What is the role of sodium in the body?
Major cation involved in:
- maintaining plasma osmolality
- nerve and muscle function - ions needed for impulses
What is plasma osmolality?
The concentration of ions and chemical substances in body fluids
How are these ions lost from the body?
Urine and sweat
What is ADH?
A hormone that is produced by the hypothalamus in the brain and stored in the posterior pituitary gland
When is ADH released?
In response to high blood osmolality (high salt conc) or a decrease in blood volume
What does ADH do?
Trigger the kidneys to conserve and produce more concentrated urine - this then dilutes the blood and lowers osmolality to the normal range
What happens if there is too little ADH or the kidneys don’t respond to ADH?
Too much water is lost through the kidneys and the urine produced is more dilute than normal and the blood becomes more concentrated
What happens when the blood is too concentrated and the urine is too dilute?
Excessive thirst, frequent urination, dehydration and if not enough water is ingested to replace what is lost hypernatraemia can occur
