Transcript Ch49WaterBalance - Environmental

Regulating the Internal
Environment
AP Biology
2006-2007
Conformers vs. Regulators
 2 evolutionary paths for organisms

regulate internal environment
 maintain relatively constant internal conditions

conform to external environment
 allow internal conditions to fluctuate along with external changes
osmoregulation
thermoregulation
regulato
r
AP Biology
conformer
regulato
r
conformer
Homeostasis
 Keeping the balance

animal body needs to coordinate
many systems all at once








AP Biology
temperature
blood sugar levels
energy production
water balance & intracellular waste disposal
nutrients
ion balance
cell growth
maintaining a “steady state” condition
Regulating the Internal
Environment
Water Balance &
Nitrogenous Waste
Removal
AP Biology
2006-2007
Animal systems evolved to
support multicellular life
aa
O2
CH
CHO
CO2
aa
NH3
CHO
O2
O2
CH
aa
CO2
aa
NH3
CO2
NH3
CH
CO2
CO2
NH3
NH3
CO2
AP Biology
NH3
NH3
CO2
CO2
aa
O2
NH3
NH3
CO2
O2
intracellular
waste
CO2
CHO
CO2
aa
Diffusion too slow!
extracellular
waste
Solving exchange problem
 Evolve of exchange systems for
distributing nutrients
 circulatory system
 removing wastes
 excretory system

CO2
CO2
aa
CO2
CO2
O2
NH3
CO2
overcoming the
limitations of diffusion
CO2
CO2
NH3
NH3
CO2
CH
AP Biology
NH3
NH3
NH3
CO2
aa
O2
NH3
NH3
CHO
CO2
aa
Osmoregulation
 Water balance

freshwater
 hypotonic
 water flow into cells & salt loss

saltwater
 hypertonic
 water loss from cells

land
 dry environment
 need to conserve water
 may need to conserve salt
Why do all land animals have to conserve water?
 always lose water (breathing & waste)
AP
may
lose life while searching for water
Biology
Waste disposal
 What waste products?

Animals
poison themselves
from the inside
by digesting
proteins!
what do we digest our food into…
 carbohydrates = CHO  CO2 + H2O
 lipids = CHO  CO2 + H2O
 proteins = CHON  CO2 + H2O + N
 nucleic acids = CHOPN  CO2 + H2O + P + N
 relatively small amount in cell
cellular digestion…
cellular waste
NH2 =
AP Biology
ammonia
H| O
||
H
N –C– C–OH
|
H
R
CO2 + H2O
Nitrogenous waste disposal
 Ammonia (NH3)

very toxic
 carcinogenic

very soluble
 easily crosses membranes

must dilute it & get rid of it… fast!
 How you get rid of nitrogenous wastes depends on

who you are (evolutionary relationship)

where you live (habitat)
AP Biology
Nitrogen waste
 Aquatic organisms


can afford to
lose water
ammonia
 most toxic
 Terrestrial


need to
conserve water
urea
 less toxic
 Terrestrial egg
layers


need to conserve
most water
uric acid
AP Biology  least toxic
Freshwater animals
 Water removal & nitrogen waste disposal

surplus of water
 can dilute ammonia & excrete it
 need to excrete a lot of water anyway so
excrete very dilute urine
 pass ammonia continuously through gills or
through any moist membrane

loss of salts
 reabsorb in kidneys or active transport across gills
AP Biology
Land animals
 Nitrogen waste disposal on land

evolved less toxic waste product
 need to conserve water
 urea = less soluble = less toxic

kidney
 filter wastes out of blood
 reabsorb H2O
 excrete waste
 urine = urea, salts, excess sugar & H2O


AP Biology
urine is very concentrated
concentrated NH3 would be too toxic
Urea
 Larger molecule = less soluble
2NH2 + CO2 = urea
 combined in liver

H
 Requires energy
to produce

worth the investment
of energy
 Filtered out by kidneys

AP Biology
collected from cells
by circulatory system
N
H
H
C
N
H
O
Egg-laying land animals
 Nitrogen waste disposal in egg
no place to get rid of waste in egg
 need even less soluble molecule

 uric acid = bigger = less soluble = less toxic

birds, reptiles, insects
itty bitty
living space!
AP Biology
Uric acid
 Polymerized urea
And that folks,
is why a male bird
doesn’t have
a penis!
large molecule
 precipitates out of solution

 doesn’t harm embryo in egg
 white dust in egg
 adults excrete white paste
 no liquid waste
 white bird “poop”!
O
H
H
N
N
O
O
N
N
AP Biology
H
H
Mammalian System
blood
filtrate
 Key functions

filtration
 fluids from blood collected
 includes water & solutes

reabsorption
 selectively reabsorb needed
substances back to blood

secretion
 pump out unwanted substances to
urine

excretion
 remove excess substances & toxins
from body
AP Biology
urine
Mammalian Kidney
inferior
vena cava
aorta
adrenal gland
kidney
nephron
ureter
renal vein
& artery
epithelial
cells
bladder
urethra
AP Biology
Nephron
 Functional units of kidney

1 million nephrons
per kidney
 Function

filter out urea & other
solutes (salt, sugar…)
 Process


blood plasma filtered
into nephron
selective reabsorption of
valuable solutes & H2O
 greater flexibility & control
AP Biology
why
selective reabsorption
& not selective
filtration?
“counter current
exchange system”
How can
different sections
allow the diffusion
of different
molecules?
Mammalian kidney
 Interaction of circulatory
& excretory systems
 Circulatory system

glomerulus =
ball of capillaries
Bowman’s
capsule
Proximal
tubule
Distal
tubule
Glomerulus
 Excretory system



nephron
Bowman’s capsule
loop of Henle
Glucose
Amino
acids
H2O
Mg++ Ca++
H2O
AP Biology
collecting duct
H2O
H2O
 descending limb
 ascending limb

