The cerebrum is the largest part of the brain and is responsible for all voluntary activities of the body. It is the substances can move readily between the inside and the outside of the vessel. In the brain, however, the endothelial cells fit tightly together and substances cannot pass out of the bloodstream.
The functions of the BBB are to protect the brain from "foreign substances" in the blood that may injure the brain and to protect it from the hormones and neurotransmitters in the rest of the body. The BBB also maintains a constant environment for the brain.
Various conditions can cause a breakdown in the function of the BBB. These conditions are as follows:
• Hypertension (high blood pressure).
• Incomplete development of the BBB at birth.
• High concentrations of certain substances in the blood.
• Exposure to microwaves.
• Exposure to radiation.
• Infection.
• Trauma or injury to the brain.
The cerebrum is the functional area of language, personality, vision, memory, emotion, problem solving, initiative, inhibition, sense of smell, generalized and mass movements, motor skills, physical reaction, and libido (sexual urges).
The cerebrum is divided into two hemispheres, the left hemisphere and the right hemisphere. The three main areas of the brain are the cerebrum, the cerebellum, and the brain stem. Each region performs specific functions. The cerebrum, which includes the cerebral cortex, controls conscious activities, the cerebellum coordinates muscle movements, and the brain stem is responsible for vital body processes.
Sense of identity
Researchers have discovered that each side of the brain (hemisphere) is associated with different abilities.
Right Hemisphere Controls the left side of the body Creativity and artistic ability Left Hemisphere (the analytical hemisphere) Controls the right side of the body Produce and understand language Analytical and mathematical ability Finally, the cerebrum consists of two types of surfaces, an outer and an inner surface. The outer surface is called the cerebral cortex and consists of layers of neurons without myelin (fatty insulation). These layers appear to be gray in color and are therefore referred to as "gray matter". The inner surface is called the cerebral medulla, which consists of layers of myelinated neurons. The myelin is white and therefore these inner layers are referred to as "white matter".
Wednesday, November 18, 2009
Human Brain
The human brain is a complex organ that allows us to think, move, feel, see, hear, taste, and smell. It controls our body, receives information, analyzes information, and stores information (our memories).
The brain produces electrical signals, which, together with chemical reactions, let the parts of the body communicate. Nerves send these signals throughout the body.
The average human brain weighs about three pounds (1300–1400 grams). As a comparison, a half-gallon of water weighs about four pounds. The brain consists of gray matter (40%) and white matter (60%) contained within the skull. Brain cells include neurons and glial cells. Although the brain is only 2% of the body’s weight, it uses 20% of the oxygen supply and gets 20% of the blood flow. If brain cells do not get oxygen for 3 to 5 minutes, they begin to die.
The brain and spinal cord make up the central nervous system (CNS). The brain is connected to the spinal cord, which runs from the neck to the hip area. The spinal cord carries nerve messages between the brain and the body. The cells of the nervous system are quite fragile and need extensive protection from being crushed, infected by disease organisms, and other harm. The brain and spinal cord are covered by a tough, translucent membrane called the dura matter. Cerebrospinal fluid (CSF) is a clear, watery liquid that surrounds the brain and spinal cord and is also found throughout the ventricles (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts.
The cranium (the top of the skull) surrounds and protects the brain. The spinal cord is surrounded by vertebrae (hollow spinal bones) and also some muscles serve to pad and support
In the early 1900s, researchers discovered that when blue dye was injected into the bloodstream of an animal, all of the tissues and organs of the body turned blue except for the brain and spinal cord. This indicated that there was a special barrier that prevented some substances from entering the central nervous system through the bloodstream. This barrier is now called the blood brain barrier (BBB). The basic attributes of the BBB are as follows:
1. Large molecules do not pass through the BBB easily.
2. Lipid (fat) soluble molecules, such as barbiturate drugs, rapidly cross the BBB into the brain. However, low lipid soluble molecules do not.
