Thirst: A drive stemming from a physiological need for WATER.Urination: Discharge of URINE, liquid waste processed by the KIDNEY, from the body.Urination Disorders: Abnormalities in the process of URINE voiding, including bladder control, frequency of URINATION, as well as the volume and composition of URINE.Toilet Training: Conditioning to defecate and urinate in culturally acceptable places.Generalization, Response: The principle that after an organism learns to respond in a particular manner to a stimulus, that stimulus is effective in eliciting similar responses.Defecation: The normal process of elimination of fecal material from the RECTUM.Urinary Retention: Inability to empty the URINARY BLADDER with voiding (URINATION).Urinary Bladder: A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.Cystitis, Interstitial: A condition with recurring discomfort or pain in the URINARY BLADDER and the surrounding pelvic region without an identifiable disease. Severity of pain in interstitial cystitis varies greatly and often is accompanied by increased urination frequency and urgency.Urinary Incontinence: Involuntary loss of URINE, such as leaking of urine. It is a symptom of various underlying pathological processes. Major types of incontinence include URINARY URGE INCONTINENCE and URINARY STRESS INCONTINENCE.Drinking: The consumption of liquids.Drinking Behavior: Behaviors associated with the ingesting of water and other liquids; includes rhythmic patterns of drinking (time intervals - onset and duration), frequency and satiety.Saline Solution, Hypertonic: Hypertonic sodium chloride solution. A solution having an osmotic pressure greater than that of physiologic salt solution (0.9 g NaCl in 100 ml purified water).Water Deprivation: The withholding of water in a structured experimental situation.Dehydration: The condition that results from excessive loss of water from a living organism.Hypernatremia: Excessive amount of sodium in the blood. (Dorland, 27th ed)Appetite: Natural recurring desire for food. Alterations may be induced by APPETITE DEPRESSANTS or APPETITE STIMULANTS.Water-Electrolyte Balance: The balance of fluid in the BODY FLUID COMPARTMENTS; total BODY WATER; BLOOD VOLUME; EXTRACELLULAR SPACE; INTRACELLULAR SPACE, maintained by processes in the body that regulate the intake and excretion of WATER and ELECTROLYTES, particularly SODIUM and POTASSIUM.Hypovolemia: An abnormally low volume of blood circulating through the body. It may result in hypovolemic shock (see SHOCK).Cardiovascular Physiological Processes: Biological actions and events that support the functions of the CARDIOVASCULAR SYSTEM.Diabetes Insipidus: A disease that is characterized by frequent urination, excretion of large amounts of dilute URINE, and excessive THIRST. Etiologies of diabetes insipidus include deficiency of antidiuretic hormone (also known as ADH or VASOPRESSIN) secreted by the NEUROHYPOPHYSIS, impaired KIDNEY response to ADH, and impaired hypothalamic regulation of thirst.Polyuria: Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes (DIABETES MELLITUS; DIABETES INSIPIDUS).Inappropriate ADH Syndrome: A condition of HYPONATREMIA and renal salt loss attributed to overexpansion of BODY FLUIDS resulting from sustained release of ANTIDIURETIC HORMONES which stimulates renal resorption of water. It is characterized by normal KIDNEY function, high urine OSMOLALITY, low serum osmolality, and neurological dysfunction. Etiologies include ADH-producing neoplasms, injuries or diseases involving the HYPOTHALAMUS, the PITUITARY GLAND, and the LUNG. This syndrome can also be drug-induced.Hemodialysis Solutions: Solutions prepared for hemodialysis. The composition of the pre-dialysis solution may be varied in order to determine the effect of solvated metabolites on anoxia, malnutrition, acid-base balance, etc. Of principal interest are the effect of the choice of buffers (e.g., acetate or carbonate), the addition of cations (Na+, K+, Ca2+), and addition of carbohydrates (glucose).Osmoregulation: The response of cells in sensing a difference in OSMOTIC PRESSURE between the inside and outside of the cell. This response includes signaling from osmotic sensors to activate transcription factors, which in turn regulate the expression of osmocompensatory genes, all functioning to maintain CELL VOLUME and the water concentration inside the cells.