This document discusses osmoregulation and excretion in animals. It describes how different organisms produce nitrogenous waste and regulate water and solute levels. The mammalian kidney is highlighted, with nephrons filtering blood to form urine via selective reabsorption and secretion. Key parts of the nephron work together to concentrate urine by actively transporting water and solutes like urea and NaCl. Hormones like ADH and aldosterone help the kidney regulate water and salt levels in response to osmolarity and blood pressure changes. The functions of the kidney are vital for homeostasis and common disorders like kidney stones and infections are also outlined.
The video lectures of Biology in easy way are available on youtube channel.
https://youtu.be/Qg_SXsAwMmA
Basic Information about Osmoregulation in Animals
The video lectures of Biology in easy way are available on youtube channel.
https://youtu.be/Qg_SXsAwMmA
Basic Information about Osmoregulation in Animals
Osmoregulation is the process of maintaining salt and water balance (osmotic balance) across membranes within the body. The fluids inside and surrounding cells are composed of water, electrolytes, and nonelectrolytes. An electrolyte is a compound that dissociates into ions when dissolved in water.
Two broad categories of behaviors are Proximate and Ultimate behaviour. The presentation gives a brief introduction on Proximate and Ultimate causes of behaviour
Introduction:
Adaptation to environment is one of the basic characteristics of the living organisms. Living organisms are plastic and posses the inherent properties to respond to a particular environment.
It is a facet of evolution and involve structural diversities amongst living organisms that are heritable. Organisms exhibit numerous structural and functional adaptations that help them to survive as species and to overcome the tremendous competition in nature.
All classes of vertebrates have their representatives leading to partial or total aquatic life.
Water is a homogenous medium for animals.
As a medium, it is heavy in concentration than air.
Stable gaseous and osmotic concentration in a specific region.
Temperature fluctuation is minimum for a particular region.
Water bodies generally have very rich food resources.
Characters of an Aquatic Animal:
An aquatic animal should have the ability to swim to overcome the resistance of the surrounding medium.
Therefore, it should have a streamlined body with an organ or ability to float.
The animal should also have to overcome the problem of osmoregulation.
There are two types of animals living in the present day water, which have undergone aquatic adaptation.
According to their origin, they are primary and secondary aquatic animals.
Adaptations to water habitat are of two types:
Primary aquatic adaptations which includes primitive gill-breathing vertebrates (fishes); Those animals, whose ancestors and themselves are living in the water from the very beginning of their evolution, are called primary aquatic animals. In other words, primary aquatic animals never had a terrestrial ancestry. They exhibit perfect aquatic adaptations. All fishes are primary aquatic animals.
Secondary aquatic adaptations which are acquired as in reptiles, birds and mammals. Those animals whose ancestors were lung breathing land animals, migrated to the water for some reason and ultimately got adapted to live in aquatic habitat, are called secondary aquatic animals. Some of them live partially while others live totally in the water. All aquatic reptiles, aves and mammals are representatives of secondary aquatic animals. Amphibians are in a transitional form between primary and secondary aquatic life.
Sensory adaptations like, electroreception for electrolocation and electro communication, olfaction (vomeronasal system), balance (spatial orientation, movement perception), vision (cornea curvature, retinal topography), and hearing (acoustics, ear anatomy) under the underwater sound reception mechanisms in various aquatic amniotes are well developed.
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes and ponds, rivers, streams and springs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. This module explains the characteristics of aquatic ecosystems-freshwater ones.
INTRODUCTION
The term urogenital refers to something that has both urinary and genital origins. The word urogenital is used because the urinary and reproductive systems in males merge.
These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways (ex. urethra).
Kidneys and urinary ducts form the urinary system.
The Urinary system performs two important homeostatic processes like excretion and osmoregulation. This system is intimately associated both anatomically, and in terms of embryonic origin with the genital system.
The genital system includes the gonads which generate gametes and the genital ducts that serve as passages for the gametes.
Though functionally different the two organ systems the urinary and the genital system are treated together as the urino- genital system, since both develop from the same segmental blocks of trunk mesoderm or adjacent tissues and share many of the ducts.
Thus although the two systems have nothing common functionally they are closely associated in their use of common ducts and are studied under the broad heading of urinogenital system.
The function of the excretory system is crucial in considering the possible environment of the ‘vertebrate life ’. Several main functions can be attributed to all vertebrate excretory systems:
Excretion of nitrogenous waste products.
