The excretory system consists of the kidneys, ureters, urinary bladder, and urethra which work together to remove waste from the body. The kidneys filter blood and regulate waste removal by selectively reabsorbing useful compounds while secreting metabolic wastes into urine. This urine is then transported through the ureters to the bladder and finally expelled from the body through the urethra, aided by other excretory organs like the skin, lungs, large intestine and liver.

1. EXCRETORY
SYSTEM

2. Excretory System
 Consists of 2 kidneys, 2
ureters, urinary bladder
and urethra
 Essential in the
removal of wastes from
the body

3. Parts of the Excretory System
1. Kidneys
 The bean-shaped organs found just above the waistline
Renal Fascia
 This is the thin fibrous layer, which anchors the kidney to the
surrounding structures to maintain the normal position of the organ.

4. The Work of the Kidneys
 The work of the kidney
is to separate urine
from the blood which
flows through it.
 Kidney plays a role in
regulating the
composition of the
plasma by extracting
excess wastes and
other substances into
the urine.
 Each kidney receives
the renal artery directly
from the dorsal aorta
and are drained by the
renal veins which pass
to the postcaval vein.

5. The Work of the Kidney
Three Processes:
1. Filtration
 The blood plasma is
filtered through the
walls of the
glomerulus and
collects in the
Bowman’s capsule
 This process forms a
fluid, the nephric
filtrate, which contains
all the ions and small
molecules present in
the blood plasma.

6. The Work of the Kidney
Three Processes:
2. Tubular reabsorption
 The nephric filtrate
passes through the
tubular parts of the
nephron where very large
quantities of water and
smaller quantities of
glucose and other useful
compounds are saved
and reabsorbed.
 This process of selective
reabsorption demands
that the gland cells in the
tubule wall transfer the
reabsorbed compounds
back into the blood
through the capillaries
surrounding the tubule.

7. The Work of the Kidney
Three Processes:
3. Tubular secretion
 The nephric tubules secrete
additional quantities of metabolic
wastes into the nephric filtrate
 Waste are extracted from the
capillaries around the tubule and
passed into the lumen of the
nephron.
 Reabsorption and secretion
greatly change the composition
of the nephric filtrate as this
fluid drains through the nephron
toward the collecting tubules.
 The fluid as it reaches the
collecting tubule contain a
number of amber colored liquid
with metabolic waste called
urine

8. Excretory System
2. Ureters
 These are two tubes which
function to convey urine
from the kidneys to the
bladder.
 Passes from the pelvis to
the posterior aspect of the
urinary bladder
 Peristalsis begins at the
renal pelvis and ending at
the bladder.

9. Parts of the Excretory System
3. Urinary Bladder
 This sac lies posterior to the
pubis.
 Separated from the rectum by
the seminal vesicles in the male
and by the vagina and uterus in
the female.
 Serves as reservoir for urine,
gradually fills and becomes
distended
Peritoneum
 Covering of the superior surface
of the bladder.

10. Parts of Excretory
System
4. Urethra
 This is where urine
is expelled.

11. Other Excretory Organ
1. Skin
 Excretes wastes,
secretes fluid and
make possible
growth and repair
of hair cells.
 Through sweating,
the skin excretes
excess salt, water
and other
metabolic wastes
in the form of
perspiration
through pores
2. Large intestine
 12-24 hours are
required for the
waste products of
digestion to pass
through the colon
and rectum.

12. Other Excretory Organ
3. Lungs
 Excreting CO2
4. Liver
 Produces bile
which is
concentrated by
the removal of
water and salts.