Studied by 0 people
Looks like no one added any tags here yet for you.
What is the osmotic pressure (osmolarity) of all water compartments of the body?
280-300 mOsm/kg
What is the target for osmoregulation?
Regulate the level of water, not regulate the number of osmoles
Where are osmoregulator located? How do they work?
Where
-hypothalamus
Function
-sense the change in size of cells caused by changes in osmolarity
What is the response of osmoregulators in the hypothalamus in response to cell shrinkage and swelling?
Shrinkage - hypertonicity
-increased production of ADH
Swelling - hypotonicity
-decreased production of ADH
What are the 2 important function of ADH?
Increases thirst sensation
Increases water retention in the kidney
When is there a difference between hyperosmolarity and hypertonicity?
When the increased osmolarity is due to increased levels of a substance that can enter cells freely
-urea, ethanol, methanol
What are 5 potential causes of hyperosmolarity and hypertonicity?
Excessive intake of salt
Excessive intake of other osmotically active substances
Diabetes mellitus
Diabetes inspidus
Loss of hypoosmolar fluid, eg. sweat
What is the response of the body to hyperosmolarity (3)?
Increases thirst
Increases ADH release
Potential decrease in aldosterone secretion
What does the consequence to hyperosmolarity depend on?
Whether the hyperosmolarity develops acutely or chronically
What happens in acute increase of osmolarity?
Brain cells shrink -> vessels stretch -> possible bleeding
What happens in a chronic increase of osmolarity?
Brain cells compensate by producing intracellular osmotically active substances, idiogenic molecules, that counteract the hyperosmolarity of the interstitium -> prevention of cells shrinkage
Why must chronic hyperosmolarity be corrected slowly?
To allow brain cells to get rid of the idiogenic osmoles, or else there will be swelling and brain edema
