10:13 Intro to the Kidney Flashcards
(206 cards)
1
Q
what are the three main roles of the kidneys?
A
Homeostatsis; Eliminate soluble wastes; Make endocrine products.
2
Q
how do the kidneys maintain homeostasis?
A
regulate blood and extracellular fluid: water, ions, acid-base
3
Q
how do the kidneys eliminate soluble wastes
A
eliminate metabolic wastes; eliminate toxins and drugs (sometimes after liver modification, e.g. glucuronidation)
4
Q
How does the kidney act as an endocrine organ?
A
Renin: (angiotensinogen proscessing); Erythropoietin; Vitamin D2 and D3
5
Q
what does Renin do?
A
Regulates Kidney function; Up blood [NaCL], volume, and pressure
6
Q
what does erythropoietin do?
A
cytokine for CFU-E (increase RBCs)
7
Q
what do vitamin D2 and D3 do?
A
Ca2+ regulation
8
Q
Big Picture: how do the kidney support homeostasis?
A
by using a filter (the basement membrane between the capillaries and the bowman’s space) to adjust blood chemistry by exchanging water, salts, and other low MW solutes, acids/base between blood and filtrate tubule.
9
Q
what are the key structures of the kidney? (atonomy)
A
outside renal cortex; medullary rays (extend from the medulla to the outside cortex); medulla (pyramids), renal column (between the medulla); renal papilla (at the base of the pyramids); minor calyces (smallest collecting ducts); major clyces; renal pelvis (large collecting space); ureter
10
Q
what is the difference in the Juxtamedullary and Cortical nephrons?
A
the Juxtamedullary extend all the way down in the pyramid into the medulla. the cortical do not extend so deep; the justamedullary have Vasa Recta (Regenerative salt exchanger)
11
Q
where does the processed urine get depositied?
A
in the calyces that feed to the ureter
12
Q
how to see the cortex vs. the medulla in the microscope
A
the cortex: circular renal corpuscles and tubes; medulla has only tubes.
13
Q
Describe the function of the Renal Corpuscle
A
Form initial filtrate (180-200) liters of fluid a day. the small capillary forces the blood out through increased blood pressure.
14
Q
The function of the rest of the nephron after the renal corpuscle
A
the rest of the job is to get all but 1 liter of the 180-200 liter/day back to the body and continuously adjust blood compostion
15
Q
location where we recover 65% initial filtrate
A
PCT (primary convoluted tubule)
16
Q
Where in the nephron do we form the high salt [] of the medulla
A
in the loop of Henle
17
Q
where do we selectively recover NaCl and secrete H+ and HCO3-
A
The collecting Tubules and Ducts
18
Q
Where do we selectively recover water?
A
in the late distal tubule, collecting tubules and ducts
19
Q
where do we regulate filtrate formation?
A
Juxtaglomerular apparatus, JGA
20
Q
what are the main components returned to the blood from the nephron filtrate?
A
3Lbs. of NaCl and 1/2 pound of glucose returned to blood/day
21
Q
what lines the inside of the glomerulus?
A
parietal cells, or the simple low epithelial and the visceral cells around the capillary bed.
22
Q
what is the filtration unit of the kidney?
A
the renal corpuscle
23
Q
what is the hole where the blood vessels come into the renal corpuscle (bowman’s capsule)
A
the vascular pole
24
Q
what is the space between the capillary bed and the wall of the renal corpuscle?
A
the urinary space or bowman’s space.
25
what is the pole where the bowman's capsule connects to the urinary?
urinary pole
26
what are the cells that surround the capillaries in the glomerular, and how are they structured?
Primary secondary and tertiary branches of the podocyte cells wrap around the capillary and extend interlocking pedicles to create filtration slits where the filtration of the blood happens
27
Endothelial cells of the capillary, podocytes hugging them, what other cell types are in the glomerulus?
mesangial cells (pericyte - like) also present in the glomerulus involved in turning over basal lamina, controlling capilalry diameter, and signaling. activities altered by disease that affect filtration like diabetes.
