Organismic Biology Bio 207
Lecture 3
Prof. Simchon
• Life in water (cont’d)
•Osmoregulation and water balance
Remember
Next week is your 1st exam
Will cover lectures 1-3 and Tutorial 1
The labs are not covered
Exam: multiple choice, multiple
answers, calculations, graphs, essay
1
Comparison conformers vs regulators
Conformers
Regulators
Homeostasis No
Yes
Equilibrium
Yes
No
Balance
Positive/negative balance Zero balance
Energy
No = Passive
requirement
Yes = active
Comparison Hyper-Hypo
osmoregulation
Final osm
Passive
Active
Hyper-osmoregulators
Osm organism > Osm out
Salt out
Salt in
Mechanism Diluted urine
Gills Chloride cells
Hypo-osmoregulators
Osm organism < Osm out
Salt in
Salt out
Gills Chloride cells
2
Mode of Osmoregulation
Internal environment (mOsm/kg)
1200
animal is hyperosmotic to environment
Osmotic Hyperegulator
line of identity
Conformer
800
400
Osmotic Hyporegulator
animal is hypo-osmotic to environment
0
0
200
400
600
800
1000
1200
External environment (mOsm/kg)
Osmotic Hyporegulation
How does an organism maintain lower
osmotic pressure than the environment?
3
Mode of Hypo-osmoregulation
1200
Internal environment (mOsm/kg)
line of identity
Conformer
800
Gain salt passively
Excrete salt Actively
400
Osmotic Hyporegulator
0
0
200
400
600
800
1000
1200
External environment (mOsm/kg)
4
Osmotic Hyper-osmoregulation
How does an organism maintain higher
osmotic pressure than the environment?
Mode of Hyper-osmoregulation
Lose salt passively
Gain salt Actively
Internal environment (mOsm/kg)
1200
line of identity
Osmotic Hyperegulator
Conformer
800
400
0
0
200
400
600
800
1000
1200
External environment (mOsm/kg)
5
Hyperosmotic regulation- pumping in solutes:
Diluted urine
out
in
Proton pump Kidneyretains Na and
excretes H+
Hyper-Hypo osmoregulation
Freshwater Fish: KIDNEY

Uptake: The Proton-K-ATPase pump on the basolateral
membrance works to create an ionic gradient favoring the
movement of Na+ and Cl- into the cell from the external
environment.
6
What type of osmoregulators are these?
Apply the appropriate term for each
Organism
Habitat
Solute (mM)
K+
Na+
A
Marine
450
4
B
Marine
160
5
C
Fresh
155
3
D
Fresh
0,1
0.01
Sea Water
450
5
Fresh Water
0,4
0.05
Osmolarity
(mOsm/L)
7
Life in brackish environments
Tolerance to variable conditions
Euryhaline- more tolerant
Osmoregulate
Osmoconform
Mode of osmo-regulation
Gains water
ECF conc
(mOsm)
Hyper-osmoregulator
lose water
Hypo-osmoregulator
Environment conc (mOsm)
8
Osmotic Hyper-regulation
100 mOsm
Passive diffusion of
Solutes
Passive diffusion of
Solutes
ECF (organism)
300 mOsm
Active uptake of
ECF (organism)
900 mOsm
Active uptake of
Solutes
Solutes
Which organism will spend more energy?
Mode of osmo-regulation
Hyper-osmoregulator C and B
ECF conc
(mOsm)
C
D
B
A
B
Hypo-osmoregulator D and B
Environment conc (mOsm)
Which organism will spend more energy at external 100mOsm?
Which organism will spend more energy at external 900mOsm?
9
Mode of Osmoregulation
Internal environment (mOsm/kg)
1200
animal is hyperosmotic to environment
line of identity
Osmotic Hyperegulator
Conformer
800
400
Osmotic Hyporegulator
animal is hypo-osmotic to environment
0
0
200
400
600
800
1000
1200
External environment (mOsm/kg)
Osmotic Hyporegulation
How does an organism maintain lower
osmotic pressure than the environment?
10
Mode of Hypo-osmoregulation
1200
Internal environment (mOsm/kg)
line of identity
Conformer
800
Gain salt passively
Excrete salt Actively
400
Osmotic Hyporegulator
0
0
200
400
600
800
1000
1200
External environment (mOsm/kg)
Solute regulation: Hypo-osmoregulation
Fish gains solutes passively.
So ECF osmolarity should increase (conformer)
Regulator:
In order to maintain constant
ECF osmolarity, the fish will have to excrete
somehow the extra solutes actively.