Maintaining homeostasis with regard to ions (i.e. salt balance).
Regaining valuable substances (glucose, salts, amino acids, etc.)
Maintaining a physiological osmotic value (i.e. water balance).
The excretory system is formed by a series of paired, segmental nephrons that begin with a nephrostome opening into the coelomic cavity.
A pair of glomeruli per segment, supplied by branches from the aorta, projects into the coelomic cavity close to these nephrostomes.
At a later stage of development, the glomerulus/nephrostome area becomes separated from the rest of the coelomic cavity by an epithelial fold.
The nephrons connect to a duct that is formed by caudal growth of the most anterior nephric tubules. These paired urinary ducts open near the anal region.
The male and female reproductive systems develop initially embryonically "indifferent", it is the product of the Y chromosome SRY gene that makes the "difference".
♂ - Male ♀ - Female
The reproductive organs are developed from the intermediate mesoderm.
The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before the end of fetal life.
These embryonic structures are the mesonephric ducts (also known as Wolffian ducts) and the paramesonephric ducts, (also known as Müllerian ducts). The mesonephric duct remains as the duct in males which gives rise to seminal vesical, epididymes and vas deferens, and the paramesonephric duct as that of the female.
Importantly its sex chromosome dependence, late embryonic/fetal differential development, complex morphogenic changes, long time-course, hormonal sensitivity and hormonal influences make it a system prone to many different abnormalities.
Gonads:
Gonads Produce eggs and sperm cells, transport and sustain egg and sperm cells, nurture developing offspring, and produce hormones.
The gonads, ovary or testis, also develop in the intermediate mesoderm.
They originally form as swellings that lie just ventral to the anterior mesonephric kidney.
A mullarian duct also develops in the intermediate mesoderm near the mesonephric duct.
Due to fusion or failure of 1st ridge to differentiate, some vertebrates (agnathans, some female lizards & crocodilians, & most female birds) have a single testis or ovary.
Hormones cause differentiation of early gonads into either testes or ovaries.
As males develop the mesonephric duct makes connection with the testis as the primary sperm conducting duct, and the mullerian duct is lost.
The integumentary system comprises the skin and its appendages. Skin + derivatives= Integument.
It aims to protect the body from various kinds of damage, such as loss of water or damages from outside.
The integumentary system in chordates includes hair, scales, feathers, hooves, and nails.
It may serve to water proof, and protect the deeper tissues.
Excrete wastes, and regulate body temperature.
It is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature.
Osmoregulation is the process of maintaining salt and water balance (osmotic balance) across membranes within the body. The fluids inside and surrounding cells are composed of water, electrolytes, and nonelectrolytes. An electrolyte is a compound that dissociates into ions when dissolved in water.
Two broad categories of behaviors are Proximate and Ultimate behaviour. The presentation gives a brief introduction on Proximate and Ultimate causes of behaviour
Introduction:
Adaptation to environment is one of the basic characteristics of the living organisms. Living organisms are plastic and posses the inherent properties to respond to a particular environment.
It is a facet of evolution and involve structural diversities amongst living organisms that are heritable. Organisms exhibit numerous structural and functional adaptations that help them to survive as species and to overcome the tremendous competition in nature.
All classes of vertebrates have their representatives leading to partial or total aquatic life.
Water is a homogenous medium for animals.
As a medium, it is heavy in concentration than air.
Stable gaseous and osmotic concentration in a specific region.
Temperature fluctuation is minimum for a particular region.
Water bodies generally have very rich food resources.
Characters of an Aquatic Animal:
An aquatic animal should have the ability to swim to overcome the resistance of the surrounding medium.
Therefore, it should have a streamlined body with an organ or ability to float.
The animal should also have to overcome the problem of osmoregulation.
There are two types of animals living in the present day water, which have undergone aquatic adaptation.
According to their origin, they are primary and secondary aquatic animals.
Adaptations to water habitat are of two types:
Primary aquatic adaptations which includes primitive gill-breathing vertebrates (fishes); Those animals, whose ancestors and themselves are living in the water from the very beginning of their evolution, are called primary aquatic animals. In other words, primary aquatic animals never had a terrestrial ancestry. They exhibit perfect aquatic adaptations. All fishes are primary aquatic animals.
