Disorders of Appetite Flashcards
Define Polydipsia
Excessive thirst or excess drinking
Define Adipsia
Inappropriate lack of thirst, with consequent failure to drink to correct hyperosmolarity
Describe Anorexia
Lack or loss of appetite for food
Describe Obesity
abnormal or excessive fat accumulation tht presents a risk to health
What are the two main types of both polydipsia and adipsia?
Primary and Secondary
Which is more common Primary or secondary polydipsia?
Secondary
How does ADH regulate osmolality?
Antidiuretic hormone (ADH) or vasopressin
Acts on the kidneys to regulate the volume & osmolality of urine
Collecting duct - Aquaporin 2 channel
When plasma ADH is low a large volume of urine is excreted (water diuresis)
When plasma ADH is high a small volume of urine is excreted (anti diuresis).
What are Chronic medical conditions that can cause Secondary Polydipsia?
Diabetes insipidus & mellitus Kidney failure Conn’s syndrome (primary aldosteronism) Addison's disease (hypoadrenocorticism) Sickle cell anaemia
Which medications can cause Secondary Polydipsia?
Diuretics
Laxatives
Both result in dehydration
Antidepressants
What can cause dehydration?
Acute illness Sweating Fevers Vomiting Diarrhoea Under hydration
What are the causes of Primary Polydipsia?
Mental illness - psychogenic polydipsia (or acquired) Schizophrenia Mood disorders - depressionandanxiety Anorexia Drug use Braininjuries Organic brain damage
Why is Polydipsia a problem?
Kidney and bone damage Headache Nausea Cramps Slow reflexes Slurred speech Low energy Confusion Seizures
How does Adipsia work?
Increased Osmolality of urine
Stimulates secretion of ADH
Water retention
Sensation of thirst decreases
What are the 4 types of Adipsia?
A (most common), B, C, D,.
How is ADH secreted?
Cells shrink when plasma is more concentrated. Proportion of cation channels increases. Membrane depolarises sending signals to the ADH producing cells to increase ADH. Fluid retention involves drinking