28
what are the constituents of the glomerulus?
the podocytes surrounding the endothelial cells, and the mesangial cells.
29
describe the movement of blood filtrate in the glomularus
blood is in very high pressure and is pushed out the thick basal lamina and between the filtration slits of the podocytes and into the urinary space.
30
what are the three layres of filtration in the glomularus?
fenestrated endothelium; thick basal lamina; filtration slits
31
what is the constiuents of the filtrate
mostly the plasma minus the cells and large protiens. (therefore very little protein)
32
what ist he protien that acts as a net between the filtration slits?
nephrin
33
how much blood plasma moves accross the 3 layers of filtration into the urinary space?
20%, limited by the oncotic pressure
34
what is the first duct after the urinary space?
proximal convoluted Tubule (PCT): primary recovery
35
returns ca. 120-130 l/day to blood (65%)
proximal convoluted tubule
36
longest section of nephron, most common component of cortex
proximal convoluted tubule
37
the epithelium of the Proximal convoluted tubule
look alot like the epithelium of the intestines: apical microvilli, ZO+ZA, basolateral Na, K-ATPase
38
what makes the PCT structure and function different from the intestines?
systems to exrete organic acids and bases
39
what is the main function of the PCT epithelium?
resorb ca. 65% of inital filtrate volume, using Na+ gradient, including amino acids, glucose, PO4, Ca, HCO3
40
the condition of the resorbed fluid
isosmotic and enters pertubular capillaries
41
how do we get protiens that leak into the filtrate back out into the blood?
reabsorb proteins via pinoytosis at the base of microvilli of the apical side of the PCT epithelium. then broken down and sent to the blood as amino acids.
42
secrete specific acids and bases into the fitrate, can occur after modifiaction by the liver
the epithelium of the PCT
43
perform the hydroxylase reaction that creats vitamin D2 and D3
The epithelium of the PCT
44
the majority of components present i the filtrate of the kidney tubules arrive there form the blood primarily due to
blood pressure
45
what situatio favors the reabsorption of fluid form the filtrate in cortical kidney tubules back to the blood in peritubular capillaries?
High oncotic pressure of blood in peritubular capillaries
46
what are the straight tubules of the kidney after the initail blood filtration?
medullary rays of Proximal straight tubules
47
how to identify the proximal tubules in the kidney?
tall cells faily large cells, therefore few nuclei
48
a counter current multiplier system
Loop of henle -- a system that uses the counterflow of two loops to establish and utilize a concentration gradient.
49
large number of aquaporins present, therefore very permiable to water. not so permiable to ions.
Thin descending limb
50
no aquaporin and impermeable to water, but actively pump out ions to make the medula very salty (high osmolarity)
Ascending Thick limb
51
Describe the changes in osmolarity through the loop of henle
the descending loop allows watter out and not ions, therefore the filtrate becomes hypertonic. The ascending loop pumps ions out and no water (set gradient for descending) and makes the filtrate hypotonic coming out of the medulla!
52
is more water or salt recovered in the loop of henle?
25% of NaCl is recovered, but only 10% of the water.
53
what pharmacutical targets does the loop of henli present?
Diuretics, inhibit a Na,K,Cl (NKCC) co-transporter to inhibit this transport of ions accross the thick ascending limb. This lowers the osmotic gradient of the medulla and therefore resorbs less water in the DL, therefore more water through the loops and is peed out!
54
supply most of the deep loops and provide most of the high salt in the medulla
juxtamedullary corpuscles
55
Describe the Cortical Nephrons
cortical: short loop; further from the corticomedullary junction, efferent arteriole supplies peritubular capillaries.
56
describe the Juxtamedullary nephron
long loop of henle; glomerulus close to coricomedullary junction; efferent arteriole supplies vasa recta.
57
what is the result of the countercurrent multiplier system?
remove a ton of water at first and then remove a ton of salt afterwards to give a much reduced volume of very hypotonic fluid
58
How do the thick and thin loops of henle differ in the microscope
cells surrounding an empty lumen are either very low or cubiodal.
