BRAINCAKEDiabetes Insipidus
Diabetes insipidus is a condition in which the kidneys cannot conserve water, so the person produces very large volumes of dilute urine (up to about 20 dm3 per day, compared with about 1.5 dm3 normally) and feels extremely thirsty. Unlike diabetes mellitus, the urine contains no glucose; 'insipidus' means tasteless.
It is caused by a failure of the ADH system. There are two main types:
• Cranial (central) diabetes insipidus: the hypothalamus or posterior pituitary does not make or release enough ADH. It can be caused by a head injury, a tumour, surgery or infection. With little ADH, few aquaporins are inserted into the collecting duct walls.
• Nephrogenic diabetes insipidus: enough ADH is released, but the kidneys do not respond to it. This may be due to faulty ADH receptors or faulty aquaporins, often caused by a gene mutation, or to some drugs such as lithium.
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Key terms in this lesson
- desmopressin
- A synthetic form of ADH used to treat cranial diabetes insipidus.
More in Homeostasis
- Control of Osmoregulation
- ADH
- Negative Feedback Control
- Extra Feedback
- Thermoregulation
- Losing or Gaining Heat
- Control of Body Temperature
- Endotherms
All 41 lessons in Homeostasis · All Edexcel A-level Biology topics