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Copyright © 2009 Pearson Education, Inc.
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Chapter 25 Control of Body Temperature
and Water Balance
Lecture by Edward J. Zalisko
Bears sleep a lot during winter
But bears do not hibernate
Instead, they become dormant
– Body temperature drops from 37°C to 31–34°C
– True hibernators may cool to 30°C
Dormant bears
– Are easily awakened
– True hibernators are slower to awaken
Introduction: Chilling Out
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Homeostasis
– Maintenance of steady internal conditions despite fluctuations in the external environment
Examples of homeostasis
– Thermoregulation—the maintenance of internal temperature within narrow limits
– Osmoregulation—the control of the gain and loss of water and solutes
– Excretion—the disposal of nitrogen-containing wastes
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Introduction: Chilling Out
THERMOREGULATION
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Thermoregulation
– The process by which animals maintain an internal temperature within a tolerable range
25.1 An animal’s regulation of body temperature helps maintain homeostasis
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Ectothermic animals
– Absorb heat from their surroundings
– Many fish, most amphibians, lizards, most invertebrates
Endothermic animals
– Derive body heat mainly from their metabolism
– Birds, mammals, a few reptiles and fish, many insects
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25.1 An animal’s regulation of body temperature helps maintain homeostasis
Heat exchange with the environment may occur by
– Conduction
– Convection
– Radiation
– Evaporation
25.2 Heat is gained or lost in four ways
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Convection
Conduction
Evaporation
Radiation
25.3 Thermoregulation involves adaptations that balance heat gain and loss
Five general categories of adaptations promote thermoregulation
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Increased metabolic heat production
– Hormonal changes boost metabolic rate in birds and mammals
– Shivering
– Increased physical activity
– Honeybees cluster and shiver
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25.3 Thermoregulation involves adaptations that balance heat gain and loss
Insulation
– Hair
– Feathers
– Fat layers
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25.3 Thermoregulation involves adaptations that balance heat gain and loss
Circulatory adaptations
– Increased or decreased blood flow to skin
– Large ears in elephants
– Countercurrent heat exchange
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25.3 Thermoregulation involves adaptations that balance heat gain and loss
Evaporative cooling
– Sweating
– Panting
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25.3 Thermoregulation involves adaptations that balance heat gain and loss
Behavioral responses
– Used by endotherms and ectotherms
– Examples
– Moving to the sun or shade
– Migrating
– Bathing
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25.3 Thermoregulation involves adaptations that balance heat gain and loss
Blood frombody corein artery
33°C
Blood frombody corein artery
Blood returningto body corein vein
Blood returning tobody corein vein
27°
18°
9°
35°
30°
20°
10°
OSMOREGULATION AND EXCRETION
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25.4 Animals balance the gain and loss of water and solutes through osmoregulation
Osmoconformers
– Have the same internal solute concentration as seawater
– Many marine invertebrates are osmoconformers
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Osmoregulators control their solute concentrations
Freshwater fishes
– Gain water by osmosis
– Excrete excess water
– Pump salt across their gills
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25.4 Animals balance the gain and loss of water and solutes through osmoregulation
Osmotic water gain through gillsand other parts of body surface
Uptake ofsalt bygills
Uptake ofsome ionsin food
Excretion oflarge amounts ofwater in diluteurine from kidneys
Saltwater fish
– Lose water by osmosis
– Drink seawater
– Pump out excess salt
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25.4 Animals balance the gain and loss of water and solutes through osmoregulation
Osmotic water loss
through gills and other
parts of body surface
Excretion of salt
from gills
Gain of water and
salt from food
and by drinking
seawater
Excretion of excess
ions and small
amounts of water
in scanty urine
from kidneys
Land animals
– Gain water by drinking and eating
– Lose water by evaporation and waste disposal
– Conserve water using
– Kidneys
– Behavior adaptations
– Waterproof skin
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25.4 Animals balance the gain and loss of water and solutes through osmoregulation
25.5 EVOLUTION CONNECTION: A variety of ways to dispose of nitrogenous wastes have evolved in animals
Nitrogenous wastes are toxic breakdown products of protein
Animals dispose of nitrogenous wastes in different ways
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Ammonia (NH3)
– Poisonous
– Soluble in water
– Easily disposed of by aquatic animals
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25.5 EVOLUTION CONNECTION: A variety of ways to dispose of nitrogenous wastes have evolved in animals
Urea
– Less toxic
– Easier to store
– Some land animals save water by excreting uric acid
– A virtually dry waste
– Urea and uric acid take energy to produce
