Lecture 14: Body fluids- Exam 3

Question 1

Osmolarity and Osmolality

Answer 1

Osmolarity: Osmole/Liter
Osmolality: Osmole/Kg

Question 2

What is an effective osmole?

Answer 2

Refers to substances that does not easily cross membrane

Offers an osmotic force for water.

Question 3

Daily intake of water

Answer 3

Ingestion (Fluids and food): 2100 mL/day
Metabolism: 200 mL/day
Total: 2300 mL/day

Question 4

Daily outtake of water

Answer 4

Insensible evaporation:Skin-350 mL/day ( 3-5L/day for severe burns), Lungs-350 mL/day
Feces-100 mL/day
Sweat- 100 mL/day (5000 mL/day during exercise)
Urine-1400 mL/day
Total- 2300 mL/day

Question 5

Distribution of body fluids in body

Answer 5

Total body water: 42 L (50% weight in female, 70-75% weight in premature and newborn)
Intracellular:28.0L
Extracellular: 14.0L (Plasma:3.0,interstitial fluid: 11.0)

Question 6

BMP (Basic Metabolic Profile)

Answer 6

Level of cations, and anions in extracellular
Does not reveal disease
Necessary for osmolar gap

Question 7

Osmolar gap

Answer 7

Helps to narrow differential diagnosis
Difference between measured osmolality and estimated osmolality
Normal

Question 8

Substances than elevate osmolar gap

Answer 8

Methanol
ethanol
ethylene glycol
Mannitol
acetone

Question 9

Plasma and Interstitial fluid

Answer 9

capillaries separates both compartments
Capillaries highly permeable to ions causes similar ionic composition
Capillaries have a low permeability to proteins which causes higher concentrations of proteins in plasma

Question 10

Intracellular fluid composition

Answer 10

Almost no calcium ions
Small amounts of sodium and chloride
Moderate amounts of magnesium and sulphate ions
Large amounts of potassium and phosphate ions

Question 11

Indicator dilution principle

Answer 11

Applies to measurement of fluid volume in body fluid compartments

Question 12

Requirements for an indicator

Answer 12

Disperses evenly throughout membrane
Disperses only in compartment being measured
Not metabolized or excreted
Not toxic
Volume B= Volume A X Concentration A/ Concentration B

Question 13

Fluid distribution and amounts

Answer 13

Amounts of extracellular fluid in interstitial spaces and plasma determined by balance of hydrostatic and colloid forces across capillary
Distribution of fluid between intracellular and extracellular compartments determined by osmotic effects primarily sodium and chloride ions.

Question 14

Potential osmotic pressure of a solution

Answer 14

1 mosm–>19.3 mm Hg
80% of total osmolarity of the interstitial fluid and plasma is due to sodium and chloride ions
For intracellular fluid half of the osmolarity is due to potassium ions

Question 15

Addition of isotonic saline o extracellular fluid

Answer 15

Increases volume of extracellular fluid

osmolarity remains the same

Question 16

Addition of hypotonic saline to extracellular fluid

Answer 16

Increases volume of both compartments

Decreases osmolarity in both compartments

Question 17

Addition of hypertonic saline to extracellular fluid

Answer 17

Increases volume of extracellular fluid
Decreases volume of intracellular fluid
Increases osmolarity of both compartments

Question 18

Anatomical organization of kidney

Answer 18

Capsule
Renal cortex (Bowman's capsule, Proximal and distal convoluted tubules)
Renal medulla (renal pyramids)
Renal pelvis (minor and major calyces)

Question 19

Structure of nephron

Answer 19

8,00.000-1 million nephrons/kidney
Decrease by 10% every year after the age of 40
Each large collecting duct(250/kidney) receive urine from about 4000 nephrons
Cortical nephrons have glomeruli in outer renal cortex and possess short loop of Henle
Juxtaglomerular nephrons have glomeruli deep in renal cortex and possess long loop of Henle

Question 20

Percentage of blood received by kidney

Answer 20

Kidney receives 22% of total cardiac output (1100mL/min)

Question 21

Regulation of hydrostatic pressure in capillaries

Answer 21

Efferents arterioles help regulation in both set of capillaries
High hydrostatic pressure in glomerular capillaries(=60 mm Hg) causes rapid fluid filtration
Low hydrostatic pressure in peritubular capillaries (=30 mm Hg) causes rapid fluid reabsorption

Question 22

Blood flow to and from kidney

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