Thirst

At one time or another, everyone has said "I am thirsty". Yet what causes this sensation of thirst? It is obvious that a certain quantity of fluid must be present for the body to function normally. How does a water deficit in the body then influence drinking habits? But supposing the physiological need is met, what about the psychological need or social need? Water is certainly the most necessary fluid; then why do we humans often prefer other beverages, even at great cost of effort or money or health? The subject of thirst and drinking behavior are uniquely discussed in this book. For the first time both the physiological and the psychological aspects of water and beverage consumption are examined in one volume. The many recent developments concerning how a lack of water is signalled physiologically and processed neurally to affect drinking behavior are critically surveyed. Prospects for understanding the cultural and sensory influences on beverage consumption are mapped out. The thirty-one chapters by authorities in the field were all mutually reviewed and revised in the light of precirculated comments and round-table discussions. Together they provide a complete picture of the current state of knowledge on what determines fluid consumption in human beings and animals.

Contenu

Section I. Perspectives on Thirst.- 1. Evolution of Physiological and Behavioural Mechanisms in Vertebrate Body Fluid Homeostasis.- Body Fluid Homeostasis.- Homeostatic Adaptations.- Phylogeny of Homeostasis in Vertebrates.- Fish.- Amphibia.- Reptiles.- Birds.- Mammals.- Drinking as a Homeostatic Adaptation.- Two Homeostatic Constants, Osmolality and Extracellular Volume, and the Two Thirsts Resulting When these Deviate from Normal.- Drinking Behaviour in Submammalian Vertebrates.- Drinking Behaviour in Mammals.- Receptors for Thirst Induced by Cellular Dehydration.- Receptors for Thirst Induced by Extracellular Dehydration.- Hormones, Neurotransmitters and Other Humoral Factors in Drinking Behaviour.- Conclusions.- 2. Water: Distribution Between Compartments and its Relationship to Thirst.- Fluid Compartments.- Extracellular and Intracellular Fluid Compartments.- Interstitial and Plasma Compartments.- The Hypothalamus and Thirst.- Regulation of Plasma Osmolality.- Dehydration Natriuresis.- Reduction of Extracellular Fluid Volume.- Interaction of Cellular and Extracellular Dehydration.- Summary.- Commentary.- 3. The Ontogeny of Drinking.- Issues in the Development of Drinking.- The Ontogeny of Ingestive Responses to Dehydration.- Infant Mammals are Highly Vulnerable to Fluid Loss, Yet.- Yet Suckling Behaviour is not Stimulated by Dehydration.- If Drinking Doesn't Come from Suckling, Where Does it Come From?.- Dehydration Modulates Early Oromotor Responses.- Maturation of Responses to Dehydration Stimuli.- The Normal Emergence of Drinking in Rodents.- Weaning in Other Species.- Opportunities of Ontogenetic Analysis: Behavioural and Neurobiological.- Commentary.- 4. Influences on Human Fluid Consumption.- Scientific Study of Thirsty Behaviour.- Sensations, Signals and Behavioural Neuroscience.- Drinking Behaviour, Thirst Ratings and Fluid Volumes.- Controls of Human Fluid Intake.- Influences on Daily Water Intake.- Temporal Pattern of Drinks.- The Single Drink.- Quantitating Causes of Drinking.- Integration Among Discrete Influences on Drinking.- An Outline Causal System of Thirst.- Sensory Sensitivity of Drinking.- The Tolerance Triangle.- Somatic Sensitivity of Drinking.- Social Sensitivity of Drinking.- Individual Analysis of Sensory and Social Interactions.- Thirst and Hunger.- Fluid Foods not Affecting Eating.- Commonalities of Hunger and Thirst.- Origins of Influences on Human Fluid Consumption.- Learned Preferences for Fluids.- Learned Water-Specific Dietary Selection.- Learned Control of Fluid Intake Volume.- Is Control of Human Fluid Intake Entirely Acquired?.- Summary.- Commentary.- Section II. Physiological Influences on Drinking.