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25.5 EVOLUTION CONNECTION: A variety of ways to dispose of nitrogenous wastes have evolved in animals
Nitrogenous bases
—NH2
Amino groups
Amino acids
Uric acid
Birds and many other
reptiles, insects, land
snails
Nucleic acidsProteins
Ammonia Urea
Mammals, amphibians,
sharks, some bony
fishes
Most aquatic animals,
including most fishes
25.6 The urinary system plays several major roles in homeostasis
The excretory system
– Expels wastes
– Regulates water balance
– Regulates ion balance
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Nephrons
– Functional units of the kidneys
– Extract a filtrate from the blood
– Refine the filtrate to produce urine
Urine
– Ureters drain the kidneys
– Stored in the urinary bladder
– Expelled through the urethra
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25.6 The urinary system plays several major roles in homeostasis
Animation: Nephron Introduction
Aorta
Inferiorvena cava
Renal pelvis
Ureter
Renal cortex
Renal artery and vein
Urinary bladder
Kidney
Ureter
Urethra
A The urinary system
Renal medulla
D Detailed structure of a nephron C Orientation of a nephron within the kidney
B The kidney
Renal cortex
Bowman’scapsule
To renalpelvis
Collectingduct
Renal artery
Renal vein
Tubule
Renal medulla
Bowman’scapsule
Arteriolefrom renalartery
Arteriolefromglomerulus
Glomerulus
Distaltubule
Proximal tubule
Branch ofrenal vein
Capillaries
Fromanothernephron
1
3
Loop of Henlewith capillarynetwork
2
Collectingduct
Aorta
Inferiorvena cava
Renal artery and vein
Urinary bladder
Kidney
Ureter
Urethra
Renal pelvis
Ureter
Renal cortex
Renal medulla
Renal cortex
Bowman’scapsule
To renalpelvis
Collectingduct
Renal artery
Renal vein
Tubule
Renal medulla
Bowman’scapsule
Arteriolefrom renalartery
Arteriolefromglomerulus
Glomerulus
Distaltubule
Proximal tubule
Branch ofrenal vein
Capillaries
Fromanothernephron
Loop of Henlewith capillarynetwork
Collectingduct
3
1
2
25.7 Overview: The key processes of the urinary system are filtration, reabsorption, secretion, and excretion
Filtration
– Blood pressure forces water and many small solutes into the nephron
Reabsorption
– Valuable solutes are reclaimed from the filtrate
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Secretion
– Excess H+
and toxins are added to the filtrate
Excretion
– The final product, urine, is excreted
Copyright © 2009 Pearson Education, Inc.
25.7 Overview: The key processes of the urinary system are filtration, reabsorption, secretion, and excretion
Filtration
H2O, other small molecules
Capillary
Nephron tubuleReabsorption Secretion
Urine
Interstitial fluid
Excretion
Reabsorption in the proximal and distal tubules removes
– Nutrients
– Salt
– Water
pH is regulated by
– Reabsorption of HCO3–
– Secretion of H+
25.8 Blood filtrate is refined to urine through reabsorption and secretion
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High NaCl concentration in the medulla promotes reabsorption of water
Antidiuretic hormone (ADH) regulates the amount of water excreted by the kidneys
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25.8 Blood filtrate is refined to urine through reabsorption and secretion
Animation: Bowman’s Capsule and Proximal Tubule
Animation: Collecting Duct
Animation: Effect of ADH
Animation: Loop of Henle and Distal Tubule
Blood
Proximal tubule
Some
drugs
and poisons
HCO3–
Nutrients
Medulla
Bowman’scapsule
Cortex
H+
NaCl
H2O
H2O
NaCl
HCO3–
H+
Urea
Glucose
Amino acids
Some drugs
Filtrate composition
NaCl
H2O
NaCl
NaCl H2O
NaClH2O
HCO3–
H+K+
Distal tubule1
2
3
Reabsorption
Secretion
Filtrate movement
Loop ofHenle
Collectingduct
Urea
Urine (to renal pelvis)
Compensating for kidney failure
A dialysis machine
– Removes wastes from the blood
– Maintains its solute concentration
25.9 CONNECTION: Kidney dialysis can be a lifesaver
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Line from arteryto apparatus
Pump Tubing made of aselectively permeablemembrane
DialyzingsolutionLine from
apparatusto vein
Fresh dialyzingsolution
Used dialyzingsolution(with urea andexcess ions)
33°C
27°
18°
9°
35°
30°
20°
10°
FreshwaterFish
Land Animal
Saltwater Fish
Osmosis
Gain water Lose water
Excretion Pump in
Salt
Drinking Osmosis Excrete,pump out
Drinking,eating
Evaporation,urinary system
Urea
Bladder
Ureter
Kidney
(a) (b) (c)
(d)(e)
(f)
(g)
(h)(i)
water and
solutes
endotherm
involves processes of
human
kidney
Homeostasis
animal may
be
maintains
balance ofboth done by
requirements
depend on
mechanisms
mostly mechanisms
include
heat production,
insulation,
countercurrent
heat exchange
may be
ocean, fresh water,
land
reproduction
(where embryo
develops)
depends on
nitrogenous
wastes
involves
removal of
form may be
Bowman’scapsule
To renalvein
From renalartery
(a) (b)
Loop of Henle
Glomerulus
Tubule
Capillaries
Collecting duct
(d)
(c)
1. Explain how bear physiology adjusts during dormancy
2. Describe four ways that heat is gained or lost by an animal
3. Describe five categories of adaptations that help animals thermoregulate
4. Compare the osmoregulatory problems of freshwater fish, saltwater fish, and terrestrial animals
You should now be able to
Copyright © 2009 Pearson Education, Inc.
5. Compare the three ways that animals eliminate nitrogenous wastes
6. Describe the structure of the human kidney
7. Explain how the kidney promotes homeostasis
8. Describe four major processes that produce urine
9. Describe the key events in the conversion of filtrate into urine
Copyright © 2009 Pearson Education, Inc.
You should now be able to