Lecture 16

Question 1

Osmolarity

Answer 1

mOsm (milliosmoles)/L = concentration of particles per liter of solution

Question 2

Osmolality

Answer 2

mOsm/kg = concentration of particles per kg of solvent (water in biological systems)

Question 3

Effective Osmole

Answer 3

Refers to a solute that does not easily cross a membrane; it is an effective osmole because it creates an osmotic force for water

Question 4

Osmolar Gap

Answer 4

Difference between the measured osmolarity and the estimated osmolarity (normally = 15); helps narrow differential diagnosis

Question 5

Where would you be more likely to find a higher concentration of proteins; Interstitial fluid or plasma?
Why?

Answer 5

Plasma because capillaries have a low permeability to plasma proteins

Question 6

Intracellular Fluid Composition

Answer 6

Small amounts of sodium and chloride ions; almost no calcium ions; large amounts of potassium and phosphate ions; moderate amounts of magnesium and sulphate ions

Question 7

Indicator-Dilution Principle

Answer 7

Applies to measurement of fluid volumes in body fluid compartments

Question 8

Requirements for an Indicator

Answer 8

Disperses evenly throughout compartment; disperses only in compartment being measured; not metabolized or excreted; not toxic

Vol B = Vol A x Conc A/Conc B

Question 9

For each mOsm concentration gradient of an impermeant soulte, how much osmotic pressure is exerted across the cell membrane?

Answer 9

19.3 mmHg

Question 10

What happens when you add a solution of isotonic saline to extracellular fluid compartment?

Answer 10

Extracellular osmolarity does not change, but volume increases

Question 11

Isotonic

Answer 11

Water cannot enter or leave the cell

Question 12

Hypertonic

Answer 12

Water will diffuse out of the cell

Question 13

What happens when you add a solution of hypertonic saline to extracellular fluid compartment?

Answer 13

Intracellular volume decreases, extracellular volume increases, osmolarity in both compartments increases

Question 14

Hypotonic

Answer 14

Water will diffuse into the cell

Question 15

What happens when you add a solution of hypotonic saline to extracellular fluid compartment?

Answer 15

Volume of both compartments increases, osmolarity in both compartments decreases

Question 16

What makes up the renal cortex of the kidneys?

Answer 16

Bowman’s capsules and proximal and distal convoluted tubules

Question 17

What makes up the renal medulla of the kidneys?

Answer 17

Renal pyramids

Question 18

What makes up the renal pelvis of the kidneys?

Answer 18

Major and minor calyces

Question 19

Compare cortical nephrons and juxtamedullary nephrons

Answer 19

Cortical nephrons have glomeruli located in outer cortex and have short loops of Henle

Juxtamedullary nephrons have glomeruli deep in renal cortex near medulla, long loops of Henle, and long efferent arterioles associated with peritubular capillaries (vasa recta)

Question 20

What does high hydrostatic pressure in glomerular capillaries cause?

Answer 20

Causes rapid fluid filtration

Question 21

What does low hydrostatic pressure in peritubular capillaries cause?

Answer 21

Permits rapid fluid reabsorption

Question 22

How does blood flow to/through/away from kidneys?

Answer 22

Renal artery–> Interlobar arteries–> Arcuate arteries–> Interlobular arteries–> Afferent arterioles–> Glomerular capillaries–> Efferent arterioles–> Peritubular capillaries–> Interlobular veins–> Arcuate veins–> Interlobar veins–> Renal veins