Anti-diuretic hormone (ADH)
The water content of the blood is controlled by a hormone called anti-diuretic hormone (ADH). Different amounts of ADH are released into the bloodstream by a gland in the brain according to the concentration of the The liquid part of the blood containing useful things like glucose, amino acids, minerals, vitamins (nutrients) and hormones, as well as waste materials such as urea..
The concentration of the blood can be altered by:
- excess drinking (increases water content)
- excess sweating (decreases water content)
- consumption of salty foods (decreases water content)
These diagrams show what happens when there is either too little or too much water in the blood.
| Plasma | Problem | ADH release | Effect of ADH | Effect on urine |
| High concentration | Too little water | Increases | More water reabsorbed by nephrons | More concentrated |
| Low concentration | Too much water | Decreases | Less water reabsorbed by nephrons | More dilute |
| Plasma | High concentration |
|---|---|
| Problem | Too little water |
| ADH release | Increases |
| Effect of ADH | More water reabsorbed by nephrons |
| Effect on urine | More concentrated |
| Plasma | Low concentration |
|---|---|
| Problem | Too much water |
| ADH release | Decreases |
| Effect of ADH | Less water reabsorbed by nephrons |
| Effect on urine | More dilute |
This type of control is an example of Mechanism to lower raised levels of something, and to raise reduced levels of something.. It keeps the concentration of the blood plasma approximately constant.