EXCRETORY SYSTEM - ummg.gov.mm file- Vertebrate kidneys, or nephroi, are all built in accordance...
Transcript of EXCRETORY SYSTEM - ummg.gov.mm file- Vertebrate kidneys, or nephroi, are all built in accordance...
EXCRETORY SYSTEM
PRESENTED BY
DAW AYE MON THET
ASSISTANT LECTURER
DEPARTMENT OF ZOOLOGY
UNIVERSITY OF MEDICINE ,MAGWAY
Objective
1. Define the term excretion and describe how this process helps maintain homeostasis
2. Name the major metabolic wastes and the processes by which they are formed
3. Describe type of vertebrate kidney.
4. Explain the parts of urinary system and the process of urine formation.
As an organism carries out its life processes ,
- waste products build up in the body fluids
Life processes
• Respiration
• Feeding
• Sensitivity
• Movement
• Reproduction
• Growth
• Excretion
Waste product ( metabolic waste )
the products of metabolic activity
- after oxygen and nutrients have
been supplied to a cell
• If these metabolic wastes were not removed from the body
the organism would die
Therefore ,
the organism must be able to remove
- metabolic waste ( no use ) and
- other excess substances ( substances in excess of
requirements from organism )
that build up over time (= as time passes)
Excretion
- metabolic wastes and excess
substances are removed from the
organism
- also removes excess heat from the
body
helping to keep the temperature of
the body constant
These organs work with - the circulatory system
- nervous system
- endocrine system
to keep the body’s internal environment constant
In other words ,
these organ systems maintain homeostasis
Major Metabolic Wastes
Excretory organs Metabolic wastes
1.Lungs Carbondioxide,Water(Cellular respiration)
2. Skin Water, Salts (Perspiration)
3. Liver Nitrogen Compounds(Ammonia,Urea,Uric acid)
4.Kidney Mineral salts(Sodium chloride and Potassium sulfate) and water (Urination)
• Many People confuse excretion with
elimination.
• Elimination, or defecation, is the removal from
the digestive tract of unabsorbed and
undigested food in the form of feces.
• Since these materials have never entered the
body cells, they are not metabolic wastes.
• Liver removes harmful substances,
• Such as bacteria,certain drugs,hormone
from the blood
• These substances are changed into inactive or less poisonous forms
• Purifies or detoxifies the blood
• Returned to blood stream
Finally excreted from the body by the kidney
- Amino acids are the breakdown products of proteins.
- Because excess amino acids cannot be stored in the body, they are broken down in the liver.
- The parts of the amino acids are changed into other substances.
- Because the ammonia produced from the amino group is very poisonous
- It is changed into the less harmful substance urea by a series of enzyme-catalyzed reactions.
- The urea diffuses from the liver into the blood stream.
- The bloodstream, then carries the urea to the kidneys.
- The kidneys filter urea from the blood, and
- It is finally excrete from the body in the urine
Filtration :
Renal corpuscle= (Bowman’s capsule & glomerulus)
Filtrates - water
glucose
amino acids
Various salts
Urea
Types of vertebrate kidney
Types of kidney
1.Archinephros Embryo of cyclostomes
2. Pronephros Adult cyclostomes( lamprey , hagfish )Embryo of anamniotes ( frog, fish)
3. Mesonephros Adult Frog , Fish Embryo of amniotes
4.Metanephros Reptiles , Aves , Mammmals ( Amniotes )
Types of vertebrate kidney
- Vertebrate kidneys, or nephroi, are all built in accordance with a basic structural pattern consisting of
1.Glomeruli , usually incorporated in renal corpuscles;
2. Tubules, surrounded by peritubular capillaries and
3. A pair of longitudinal ducts.
Variations in the details from fish to man are primarily in - the number and arrangement of glomeruli
and - the relative length of the tubules.
In present –day vertebrates
- The uriniferous tubules develop
antero-posteriorly in two or three stages
- In succession these stages are
pronephros
mesonephros evolved from the
metanephros original archinephros
Uriniferous tubules - open into a common pronephric duct
- runs backward to enter
the embryonic cloaca
Uriniferous tubules - open into a
common
pronephric duct
- runs backward to
enter
the embryonic cloaca
- A pair of pronephroi become functional only
in some cyclostomes and embryos of all
anamniote
- In other vertebrates ,they degenerate during
development.
Mesonephros
- develops from that part of the nephrotome which lies
behind the pronephros.
At First- consists of paired segmental uriniferous tubules,
- each with a peritoneal funnel opening into the coelom,
and a glomerulus enclosed in a Bowman’s capsule.
- Mesonephric uriniferous tubules
join the existing pronephric duct
on each side, called mesonephric duct
or Wolffian duct
Later
Mesonephric tubules undergo budding to form hundreds of tubules
- their segmental arrangement is lost
- the later tubules have no peritoneal funnels.
- form the adult functional kidneys in some
fishes and amphibians
-form the embryos of amniotes,degenerate
in the adult
Metanephros
• The first embryonic hint of a metanephros is the formation the metanephric duct that appear as a ureteric diverticulum arising at the base of the preexisting mesonephric duct.
The ureteric diverticulum grows dorsally into the posterior region of the nephric ridge.
-Here it enlarges and stimulates the growth of metanephrictubules that come to make up the metanephric kidney .
The metanephros- becomes the adult kidney of amniotes and
the metanephric duct is called the ureter.