tubular reabsorption?
a. Na is reabsorbed actively at the luminal membrane in the proximal tubule
b. Glucose is reabsorbed via facilitated diffusion
c. Cl reabsorption is both transcellular and paracellular
d. Most water is reabsorbed in the descending loop of Henle
c. Cl reabsorption is both transcellular and paracellular
106
Reabsorption in initial distal tuble
1. Na K ATPase generates Na gradient
2. Na enters cell via NKCC1 symporter and Na H antiporter.
3. +ve TPD means cations move down electrochemical gradient via paracellular route. Water does not follow because it is not permeable here.
107
What is the mechanism of loop diuretics?
Loop diuretics like furosemide inhibit NKCC1 symporter
108
ion movement by NKCC1 symporter
2 cl and 1 Na moves inside cell down electrochemical gradient, 1 K moves inside cell against electrochemical gradient
109
reabsorption in later distal tubule
Still impermeable to water
1. Na K ATPase generates Na gradient
2. Na enters cell via Na Cl symporter
110
What is the mechanism of Thiazide diuretics
inhibit Na Cl symporter in later distal tubule
111
reabsorption by principal cells
in collecting ducts
1. Na K ATPase generates Na gradient
2. Na enters cell via amiloride sensitive Na channels. Water follows via aquaporin when ADH is present
3. K leaves through K channels down K gradient (important for K homeostasis)
4. Na reabsorption generates negative PD so Cl are reabsorbed via paracellular route
112
Reabsorption by intercalated cells
in papillary collecting ducts
Can secrete H or HCO3-, which is important for maintaining acid-base balance (maybe, proton could be secreted just to balance the Na absorbed by principal cells)
113
Which of these is in order from most Na reabsorption to least Na reabsorption?
a. distal tubule, proximal tubule, loop of Henle
b. Distal tubule, loop of Henle, proximal tubule
c. proximal tubule, loop of Henle, distal tubule
d. proximal tubule, distal tubule, loop of Henle
e. loop of Henle, Proximal tubule, distal tubule
c. proximal tubule, loop of Henle, distal tubule
114
Countercurrent Multiplication in Loop of Henle
Most water is reabsorbed in proximal tubule since it follows the concentration of ions.
Loop of Henle dissociates water reabsorption from the absorption of glucose, phosphates, and amino acid molecules,
Fluid is moving in two directions, action in ascending limb amplifies water absorption descending limb and vice versa
115
How does interstitial osmolarity change between cortex and medulla?
the deeper into the medulla, the higher the interstitial osmolarity
116
What is the tonicity of fluid entering the distal tubule?
Hypotonic
117
Which is true about the loop of Henle?
a. Distal tubule fluid is hypertonic compared to interstitium
b. Na is reabsorbed passively at the descending limb
c. Water is reabsorbed down an osmolarity gradient (low to high osmolarity)
d. interstitial osmolarity decreases towards papilla
c. Water is reabsorbed down an osmolarity gradient (low to high osmolarity)
118
What are the monitoring locations for release of ADH hormone?
osmoreceptors in hypothalamus shrink and swell to detect changes in body fluid osmolality
Baroreceptors in circulatory system detect changes in plasma volume or arterial pressure. Suppresses ADH production when blood pressure and fluid volume increases.
119
Other names for Antidiuretic hormone?
abbreviated ADH, vasopressin and arginine vasopressin
120
Mechanisms of ADH
1. Changes collecting duct permeability to water by increasing expression of aquaporins
2. Changes MEDULLARY collecting duct permeability to urea by increasing expression of urea transporters
121
diuresis
production of a large volume of dilute urine
| Occurs when ADH levels are low and the animal is trying to excrete water
122
Antidiuresis
when ADH levels are high, Low volume of concentrated urine is produce because collecting duct is able to reabsorb water
123
reabsorption of urea
excreted into blood stream by liver, a little is reabsorbed in proximal tubule. Loop of Henle is not very permeable to urea. As water leaves the descending limb, concentration of urea increases in tubules. When ADH is present, urea can exit the medullary collecting duct into the medullary interstitial fluid. Here urea is an ineffective osmole, but it is an effective osmole at the loop of Henle and helps to reabsorb more water than normal in the descending limb
124
Which is true during diuresis?
a. Medullary urea concentration is relatively low
b. collecting duct permeability to water is high
c. water reabsorption in the descending limb of the loop is increased
d. fluid in the collecting duct is hypertonic to interstitium
a. Medullary urea concentration is relatively low
125
vasa recta
network of blood vessels that acts as a countercurrent multiplier to remove the reabsorbed water and solutes in the interstitium surrounding the loop of Henle to maintain the right concentrations.
