Biology Concepts and Connections Chapter 25
Chapter 25
Control of Body Temperature and Water Balance
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Lecture by Edward J. Zalisko
Copyright © 2009 Pearson Education, Inc.
Introduction: Chilling Out
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
Copyright © 2009 Pearson Education, Inc.
Introduction: Chilling Out
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
Copyright © 2009 Pearson Education, Inc.
THERMOREGULATION
Copyright © 2009 Pearson Education, Inc.
25.1 An animal’s regulation of body temperature helps maintain homeostasis
Thermoregulation
– The process by which animals maintain an internal temperature within a tolerable range
Copyright © 2009 Pearson Education, Inc.
25.1 An animal’s regulation of body temperature helps maintain homeostasis
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
Copyright © 2009 Pearson Education, Inc.
25.2 Heat is gained or lost in four ways
Heat exchange with the environment may occur by
– Conduction – Convection – Radiation – Evaporation
Copyright © 2009 Pearson Education, Inc.
Radiation Convection Evaporation
Conduction
25.3 Thermoregulation involves adaptations that balance heat gain and loss
Five general
Control of Body Temperature and Water Balance
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Lecture by Edward J. Zalisko
Copyright © 2009 Pearson Education, Inc.
Introduction: Chilling Out
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
Copyright © 2009 Pearson Education, Inc.
Introduction: Chilling Out
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
Copyright © 2009 Pearson Education, Inc.
THERMOREGULATION
Copyright © 2009 Pearson Education, Inc.
25.1 An animal’s regulation of body temperature helps maintain homeostasis
Thermoregulation
– The process by which animals maintain an internal temperature within a tolerable range
Copyright © 2009 Pearson Education, Inc.
25.1 An animal’s regulation of body temperature helps maintain homeostasis
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
Copyright © 2009 Pearson Education, Inc.
25.2 Heat is gained or lost in four ways
Heat exchange with the environment may occur by
– Conduction – Convection – Radiation – Evaporation
Copyright © 2009 Pearson Education, Inc.
Radiation Convection Evaporation
Conduction
25.3 Thermoregulation involves adaptations that balance heat gain and loss
Five general