3. Molecules that have a high electrical charge to them are slowed as they pass through the BBB.
The BBB is semi-permeable, which means it allows some materials to pass through it but prevents others from doing so. The smallest blood vessels in the body are called capillaries and are lined with endothelial cells. Endothelial tissue has small spaces between each individual cell so the spine. More subtly, the blood-brain barrier protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain. The brain has three main parts, the cerebrum, the cerebellum, and the brain stem. The brain is divided into regions that control specific functions.
The brain produces electrical signals, which, together with chemical reactions, let the parts of the body communicate. Nerves send these signals throughout the body.
The average human brain weighs about three pounds (1300–1400 grams). As a comparison, a half-gallon of water weighs about four pounds. The brain consists of gray matter (40%) and white matter (60%) contained within the skull. Brain cells include neurons and glial cells. Although the brain is only 2% of the body’s weight, it uses 20% of the oxygen supply and gets 20% of the blood flow. If brain cells do not get oxygen for 3 to 5 minutes, they begin to die.
The brain and spinal cord make up the central nervous system (CNS). The brain is connected to the spinal cord, which runs from the neck to the hip area. The spinal cord carries nerve messages between the brain and the body. The cells of the nervous system are quite fragile and need extensive protection from being crushed, infected by disease organisms, and other harm. The brain and spinal cord are covered by a tough, translucent membrane called the dura matter. Cerebrospinal fluid (CSF) is a clear, watery liquid that surrounds the brain and spinal cord and is also found throughout the ventricles (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts.
The cranium (the top of the skull) surrounds and protects the brain. The spinal cord is surrounded by vertebrae (hollow spinal bones) and also some muscles serve to pad and support
In the early 1900s, researchers discovered that when blue dye was injected into the bloodstream of an animal, all of the tissues and organs of the body turned blue except for the brain and spinal cord. This indicated that there was a special barrier that prevented some substances from entering the central nervous system through the bloodstream. This barrier is now called the blood brain barrier (BBB). The basic attributes of the BBB are as follows:
1. Large molecules do not pass through the BBB easily.
2. Lipid (fat) soluble molecules, such as barbiturate drugs, rapidly cross the BBB into the brain. However, low lipid soluble molecules do not.
3. Molecules that have a high electrical charge to them are slowed as they pass through the BBB.
The BBB is semi-permeable, which means it allows some materials to pass through it but prevents others from doing so. The smallest blood vessels in the body are called capillaries and are lined with endothelial cells. Endothelial tissue has small spaces between each individual cell so the spine. More subtly, the blood-brain barrier protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain. The brain has three main parts, the cerebrum, the cerebellum, and the brain stem. The brain is divided into regions that control specific functions.
About Alzheimer’s
There are several organizations dedicated to educating patients, families, and caregivers about Alzheimer’s, providing helpful insights into where to go for help and support. These organizations are listed in the Resources section of this book.
Researchers have been studying the AD brain, with all its complexities, since Alois Alzheimer presented his patient in 1907. Science is now closer to finding some answers about what may cause AD, and therefore gaining momentum on what may prevent or treat the disease.
The changes that occur in the brain in Alzheimer’s disease provide some background to the medications used in this disease. It is important to keep in mind that there is currently no definitive explanation as to why this disease process begins. First, it is essential to have some knowledge of the functions of the brain to understand Alzheimer’s and how the medications are developed and utilized.
Researchers have been studying the AD brain, with all its complexities, since Alois Alzheimer presented his patient in 1907. Science is now closer to finding some answers about what may cause AD, and therefore gaining momentum on what may prevent or treat the disease.
The changes that occur in the brain in Alzheimer’s disease provide some background to the medications used in this disease. It is important to keep in mind that there is currently no definitive explanation as to why this disease process begins. First, it is essential to have some knowledge of the functions of the brain to understand Alzheimer’s and how the medications are developed and utilized.
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