Sodium moves into the lumen of the descending limb and water moves into the lumen of the ascending limb
126
Mannitol can be used as an osmotic diuretic. It is freely filtered and acts as an effective osmole within the collecting duct, increasing the osmolarity of the tubular fluid in the collecting. What would happen to urine volume?
it will increase
127
How does the kidney regulate ECF osmolarity?
| Volume?
Kidney regulates ECF osmolarity by changing ECF Na concentration. Kidneys regulate ECF volume by changing ECF Na amount.
128
What is the only organ in the animal that can regulate Na concentration and amount in the ECF and therefore the only organ that can regulate ECF osmolarity and volume?
the kidney
129
What molecule/ion is the primary determinant of ECF osmolarity?
sodium
130
consequences of hypernatremia
high ECF Na concentration:
| rupture of cerebral vessels/ hemorrhage, muscle weakness, behavioral changes/ ataxia, coma leading to death
131
consequences of hyponatremia
low ECF Na concentration: cerebral/ pulmonary edema, muscle weakness, incoordination and seizures
132
Defense against changes in ECF Osmolarity
osmoreceptors swell or shrink and can create thirst response in pituitary to produce ADH
133
Which is true about hyponatremia?
a. There will likely be translocation of fluid from ECF to ICF
b. Osmoreceptors in hypothalamus will shrink
c. ADH release will be increased
d. The animal will feel thirsty
e. A hyponatremic animal will have high ECF Na concentration
a. There will likely be translocation of fluid from ECF to ICF
134
consequences of high ECF volume
hypervolemia, high blood pressure, ascites, pulmonary edema
Must increase Na excretion
135
consequences of low ECF volume
hypovolemia, hypovolemic shock, organ damage, low blood pressure
136
potential causes of changes to ECF fluid volume
Changes to ECF sodium amount, blood loss, vomiting, liver failure
137
ascites
fluid accumulation in the abdomen
| due to high ECF volume
138
hypovolemic shock
due to low ECF volume, increases heart contraction, tachycardic, dizziness
139
diseases impacting sodium reabsorption in the kidney
Addison's and Cushing's disease
140
How does liver failure impact ECF volume?
less protein, decreased capillary oncotic pressure, decreased ECF volume in bloodstream
141
Baroreceptors
stretch receptors, in heart, aorta, carotid sinus, causes sympathetic nervous system to increase low ECF volume, causes natriuretic peptide release to decrease a high ECF volume
142
How does sympathetic flow regulate ECF volume?
Baroreceptors detect decreased ECF volume to increase sympathetic flow which increases Na and water reabsorption which increases ECF volume.
1. Norepinephrine is a vasoconstrictor.
Efferent arteriole constricts more than afferent= increased GFR. Alters Starling's forces to increase Na reabsorption
2. Stimulates Na reabsorption from proximal tubule
3. Stimulates renin release from JGA to activate RAS
143
Decreased ECF volume and the RAAS
Stimulation of RAS increases Na and water reabsorption, increasing ECF volume
1. angiotensin II constricts efferent arterioles to increase GFR and change starling's forces to increase Na and water uptake
2. Angiotensin II stimulates Na H antiporter to increase Na uptake
3. Angiotensin II stimulates ADH release to increase water uptake
4. Angiotensin II stimulates aldosterone release to increase Na uptake
144
Aldosterone
1. increases NKCC1 transporter
2. increases sodium channels in luminal membrane of collecting duct
3. increases number and activity of Na K ATPase
145
natriuretic peptides
Increased natriuretic peptide decreases Na reabsorption which reduces water reabsorption and decreases ECF volume
1. Constricts efferent arterioles and dilates afferent arterioles. This increases GFR to increase Na and water load entering tubules
2. Inhibits renin release from JGA to inhibit RAS
3. Inhibits ADH release by inhibiting RAS
4. Inhibits aldosterone release by inhibiting RAS and acting directly on adrenal cortex
5. Inhibits NaCl reabsorption in collecting duct by inhibiting Na channels
146
Which is correct about hypovolemia?
a. The animal will respond by increasing sympathetic flow to the kidneys
b. To correct it, the Renin-Angiotensin system will be inhibited
c. The animal will respond by increased release of natriuretic peptides
d. It is defined as high ECF volume
e. It is caused by low ECF Na concentration
a. The animal will respond by increasing sympathetic flow to the kidneys
Want to increase Na reabsorption
147
Low ECF volume is returned to normal by:
a. stimulation of RAAS
b. increased natriuretic peptide release
c. increased sympathetic flow to kidneys
d. A and C only
e. all of the above
d. A and C only
148
potassium
main intracellular cation
Major determinant of resting membrane potential, therefore determines behavior of all excitable cells
concentration
149
Hypokalemia
decreased serum potassium concentration
action potential harder to initiate
Presents with muscle weakness, respiratory problems, cardiac arrhythmia, renal dysfunction
150
Hyperkalemia
increased serum potassium
action potential harder to repeat
Presents with muscle weakness, cardiac dysfunction
151
regulators of K balance
Insulin: promotes movement of K into cells by stimulating Na K ATPase
Epinephrine: promotes movement of K into cells (beta stimulation of Na K ATPase) and out of cells (alpha)
152
impacts of acidosis/alkalosis on K balance
High H+ (acidosis) promotes movement of K out of cells (to maintain electroneutrality)
low H+ (alkalosis) moves K into cells
153
What is the only regulated site of potassium excretion?
