ap biology 2009-2010 water balance & nitrogenous waste removal kidney function
TRANSCRIPT
2009-2010 AP Biology
Water Balance & Nitrogenous Waste Removal
Kidney Function
AP Biology
intracellular waste
extracellular waste
Animal systems evolved to support multicellular life
O2
CHO
CHO
aa
aa
CH
CO2
NH3aa
O2
CH
O2
aa
CO2
CO2
CO2
CO2
CO2
CO2 CO2
CO2
CO2
CO2
NH3
NH3 NH3
NH3
NH3
NH3
NH3NH3
O2
aa
CH
aa
CHO
O2
Diffusion too slow!
AP Biology
Overcoming limitations of diffusion Evolution of exchange systems for
systems to support multicellular organisms
systems to support multicellular organisms
aa
CO2
CO2
CO2
CO2
CO2
CO2 CO2
CO2
CO2
CO2
NH3
NH3 NH3
NH3
NH3
NH3
NH3NH3
O2
aa
CH
aa
CHO
O2
AP Biology
Osmoregulation Water balance vs. habitat
Why doall land animals
have to conservewater?
AP Biology
Intracellular Waste What waste products?
what do we digest our food into… carbohydrates = CHO lipids = CHO proteins = CHON nucleic acids = CHOPN
CO2 + H2O
NH2 =
ammonia
CO2 + H2O CO2 + H2O
CO2 + H2O + N
CO2 + H2O + P + N
|
| ||H
HN C–OH
O
R
H–C–
Animalspoison themselves
from the insideby digesting
proteins!
lots!verylittle
cellular digestion…cellular waste
AP Biology
Nitrogenous waste disposal Ammonia (NH3)
_________________________ carcinogenic
_________________________ 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)
aquatic terrestrial terrestrial egg layer
AP Biology
AP Biology
Freshwater animals Hypotonic environment
water diffuses into cells
Manage water & waste together remove surplus water & waste
use surplus water to dilute ammonia & excrete it also diffuse ammonia continuously through gills
overcome loss of salts reabsorb in kidneys or active transport across gills
AP Biology
Land animals Nitrogen waste disposal on land
need to conserve water must process ammonia so less toxic
urea = larger molecule = less soluble = less toxic 2NH2 + CO2 = urea produced in liver
kidney filter solutes out of blood reabsorb H2O (+ any useful solutes) excrete waste
urine = urea, salts, excess sugar & H2O urine is very concentrated concentrated NH3 would be too toxic
OC
HNH
HNH
Ureacosts energyto synthesize,
but it’s worth it!
mammals
AP Biology
Egg-laying land animals
itty bittyliving space!
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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
AP Biology
N
N N
N
O
HO
O
H
HH
Uric acidAnd that folks,
is why mostmale birds don’t have a penis! Polymerized urea
large molecule precipitates out of solution
doesn’t harm embryo in eggwhite dust in egg
adults still excrete N waste as white pasteno liquid wastewhite bird “poop” =
uric acid paste!
AP Biology
Mammalian System Filter solutes out of blood &
reabsorb H2O + desirable solutes
Key functionsfiltrate
blood filtration
reabsorption
secretion
excretion
urine
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Mammalian Kidney
kidney
bladder
ureter
urethra
renal vein& artery
nephron
epithelialcells
adrenal glandinferior
vena cavaaorta
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Nephron Functional units of kidney
1 million nephrons per kidney
Function filter out urea & other
solutes (salt, sugar…) blood plasma filtered
into nephron high pressure flow
selective reabsorption ofvaluable solutes & H2O back into bloodstream greater flexibility & control
“counter current exchange system”
whyselective reabsorption
& not selectivefiltration?
AP Biology
Mammalian kidney
Proximaltubule
Distal tubule
Glomerulus
Collecting ductLoop of Henle
Aminoacids
Glucose
H2O
H2O
H2O
H2O
H2O
H2O
Na+ Cl-
Mg++ Ca++
Interaction of circulatory & excretory systems
Circulatory system _________________ =
ball of capillaries Excretory system
_________________ _________________ _________________
proximal tubule descending limb ascending limb distal tubule
_________________
How candifferent sectionsallow the diffusion
of different molecules?
