The document discusses the human excretory system. It explains that the kidneys filter waste from the blood and regulate homeostasis. The nephrons are the functional units of the kidneys that filter blood to form urine via filtration, reabsorption of needed substances, and secretion of unwanted compounds. Urine contains waste products and is stored in the bladder before being expelled through the urethra.

2. Excretory System
• Metabolic wastes of the chemical
reactions in the cell are removed
from the body.
• This process is called EXCRETION.

3. Function of Excretory
System
1. Filtration and excretion of metabolic
wastes
2. The regulation of blood content.
3. The regulation of blood pH.
4. Homeostasis.

4. Excretory Substances
The metabolic wastes of cells are;
WATER,
CO2,
NITROGENOUS COMPOUNDS

5. WATER and CO2
• Water and CO2 are formed by means
of cellular respiration.
• Water is excreted by lungs, sweating
and kidneys.
• CO2 is excreted only by lungs.

6. NITROGENOUS WASTES
•At the end of the catobolisation of
aminoacids, AMMONIA(NH3) is formed.
•In some organisms, ammonia is
removed fro body directly.
•But in some organisms ammonia is
converted to other substances such as
UREA and URIC ACID.

7. AMMONIA (NH3)
• Ammonia is the most toxic nitrogenous
waste material.
• It can soluble in water.
• Organisms need large amount of water
for excretion of ammonia.
• Organisms need small amount of
energy for formation of NH3
• Ammonia is excretory substances of
freshwater organisms.

9. UREA [CO (NH2)2]
•Urea is less toxic than ammonia.
•It is formed in the liver by ornithin cycle.
•Urea is excreted by the kidney.
•Urea is the excretory substances of
amphibians,mammals,fish and human.
• O rganisms use more energy in formation
of urea than formation of ammonia.
•Living things need normal amount of
water.

10. URIC ACID (C5NH4O3)
• Uric Acid is least toxic nitrogenous waste.
• It is insoluble in water.
• Uric acid is excreted by with only small
amount of water.
• Uric acid is the excretory substance of
terrestial organisms such as INSECTS,
REPTILES AND BIRDS.

13. • There is no special excretory system in
plants.
• The STOMA, LENTICELS,
HYDRATHODES are used for excretion in
plants.
• CO2 is excreted by stomata and lenticels.
• Water is excreted by hydrathodes and
stomata by TRANSPIRATION.

18. Excretion in
Unicellular
• Excretory Ostrrucgtuarne oifs pmrotsista is called
CONTRACTILE VACUOLE.
• Excess water and NH3 are pumped by
contractile vacuole.
• Some NH3 molecules release from
unicellular organisms by diffusion.

21. • In simple animals such as Spongy
and hydra excretory substances are
excreted by diffusions.

24. Excretion in Planaria
(Flatworms)
• In planaria, excess water is excreted by
flame cells.
• Flame cell take ewcess water from body.
• Than water pass excretory canal. And than
water is given out of the body by excretory
pore.
• CO2 and NH3 release from planaria by
means of DIFFUSION.

26. Excretion in Earthworm
• Excretory organ of earthwom is
nephridium.
• Nephridium is surrounded by capillaries.
• It takes water, glucose, minerals and wastes
from body. Than water, food and minerals
are reabsorbed from nephridium canal by
capillaries.
• And than waste materials pass into
intestine.

29. Excretion in Insects
• Insects have specialized excretory
tubules that called MLPIGHIAN
TUBULES.
• Wastes pass from blood into
malpighian tubules Than malpighian
tubules empty into digestive track.
• Finally waste materials are excreted by
anus with undigested materials.

31. GRASSHOPPER
DRAGON FLY

33. The excretory and reproductive
system of vertebrates are
interrelated and this complex is
called UROGENITAL SYSTEM
• The kidney is the main excretory
organ of vertebrates.

