AP Biology 2005-2006 Regulating the Internal Environment Chapter 44.
Regulating the Internal Environment (Ch. 44)
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Transcript of Regulating the Internal Environment (Ch. 44)
Regulating the Internal Environment(Ch. 44)
Conformers vs. Regulators • Two 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
conformer
thermoregulation
regulator
conformer
osmoregulation
regulator
Homeostasis • Keeping the balance
– animal body needs to coordinate many systems all at once
• temperature• blood sugar levels• energy production• water balance & intracellular waste disposal• nutrients• ion balance• cell growth
– maintaining a “steady state” condition
Countercurrent heat exchangersArteries carrying warm blood down the
legs of a goose or the flippers of a dolphinare in close contact with veins conveyingcool blood in the opposite direction, back
toward the trunk of the body. Thisarrangement facilitates heat transfer
from arteries to veins (blackarrows) along the entire length
of the blood vessels.
Near the end of the leg or flipper, wherearterial blood has been cooled to far below the animal’s core temperature, the artery can still transfer heat to the even colder
blood of an adjacent vein. The venous bloodcontinues to absorb heat as it passes warmer
and warmer arterial blood traveling in the opposite direction.
As the venous blood approaches the center of the body, it is almost as warm
as the body core, minimizing the heat lost as a result of supplying blood to body parts
immersed in cold water.
In the flippers of a dolphin, each artery issurrounded by several veins in a
countercurrent arrangement, allowingefficient heat exchange between arterial
and venous blood.
Canadagoose
Artery Vein
35°C
Blood flow
Vein
Artery
30º
20º
10º
33°
27º
18º
9º
Pacific bottlenose dolphin
1
2
3
2
1 3
1
3
2
3
Osmoregulation
Why do all land animals have to conserve water?
always lose water (breathing & waste) may lose life while searching for water
• Water balance – freshwater
• hypotonic• water flow into cells & salt loss
– saltwater• hypertonic• water loss from cells
– land• dry environment• need to conserve water• may also need to conserve salt
hypotonic
hypertonic
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
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)
aquatic terrestrial terrestrial egg layer
Aquatic organisms can afford to lose
water - gills Ammonia: most toxic
Terrestrial need to conserve
water Urea: less toxic
Terrestrial egglayers need to conserve
water need to protect
embryo in egg uric acid: least toxic
Nitrogen waste
Mammalian System• Filter solutes out of blood & reabsorb
H2O + desirable solutes• Key functions
– Filtration: fluids (water & solutes) filtered out of blood into glomerulus
– Reabsorption: selectively reabsorb (diffusion) needed water + good solutes back to blood
– Secretion: toxins extracted from body fluids added here!
– Excretion: expel concentrated urine (N waste + solutes + toxins) from body
blood filtrate
concentratedurine
Mammalian Kidney
kidney
bladder
ureter
urethra
renal vein& artery
nephron
epithelialcells
adrenal glandinferior
vena cavaaorta
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?
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– glomerulus =
ball of capillaries• Excretory system
– nephron– Bowman’s capsule– loop of Henle
• proximal tubule• descending limb• ascending limb• distal tubule
– collecting duct
Bowman’s capsule
Na+ Cl-
Summary • Not filtered out
– Cells, proteins (antibodies, enzymes) remain in blood, they’re too big
• Reabsorbed: active transport– Na+ Cl-, amino acids, glucose (size)
• Reabsorbed: diffusion– Na+, Cl–, H2O
• Excreted– Urea, excess H2O , excess solutes (glucose, salts),
toxins, drugs, “unknowns”
H2O
H2O
H2O
Maintaining Water BalanceGet morewater intoblood fast
Alcohol suppresses ADH…
makes youurinate a lot!
• High blood osmolarity level– too many solutes in blood
• dehydration, high salt diet– stimulates thirst = drink more – release ADH from pituitary gland
• antidiuretic hormone– increases permeability of collecting duct
& reabsorption of water in kidneys• increase water absorption back into blood• decrease urination
Maintaining Water Balance
• Low blood osmolarity level or low blood pressure– 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
Get morewater & salt into
blood fast!
adrenalgland
nephron
low
Blood Osmolarity
blood osmolarityblood pressure
ADH
increasedwater
reabsorption
increasethirst
renin
increasedwater & saltreabsorption
high
Endocrine System Control
pituitary
angiotensinogenangiotensin
nephronadrenalgland
aldosterone
JuxtaGlomerularApparatus
Can animals switch? Salmon
• Vampire bats – drink a blood meal (high protein right?). They drink a ton and then can’t fly so they urinate lots of water on the spot. They fly to roost and don’t drink so excrete pasty urea (guano)