1 Intracellular fluid (2/3 of body water). 2  Per Guyton, in a body containing 40 litres of fluid, about 25 litres is intracellular, which amounts to 62.5% (5/8), close enough to the 2/3 rule of thumb. 3  Jackson's texts states 70% of body fluid is intracellular. 4  Extracellular fluid (1/3 of body water).
However, if you provided support to your brother, depending on the level of support and your brotherâs gross income for 2010, you may be able to claim him as a dependent on your tax return (under the qualifying relative rules).
The sibling who claims the parent as a dependent must fill out IRS Form 2120 and file it with his or her tax return: IRS Form 2120: Multiple Support Declaration (pdf). Medical deductions. Even if you can't claim your mom as a dependent, you may still get a tax break for helping pay her medical costs. The IRS lets taxpayers deduct money spent on a parent's health care, even if the parent doesn't qualify as a dependent.