Secondary aquatic adaptations which are acquired as in reptiles, birds and mammals. Those animals whose ancestors were lung breathing land animals, migrated to the water for some reason and ultimately got adapted to live in aquatic habitat, are called secondary aquatic animals. Some of them live partially while others live totally in the water. All aquatic reptiles, aves and mammals are representatives of secondary aquatic animals. Amphibians are in a transitional form between primary and secondary aquatic life.
Sensory adaptations like, electroreception for electrolocation and electro communication, olfaction (vomeronasal system), balance (spatial orientation, movement perception), vision (cornea curvature, retinal topography), and hearing (acoustics, ear anatomy) under the underwater sound reception mechanisms in various aquatic amniotes are well developed.
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes and ponds, rivers, streams and springs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. This module explains the characteristics of aquatic ecosystems-freshwater ones.
INTRODUCTION
The term urogenital refers to something that has both urinary and genital origins. The word urogenital is used because the urinary and reproductive systems in males merge.
These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathways (ex. urethra).
Kidneys and urinary ducts form the urinary system.
The Urinary system performs two important homeostatic processes like excretion and osmoregulation. This system is intimately associated both anatomically, and in terms of embryonic origin with the genital system.
The genital system includes the gonads which generate gametes and the genital ducts that serve as passages for the gametes.
Though functionally different the two organ systems the urinary and the genital system are treated together as the urino- genital system, since both develop from the same segmental blocks of trunk mesoderm or adjacent tissues and share many of the ducts.
Thus although the two systems have nothing common functionally they are closely associated in their use of common ducts and are studied under the broad heading of urinogenital system.
The function of the excretory system is crucial in considering the possible environment of the ‘vertebrate life ’. Several main functions can be attributed to all vertebrate excretory systems:
Excretion of nitrogenous waste products.
Maintaining homeostasis with regard to ions (i.e. salt balance).
Regaining valuable substances (glucose, salts, amino acids, etc.)
Maintaining a physiological osmotic value (i.e. water balance).
The excretory system is formed by a series of paired, segmental nephrons that begin with a nephrostome opening into the coelomic cavity.
A pair of glomeruli per segment, supplied by branches from the aorta, projects into the coelomic cavity close to these nephrostomes.
At a later stage of development, the glomerulus/nephrostome area becomes separated from the rest of the coelomic cavity by an epithelial fold.
The nephrons connect to a duct that is formed by caudal growth of the most anterior nephric tubules. These paired urinary ducts open near the anal region.
The male and female reproductive systems develop initially embryonically "indifferent", it is the product of the Y chromosome SRY gene that makes the "difference".
♂ - Male ♀ - Female
The reproductive organs are developed from the intermediate mesoderm.
The permanent organs of the adult are preceded by a set of structures which are purely embryonic, and which with the exception of the ducts disappear almost entirely before the end of fetal life.
These embryonic structures are the mesonephric ducts (also known as Wolffian ducts) and the paramesonephric ducts, (also known as Müllerian ducts). The mesonephric duct remains as the duct in males which gives rise to seminal vesical, epididymes and vas deferens, and the paramesonephric duct as that of the female.
Importantly its sex chromosome dependence, late embryonic/fetal differential development, complex morphogenic changes, long time-course, hormonal sensitivity and hormonal influences make it a system prone to many different abnormalities.
Gonads:
Gonads Produce eggs and sperm cells, transport and sustain egg and sperm cells, nurture developing offspring, and produce hormones.
The gonads, ovary or testis, also develop in the intermediate mesoderm.
They originally form as swellings that lie just ventral to the anterior mesonephric kidney.
A mullarian duct also develops in the intermediate mesoderm near the mesonephric duct.
Due to fusion or failure of 1st ridge to differentiate, some vertebrates (agnathans, some female lizards & crocodilians, & most female birds) have a single testis or ovary.
Hormones cause differentiation of early gonads into either testes or ovaries.
As males develop the mesonephric duct makes connection with the testis as the primary sperm conducting duct, and the mullerian duct is lost.
The integumentary system comprises the skin and its appendages. Skin + derivatives= Integument.
It aims to protect the body from various kinds of damage, such as loss of water or damages from outside.
The integumentary system in chordates includes hair, scales, feathers, hooves, and nails.
It may serve to water proof, and protect the deeper tissues.
Excrete wastes, and regulate body temperature.
It is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature.
There needs to be a balance between water ingested and water eliminated.
In order to maintain homeostatic levels of water, the body must undergo osmoregulation.