59
The macula densa
the thick hyperplasia of cells from the thick ascending loop that touch the original corpuscle from whence the tubule came
60
help to turn over the basement membrane and keep it cleen and maintain the epithelium
pericytes
61
resorb some Ca2+ and NaCl, Target of Thiazide diuretics, not a major target of aldosterone (except at the end?)
Distal convoluted tubles
62
The microscopic view of the distal convoluted tubule
simple cuboidal cells, no fuzy lining of microvilli etc.
63
The track of the filtrate trough a nephron to the toilet?
through the three layers of filter, urinary space, urinary pole; proximal convoluted tubule; thick descending loop, thin descending loop; thin asscending loop; ascending thick loop; past macula densa of the juxtaglomerular apparatus (JGA); Distal convoluted tubule; connecting tubule; collecting tubules, collecting ducts; papillary ducts, area cribosa, minor calyx, major calyx, renal pelvis, ureter, bladder, urethra, toilet!
64
stimulates Na channel open on the apical side of the CT/CD and incrrese the Na, K-ATPase in basolateral membranes pumping ions out of the filtrate!-- water will follow this reabsorption of ions
Aldosterone
65
what is the net result of aldosterone
sodium resorption, water resorption, increase fluid in body, and blood stream, increasing blood pressure.
66
inserts aquaporin in the membrane of collecting duct cells, water moves from the filtrate to the body
Antidiuretic hormone (ADH)
67
havn't had much to drink how is my ADH level?
High
68
how does BP change with fluid level?
more fluid retained, therefore the BP goes up
69
where is ADH made and retained?
made in the hypothalamus and stored in the pituitary
70
how does the level of ADH relate to the concentration of the urine?
High ADH means concentrated urine; Low ADH means Dilute Urine
71
ADH is also known as:
arginine vasopressin (AVP)
72
how does the osmolarity relate to the position of the filtrate in the tubule?
Initially it is 300 mOsm (isotonic); in the thick descending it becomes hypertonic (600 mOsm). in the thin descending loop it is very hypertonic (1200 mOsm). in the thick ascending loop it becomes hypotonic (120 mOsm).
73
how does the filtrate move from the Collecting duct to the minor Calyx?
It moves through the Urothelium lined papillary ducts and through small openings at the area cribosa into the minor calyx
74
what would remove a low molecular weight acid drug in the renal system.
the proximal convoluted tubules, that have specific import elements to remove organic bases and acids from the blood.
75
where does the filtrate become hypotonic?
in the thick ascending limb
76
the components of the juxtaglomerular apparatus, JGA
Extraglomerular mesengial cells; Juxtaglomerular cells (specialized smooth muscle cells of the afferent arteriole); Macula densa.
77
specialized smooth muscles cells that contain the protease Renin
Juxtaglomerular cells of the afferent arteriole
78
The rate of filtrate moving through the Bowman’s capsule into the PCT
GFR
79
The ideal rate of filtration that allows removal of unwanted element and recovery of wanted elements
this is known as the ‘set point’.
80
Two general types of regulation of the GFR
Intrinsic mechanism (tubuloglomerular feedback and myogenic control) and Extrinsic mechanisms (sympathetic, adrenal, Renin-angiotensin)
81
how does the GFR relate to the comparative BP of the aA and eA?
the differential constriction of the afferent and efferent arterioles of the RC control the blood pressure in the RC which is the driving force for the formation of the GFR!
82
feedback that says we need more filtrate or less filtrate
tubuloglomerular feedback
83
what is measured to control flow rate through the glomularous?
NaCl concentration in the thick ascending limb as monitored at the thick ascending loop.
84
what happens if there is too much NaCl in the Thick ascending limb?
then the macula densa will signal a decrease in the initial filtrate by constricing the afferent arteriole
85
How does the macula densa succeed in reducing the initial filtrate?
