AP Biology

Kidney Structure& Function

Collecting ductLoop of Henle

Aminoacids

Glucose

H2O

H2O

H2O

H2O

H2O

H2O

Na+ Cl-

Mg++ Ca++Na+ Cl-

Removing IntracellularWaste

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intracellular waste

Animal systems evolved to support multicellular life

O2

CHO

CHO

aa

aaCH

CO2

NH3aa

O2

CH

O2

aa

CO2CO2

CO2

CO2

CO2

CO2 CO2

CO2

CO2

CO2

NH3

NH3 NH3

NH3

NH3

NH3

NH3NH3

O2

aa

CH

aa

CHO

O2

Diffusion too slow!

single cell

but whatif the

cells areclustered?

for nutrients in & waste out

extracellular waste

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Overcoming limitations of diffusion Evolution of exchange systems for

distributing nutrients _____________________

removing wastes _____________________

systems to support multicellular organisms aa

CO2CO2

CO2

CO2

CO2

CO2 CO2

CO2

CO2

CO2

NH3

NH3 NH3

NH3

NH3

NH3

NH3NH3

O2

aa

CH

aa

CHO

O2

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Osmoregulation

Why do all land animals have to conserve water? always lose water (breathing & waste) may lose life while searching for water

Water balance vs. Habitat freshwater

___________________________ water flow into cells & salt loss

saltwater ___________________________ water loss from cells

land dry environment need to conserve water may also need to conserve salt

hypotonic

hypertonic

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Intracellular Waste What waste products

are made inside of cells? what do we digest our food into…

carbohydrates = CHO lipids = CHO proteins = CHON nucleic acids = CHOPN

CO2 + H2ONH2

=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

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Nitrogenous waste disposal Ammonia (NH3)

__________________________ carcinogenic

__________________________ easily crosses membranes

must dilute it & get rid of it… fast! How you get rid of ___________________depends on

who you are (evolutionary relationship) where you live (habitat)

aquatic terrestrial terrestrial egg layer

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Nitrogen waste _____________________

can afford to lose water ___________________

most toxic _____________________

need to conserve water

___________________ less toxic

____________________________________________

need to conserve water need to protect

embryo in egg ___________________ least toxic

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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

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Land animals Nitrogen waste disposal on land

need to conserve water must process ammonia so less toxic

_______= larger molecule = less soluble = less toxic 2NH2 + CO2 = urea _________________________

__________________ filter solutes out of blood reabsorb H2O (+ any useful solutes) excrete waste

_______ = 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

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Nitrogen waste disposal in egg no place to get rid of waste in egg need even less soluble molecule

___________ = BIGGER = less soluble = less toxic birds, reptiles, insects

Egg-laying land animals

itty bittyliving space!

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N

N N

N

O

HO

O

H

HH

Uric acid And that folks,is why most

male birds don’t have a penis! Polymerized urea

large molecule ______________________________

doesn’t harm embryo in eggwhite dust in egg

adults still excrete N waste as white pasteno liquid wasteuric acid = white bird “poop”!

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Mammalian System Filter solutes out of blood &

reabsorb H2O + desirable solutes Key functions

______________________ fluids (water & solutes) filtered out

of blood ______________________

selectively reabsorb (diffusion) needed water + solutes back to blood

______________________ pump out any other unwanted

solutes to urine ______________________

expel concentrated urine (N waste + solutes + toxins) from body

blood filtrate

concentratedurine

filtrate

filtrate

filtrate

filtrate

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Mammalian Kidney

kidney

bladder

ureter

urethra

renal vein& artery

nephron

microvilli onepithelial

cells

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?

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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

How candifferent sectionsallow the diffusion

of different molecules?

Bowman’s capsule

Na+ Cl-

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Nephron: _______________ At glomerulus

high blood pressure in kidneys force to push (filter) H2O & solutes out of blood vesselBIG problems when you start out with high blood pressure in systemhypertension = kidney damage

H2O&

solutes

cells &large

molecules

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Nephron: _______________ Proximal tubule

reabsorbed back into blood

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Nephron: Re-absorptionstructure fits

function! Loop of Henle ___________________ reabsorbed

_________________ structure

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Nephron: Re-absorptionstructure fits

function! Loop of Henle ___________________ reabsorbed

_________________ structure

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Nephron: Re-absorption Distal tubule

reabsorbed

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Nephron: Reabsorption & Excretion Collecting duct

reabsorbed _______________

_______________ excretion

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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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Summary why

selective reabsorption& not selective

filtration?

AP Biology

Any Questions?