Transcript Excretory System

Excretory System
Cellular Level
Involves transport of
needed materials
into and out of cells
Organ Level
Involves movement of
materials through the
kidneys
Consists of kidneys, ureters,
urinary bladder, urethra
Eliminates waste products
from the body in ways that
maintain homeostasis
Kidneys
 Kidneys remove waste products
from the blood, maintain blood
pH and regulate the water
content of the blood
 Kidneys are located near the
lower back on either side of the
spinal column
Kidneys
Kidneys filter the waste
filled blood removing urea,
excess water and other
waste products
The clean blood returns
through the renal vein and
into circulation
Kidneys
 As the kidney works, purified
blood is returned to circulation
while urine is collected in the
urinary bladder
 Urine is stored until it can be
released from the body through
a tube called the urethra
The Excretory System
Blood Purification
The mechanism of blood
purification involves two
distinct processes:
Filtration
Reabsorption
Filtration
 Takes place in the glomerulus (small
network of capillaries encased in the
upper end of the nephron by a hollow,
cup shaped structure called Bowman’s
Capsule)
 The materials that are filtered from the
blood are called filtrate
 The end filtrate contains water, urea,
glucose, salts amino acids & some
vitamins
Reabsorption
 The process in which liquid is taken
back into a vessel
 Materials including amino acids,
fats & glucose are removed from
the filtrate by active transport &
reabsorbed into the capillaries
(water is returned by osmosis)