the kidney
| balances excretion with K consumption
154
Which is true about extracellular fluid K concentration?
a. Oliguria (low urine output) may increase ECF K concentration
b. ECF K concentration is higher than that of ICF
c. Insulin will increase ECF K concentration
d. Acidemia (decreasing ECF K concentration)
e. Increased dietary K will decrease ECF K concentration
a. Oliguria (low urine output) may increase ECF K concentration
155
Reabsorption of K in proximal tubule
67% of K reabsorption, through channels in basolateral membrane and Lumen +ve PD moves K via paracellular route
156
K secretion
principal cells in collecting duct
1. Na K ATPase generates Na gradient
2. Na enters cell via amiloride sensitive Na channels
3. K leaves through K channels down K gradient
157
amiloride like diuretics
a.k.a K sparing diuretics don't let potassium leak out and be secreted
158
K reabsorption in distal tubule and collecting duct
alpha intercalated cells in distal tubule and collecting duct: H+ leaves through H K ATPase and K enters
159
Which section of the nephron is able to both absorb and secrete K?
distal tubule
160
Bartter's syndrome is a genetic disorder that causes a dysfunctional, impaired NKCC1. What can be a result?
hypokalemia
161
How does increased plasma K concentration impact K excretion?
```
Aldosterone:
1. Increases Na K ATPase
2. Increases Na channels
3. Increases K channels
These processes are less active when plasma K is decreased
```
162
Kon's disorder
hyperaldosteronism and hypokalemia
163
Addison's disese
Hypoaldosteronism and hyperkalemia
164
How does tubular flow rate impact K excretion?
Decreased tubular flow rate decreases K secretion.
Increased tubular flow rate increases K secretion.
Exception: normal everyday diuresis and antidiuresis
165
How does lumen electronegativity impact K excretion?
Increased lumen electronegativity increases K secretion.
Decreased lumen electronegativity decreases K secretion.
(Acidosis promotes K secretion at basolateral membrane causing hyperkalemia)
166
Which of the following could lead to hypokalemia?
a. Decreased lumen electronegative (less, negative, more positive)
b. Low tubular flow rate
c. increase aldosterone release
d. amiloride-like diuretics
c. increase aldosterone release
167
normal blood pH
7.35 to 7.45
168
acidosis
processes by which acidemia occurs (pH<7.35
| Protons bind to proteins denaturing them
169
alkalosis
the processes by which alkalemia occurs (pH>7.45 protons dissociate from proteins, netaturing them
170
3 things that determine pH
1. partial pressure of carbon dioxide
2. strong ion difference (SID)
3. Weak acid buffers (Atot)
171
respiratory acidosis
decreased ventilation rate causes increase ECF CO2 and more protons
172
respiratory alkalosis
increased ventilation rate causes decreased ECF CO2 and less protons
173
T/F Increasing ventilation rate will decrease ECF pH
False, respiratory alkalosis, increased pH
174
strong ion difference
SID, difference between the greater amount of positive ions and lesser amount of negative ions
Changing SID changes ionic strength of ECF. SID drives dissociation of water to maintain electroneutrality with more cations than anions.
175
How do vomiting and diarrhea impact SID?
vomiting causes loss of chloride ions, diarrhea causes excessive loss of sodium ions.
176
What are the effects on SID and acid base balance by diarrhea? (excessive loss of sodium)
SID will decrease and cause metabolic acidosis by increasing H+ relative to OH-
177
How do proteins impact pH?
they are negatively charged and weak acids so if Atot increases, pH will decrease
178
Which statement about Atot is correct?
a. It is primarily determined by ECF phosphate concentration
b. it will increase if animal is hypoproteinemic
c. It is decreased by proteinuria
c. It is decreased by proteinuria
179
How do the three determinants of pH interact?
Disturbance in one factor is compensated by the other two so respiratory acidosis is compensated by metabolic alkalosis
180
How is renal NH4+ synthesis and secretion impacted by acidosis or alkalosis?
Acidosis stimulates renal NH4+ synthesis and secretion to maintain electroneutrality. In alkalosis, renal NH4+ is suppressed