Problem:
Fish cannot concentrate urine
11
Osmotic Hyper-osmoregulation
How does an organism maintain higher
osmotic pressure than the environment?
Mode of Hyper-osmoregulation
Lose salt passively
Gain salt Actively
Internal environment (mOsm/kg)
1200
line of identity
Osmotic Hyperegulator
Conformer
800
400
0
0
200
400
600
800
1000
1200
External environment (mOsm/kg)
12
Solute regulation: Hyper-osmoregulation
Fish lose solutes passively.
So ECF osmolarity should decrease (conformer)
Regulator: In order to maintain constant ECF
osmolarity, the fish will have to take in somehow
the extra solutes actively.
Very important for exam
•
Hyper/Iso/Hypo-OSMOTIC is comparing
concentration.
• Compare Osmolarities of 2 solutions
13
Tonicity
Tonicity is determined by the response of a cell
when it is placed in a solution.
Hyper/Iso/Hypo-TONIC accounts for physiological
behavior of cell.
If a red blood cell swells and stays swollen (or bursts)
when placed in a particular solution, that solution is
said to be hypotonic.
Example: RBC (300 mOsm) in Urea (300 mOsm)
Remember
If the question is given as mM
So you multiply by dissociation constant to get osmolarity
If the question state that NaCl is completely dissociation
Use dissociation constant as 2
14
Very important for exam
Only impermeable particles will contribute
to tonicity
Note
Many animals can tolerate only a narrow
range of external osmotic environments
= Stenohaline.
In contrast, other organisms can function
well over a wide range of external saline
concentrations including freshwater and
seawater = Euryhaline.
15
Adaptation
Aquatic Organisms: Conformer
Equilibrium with environment
Many aquatic invertebrates are not able to regulate their
hemolymph (“blood”) osmolality. Therefore the concentration
of solutes in their hemolymph mirrors their external
environment Fall on line of identity
Adaptation
Other marine organisms their hemolymph
osmolality will remain relatively constant
over a change in environmental salinity.
The ability to maintain the hemolymph
osmolality constant is defined as an
osmoregulator.
16
Adaptation: Conformer
•
•
•
•
•
equilibrium
Does not spend energy is passive
input > output or input < output
why cell do not swell / shrink
remember tonicity; only impermeable
particles contribute
Adaptation: modulator
• zero balance; input = output
• If input is passive  output will be active
• If output is passive  input will be active
17
Terrestrial habitats?
Types of terrestrial habitats?
Grassland
Temperate
Tropical
Rain-forests
Deserts
18
19
20
Compare the desert environment to
the aquatic environment,
What challenges confront these antelope?



Water and solutes not readily available to organism.
Need to acquire water and solutes by drinking and eating.
Very little solute/ water exchange through skin.
21
Water Balance
Expired air
Sweat from skin
Fecal water
Urine
Preformed water
Drinking water
Oxidative
Loss
Gain
 Evaporation from lungs
 Water in food
 Evaporation from skin
 Drinking water
 Water in feces
 Oxidation water
 Water in urine
Water Gain
What are the sources of water available
to animals living in the desert?
22
Water Gain
 Drinking
 Uptake via body surface
 From water
 From air
 Water in food (preformed water)
 Metabolic water
Water Gain: Drinking
 Not readily available to small organisms
 lick dew or fog
 moisture from food
 Large organisms
 predation at water holes
 Foraging range restricted by need to return to
waterhole to drink
23
Water Gain: Uptake
 From air, mainly plants and insects
 From water- travel far sandgrouse
 From preformed water in food
 Meat 70% water
 Plants 10-90% water
Oxidative water
What is this?
24
Oxidative water (MW)
How much water comes from metabolizing fuels?
C6H12O6 + 6 O2
(180g)
(192g)
6 CO2 + H2O
(264g) (108g)
1.07g MW /g fat
180g FAT x1.07 = 192 g MW
Oxidative water from different food types
Food
CHO
Fat
Protein
g MW/g food
0.56
1.07
0.40
Energy (kcal/g)
4.2
9.4
4.3
25
Which body fluid results in the greatest water
loss in arid environments?
 Feces
 Evaporation
 From body surface
 From respiratory surfaces
 Urine
 Other body fluids. Milk, scent glands
Fecal water loss
 What does it depend upon?
 Is it regulated?
26
Fecal water loss
 Depends mainly on diet
 Largely unregulated
 Some animals (e.g. insects) can increase
water re-uptake in hindgut
 Arid-adapted animals produce dry feces 4050%
 Most animals excrete fecal waste that
contains approximately 70-80% water
Evaporative water loss
 What does it depend upon?
