Lecture 2 - Body Fluids and Clearance

Question 1

_____ water accounts for about 40% of body weight, _____ water accounts for about 15% of body weight, and Plasma water accounts for about 5% of body weight.

Answer 1

ICF

ECF

Question 2

Hematocrit (Hct) = _______

Answer 2

Vrbc/Vblood (typically about 0.45)

Question 3

Blood Vol = _______

Answer 3

Vplasma/ (1-Hct)

Question 4

Primary volume changes ALWAYS occur in the _____, and osmotic concentration will equilibrate via movement of water between the ECF and ICF.

Answer 4

ECF

Question 5

The major sensors in Na+ regulation are _____ sensors (indirectly detecting volume) –> thus the major regulator is the _______ system.

Answer 5

Pressure

RAAS

Question 6

The major sensors in H2O regulation are ________ –> the major regulator is ______.

Answer 6

Osmosensors

ADH

Question 7

Isoosmotic volume depletion can occur via _____ or _____ loss through burns.

Isoosmotic volume expansion can occur via edema or renal _____ retention.

Answer 7

Hemorrhage or Plasma loss

Na+ retention

Question 8

Hypotonic volume depletion can occur via renal loss of _____ (e.g. bc of lack of Aldosterone).

Hypotonic volume expansion can occur via excess water ingestion or excess ______ (which hormone?)

Answer 8

NaCl

ADH

Question 9

Hypertonic volume depletion can occur with excessive sweating or dehydration, consumption of ____ inhibitors (i.e. alcohol or caffeine), or ______ insipidus/mellitus).

Answer 9

ADH inhibitors

Diabetes

Question 10

Why is Inulin used to determine the GFR?

Answer 10

It is freely filtered, and it is not at all secreted or reabsorbed. So, the amount that is excreted in the urine is directly equal to the amount that was filtered –> that gives the GFR.

Question 11

Why is the Clearance (C) value of glucose = 0?

Answer 11

Glucose is completely reabsorbed!

Question 12

If filtered substances are reabsorbed to a greater degree than they are secreted, how will their Clearance (C) relate to GFR? Keep in mind this is true of Na+

Answer 12

C < GFR

Question 13

Why does Clearance (C) of Para-aminohippurate (PAH) approximate Effective Renal Plasma Flow (ERPF)?

Answer 13

PAH is freely filtered but also completely Secreted from the renal venous vessels, so the Clearance of PAH is equal to the amount of blood filtered by the glomerulus + the amount not filtered that enters the efferent arteriole.