Na+ ClNa+ ClH2O
H2O
Loop of Henle
Collecting
duct
Nephron: Filtration
 At glomerulus

filtered out of blood
 H2O
 glucose
 salts / ions
 urea

not filtered out
 cells
 proteins
AP Biology
high blood pressure in kidneys
force to push H2O & solutes out of
blood vessel
BIG problems when you start out
with high blood pressure in system
hypertension = kidney damage
Nephron: Re-absorption
 Proximal tubule

reabsorbed
 NaCl
 active transport Na+
 Cl- follows by
diffusion
 H2O
 glucose
 HCO3 bicarbonate
 buffer for
blood pH
AP Biology
Descending
limb
Ascending
limb
Nephron: Re-absorption
structure fits
 Loop of Henle
function!

descending limb
 high permeability
to H2O
 many aquaporins
in cell membranes
 low permeability to
salt

reabsorbed
 H2O
AP Biology
Descending
limb
Ascending
limb
Nephron: Re-absorption
structure fits
 Loop of Henle
function!

ascending limb
 low permeability
to H2O
 Cl- pump
 Na+ follows by
diffusion
 different membrane
proteins

reabsorbed
 salts
 maintains osmotic
AP Biology
gradient
Descending
limb
Ascending
limb
Nephron: Re-absorption
 Distal tubule

reabsorbed
 salts
 H2O
 HCO3 bicarbonate
AP Biology
Nephron: Reabsorption & Excretion
 Collecting duct

reabsorbed
 H2O

excretion
 urea passed
through to
bladder
AP Biology
Descending
limb
Ascending
limb
Osmotic control in nephron
 How is all this re-absorption achieved?
tight osmotic
control to reduce
the energy cost
of excretion
 use diffusion
instead of
active transport
wherever possible

the value of a
counter current
exchange system
AP Biology
why
selective reabsorption
& not selective
filtration?
Summary
 Not filtered out


remain in blood (too big)
cells
 proteins
 Reabsorbed: active transport


Na+
Cl-
amino acids
 glucose

 Reabsorbed: diffusion


Na+
H2O

Cl-
 Excreted


AP Biology
urea (highly concentrated)
excess H2O
 excess solutes (glucose, salts)
toxins, drugs, “unknowns”
Any Questions?
AP Biology
2006-2007
Regulating the Internal
Environment
Regulation of
Homeostasis
AP Biology
2006-2007
Negative Feedback Loop
 Maintaining homeostasis
Response
Return to
set point
Perturbing
factor
Stimulus
deviation from
set point
Negative
feedback loop
completed
Sensor
constantly
monitors
conditions
AP Biology
Effector
causes changes
to compensate
for deviation
Integrating
center
compares
conditions to
set point
Negative Feedback Model
hormone 1
lowers
body condition
gland
(return to set point)
high
sensor
specific body condition
sensor
raises
body condition
gland
(return to set point)
AP Biology
low
hormone 2
Nervous System Control
Controlling Body Temperature
nerve signals
brain
sweat
high
body temperature
low
brain
constricts surface shiver
blood vessels
AP Biology
nerve signals
dilates surface
blood vessels
Endocrine System Control
Blood Osmolarity
ADH
pituitary
increased
water
reabsorption
nephron
high
blood osmolarity
blood pressure
low
AP Biology
increase
thirst
Maintaining Water Balance
 High blood osmolarity level

too many solutes in blood
Get more
water into
blood fast
 dehydration, high salt diet


stimulates thirst = drink more
release ADH from pituitary gland
 anti-diuretic hormone

increases permeability of collecting duct
& reabsorption of water in kidneys
H2O
H2O
 increase water absorption back into blood
 decrease urination
AP Biology
Alcohol
suppresses ADH…
makes you
urinate a lot!
H2O
Endocrine System Control
Blood Osmolarity
ADH
increased
water
reabsorption
pituitary
increase
thirst
nephron
high
blood osmolarity
blood pressure
adrenal
gland
low
increased
water & salt
reabsorption
JuxtaGlomerular
Apparatus
nephron
renin
aldosterone
AP Biology
angiotensinogen
angiotensin
Maintaining Water Balance
 Low blood osmolarity level
or low blood pressure
Low solutes
renin (from JGA) activates
angiotensinogen
angiotensin triggers
aldosterone
aldosterone
increases absorption
of NaCl
& H2O in kidney
AP
Biology
Oooooh,
zymogen!
Maintaining Water Balance
 Low blood osmolarity level
or low blood pressure



Get more
water & salt into
blood fast!
JGA releases renin in kidney
renin converts angiotensinogen to angiotensin
angiotensin causes arterioles to constrict
 increase blood pressure


angiotensin triggers release of aldosterone from
adrenal gland
increases reabsorption of NaCl & H2O in kidneys
 puts more water & salts back in blood
AP Biology
Why such a
rapid response
system?
Spring a leak?
adrenal
gland
Don’t get batty…
Ask Questions!!
AP Biology
2006-2007
Homeostasis
 Osmoregulation

solute balance & gain or loss of water
 Excretion

elimination of nitrogenous wastes
 Thermoregulation

AP Biology
maintain temperature within tolerable range
Maintaining Water Balance
 Monitor blood osmolarity

amount of dissolved material in blood
High solutes
in brain
AP Biology
ADH
= anti-diuretic hormone