34. TYPES OF KIDNEYS
There are three types of Kidneys;
a) Pronephros kidney
b) Mesonephros kidney
c) Metanephros kidney

35. PRONEPHROS KIDNEY
•Pronephros kidney is found in the
embryonic stage of fish and amphibia and in
adult form of shark.
•Pronephros kidneys contain many nephridia.
•Nephridia have ciliary funnels that is
connected to ball of capillaries or glomerulus
by ciliary funnels.
•Than wastes pass wolf channel for transport
to the cloaca.

36. MESONEPHROS KIDNEY
• Mesonephros kidney is found in embryonic
stage of reptiles, birds an mammals and
adutlt stage of fish and amphibia.
• In mesonephros kidney, ciliary funnels are
replaced with Bowman’s capsules.
• A glomerulus is located in Bowman’s
capsule. Waste materials pass to Bowman’s
capsule from glomerulus.
• Than wastes flow the wolf channel. And
than they are expelled through cloaca.

37. METANEPHROS KIDNEY
• Metanephros kidney is found in adult
reptiles, birds, mammals and human.
• Each kidney contains a millions of
nephrons.

39. CLOACA
• In fish, amphibians, reptiles and birds;
excretory substances, unigested
materials and reproductive cells are
expelled through the same channel or
openin that called CLOACA.

41. PARTS OF HUMAN
EXCRETORY SYSTEM
1.Kidneys
2.Ureter
3.Urinary bladder
4.Urethra

45. • Kidneys are bean shaped organs that
filtere 180 lt. blood in a day.
• Blood is come into kidney by renal
artery.
• Filtered blood leaves from kidney by
renal vein.

46. 1. They remove wastes of cellular
metabolism from the blood.
2. They control concentration of various
substances found in the body fluid.

47. Structure of Kidneys
1.Renal Capsule: It surrounds and protects
the kidneys.
2.Cortex: It contains glomerulus and
Bowman’s capsules.
3.Medulla:It is located under the cortex and
has malphigian pyramids. Malphigian
pyramids contains urine collecting canal and
loop of henle.
4.Pelvis: It is innermost part of kidney. The
urine is collected in pelvis.

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50. NEPHRONS
• They are structural unit of kidneys.
• A nephron begins with a glomerulus.
• Glomerulus is surrounded by a
Bowman’s capsule.
• Each glomerulus is formed by
capillaries from a branch of renal
arteriole.

53. • The complex of Bowman’s capsule and
glomerulus is called malpighian body.
Bowman’s capsule is connected with
long tubule that is called Loop of
Henle.
• Loop of Henle is joined with collecting
duct.
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54. URINE FORMATION
There are three steps during urine formation.
1. Filtration
2. Reabsorbtion
3. Secretion
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55. Filtration
• During filtration, substances pass
from the blood into the Bowman’s
capsule.
• Under pressure, water and many
small molecules such as salts, urea,
glucose and aminoacids pass from
glomerulus into Bowman’s capsule.

56. Reabsorbtion
• The absorbtion of needed materials
such as glucose, amino acids and water
from nephrons to blood capillaries is
called reabsorbtion.
• Water is reabsorbed passively by
osmosis. But reabsorbtion of glucose,
aminoacids and salt ions occurs by
active transport.

57. • All glucose, aminoacids and many salt ions
are reabsorb during reabsorption.
• Most reabsorbtion takes places in loop of
henle.
• Antidiuretic hormone (ADH or
Vasopressin) regulates concentration of
water in blood.
• It increases water permeablity of the cells of
the distal tubules.
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58. Secretion • The cells of distal tubule excrete
molecules such as penicilin, ammonia,
potassium and excess acids. This
process is called secretion.
• After secretion, the fluid remaining in
the nephrons is called urine.
• Urine contains urea, uric acid, sodium,
potassium, calcium, chlorine,
phosphorus, water and small amount of
cells.

59. • Urine flows from the tubules into the
collecting ducts and it is stored
temporary in pelvis.
• Than urine is transported into the
urinary bladder by the urether of each
kidney.
• And than it is expelled through the
urethra.

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