A low hemoglobin count can also be due to blood loss, which can occur because of: 1  Bleeding from a wound. 2  Bleeding in your digestive tract, such as from ulcers, cancers or hemorrhoids. 3  Bleeding in your urinary tract.  Frequent blood 1  donation. Heavy menstrual bleeding.
The brain is the control centre for your body and it sits in your skull at the top of your spinal cord. The brain has three main parts. 1  The cerebellum (say se-re-bell-um). The brain stem, that controls a lot of the 'automatic' actions of your body such as breathing and heart beat, and links the brain to the spinal cord and the rest of the body.
Functions of the BBB. The BBB has several important functions: 1  Protects the brain from foreign substances in the blood that may injure the brain. 2  Protects the brain from hormones and neurotransmitters in the rest of the body. Large molecules do not pass through the BBB easily. 2  Low lipid (fat) soluble molecules do not penetrate into the brain. 3  However, lipid soluble molecules, such as barbituate drugs, rapidly cross through into the brain. 4  Molecules that have a high electrical charge are slowed.