WATER GAIN (milliliters)

WATER LOSS (milliliters)

by ingesting solidsby ingesting liquidsby metabolism

in urinein fecesby evaporation

6.00.0

54.060.0

8501,400

3502,600

13.52.6

43.960.0

1,500200900

2,600

KANGAROO RAT HUMAN

Maintaining water balance is tricky!

These are actually two different problems – with one mechanistic solution!

These are actually two different problems – with one mechanistic solution!

2% sucrose solution

1 liter of distilled water

1 liter of 10% sucrose

solution

1 liter of 2% sucrose

solution

HypotonicConditions

HypertonicConditions

IsotonicConditions

Tonicity and Tonicity and OsmosisOsmosis

PROBLEMS

saltin food

FRESHWATERFISH

MARINE BONYFISH

s

S(hyper)

(hypo)W

w

large volumedilute urine S

s

(hyper)

(hypo)

w

W

PROBLEMS

drinkssea water

salt AT outof blood by gills

small volumeurine

salt AT into bloodby gills

LOSSGAIN

H2O

SOLUTE

1. Absorbed by gut- solid foods- beverages

2. Metabolic H2O

1. Urine2. Evaporation

- skin (sweat)- lungs

3. Feces

1. Absorbed by gut2. Secreted by cells

- hormones3. Metabolism

- CO2

- ammonia- urea- uric acid

4. Respiration - O2

1. Sweat - NaCl

2. Respiration - CO2

3. Urine

US water contest radio sacks 10

The KDND 107.9 station in Sacramento sacked the hosts of its morning show and other members of staff.

The show had challenged listeners to drink as much water as they could to win a Nintendo Wii video game system.

One participant - Jennifer Strange - later died as a result of drinking too much water, initial tests showed.

Ms Strange, 28, said she wanted to win the game - "Hold Your Wee for a Wii" game - for her children.

A work colleague said Ms Strange had complained her head was hurting hours after the contest and was going home.

She was found dead on Friday at her house in Rancho Cordova.

The Sacramento County coroner later said preliminary autopsy findings suggested she had died of water intoxication.

kidney

ureter

bladder

urethra

diaphragm

adrenal glandaorta

vena cava

renal arteryrenal vein

Kidney Blood Flow

ureter

renalartery

cortex

medulla

med

ulla

cort

ex

pelvis‘funnellike’

renalvein

Bowman’s capsule

proximal distal

loop of Henle(in medulla)

colle

cting

duc

t

cort

exm

edul

la

Bowman’s capsule

glomerularcapillaries

peritubularcapillaries

(thread aroundtubule)

glomerulus

Filtration – in the glomerulus (~49 gal / day) Reabsorption – along tubule Secretion – in distal tubule (mostly)

Nephron Anatomy

Millions of these units accomplish the filtering of blood

Filtration occurs here through fenestrations Formed elements and plasma proteins remain

How is the osmoregulatory economy regulated?

How is the osmoregulatory economy regulated?

Osmoregulation Too many solutes!

Stimulates release of ADH Increases permeability on

distal tubule More H2O reabsorbed

Too few solutes! ADH levels decrease Decreases permeability

of distal tubule Less H2O reabsorbed

Osmoregulation BP / volume too low!

Renin released Arterioles constricted Aldosterone released More H2O reabsorbed

BP / volume too high! Renin not released Arterioles relaxed Less aldosterone produced Less H2O reabsorbed

The long, slow journey into night…

Symptoms of heart failure Shortness of breath Weight gain from fluid

buildup Swelling that gets worse at

the end of the day or after standing for long periods

Shoes may no longer fit Abdominal swelling

Why?