PRIN Review

Question 1

How can you calculate plasma volume?

Answer 1

(Blood Volume) x (1 - hematocrit)

Question 2

How is ECFV measured?

Answer 2

Using inulin and Na+*

These remain in ECF compartment.

Question 3

How is plasma volume measured?

Answer 3

Albumin* or Evans blue dye.

These remain in the vasculature.

Question 4

How is TBW measured?

Answer 4

D2O and antipyrine.

These distribute to all body compartments.

Question 5

What is the difference btwn mmol and mEq?

Answer 5

mEq reflects charges:

mEq = (mmol) x (valence charge)

Question 6

What is the difference btwn mol and osmol?

Answer 6

osmole reflects number of osmotically active particles.

1 mol NaCl = 2 osmoles

Question 7

What is osmotic pressure?

Answer 7

The pressure required to stop water from diffusing across a semi-permeable membrane.
Proportional to the number of osmotic particles dissolved.

Question 8

What are the major cations and anions in ECF?

Answer 8

Na+

Cl-
HCO3-

Question 9

What are the major cations and anions in the ICF?

Answer 9

K+

proteins
amino acids
organic phosphates

Question 10

What is the range of normal osmolality for ECF & ICF?

Answer 10

280-300 mosmol/kg H2O

Question 11

What is an effective osmol?

Answer 11

particle that cannot diffuse across a membrane

Question 12

What is the difference btwn osmolality and tonicity?

Answer 12

Tonicity measures effective osmoles whereas osmolality measures everything even if it can diffuse across the membrane.

Question 13

What is the normal [Na+] in plasma?

Answer 13

135-145 mmol/L

Question 14

What is Starling’s Law?

Answer 14

Fluid Flux = (Kf) x [ (Pc - Pi) - (pi c - pi i) ]

Question 15

Between the ICF and ECF,

• what travels freely?
• what requires transport proteins?

Answer 15

Water and urea diffuse freely.

Glucose and electrolytes require transport proteins.

Question 16

Between the ISF and plasma,

• what travels freely?
• what requires transport proteins?

Answer 16

Water and solutes (urea, electrolytes, glc) diffuse freely.

Proteins (albumin) require transport proteins

Question 17

What are the regulatory functions of the kidneys?

Answer 17

Maintains and regulates:

• [electrolytes]
• pH
• ECFV
• CO

Question 18

What are the endocrine functions of the kidneys?

Answer 18

Produce and secrete hormones:

• Erythropoietin (from renal peritubular cells)
• Vitamin D (from proximal tubular epithelial cells: helps Ca++ & PO4— metabolism)
• RAAS (prorenin–>renin in JG cells)
• Vasodilators: Kinins & PGs

Question 19

What is the excretory function of the kidneys?

What are the main waste products?

Answer 19

Concentration and dilution of urine, then voiding/micturition.

Waste products:

• Urea (from protein metab)
• Uric acid (from purine metab)
• Creatinine (from muscle metab)

Question 20

What spinal level are the kidneys located at?

Answer 20

T12 - L3

Question 21

List 4 methods used to estimate GFR.

Answer 21

1. Clearance of inulin or creatinine
2. Serum/Plasma [creatinine]
3. Cockcroft-Gault equation
4. Starling’s Forces

Question 22

What is the function of mesangial cells?

Answer 22

Provide support for the capillary network.

Help regulate GFR (by contracting/relaxing).

Question 23

What are the 3 layers in the filtration barrier?

Answer 23

1. Glomerular capillary endothelium (fenestrated)
2. Glomerular basement membrane (collagen & proteoglycans)
3. Bowman’s Capsule epithelium (podocytes)

Question 24

When does GFR = Clearance?

Answer 24

When referring to a substance that is:

• freely filtered
• not reabsorbed
• not secreted
• not produced by kidneys

ex. Creatinine or Inulin

Question 25

What is the filtered load?

Answer 25

(Plasma [X]) x (GFR)

Question 26

Why is GFR estimated from creatinine rather than inulin?

Answer 26

Inulin is an exogenous substance so it needs to be introduced into the body which is more invasive.

Question 27

What is a normal value of plasma [creatinine]?

Answer 27

40-120 micro-mol/L

Question 28

What is the Cockcroft-Gault equation for estimating GFR?

Answer 28

Creatinine Clearance = { (140 - years of age) x (kg body weight) x (0.85**if female) }
/
{ (72) x (mg/dL Plasma [creatinine]) }

Question 29

What is the equation for blood flow?

Answer 29

Blood flow = (change in Pressure) / (change in Resistance)

Flow = P / R

Question 30

What cells compose the Juxtaglomerular Apparatus (JGA)?

Answer 30

1. Extraglomerular Mesangial Cells
2. Macula Densa (tubule epithelium)
3. Juxtaglomerular Cells (afferent arteriole wall - secrete renin)

Question 31

How does aldosterone act on the kidney?

Answer 31

Increases reabsorption of Na+ in the DCT & CD.

Question 32

How does ADH/Arginine Vasopressin act on the kidney?

Answer 32

Increases water reabsorption in the CD

Increases Na+ reabsorption in the TAL