d.

-2)]-

Function: As the blood passes through the kidneys, the waste pro-

ducts are extracted in two ways:

(1) Mechanical filtration
(2) Selective action of cells

The urine thus excreted is gathered by series of tubules and emptied
into the duct (ureter) of the kidney and is carried to the bladder.

e. Mechanism of excretion: The extreting unit of the kidney is made up

 

Be

of a microscopic collecting tubule connected with a tuft of capil-
laries.

Significant structural features

(1) Arrangement of capillaries to secure higher capillary pressure
than elsewhere in the body.

(2) Exceptional thinness of membrane.

(3) Cells capable of secretory function.

Significant function features

(1) Mechanical filtration.
(2) Re-absorption and secretion in tubules.

Amount of excretion: The amount of urine varies considerably under

 

normal circumstances, Average amount 3 pints (1200 - 1500 ce or
40-50 ounces). Amounts less than 500 ce (1 pt.) or more than 3000
ce (3 ats.) if persistent should be considered as a departure from

normal.

i. Composition: Color - yellowish or amrer

2. Lungs
organ

ae

Reaction - acid

Sp. Gravity - 1015 - 1025

Water - 96-97%

Solids - 4-3% -- Urea, ereatinin, uric acid, inorganic
salts.

are an important excretory organ, heat regulatory apparatus, and an
of nutrition.

Area: Inner surface total area 90 sq, meters or 100 times as large

as the total area of the skin surface. This inner surface of the
lungs is in direct contact with the air in the spaces (alvcoli) of
the lungs. Thc mombranous walls contain the blood vessels that
bring blood from the heart. The entire blood supply is spread out
in the pulmonary capillaries every fow minutes. .

bs Lung capacity

) Residual air 1000 ce after cxtreme expiratory effects.
) Tidal air 500 ce ordinary quiet inspiration.
) Complemental air 1600 ce deep inspiration.
) Supplemental air 1600 ce deep expiration |
Total capacity 4700 ce

(1
(2
(3
(4

Vital capacity = Tidal plus complemental plus supplemental air.