Homeostasis in Desert Reptiles - Index of

scans.hebis.de

Homeostasis in Desert Reptiles - Index of

S. Donald Bradshaw

Homeostasis

in Desert Reptiles

With 62 Figures and 40 Tables

Springer


Contents

Introduction 1

1 The Osmotic Anatomy of the Reptiles 9

1.1 Evidence for Homeostasis 9

1.2 A Comparative Account 9

1.3 Water and Electrolytes in Reptiles as a Group 12

1.4 Conclusions 12

2 Water and Electrolyte Homeostasis 21

2.1 Basic Concepts 21

2.2 The Maintenance of Homeostasis 23

2.2.1 Regulatory Responses 24

2.2.2 The Concept of Stress 25

2.3 Effector Systems 25

2.3.1 Kidney Morphology 26

2.3.2 Derivation of Renal Parameters 28

2.3.3 The Cloacal-Colonic Complex in Reptiles 31

2.3.4 The Cephalic Salt-Secreting Glands 32

2.4 Osmoregulation in Crocodiles,

Alligators and Chelonians 33

2.4.1 Extent of Environmental Exchange 33

2.4.2 Kidney and Cloaca 34

2.4.3 Salt-Excreting Glands 35

2.4.4 Desert Tortoises 35

2.5 Osmoregulation in Lizards 39

2.5.1 Hypernatraemia and Hyperkalaemia in Lizards 39

2.5.2 Studies of the Agamid Genus Amphibolurus

(Ctenophorus and Pogona) in Australia 40


X Contents

2.5.3 The Desert Iguana (Dipsosaurus dorsalis)

in North America 52

2.5.4 The Chuckwallas (Sauromalus obesus

and S. hispidus) 55

2.5.5 Two Saharan Lizards: Le Fouette-Queue

(Uromastix acanthinurus) and the Varanid

Varanus griseus 58

2.5.6 The Mountain or Thorny Devil

(Moloch horridus) 65

2.6 Osmoregulation in Snakes 67

2.7 Conclusions 70

3 Activity and Hormonal Control of Excretory Organs ... 73

3.1 Avant Propos 73

3.2 The Kidney 74

3.2.1 Renal Clearances and the Handling

of Water and Solutes 74

3.2.2 Neurohypophysial Hormones 79

3.2.3 Adrenocortical Hormones 88

3.2.4 Localisation of Action of Arginine Vasotocin

in Kidney Tubules 95

3.3 The Cloacal-Colonic Complex 99

3.4 Cephalic Salt-Secreting Glands 107

3.5 Conclusion 120

4 Thermal Homeostasis 123

4.1 Generalities 123

4.2 The Interpretation of Field Studies 124

4.3 Physiological Mechanisms 126

4.3.1 Metabolic Characteristics of Ectotherms 126

4.3.2 Sources of Heat Production in Reptiles 126

4.3.3 Thermal Hysterisis and Changes

in Dermal Vascularity 130

4.3.4 Panting and Evaporative Heat Loss 136

4.3.5 The Pineal Eye and Photoperiod 139

4.3.6 Hormonal Influences on Thermoregulation 141


Contents XI

4.4. Behavioural Mechanisms 147

4.4.1 The Neuronal Basis for Thermoregulation 147

4.4.2 Maintenance of Thermal Homeostasis

in the Field 151

4.5 Conclusion 163

5 Conclusion 167

References 175

Subject Index 199

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