- 5. Osmoreceptors for Thirst.- Osmoregulatory Responses.- Cellular Dehydration and Thirst.- Location of the Osmoreceptors.- Osmoreceptors in the Brain.- Sites in the CNS.- Osmoreceptors and/or Sodium Sensors.- Evidence for Sodium Receptors.- Criticisms of the Sodium Receptor Hypothesis.- Summary.- Physiological Significance of Osmoreceptors.- Commentary.- 6. Volume Receptors and the Stimulation of Water Intake.- Integrated Responses to Acute Hypovolaemia.- Restoration of ECF Volume.- Evidence for Reflex Stimulation of Drinking.- Receptors Mediating Reflex Effects on Drinking.- Evidence for Ang II Stimulation of Drinking.- Blockade of the Renin-Angiotensin System and Hypovolaemic Drinking.- Effect of SFO Ablation.- Effect of Nephrectomy on Hypovolaemic Drinking.- Is Either the Reflex or the Ang II Stimulus to Drink Essential?.- Dehydration as a Stimulus to Drinking.- Contribution of Osmotic and Volaemic Factors to Dehydration-Induced Thirst.- Does Ang II Contribute to Dehydration-Induced Drinking?.- Atrial Natriuretic Peptides and Drinking.- Concluding Remarks.- Commentary.- 7. Hormonal Inputs to Thirst.- Hormones: Their Access to the Thirst System and Their Mechanism of Action.- Hormones: General Comments.- Access of the Blood-Borne Hormones to the Thirst System.- Site and Mechanism of Action.- Evidence Suggesting Involvement of a Hormone in the Control of Thirst.- Renin-Angiotensin System (RAS).- Peripheral and Brain Renin-Angiotensin System.- Site and Mechanism of Action.- Regulatory Significance of Dipsogenic Properties of Ang II.- Vasopressin.- Effect of Peripheral and Central VP on Water Intake.- Site and Mechanism of Action.- Physiological and Pathophysiological Significance.- Other Hormones.- Atrial Natriuretic Peptide.- Tachykinins (TCKs).- Oxytocin.- Neuropeptide Y.- Corticotropin Releasing Factor and Pro-opiomelanocortin Derived Peptides. Opioid Peptides.- Other Peptide Hormones.- Steroid Hormones.- Thyroid Hormones.- Summary.- 8. Mineral Appetite: An Overview.- Overview of Mineral Appetite.- Species Differences.- Sodium Appetite is Innate.- The Mechanism of Evocation of Sodium Appetite: General Considerations.- Experiments to Determine the Effect of Changes in Sodium Concentration of Brain ECF and Intracellular Fluid on Sodium Appetite and Thirst.- Renin-Angiotensin System in the Brain.- Commentary.- Section III. Neural Pathways of Water Deficit Signals.- 9. Central Projections of Osmotic and Hypovolaemic Signals in Homeostatic Thirst.- Mechanisms of Afferent Signalling in the Control of Drinking.- The Distribution of Receptors and Nature of Afferent Signalling in the Monitoring of Body Fluid Status.- The Interaction of the Facilitatory and Inhibitory Influences in Deprivation-Induced and Experimental Thirsts.- Mechanisms of Central Integration and Thirst.- The Integrative Role of the SFO/AV3V.- Hindbrain Mechanisms in the Control of Fluid and Electrolyte Balance.- Summary and Conclusions.- 10. Neurochemistry of the Circuitry Subserving Thirst.- The Role of Angiotensin II in the Initiation of Thirst.- Central Angiotensinergic Pathways.- Central Production of Angiotensin II.- Neural Circuits Containing Angiotensin II.- Angiotensin Receptors and Their Involvement in the Circuitry of Thirst.- Correlation of Angiotensin Receptors with Angiotensin-Containing Pathways.- Other Peptides and Monoamines Involved in Thirst.- Catecholamines - Lateral Hypothalamus.- Acetylcholine.- Prostaglandins.- Tachykinins.- Angiotensin Fragments.- Summary.- 11. Central Control of Water and Sodium Chloride Intake in Rats During Hypovolaemia.- Hypovolaemia.- Interaction of Neural and Endocrine Signals.- Integrative Function of Paraventricular Nucleus.- Osmotic Dehydration.- Hypovolaemia.- Stress.- Other Elements in Central Neural Control.- Summary and Conclusions.- Commentary.- 12. Rostro-Sagittal Brain: Site of Integration of Hydrational Signals in Body Fluid Regulation and Drinking.- Evolution of Ideas.- Integration of Neural and Humoral …