Lecture 14 Body Fluids and Compartments and Urinary System Overview

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 solute that does not easily cross a membrane

It is an effective osmole because it creates an osmotic force for water.

Question 4

______ are effective osmoles for the vascular compartment

Answer 4

Proteins

Question 5

Daily intake of water through ingestion (fluids or foods)

Answer 5

2100 ml/day

Question 6

Daily intake of water through metabolism

Answer 6

200 ml/day

Question 7

Total daily intake of water

Answer 7

2300 ml/day

Question 8

Daily loss of water through insensible evaporation

Answer 8

350 ml/day through skin
350 ml/day via lungs
3-5 Liters/day for severe burns

Question 9

Daily loss of water through sweat

Answer 9

100 ml/day

5000 ml/day during exercise

Question 10

Daily loss of water through feces

Answer 10

100 ml/day

Question 11

Daily loss of water through urine

Answer 11

1400 ml/day

500 ml/day during exercise

Question 12

Total daily loss of water

Answer 12

2300 ml/day

Question 13

Osmolar Gap

Answer 13

Helps to narrow the differential diagnosis

Difference between the measured osmolality and the estimated osmolality

Question 14

Common things that can elevate the osmolar gap:

Answer 14

Ethanol
Methanol
Ethylene glycol
Acetone
Mannitol

Question 15

Ionic composition of plasma and interstitial fluid is similar because:

Answer 15

they are separated by a highly permeable capillary membranes

Question 16

Why is there a higher concentration of proteins in the plasma?

Answer 16

Because capillaries have a low permeability to plasma proteins

Question 17

Intracellular fluid composition:

Answer 17

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 18

Indicator-Dilution Principle

Answer 18

Applies to measurement of fluid volumes in body fluid compartments

Question 19

Requirements for an indicator:

Answer 19

Disperses evenly throughout compartment
Disperses only in compartment being measured
Not metabolized or excreted
Not toxic

Question 20

Relative amounts of extracellular fluids in interstitial spaces and plasma are determined primarily by:

Answer 20

Balance of hydrostatic and colloid forces across capillary membranes

Question 21

Distribution of fluid between intracellular and extracellular compartments is determined mostly by:

Answer 21

osmotic effects primarily of sodium and chloride

Question 22

Units of concentration in body fluids are typically expressed in terms of:

Answer 22

Milliosmoles (mOsm)

Question 23

For each mOsm concentration gradient of an impermeant solute, about _____ mmHg osmotic pressure is exerted across the cell membrane.

Answer 23

19.3

Question 24

Calculating Potential Osmotic Pressure of a Solution

Answer 24

Slide 21

Question 25

About 80% of the total osmolarity of the interstitial fluid and plasma is due to:

Answer 25

Sodium and chloride ions

Question 26

For intracellular fluid, about half the osmolarity is due to:

Answer 26

Potassium ions

Question 27

Addition of isotonic saline to extracellular fluid compartment:

Answer 27

Extracellular osmolarity does not change

Extracellular volume increases

Question 28

Addition of a hypertonic saline to extracellular fluid compartment:

Answer 28

Intracellular volume decreases
Extracellular volume increases
Osmolarity in both compartments increases

Question 29

Addition of hypotonic saline to extracellular fluid compartment:

Answer 29

Volume of both compartments increases

Osmolarity in both compartments decreases

Question 30

A solution of impermeant solutes having an osmolarity of 282 mOsm/L is isotonic –> ?

Answer 30

Water cannot enter or leave the cell

Question 31

A solution of impermeant solutes haveing an osmolarity > 282 mOsm/L = hypertonic –> ?

Answer 31

Water will diffuse out of the cell

Question 32

A solution of impermeant solutes having an osmolarity ?

Answer 32

Water will diffuse into the cell

Question 33

Describe acute hyponatremia is regards to the brain

Answer 33

Acute loss of plasma sodium or excess water causes brain to swell
May lead to seizures, coma, permanent brain damage, death

Question 34

Describe chronic hyponatremia in regards to the brain

Answer 34

Chronic loss of plasma sodium or excess water allows tissues to transport sodium, chloride, potassium, and other solutes into extracellular spaces.
Tissue swelling os tissues is much less.