It signals with adenosine / ATP to cause constriction of the smooth muscle cells of the aA, that with down filtration pressure, down initial filtrate, and down NaCl in filtrate at JGA.
86
where is angiotensis produced
angtiotensinigin in the liver.
87
what about angiotensinigin?
released from the liver, cleaved by renin in the kidney to angiotensin 1 and then become angiotensin 2 by ACE and that will constrict the efferent arterioles and act on the adrenal cortex to give aldosterone and raise BP in RC and overall in the body.
88
What is the difference in the collecting duct and the distal convoluted duct and the proximal convoluted tubule In the microscope
CD every cell is clearly delaminates and divided; DCT has non clearly divided cells and PCT is non clearly deliminated and has stuff in the middle of the lumen they all have cuboidal cells
89
What if there is too little sodium passing by the macula densa?
then it will signal with PGE2 to cause release of renin from the JG cells of the aA. this ups angiotensin 1/2 and and ups alsosterone, and causes vasoconstriction of eA. therefore: up filtration pressure and initial filtrate, up NaCl in filtrate at JGA. up NaCl recovery, increase BP.
90
a protease that converts angtiotensinogen (liver) to angiotensin I in the blood
Renin
91
Converts angiotensin I to angiotensin II
ACE
92
How does Angiotensin II increase blood pressure?
signals release of aldosterone from adrenals, which increases NaCl and fluid resorption from CTs, and CDs, increasing blood volume. AND contricts arterioles, immediately increasing blood pressure.
93
important drug used to decrease blood pressure by effectively removing angtiontensin II
ACE inhibitor.
94
If the [NaCl] of the fluid in a thick ascending limb entering the JGA is sensed by macula densa cells as being too high, a response is initiated that results in what change to a nearby structure?
The afferent arteriole constricts.
95
Describe the flow of a RBC from the heart to the kidney and back again!
heart, DA, Renal artery; segmental branch; INTERLOBAR artery; arcuate artery; INTERLOBULAR artery; afferent arterioles; glomerular capillaries; efferent arterioles; peritubular capillary network OR vasa Recata (made of arteriolae rectae down and venae rectae up linked by capillary plexi);
96
the comparitive size of arteriles to/from the glomerularus
afferent arterioles are bigger than efferent arteriles.
97
How can we supply blood to the varied salt concentration of the medulla and not suck up all of the ions in the high conc. areas and transport them to the low conc. areas and ruin the ion concentration gradient?
by using a counter current exchanger that is similar to a regenerative heat exchanger in a power plant. Blood goes into the high salt environment right next to the blood coming out of the high salt environment, so the new blood absorbs all of the salt from the old and transports it back down to the gradient.
98
what is the salt conc. in the blood as it moves down and back up the medulla?
300mOsm; then up to 900mOsm at the bottom and then back down to 400mOsm at the top.
99
the structural cells of the kidneys:
the intersitital cells: fibroblasts (little extracellular matrix in the kidney) there is more interstitium (space between tubules in the medulla.
100
makes a cytokine in the kidney to stimulate red blood cell production in marrow
Fibroblasts in the cortex make erythropoietin (EPO) that stimulates RBC production!
101
The path of the filtrate after it makes it into the minor calyx
major calyx, renal pelvis; ureters (urothelium); bladder; urethra; outside (st. Squamous at the very end)
102
Layers of the Ureter
mucosa: urothelium (4-5 cells); Lamina propria: DCT; Submucosa: very little to none; Muscularis: inner longitudinal, outer circular (sortof), periodic peristalsis; Adventitia: CT
103
layers of the bladder:
Mucosa: urothelium, 6 or so layers thick if relaxed; lamina propria: as per ureter; muscularis: three layers (sort of middle thickest; submucosal layer present in the bladder; adventitia: upper portion is serosa (mesothelial covering.
104
The surface cells of the bladder
umbrella cells
105
Describe the surface of umbrella cells
polygonal indentations, seperated from other cells by ocasional creases; containing disc-like vesicles that can be added to the surface to allow the bladder to expand.