 Is it regulated?
27
Evaporative water loss
 Passive process through leaky skin
 Many animals try and make the integumentthe barrier between the extracellular fluid
and the environment impermeable
 Fur and or scales good barrier to water loss.
Evaporative water loss
Waxy lipid layer is an important
barrier to evaporative water loss in
insects
28
Evaporative water loss







Water loss through respiration
considerable
Every time breath out lose water as
moist air
Many mechanisms to reduce water
loss
Get a temporal counter current
As air is inhaled it is warmed and
humidified removing heat and water
from nasal passages
As air is exhaled it is cooled and
water is deposited on cool nasal
surfaces
The bigger an animal’s nose the
greater the water conserving ability
Sensible evaporative water loss
 Regulated water loss primarily for cooling
via sweating or panting
 Latent heat of vaporization 600cal/g
 Not all animals have sweat glands
 Humans, horses and cows have sweat
glands
 Sheep, pigs, dogs, birds, reptiles and
insects do not
29
How do desert rodents manage
without drinking water?
Animals living in deserts may have it a
little easier than we would think!
• Mole-rats always live underground
• Beetles stay under the soil surface until wind
and temp right for foraging.
• Geckos and most rodents are nocturnal
30
How do desert rodents manage without
drinking water?




Nocturnal – avoid hottest
times of day
Microclimate- rest in
favorable cool, moist
burrow
Stores seeds in burrowshygroscopic
Minimizes water loss respiratory moisture
condenses in nose
 concentrated urine
 dry feces
Water balance
Gain
(ml/month)
Oxidative
Preformed
54
6
Total
60
Loss
(ml/month)
Urine
13.5
Feces
2.6
EWL
43.9
60
Preformed = Water in food; EWL = evaporative water loss
Negative water balance leads to dec ECF and other water
compartments - leads to circulatory failure and death.
Positive water balance leads to electrolyte imbalance
– neuromuscular, circulatory problems and death.
31
Adaptation: animals living in terrestrial habitats
Short term adaptation to lower its water output




Nocturnal – avoid hottest times of day
Microclimate- rest in favorable cool, moist burrow
Stores seeds in burrows- hygroscopic
Minimizes water loss
- dry feces
- respiratory moisture condenses in nose
- Minimizes evaporation through the skin
Animals living in deserts may have it a
little easier than we would think!
• Mole-rats always live underground
• Beetles stay under the soil surface until wind
and temp right for foraging.
• Geckos and most rodents are nocturnal
32
Water Loss




Feces
Body fluids: milk, secretions
Evaporation
Kidney: Urine
Evaporative loss may be:
a) Insensible water loss: from respiration or directly
from skin
b) Sensible water loss: from sweating.
33
34
GFR
• GFR is the amount plasma filtered per unit time.
• Indicator of kidney function.
• Measured using something that is freely filtered and
neither reabsorbed nor secreted
GFR = =125ml/min or 180 L/day
Filtered load
• Amount of a substance passing through the
kidneys per unit time
• = GFR X Plasma concentration
• If GFR is 180L/day and plasma glucose conc is 1g/L
• Filtered load of glucose is GFR x Plasma concentration
• 180L/d x 1g/L = 180d/day
35
Filtered load
Amount of a substance filtered per unit time
Amount = volume x concentration = GFR X Plasma concentration
If GFR is 125 ml/min ; plasma inulin = 1 mg/ml and plasma glucose = 1 mg/ml
Filtered load of inulin is 125 ml/min x 1mg/ml = 125 mg/min
Filtered load of glucose is 125 ml/min x 1mg/ml = 125 mg/min
What is amount of inulin and glucose excreted in urine?
For inulin 125 mg/min
For Glucose 0 mg/min
WHY?
Inulin is not reabsorbed; glucose is complete reabsorbed.
Kidney Functions: Homeostasis
Removing waste products - metabolites
Water and salts homeostasis
pH homeostasis (acid-base)
Blood pressure homeostasis
Stimulates the bone marrow to make red blood
cell (RBC homeostasis)
• Activating vitamin D (calcium homeostasis)
•
•
•
•
•
The kidney does not just make urine!
36
Amount excreted in urine = amount filtered – reabsorbed + secreted
Measure Filtration rate
Consider a substance which is
only filtered by the kidney; it is
neither reabsorbed nor actively
secreted
Filtration = Urinary excretion
X
X
This Substance Is Inulin Or Creatinine
37
GFR = Glomerular Filtration Rate
• GFR is the volume of protein free plasma filtered per unit time.
