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LAB 3 - The Pee Lab
Human Osmoregulation



 

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Kidney Function

kidney1.jpg (63203 bytes)

Procedure
Your kidney regulate the chemical composition of body fluids by removing metabolic wastes and retaining the proper amounts of water, salts, and nutrients. Waste is removed from the body by the kidneys in the form of urine. Your kidneys produce approximately 1ml of urine per min, and maintain an average ECF osmolarity of 300mosmoles/L. The purpose of this lab was to observe and measure the affects of different substances on the kidney.

Four different people from each group were chosen to consume one of the following substances:

800 ml of delicious tap water

800 ml of 0.9 % NaCl.

80 ml of 9 % NaCl.

800 ml of a heavily caffeinated soft drink(Mt Dew).

At 40 and 80 minute intervals after consuming the drink, each person was to go to the bathroom and collect all of their urine in a beaker. After collecting their urine sample, the urine flow rate was determined for each of the four samples. The urine flow rate was determined by taking the total volume of urine collected, which was measured using a graduated cylinder, and dividing it by 40 for the first interval, and 80 for the second interval (ml/min). The osmolarity of the urine samples was also collected using the freezing point depression osmometer.

Equipment

Osmometer

Freezing point is found by detecting the temperature at which a small quantity of the fluid freezes in a small Cuvette This device was used to freeze a 50:l sample of urine and then determine the freezing point.

How it works - A small stirrer or vibrator and a thermistor probe are immersed in the 50:l urine sample and the cuvette is lowered into a cooling device. The stirrer is arrested by the freezing of the solution and this triggers the measurement of temperature.The osmometer will readout the urine concentration in mosmoles/L using a digital display.

Graduated Cylinders

Device used to measure the ml of urine collected

Micro Pipettorpipettor.jpg (30573 bytes)

Used to place samples in microtubes.

Effects of NaCl on the Kidney -
The hypothalamus detects changes in the amount of water present in the blood.  If there is too little water (the blood is too concentrated) it tells the pituitary gland to secrete ADH.  This hormone has an effect on the kidney, ADH makes the kidney re-absorb water from the ultra-filtrate.  Higher levels of ADH make the kidney work harder to reabsorb more and more water.  This results in the production of very small quantities of very concentrated urine.

Effects of Water on the Kindey -
The hypothalamus detects that there is too much water in the blood.  When the blood becomes too dilute, the pituitary glands stop making ADH, and the kidney stops reabsorbing water.  Large volumes of very dilute urine are formed.

Effects of Mt. Dew on the Kidney -
Mountain Dew is a highly caffinated drink and acts as a diuretic which makes you produce lots of urine and this results in your blood becoming very concentrated.

BEVERAGE

40 minute sample

 

80 minute sample

 

800 ml water

osmolarity

flow rate (ml/min)

osmolarity

flow rate (ml/min)

Tester 1

68.3

2.875

99

6.875

Tester 2

113

11

82

10

Tester 3

661

1.76

124

7.5

Tester 4

965

1.788

121

2.58

Tester 5

322

9.5

62

6.5

Average

425.86

5.3846

97.6

6.691

 

BEVERAGE

40 minute sample

 

80 minute sample

 

800 ml 0.9% NaCl

osmolarity

flow rate (ml/min)

osmolarity

flow rate (ml/min)

Tester 1

387

8.25

968

3.15

Tester 2

848

1.18

1088

0.4

Tester 3

353

4.97

300

2.75

Tester 4

944

1.99

879

1.7

Tester 5

318

12.55

513

2.67

Average

570

5.788

749.6

2.134

 

BEVERAGE

40 minutesample

 

80 minute sample

 

80 ml 9.0% NaCl

osmolarity

flow rate (ml/min)

osmolarity

flow rate (ml/min)

Tester 1

399

3.75

605

0.925

Tester 2

730

1.3

644

0.5

Tester 3

851

0.8875

829

0.6325

Tester 4

907

0.987

778

0.275

Tester 5

873

1.95

820

1.45

Average

752

1.7749

735.2

0.7565

 

BEVERAGE

40 minute sample

 

80 minute sample

 

800 ml Mountain Dew

osmolarity

flow rate (ml/min)

osmolarity

flow rate (ml/min)

Tester 1

691

6.25

93

10.25

Tester 2

367

3.625

79

6.125

Tester 3

581

4

101

7.4

Tester 4

133

12

103

6.88

Tester 5

131

15

145

8.75

Average

380.6

8.175

104.2

7.881


Graphs

wpe2.jpg (18719 bytes)

wpe5.jpg (16237 bytes)

 

ZOOLOGY 310 GUIDE TO PEE LAB