106
What would be indicated by the absence of sharp-edged, fusiform vesicles in the cytoplasm of umbrella cells of the urinary bladder?
The bladder is full!
107
What are the 4 major renal processes?
Glomerular filtration; Tubular reabsorption; tubular secretion; urinary excretion
108
What are the 4 main purposes of the processes of the kidney?
regulate blood pressure, keep acid base balance in body, regulate osmolarity, balance electrolytes
109
of nephrons
1 million per kidney
110
Healthy GFR
100ml/min women; 120mL/min men — entire blood plasma - 60 times per day. (55 Gallons)
111
The initial filtrate, and the origin of urine
glomerular filtrate
112
Urinary excretion equation
glomerular filtration - tubular reabsorption + Tubular secretion
113
driving force for glomerular filtration
(Filtrate osmotic pressure + Glomerular capillary hydraulic pressure + Gravitational forces) - (capsular hydrostatic pressure + Glomerular Capillary oncotic pressure)
114
what is capsular hydrostatic pressure?
the pressure of the filtrate within the capsular space exerted on the membrane.
115
the pressure pulling water from the blood into the capsular space
filtrate osmotic pressure
116
the pressure blood is exerting on the membrane
glomerular capillary hydraulic pressure
117
what is the pressure pulling water from the capsular space into the blood
glomerular capillary oncotic pressure.
118
the layers that the plasma passes to get to the urinary space
capillary endothelium; basement membrane; outermost laryer
119
what is oncotic pressure?
the osmotic pressure exerted by the larger proteins in the blood (albumin)
120
memory aids for the order of the arteriole
afferent before efferent - alphabetical or efferent starts with E and so does Exit!
121
what are secretion and excretion?
secretion is movement into the urine and excretion is out of the body
122
describe the layer that the filtrate passes through first
the capillary is fenestrated and has the largest openings (70-100nm)
123
describe the layer that the filtrate passes through second
basement membrane is the thickest, collagen rich layer that is porous and neg. charged.
124
describe the last layer that the filtrate passes through to get to the urinary space
the outermost layer is adjacent to the capsular space formed by podocytes that make filtration slits of 20-30 nm;
125
What is the normal filtration fraction?
the % of plams a that is filtered during a pass through the kidneys (usually 20%)
126
stage 3 chronic kidney disease
filtration les than 60ml/min
127
The highest hematocrit of the body
is in the efferent venule of the glomerular.
128
what is the normal hydrostatic pressure of the glomerular?
40-55mm Hg
129
what is te the glomerular osmotic oncotic prssure
25-30mmHg
130
what is the capsular hydrostatic pressure
10mmHg
131
what isthe net fitration pressure
the result of the glomular hydrostatic minus the glomular osmotic minus the capsular hydrostatic pressure
132
what is the normal net filtration pressure?
about 10-15 mm Hg
133
what is the best indication of GFR in a lab test?
the Creatinine clearance (freely filtered and not secreted into or reabsorbed from the tubules)
134
Official GFR equation
Kf [(Pgc-Pbs) - (Osmoticgc - Osmotic bs)]
135
What would a higher than normal creatinine clearance indicate?
decreased creatinine clearance, and thus decreased GFR (not hard and fast!)
136
Equation of Creatinine Clearance
product of volume of urine per time and urinary conc. of creatinine divided by plasma conc. of creatinine.
137
what is the myogenic cmechanism
the arteriolas will naturally contstrict to decreased pressure etc.
138
these should pass freely through the glomerular membrane
139
These should not pass through the membrane
> 3nm: RBCs WBCs platelets; many plasma proteins; albumin (neg. charge too); immunoglobulins; large charged particles
140
Intrinsic control of the renal
most of the time controls GFR; myogenic mechanism; tubuloglomerular feedback mechanism
141
extrinsic control of renal
systemic BP control; renin-angiotensin mechanism; sympathetic nervous system control. ANP (atrial natriuretic peptide).
