Slides on human excretory system

1. HUMAN EXCRETORY SYSTEM

2. THE EXCTRETORY SYSTEM
The excretory system in humans constitutes of a
pair of kidneys, a pair of ureters, urinary bladder
and a urethra.
The excretory system

3. THE KIDNEYS
LOCATION- The kidneys are compact ,reddish
brown bean shaped organs present on
either side of the spinal cord in the lower
back. More precisely they are situated
between the last thoracic and third lumbar
vertebrae in close proximity to the dorsal
inner wall of the abdominal cavity .
SIZE- In an adult each kidney measures
about 10-12cm in length, 5-7 cm in breadth
and 2-3 cm in thickness. Each kidney weighs
about 120-170 g

4. STRUCTURE- The kidneys have an notch on their inner
concave surface called the hilum through which blood
vessels, nerves and ureter enter.
The kidney has a tough outer layer called the capsule
and its longitudinal sections shows that its inside is
differentiated into two main regions an outer cortex
and an inner medulla.
The medulla is divided into conical masses called
medullary pyramids, which project into the calyces
The cortex protrudes or extends between the
pyramids as renal columns known as the Columns of
Bertini.
The medullary pyramids projects into the calyces
which then leads to a wide funnel shaped space
known as the renal pelvis
Longitudinal section of kidney

5. Each kidney contains about one million nephrons which
are the functional units of the kidney
Each nephron has two parts the glomerulus and the
renal tubules.
Glomerulus is a tuft of capillaries formed by the afferent
arteriole which is a fine branch of the renal artery. Blood
from the glomerulus exits by the efferent arteriole.
The renal tubule begins with the bowman’s capsule and
consists of Proximal convoluted Tubule (PCT), Henle’s
loop and Distal Convoluted Tubule.
The Bowmans capsule is a double walled, cup shaped
structure which encloses the glomerulus.
The bowman’s capsule along with the glomerulus is
called the Malpighian body or the renal corpuscle. Malpighian body

6. The bowman’s capsule opens into the proximal
convoluted tubule which is a highly coiled
structure. It is followed by a hairpin shaped
structure called Henle’s loop
Henle’s loop has a descending limb and an
ascending limb. The ascending limb opens into
the distal convoluted tubule (dct) which is also a
highly convoluted structure. The distal
convoluted tubules of several nephrons open into
a straight tube called the collecting duct, many of
which converge and open into the renal pelvis
through the ,medullary pyramids in the calyces
The Malpighian body, PCT, DCT of the nephron lie
in the cortex of the kidney but Henle’s loop dips
into the medulla.
The nephrons in the kidney are also distinguished
as cortical nephrons and juxta medullary
nephrons based on the length of Henle’s loop
Nephron