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Questions and Answers
What is polydipsia?
What is polydipsia?
What is polyuria?
What is polyuria?
What do pd and pu indicate?
What do pd and pu indicate?
Both appear consistently in several polysystemic disorders.
Polydipsia usually results from primary _____________
Polydipsia usually results from primary _____________
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What is the 1st basic principle mentioned?
What is the 1st basic principle mentioned?
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What does the 2nd basic principle address?
What does the 2nd basic principle address?
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What is thirst defined as?
What is thirst defined as?
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Where is the Antidiuretic hormone control center located?
Where is the Antidiuretic hormone control center located?
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Primary thirst is well understood.
Primary thirst is well understood.
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Secondary thirst is well understood.
Secondary thirst is well understood.
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What are dipsenogenic compounds?
What are dipsenogenic compounds?
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What is pathologic thirst caused by?
What is pathologic thirst caused by?
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What is a potential cause of neuronal irritation leading to pathologic thirst?
What is a potential cause of neuronal irritation leading to pathologic thirst?
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What is compulsive water drinking associated with?
What is compulsive water drinking associated with?
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What is hypercalcemia associated with?
What is hypercalcemia associated with?
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What constitutes the renal concentrating mechanism?
What constitutes the renal concentrating mechanism?
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What happens when extracellular fluid osmolality increases?
What happens when extracellular fluid osmolality increases?
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Isosthenuric refers to glomerular filtrate with a specific gravity equal to plasma, which is __________ to __________.
Isosthenuric refers to glomerular filtrate with a specific gravity equal to plasma, which is __________ to __________.
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What does iatrogenic mean?
What does iatrogenic mean?
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What are some disorders that produce polydipsia and polyuria?
What are some disorders that produce polydipsia and polyuria?
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What are some diseases that cause polyuria by affecting renal concentrating mechanisms?
What are some diseases that cause polyuria by affecting renal concentrating mechanisms?
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How many types of diabetes insipidus are there?
How many types of diabetes insipidus are there?
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What causes diabetes mellitus?
What causes diabetes mellitus?
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What is hyperadrenocorticism characterized by?
What is hyperadrenocorticism characterized by?
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Study Notes
Polydipsia
- Defined as excessive thirst that persists over long periods, leading to constant drinking.
- A symptom commonly associated with various medical conditions affecting water homeostasis.
Polyuria
- Characterized by the passage of a large volume of urine over a specific time frame, typically with decreased specific gravity (SG).
- Often results in abnormal excessive urination.
Polydipsia and Polyuria Relationship
- Both symptoms consistently appear in several polysystemic disorders, indicating disturbances in water regulation.
Primary Causes
- Polydipsia generally results from primary polydipsia conditions, which may lead to excessive thirst and urination.
Basic Principles
- The balance of water intake and output is crucial (water in = water out).
- Overhydration and dehydration need to be managed, affecting intracellular fluid levels.
Thirst Mechanism
- Thirst is a physiological desire for water, controlled by the hypothalamus, serving as a stimulus to drink.
Antidiuretic Hormone (ADH) Control
- The control center for ADH, responsible for managing fluid balance, is adjacent to the thirst center and responds to extracellular fluid osmolality.
Primary Thirst (PD)
- Well-understood, often triggered by intracellular dehydration and changes in blood volume, influencing thirst and ADH secretion.
Secondary Thirst (PD)
- Poorly understood and anticipates water needs before deficiencies arise; more common than primary thirst causes.
Dipsenogenic Compounds
- Renin and Angiotensin play a role in stimulating thirst through direct actions on neurons in the thirst center, influenced by certain diseases.
Pathologic Thirst
- Defined as primary polydipsia resulting from conditions like neuronal irritation, compulsive drinking, increased plasma renin, and hypercalcemia.
Neuronal Irritation Causes
- Hypothalamic tumors, trauma, or inflammation can lead to disturbances that trigger thirst.
Compulsive Water Drinking
- Often associated with psychological factors like anxiety or boredom, leading to non-physiological thirst responses.
Hypercalcemia Causes
- Conditions like cancer or kidney disease, resulting in mineral imbalances, can contribute to pathologic thirst.
Renal Concentrating Mechanism
- In a typical 25 lb dog, approximately 68 liters of fluid are filtered daily by the glomeruli, with less than 500 ml excreted as urine.
ADH Osmoreceptor Control System
- ADH is produced by specialized neurons and stored in nerve endings, responding to increased extracellular fluid osmolality by enhancing water reabsorption.
Countercurrent System
- Loops of Henle facilitate water reabsorption along concentration gradients, effectively reducing osmolality.
Isosthenuric Urine
- Refers to urine with a specific gravity similar to plasma (1008 to 1012), indicating renal abnormalities if more concentrated urine is expected.
Iatrogenic Factors
- Conditions or symptoms induced by human actions, generally drug-related.
Disorders Inducing Polyuria and Polydipsia
- A variety of disorders can disrupt tubular function, leading to these symptoms, including diabetes insipidus and mellitus.
Diseases Affecting Renal Concentrating Mechanisms
- Conditions that stimulate primary polydipsia and lead to polyuria include diabetes insipidus, diabetes mellitus, hyperadrenocorticism, and several others.
Diabetes Insipidus
- Two types exist: neurogenic (due to neural injury causing ADH deficiency) and nephrogenic (due to unresponsiveness of tubules to ADH).
Diabetes Mellitus
- characterized by insulin deficiency leading to hyperglycemia and glucosuria, which increases absorbable solute levels and may be tested with dipsticks.
Hyperadrenocorticism
- Involves increased glucocorticoid production, inhibiting ADH in collecting ducts, often associated with Cushing’s disease symptoms.
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Explore key terms related to polydipsia and polyuria with these flashcards. Learn their definitions and how they relate to various polysystemic disorders. Perfect for students or healthcare professionals looking to enhance their understanding of these conditions.