1 . EXCRETION
Waste product removal e.g. nitrogenous – uric acid (mammals urea , fish ammonia)
Kidneys – secrete uric acid (product of protein metabolism)
Gastro-intestinal tract secretions e.g. bile
No sweat glands
Salt glands (water birds)
Water loss – lungs
2. URINARY SYSTEM
• Major organs are the kidneys, the ureter and the cloaca.
• No urinary bladder in bird.
3 . ANATOMICAL STRUCTURE OF KIDNEY
Avian kidneys are paired fitted closely the bony depression on the dorsal wall of the pelvis . Each kidney is divided into three lobes.
4 .
5 . NEPHRON
Two kinds of nephrons.
1. Reptilian nephron
2. Mammalian nephron
• 6 .
• 7. DIFFERENCE BETWEEN AVIAN AND MAMMALIAN KIDNEY
8. RENAL PORTAL SYSTEM
Uric acid is formed in the liver as well as the kidneys of the birds from ammonia, which is the most toxic protein metabolic by product .
9. GLOMERULAR FILTRATION
Fluid pressure forces water and dissolved substances from glomerular blood to Bowman’s capsule .
Filtration averages 125 ml/min form two kidneys.
10 . TUBULAR REABSORPTION
Return of the useful substances from the filtrate to the blood capillaries or interstitial fluid.
11 . COUNTER CURRENT MECHANISM
This mechanism works in the loop of henle to increase water reabsorbed from the descending limb as a result of salt reabsorbed from the ascending limb .
12 . POST RENAL URINE MODIFICATION
After the presentation of urine to cloaca their might be retrograde flow or backward flow of urine into the colon.
In the colon reabsorption of excessive amount of water as well as sodium ion takes place.
13 . HORMONES RESPONSIBLE FOR URINE FORMATION
Arginine vasotocin ,Angiotensin ׀׀ ,Aldosterone ,ANP (arterial natriuretic peptide)
Aldosterone is responsible for the reabsorption of sodium and excretion of potassium in the filtrate.
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2. Key Concepts
Osmoregulation balances the uptake and loss of
water and solutes
An animal’s nitrogenous wastes reflect its
phylogeny and habitat
Diverse excretory systems are variations on a
tubular theme
Nephrons and associated blood vessels are the
functional units of the mammalian kidney
The mammalian kidney’s ability to conserve water
is a key terrestrial adaptation
Diverse adaptations of the vertebrate kidney have
evolved in different environments
4. Types of metabolic waste produced by living
systems
1. Digestive waste
2. Respiratory waste
3. Excess water and
salts (through
osmoregulation)
4. Nitrogenous waste
(through excretion)
5. Osmoregulation
Balance of uptake and
loss of water and solutes
Controlled movement of
solutes between internal
fluids and environment
Osmoconformer
(marine animals
isoosmotic with
environment)
Osmoregulator
(freshwater, marine, and
terrestrial animals that
adjust internal osmolarity)
6. Types of
nitrogenous wastes
Deamination –
protein and nucleic
acid metabolism
Three main types
differing in terms of:
1. Toxicity
2. Amount of water
needed for
excretion
3. Energy needed for
synthesis 300 – 500 mL/gN
1 step rxn
50 mL/gN
4 step rxn
10 mL/gN
15 step rxn
7. Type of
Organism
Structure Product of
excretion
Otherfeatures
Plants
Stomata, lenticels Insoluble crystals
Crystals are kept
inside plant cells
Cnidarians and
e chino de rm s
No excretory organ -
Osmoconformers,
isoosmotic with
environment
Fre shwate r pro tists
and spo ng e s
Contractile vacuole
8. Excretory Systems
Dispose of metabolic wastes
Regulate solute concentrations in the
body
Transport epithelia arranged in tubes
4 major processes
1. Filtration, pressure-filtering of body
fluids producing a filtrate (water,
salts, sugars, amino acids, N-
wastes)
2. Reabsorption, reclaiming valuable
solutes (glucose, salts, amino acids)
from the filtrate
3. Secretion, addition of larger
molecules like toxins and other
excess solutes from the body fluids
to the filtrate
4. Excretion, the filtrate leaves the
system
9. Flatwo rm s Flame cells
Unse g m e nte d
ro undwo rm s
Protonephridia, closed
network of dead-end tubes
lacking openings
Anne lids
Metanephridia, open-ended
network of tubes with
internal openings that
collect body fluids
Type of
Organism
Structure Product of
excretion
Otherfeatures
10. Mo lluscs Nephridia or metaphridia
Crustace ans Antennal/green gland
Inse cts
Malpighian tubules and
digestive tract
Uric acid
Type of
Organism
Structure Product of
excretion
Otherfeatures
11. Marine fishe s Gills Ammonia
Elasm o branchs
(sharks, skate s, rays)
Kidneys Urea
Rectal glands –
excrete excess NaCl
Freshwater fishes Gills Ammonia or urea
Am phibians and
m am m als
Kidneys Urea
Liver converts
ammonia to urea
Re ptile s and birds Kidneys Uric acid Salt glands
Type of
Organism
Structure Product of
excretion
Otherfeatures
12.