142
paracrine control of renal
local signaling molecules: Prostaglandin E2; intrarenal angiotensin II; adenosine; nitric oxide
143
three classes of renal control:
intrinsic; extrinisic; paracrine
144
Describe the myogenic mech. of GFR control
Smooth muscle in afferent arterioles tend to contract when stretched, therefore up BP and they contrict. this lowers the GFR and lowers glomerular hydrostatic pressure.
145
what are the cells that produce renin?
the Granular cells of the afferent arteriola
146
what if the NaCl is high in the ascending loop?
macula densa send vasoconstrictor to afferent arteriole (ATP/adenosine). Afferent arteriole constricts. GFR decreases. Tubular flow rate slows. Renin secretion…inhibited!
147
Where is Angiotensin I converted to angiotensin II?
ACE (angiotensin converting Enzyme) acts primarily in the lung!
148
what are the two affects of Agiotensinogen becoming angiotensin II?
aldosterone secretion stimulated, act on Collecting ducts, up salt retention, up water retention, and up BP “preload” ;; Also constrict vessels esp. efferent arteriole, increase “afterload” up GFR
149
how could systemic BP be affected by losing granular cells?
granular cells of the afferent areterioles monitor systemic blood pressure as well, and release renin in response to low systemic blood pressure.
150
how could the nervous system affect granular cells?
sympathetic nervous system signals on beta-adrenergic receptors cause activation of granular cells.
151
Everthing that this hormone does is aimed at increasing systemic blood pressure or blood volume
Angiotensin II
152
Act to increase the GFR by dilating the afferent arteriole
prostaglandins
153
Drugs that block prostaglandins
NSAIDs (ibuprofen, naproxen, aspirin)
154
How do NSAIDs affect the renal system
they block the prostaglandins that help regulate the kidney by dilating the afferent arteriole to increase GFR.
155
how does the heart act to regulate the kidneys
can produce ANP to dilate aA to increase GFR and lower BP.
156
what does the sympahtetic nervous system do to the kidney?
it overrides all signals and causes intense constriction of all renal blood vessels. Send more blood to other organs. decrease the GFR alot!
157
what will the extrinsic control through the nervous system do to the intrinsic control?
sympathetic signal will lower NaCl alot and trip the renin-angiotensin sysytem…can’t increse GFR while sympathetic signal…but will up systemic BP and up blood volume.
158
Too much water and solute (sodium) in the body
hypervolemia
159
how would hypervolemia affect the plasma osmolality?
it doesn’t the osmolality would remain the normal.
160
loss of water and solute
hypovolemia
161
how would hypovolemia affect the osmolality of the plasma?
it wouldn’t. It would still be normal
162
loss of water and no loss of solute
dehydration
163
how would dehydration affect osmolality?
it would increase the plasma osmolality
164
too much water taken without solute
overhydration
165
how would overhydration affect osmolality
decrease plasm osmolality
166
the branches off of the efferent arteriole, or the post-glomerular capilary
the peritubular capillary
167
capillary next to the loop of henle…long loop that is
vasa recta
168
what does by far the most energy along the tubule get used doing?
reabsorbing sodium along the nephron
169
why spend so much energy focused on Na reabsorption in the kidney?
it provides the energy in the form of concentration gradient for the reabsorption of water, other ions, and nutrients, and for acid/base regulation.
170
what are the Three active Na+ reabsorption processes in the liver?
basolateral Na+/K+ aTPase pump; Na+ - glucose symporter. Na+/H+ antiporter.
171
when is sodium secreted into the filtrate?
never ever!
172
where does most of the Na+ get reabsorbed in teh tubules?
in the Proximal convoluted tubule (67%) and then the thick ascending limb (25%)
173
what gets reabsorbed in the PCT
65-80% of sodium and water; Cations (Na+, K+, Mg2+, Ca2+, etc.) Anions (HCO3- , Cl, etc.) Glucose, amino acids, proteins;
174
what gets secreted in the PCT?
pH control: H+ and NH4+ secreted into filtrate. Some drugs secreted into filtrate
175
the most important roles of the PCT?
sodium, water, and HCO3- reabsorb. pH Control
176
where is the pump that sets up the sodium gradient in the cells of the PCT and sets up a temporary osmotic gradient in the interstitual to drive water out of the filtrate?
the Na+/K+ ATPase pump is located in the basolateral membrane!.