Bowman’s capsule
Na+ Cl-
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Nephron: Filtration At glomerulus
filtered out of blood ______________ ______________ ______________ ______________
not filtered out ______________ ______________
high blood pressure in kidneys force to push (filter) H2O & solutes out of blood vessel
high blood pressure in kidneys force to push (filter) H2O & solutes out of blood vessel
BIG problems when you start out with high blood pressure in systemhypertension = kidney damage
BIG problems when you start out with high blood pressure in systemhypertension = kidney damage
AP Biology
Nephron: Re-absorption
Descendinglimb
Ascendinglimb
Proximal tubule reabsorbed back into blood
________________
________________ ________________ ________________
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Descendinglimb
Ascendinglimb
Nephron: Re-absorption Loop of Henle
descending limb reabsorbed
___________________ structure
structure fitsfunction!
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Nephron: Re-absorption
Descendinglimb
Ascendinglimb
Loop of Henle ascending limb reabsorbed
___________________ structure
structure fitsfunction!
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Nephron: Re-absorption Distal tubule
reabsorbed ______________ ______________ ______________
HCO3-
regulate blood pH
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Nephron: Reabsorption & Excretion Collecting duct
reabsorbed ________________
excretion ________________ to bladder
Descendinglimb
Ascendinglimb
AP Biology
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 transportwherever possible
the value of acounter current exchange system
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Recap…
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Summary Not filtered out
cells proteins remain in blood (too big)
Reabsorbed: active transport Na+ amino acids Cl– glucose
Reabsorbed: diffusion Na+ Cl–
H2O Excreted
urea excess H2O excess solutes (glucose,
salts) toxins, drugs, “unknowns”
whyselective reabsorption
& not selectivefiltration?
2009-2010 AP Biology
Maintaining Homeostasis
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sensor
Negative Feedback Loop
high
low
hormone or nerve signal
lowersbody condition(return to set point)
hormone or nerve signal
gland or nervous system
raisesbody condition (return to set point)
gland or nervous system
sensor
specific body condition
AP Biology
nephron
low
Water Balance: Blood Osmolarity
blood osmolarityblood pressure/volume
ADH
increasedwater
reabsorption
increasethirst
high
Endocrine System Control
pituitary
ADH = AntiDiuretic Hormone
AP Biology
H2O
H2O
H2O
Maintaining Water Balance
Alcohol suppresses ADH…
makes youurinate a lot!
High blood osmolarity level too many solutes in blood
dehydration, high salt diet triggers release antidiuretic hormone (ADH)
produced in hypothalamus stored in pituitary
makes collecting duct more permeabilityto water increase water absorption back into blood more concentrated urine; decrease urination
Get morewater into
blood
AP Biology
low
Blood Pressure / Volume
blood osmolarityblood pressure/volume
renin
increasedwater & saltreabsorption
high
Endocrine System Control
angiotensinogenangiotensin
nephronadrenalgland
aldosterone
JGA
JGA = JuxtaGlomerular Apparatus
Oooooh,zymogen!
AP Biology
Maintaining Water Balance Low blood volume or
low blood pressure JGA releases renin which acts as an enzyme
activates angiotensinogen angiotensin angiotensin acts as a hormone
causes arterioles to constrict = raises blood pressure triggers release of aldosterone from adrenal gland
aldosterone acts as a hormone increases kidney reabsorption of Na+ & H2O
puts more water & salts back in blood
Get morewater & salt into
blood fast!
adrenalgland
Why such arapid response system?
Spring a leak?
AP Biology
nephron
low
Water Balance
blood osmolarityblood pressure/volume
ADH
increasedwater
reabsorption
increasethirst
renin
increasedwater & saltreabsorption
high
Endocrine System Control
pituitary
angiotensinogenangiotensin
nephronadrenalgland
aldosterone
JuxtaGlomerularApparatus
2009-2010 AP Biology
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