Gu Block - Lect 1.5: Renal Fxn - Urine Formation

Front 1

20% of renal blood is filtered in the _____________.

Back 1

Glomerulus. The "normal" human glomrular filtration rate (GFR) is 150L/day

Front 2

T/F: 99% of the Na+ filter is reabsorbed

Back 2

TRUE; of the 22,500 mmol of Na+ filters, the kidney reabsorbs 99% of it

Front 3

formation of the urine involves 3 basic processes: 1) ____________ of the plasma by the glomerulus, 2) ____________ of H2O & solutes from the ultrafilrate, 3) ____________ of selected solutes into the tubular fluid

Back 3

1) ultrafiltation, 2) reabsorption, 3) secretion

Front 4

renal tubules regulate the volume and composition of the urine and blood via __(active/passive/both)__ transport processes

Back 4

both active and passive; NOTE: these processes include: 1) regulation of the net concentration of major cations (Na+, H+, Ca2+, Mg2+) and anions (Cl-, HCO3-); 2) conserve and maintain optimal concentrations of other essentials such as glc and aa's; 3) maintain acid-base balance

Front 5

the ___________ makes filtrate

Back 5

glomerulus

Front 6

the ___________ pulls back (reabsorbs) Na+ and H2O follows

Back 6

PCT

Front 7

the _____________ loop of Henle pulls things back, but H2O cannot follow

Back 7

Ascending

Front 8

the _____________ serves to fine tune the composition of the filtrate

Back 8

DCT

Front 9

the _____________ has ltd mvmt of substances across it

Back 9

CD

Front 10

**As you move down the tubule (ie from PCT --> CD), processes go from being hormone __(dependent/independent)__ at the beinginning to hormone __(dependent/independent)__ at the end.

Back 10

beginning = independent; end = depentent (ADH, Aldosterone!!!!)

Front 11

the ___A____ consists of a tuft of capillaries enclosed within an epithelial cell capsule (aka ______B______) that is between the afferent and efferent arterioles

Back 11

A = glomerulus, B = Bowman's capsule

Front 12

the glomerular capillary wall through which the filtrate must pass, consists of 3 layers:

Back 12

1) the fenestrated endothelial layer, 2) the continuous GBM, 3) the visceral epithelial cells (podocytes)

Front 13

in the glomerulus, the epithelial cell s are attached to the GBM by discrete _____________ _____________

Back 13

foot process that form slit pores with a slit diaphragm composed mainly of nephrin

Front 14

_______ ________ forces water and dissolves nutrients through the capillary walls for filtration by the nephron

Back 14

blood pressure

Front 15

the ___________ performs most of the reabsorptive work of the nephron (it's the workhorse)

Back 15

PCT

Front 16

name the 6 main things reabsorbed in the PCT

Back 16

1) Na+!!!!, 2) Cl, 3) BiCarb, 4) Glc, 5) aa's, 6) H2O

Front 17

How much (%) or Na+ is reabsorbed in the PCT, if any at all?

Back 17

60-70%!!! Water follows passively and is directly proportional to Na+ (high permeability)

Front 18

In the early PCT, ____ is reabsorbed with Na+ and H2O. In the late PCT, _____is reabsorbed with Na+ and H2O.

Back 18

early = Bicarb; late = Cl-

Front 19

__________ is the main place of reabsorptions for Na+ and H2O

Back 19

PCT

Front 20

in the PCT, ______________ hormone does regulate phosphate and bicarb, though, this part of the nephron is largely hormone independent.

Back 20

parathyroid hormone

Front 21

__________ is the site of organic acid/base secretory system (transport from blodstream to tubular lumen), and this process is saturable

Back 21

PCT

Front 22

in the _______A______ the inc'd tnicity of the medulla facilitates water resorption via a _________B_____ mechanism

Back 22

A = loop of Henle; B= countercurrent mechanism

Front 23

LOH: the ______________ limb has LOW/no solute permeability; has H2O permeability; approx 15% of filtered H2O is resorbed here

Back 23

descending limb of loop of Henle

Front 24

LOH: the ______________ limb is impermeable to H2O, but is ion permeable

Back 24

thin ascending limb

Front 25

LOH: the ______________ limb is impermeable to H2O; has a Na+-K+-2Cl- cotransporter (up to 25% of filtered Na+); the electrochemical here also drives further reabsorption of Na+, as well as Mg2+ and Ca2+

Back 25

thick ascending limb

Front 26

at which point in the tubules do we begin to separate reabsorption of H2O from certain electrolytes?

Back 26

LOH

Front 27

the ______A_____ is a zone of transition; it consists of the segments B-__(name them)__

Back 27

A-DCT; B- DCT, connecting tubule, initial collecting duct

Front 28

in the ____A_______tubule water permeability is variable: in the initial segment, it's low, but in the later segment it is ___B___-dependent

Back 28

A = distal tubule, B = ADH

Front 29

The __Na+ -____ cotransporter in the distal tubule absorbs up to 7% of filtered Na+

Back 29

Na+-Cl- cotransporter

Front 30

in the __________ distal tubule, Na+ reabsorption continues; as it does, Na+ concentration __inc/dec__

Back 30

early, decreased (concentration in the tubule decreases… low H2O reabsorbed here!)

Front 31

in the _____A_____ distal tubule, Na+ reabsorption occurs via a(n) ______B______;

Back 31

A = late distal tubule; B = Na+-K+ ATPase; this occurs with Cl- reabsorption or H+ or K+ secretion

Front 32

in the late distal tubule what 2 molecules can be reabsorbed, and what 2 can be secreted?

Back 32

absorbed: Na+ and Cl-; secreted: K+ and H+

Front 33

the _______A__ _______ responds to distal fluid chloride concentration and regulates (via tubuloglomerular feedback). First it triggeres dilation of the renal afferent arteriole, decreasting aff. art. resistance and thus offsetting the decrease in glomerulat hydrostatic pressure caused by a drop in bp. 2nd, these cells release ___B____s which trigger grnaular juxtaglomerular cells lining the aff art to relax and release __C___ into the bloodstream.

Back 33

A = macula densa, B = prostaglandins, C= renin

Front 34

the ___________ ________ handles the remaining 2% of the filtered load; thus, this is where the final excretion of solutes is fine tuned.

Back 34

collecting duct

Front 35

T/F: the CDs have both cortical and medullary segments

Back 35

TRUE!

Front 36

in the CD, what controls H2O permeability?

Back 36

ADH

Front 37

at the start of the CDs, Na+ is resorbed and linked with what 3 molecules? Are these three secreted or reabsorbed incotransport with Na?

Back 37

K+ or H+ secretion, or Cl- reabsorption

Front 38

____A_____ cells of the CDs resorb Na+ and Cl- and secrete K+; _____B______ cells of the CDs secrete H+ (alpha) or HCO3- (beta).

Back 38

A= principal cells; B= intercalated cells

Front 39

the beginning of the tubules have __(high/low)__ surface area, __(high/low)__ # of mitochondria, and use __(high/low)__ amounts of energy, while the end of the tubules have __(high/low)__ surface aread, __(high/low)__ # of mitochondria, and use __(high/low)__ amounts of energy

Back 39

beginning = high SA2, high #mt, high E usage; end = low SA2, low # mt, and low E usage

Front 40

NOTE: be able to walk yourself thru the last slide of the summary of renal fxn

Back 40

NOTE: be able to walk yourself thru the last slide of the summary of renal fxn