177
what is the direction and net ionic movement of the ATPase in the basolateral membrane of the PCT?
moves 3 Na+ out of the cell and 2K+ into the cell.
178
how do we get potasium and glucose into the interstitium and to the blood?
facilitated diffusion through membrane channels.
179
How does water move through the cells of the PCT?
diffuses between cells, and through aquiporins on both sides of the cell.
180
what drives the movement of water from the filtrate to the interstitium?
the osmolality of the interstitium. It if is higher than filtrate, then water will move out!
181
what part of the tubule is not water permeable
the ascending loop
182
what are the transporters of the luminal membrane of the tubule of the kidney?
Glucose/Amino acids/ Lactate/ vitamins/ HCO3-/Drug reabsorbing channels. H+ secreting channels.
183
Why would the efferent arteriole blood tend to be a little more acidic if the H+ pumps were to be blocked?
only 80% of the HCO-3 is reabsorbed.
184
What are the components that contribute to medullary osmotic gradient?
NaCl (70%) and Urea (30%).
185
What is BUN
blood urea nitrogen, a measure of the nitrogen in the blood. can give an indication of kidney filtration.
186
Important membrane co-transporter in thick ascending loop driven by the Na+ gradient.
Na+ -K+ -2Cl- or the NKCC cotransporter.
187
where is urea permeable in the loop of henle
facilitated diffusion the thin ascending loop
188
what happens to the K+ that comes in by the NKCC pump?
it diffuses back into the filtrate by way of luminal ion channels.
189
where else could NaCl be reabsorbed besides the NKCC pump?
also through simple diffusion at the tight junctions.
190
The target of Thiazide diuretics
Na-Cl symporter in the DCT.
191
What is the effect of transport in the DCT
Na-Cl symporter will dilute the urine even further so that it is even more hypotonic!
192
What about Ca reabsorbtion in the distal tubule?
reabsorbed in the DCT under influence of parathyroid hormone (PTH)
193
What is the main reabsorption/excretion of the collecting duct?
Na+ and water excretion controlled by ADH (water); and Aldosterone (Na+) hormones.
194
Cells that mediate Na+, K+ and water in response to aldosterone and ADH in the collecting duct
Principal cells
195
cells that secrete hydrogen ions into the filtrate in the collecting duct
Intercalated cells.
196
Aldosterone acting on principal cells of the collecting ducts
up basolateral Na+/K+ ATPase;; Up Luminal Na+ and K+ channels. K+ is returned to filtrate. therefore: K+ up in urine. Na+ and water up in serum!
197
ADH acting on principal cells
insert luminal aquaporins. Increase water in blood, and decrease water in urine.
198
ADH acting on the medullary collecting duct
increase urea transport into medulla (increase the osmolality of the gradient). Low ADH and urea and water stay in filtrate.
199
Secretes ADH
Posterior pituitary
200
why does posterior pituitary secrete ADH
high serum osmolality
201
what senses serum osmolality to cause the posterior pituitary to secrrete ADH?
hypothalamic osmoreceptors.
202
when would BUN be high in the blood
kidney disease.
203
contrast the nephron when high or low ADH
ADH makes the DCT and the CD permeable to water otherwise no water gets out after the descending loop!
204
how can we change the osmotic gradient and increase the action of the NKCC transporters?
ADH causes a higher medullary osmotic gradient by causing urea to be pumped into interstitium!
205
The main action of Aldosterone
Na+ goes into blood, K+ goes into urine. (water follows the Na)
206
What does aldosterone do the principal cell membrane?
increases basal Na+ and K+ channels. and increases basolateral Na-K ATPases.
