Lecture 15: GU Overview

Question 1

Cations intra/extracellular:

Answer 1

Intracellular: K+ and Mg++

Extracellular: Na+, and Ca++

Question 2

Anions Extra/intracellular:

Answer 2

Intracellular: PO4

Extracellular: Cl- and HCO3-

Question 3

Osmolarity vs. Osmolality

Answer 3

Osmolarity: mOsm / LITER

Osmolality: mOsm/ KILOGRAM

Question 4

Define effective osmole and give ex:

Answer 4

Refers to a solute that does not easily cross a membrane- named because it creates an osmotic force for water.

Proteins are effective osmoles

Question 5

Major sources of fluid intake / loss:

Answer 5

Input: INGESTION and metabolism.

Loss: insensible evaporation, sweat, feces, URINE.

Question 6

Components of a BMP test:

Answer 6

Na+ Cl- BUN
K+ HCO3 Cr Glu

Norm Cl: 104
Norm HCO3: 24
Norm BUN: 15
Norm Cr: 1
Norm Glu: 80

Question 7

Define osmolality gap:

How is it calc?

Answer 7

Difference btw the measured osmolality and the estimated osmolality (norm <15)

[2xNa+] + [Glu/18] + [urea/2.8]

Question 8

What can elevate osmolality gap?

Answer 8

Ethanol
Methanol
Ethylene glycol
Acetone 
Mannitol

Question 9

Know difference btw osmolarity and osmolality

Answer 9

Osmolarity: osmoles / L

Osmolality: osmoles / KILOGRAM water

Question 10

How to calc potential osmotic pressure for a given osmolarity:

Answer 10

NS: (0.9%) 9g/L / 58.5g/mol = .308

308 mOsm/L x 19.3 mm Hg=

5944 mm Hg

[19.3 mm Hg-osmotic pressure]

Question 11

What are the major ions that makeup 80% of total osmolarity of interstitial fluid and plasma?

What about intracellular, which ion makes up 50% osmolarity?

Answer 11

80%= Na+ and Cl- ions

Intracellular: K+

Question 12

Define isotonic

Answer 12

Osmolarity of 282 mOsm/L

Question 13

Define hypertonic

Answer 13

Osmolarity > 282 mOsm/L

Question 14

Define hypotonic

Answer 14

Osmolarity: < 282 mOsm/L

Question 15

Effects of isotonic sol’n added to ECF

Answer 15

No Osmolarity change

Extracellular volume increases !

Question 16

Effects of hypertonic sol’n added to ECF

Answer 16

Intracellular volume decreases

Extracellular volume increases

Osmolarity in both intracellular and extracellular increases

Question 17

Effects of hypotonic sol’n added to ECF

Answer 17

volume of both intracellular and extracellular increases

Osmolarity in both decreases

Question 18

What’re the causes and consequences of hyponatremia?

Answer 18

Causes: adrenal insufficiency, diuretics, excess ADH (SIADH), bronchogenic tumors

Consequences: Brain cell edema, and neurological symptoms [HA, N, lethargy. Disorientation]

Question 19

What’re the causes and consequences of hypernatremia?

Answer 19

Causes: Diabetes, excessive sweating, Cushing’s Dz, primary aldosteronism

Consequences: Thirst, compensatory mechanisms that increases intracellular {NA+ and other solutes]

Question 20

Compare/ contrast intracellular and extracellular edema:

Answer 20

Intracellular is interstitial fluid and extracellular is in the blood, lymph, etc.

Question 21

3 conditions especially prone to cause intracellular swelling:

Answer 21

hyponatremia

Depression of the metabolic systems of the tissues

Lack of adequate nutrition to the cells

Question 22

Causes of extracellular edema:

Answer 22

Abnormal leakage of fluid from the plasma to the interstitial spaces across the capillaries

Failure of lymphatics to return fluid from interstitium back to the blood [lymphedema]

Question 23

Cerebral edema and hypo/hypernatremia:

Answer 23

Brain swells w/ acute hyponatremia

Chronic hyponatremia causes less swelling but some.

Question 24

Be familiar w/ gross anatomy of the kidney.

Answer 24

Capsule
Renal cortex
Renal medulla
Renal pelvis

Question 25

Trace the blood flow through the kidney and identify the levels of vessels involved.

Answer 25

To kidney:
Renal artery->interlobar arteries->arcuate arteries-> interlobular arteries->afferent arterioles->glomerular capillaries->efferent arterioles

FRom kidney:
Peritubular capillaries->interlobular veins->arcuate veins->interlobar veins->renal veins

Question 26

Describe the structure of a nephron and differentiate btw cortical and juxtamedullary nephrons

Answer 26

Structure: million/kidney

Cortical: have glomeruli located in outer cortex and have short loops of henle

Juxtamedullary: (20-30%) have glomeruli deep in renal cortex near medulla and have long loops of henle

Question 27

States approximate percentage of total CO received by the kidney:

Answer 27

22%

Question 28

Compare the effects of high and low hydrostatic pressure on the kidney filtration/reabsorption

Answer 28

High hydrostatic pressure in glomerular capillaries: causes rapid fluid filtration.

Low hydrostatic pressure in peritubular capillaries: permits rapid fluid reabsorption.

This is regulated by efferent arterioles