Lecture 19: Renal System 1

Question 1

Describe the breakdown of fluids within the body

Answer 1

14L extracellular, 28L intracellular
total fluid = 0.6 of body weight
extracellular = 0.2
interstitial fluid = 0.75 of ECF
plasma = 0.25 of ECF
intracellular = 0.4

Question 2

What are the 6 functions of the renal system

Answer 2

1) waste excretion (billirubin, urea, metabolites, toxins)
2) Acid/Base regulation
3) Regulation of Na and K
4) ECF osmolarity regulation
5) gluconeogenesis
6) produce hormones (renin, vitamin D, erythropoietin)

Question 3

Describe the starling equation

Answer 3

J = Kfc * [(Pcap-Pif)-δ(πplasma - πif)]

Kfc = filtration co-efficient
balance between hydrostatic and oncotic pressure

Question 4

How can you measure GFR?

Answer 4

By looking at the clearance rate of a special molecule (ex. creatinine)
must be freely filtered, not actively secreted or reabsorbed

[urine]/[plasma] * flow = GFR = clearance

Question 5

Review how to calculate GFR

Answer 5

ghjlk;

Question 6

What factors mediate selectivity of filtration?

Answer 6

size (small goes through)
charge (neutral or positive goes through) - no negatives since many of the body proteins are negatively charged, don’t want to lose those

Question 7

How is renal blood flow regulated?

Answer 7

1) myogenic response: automatic, local, in response to stretch of the afferent arteriole smooth muscle
2) tubular fluid solute concentration sensed by macula dense of the juxtaglomerular apparatus, releases signals to constrict afferent arteriole

ions enter through NKCC (Na/K/Cl co-transporter), ATP converted to ADP at Na/K ATPase, adenosine binds to A1 receptor, ATP binds to P2X receptor and causes vasoconstriction at smooth muscle cells