13. Proximal tubule – secretion and reabsorption
Filtrate
H2O
Salts (NaCl and others)
HCO3
–
H+
Urea
Glucose; amino acids
Some drugs
>> Same concentration of
substances in blood plasma
Key
Active transport
Passive transport
CORTEX
OUTER
MEDULLA
INNER
MEDULLA
Descending limb
of loop of
Henle – reabsorption
-Permeable to water but not to salt
Thick segment
of ascending
limb –
reabsorption
- Impermeable to
water but
permeable to salt
Thin segment
of ascending
limb
Collecting
Duct – permeable to water
but not to salt, bottom portion is
permeable to urea
NaCl
NaCl
NaCl
Distal tubule – secretion and reabsorption
NaCl Nutrients
Urea
H2O
NaCl
H2O
H2OHCO3
K+
H+
NH3
HCO3
K+
H+
H2O
1 4
32
3 5
From Blood Filtrate to Urine: A Closer Look
14. Two solutes: NaCl
and urea,
contribute to the
osmolarity of the
interstitial fluid
Cause the
reabsorption of
water in the kidney
and concentrates
the urine
H2O
H2O
H2O
H2O
H2O
H2O
H2O
NaCl
NaCl
NaCl
NaCl
NaCl
NaCl
NaCl
300
300 100
400
600
900
1200
700
400
200
100
Active
transport
Passive
transport
OUTER
MEDULLA
INNER
MEDULLA
CORTEX
H2O
Urea
H2O
Urea
H2O
Urea
H2O
H2O
H2O
H2O
1200
1200
900
600
400
300
600
400
300
Osmolarity of
interstitial
fluid
(mosm/L)
300
15. Nervous system and
hormones regulate
kidney functions
Antidiuretic hormone
(ADH)
Stimulated by a rise in the
blood’s osmolarity (>300
mosm/L)
Enhances fluid retention by
making the kidneys reclaim
more water
Increases water reabsorption
in the distal tubules and
collecting ducts of the kidney
Osmoreceptors
in hypothalamus
Drinking reduces
blood osmolarity
to set point
H2O reab-
sorption helps
prevent further
osmolarity
increase
STIMULUS:
The release of ADH is
triggered when osmo-
receptor cells in the
hypothalamus detect an
increase in the osmolarity
of the blood
Homeostasis:
Blood osmolarity
Hypothalamus
ADH
Pituitary
gland
Increased
permeability
Thirst
Collecting duct
Distal
tubule
16. Increased Na+
and H2O reab-
sorption in
distal tubules
Homeostasis:
Blood pressure,
volume
STIMULUS:
The juxtaglomerular
apparatus (JGA) responds
to low blood volume or
blood pressure (such as due
to dehydration or loss of
blood)
Aldosterone
Adrenal gland
Angiotensin II
Angiotensinogen
Renin
production
Renin
Arteriole
constriction
Distal
tubule
JGA
The renin-angiotensin-
aldosterone system
(RAAS)
Responds to a loss of salt
and water in the blood
Stimulated by low blood
volume or pressure
Increases water and sodium
ion reabsorption in the
proximal and distal tubules
Leads to an increase in
blood volume and pressure
Opposed by the hormone
atrial natriuretic factor (ANF)
Released by atria
Inhibits release of renin
17. Some medical aspects concerning the
excretory system
Urinary tract infection (UTI)
bacterial infection
cystitis/pyelonephritis
treated by antibiotics and prevented through proper
hygiene
Kidney stones
solidified crystals in kidneys or ureters
Calcium oxalate
Uric acid
nephrolithiasis/urolithiasis
prevention:
Drinking adequate water
Proper diet low in protein, N, and Na
Avoid excess Vitamin C intake
Dialysis
Hemodialysis
Peritoneal dialysis