• Indicator of kidney function.
• Measured by using substance that is freely filtered and neither
reabsorbed nor secreted, example creatinine (Cr) or Inulin (in)
where:
Amount creatinine filtered
= amount creatinine excreted in urine
Amount creatinine filtered
= vol filtered x plasma concentration
= GFR x Pl {Cr}
GFR x P{Cr} = Amount excreted in urine
amount excreted in urine
GFR = --------------------------------P{Cr}
Filtration Rate
• P = plasma (blood) concentration of inulin, in mg/ml
• U = urine concentration of inulin, in mg/ml
• V = rate of urine production in, in ml/min
Since inulin is filtered out from the blood and is not
reabsorbed, we can assume that inulin excreted in one
minute reflects the filtering of blood plasma volume that
contains an amount of inulin
38
Example: Normal kidney
Amount inulin excreted in urine = 125 mg/min
P{In} = 1mg/ml
Clearance
• Clearance indicates the volume of plasma cleared from a
substance per min or per day.
• Need to know plasma concentration and amount
excreted
Amount excreted in urine = urine conc x urine volume
Vol of plasma cleared = amount excreted / plasma conc
39
Clearance
• Clearance indicates the ratio of the filtered
load that is excreted per day.
• Need to know GFR, plasma conc, (ie. Filtered
load) urine conc and urine volume
Clearance (C)
Clearance measurements tell you how the
kidney handles the substance:
Urine = C
40
Adaptation: animals living in terrestrial
habitats: Trick of kidney
Medium term adaptation: Hormonal
 Antidiuretic hormone (ADH), Aldosterone: concentrated
urine
Long term adaptation: Genetic
 Long loops of Henle/Na/K pumps: concentrated
urine
Urinary water loss
 Is regulated tightly by hormones
antidiuretic hormone (ADH) and
aldosterone
 Can concentrate the urine relative to
plasma and reduce the water loss via
urine considerably
41
Insect urine concentration
• Ions are transported by
several different
mechanisms including Na/K
pumps.
• Net effect reabsorption of
KCl and water and the
excretion of ammonia and
H+ ions.
• Countercurrent draws water
back into hemocoel
Life in marine environments
Why can’t humans drink sea water?
42
Why can’t humans drink sea water?
Cannot concentrate urine sufficiently to get rid of excess salt
Lose large amounts of water with salt- dehydrated
43
Urine/plasma ratio
Animal
Chicken
Ostrich
Pig
Human
Bedouin goat
Cat
Springbok
Camel
Kangaroo rat
Hopping mouse
Maximum
Urine
Conc (Osm/l)
Urine/Plasma
0.5
0.8
1.1
1.2
2.0
3.0
3.1
3.2
5.5
9.4
1.5
2.7
3
4
7
10
10
8.0
14
25
Ratio
Nitrogenous Waste and Water Loss
Ammonia
requires lots of water
Urea
Uric acid
excreted with least
amount of water
44
2 mechanisms to concentrate urine
ADH
Counter current
What will be level of ADH if no water available?
Principles for Control of urine volume
Increased urine volume is:
Diuresis = Diuretic
Decreased urine volume is:
Anti-diuresis = Antidiuretic
45
High urine/plasma ratio
• Regulates
– water loss,
– plasma volume,
– solute concentration
– pH
• Processes involved
– ultrafiltration - high pressure
process removes everything from
blood
– reabsorption – passive & active
transport
– secretion – adds things
• Output of kidney depends on
hormonal control
The Countercurrent System
The kidneys concentrates urine by interaction of
events the so-called "countercurrent multiplier
system" in the loop of Henle of juxtamedullary
nephrons. The loop of Henle, which is a hairpin
loop, extending into the inner portions of kidney
(the renal medulla). The fluid flows in opposite
directions in the two limbs of the loop giving it
the name of countercurrent, making medulla
hyperosmotic.
46
Counter Current
Figure 9.33 Blood flow with and without countercurrent heat exchange
47
Counter Current
48
Kidney structure and urine concentrating ability
Long loops of Henle enable both active transport of sodium and
passive water flow along a concentration gradient.
U/P ratios
Active transport
ADH
Remember
For your 1st exam
Will cover lectures 1-3 and Tutorial 1
The labs are not covered
Exam: multiple choice, multiple
answers, calculations, graphs, very
short essays
49