Anatomy And Physiology

Anatomy Physiology



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Interesting facts about the brain

The brain contains about 10 billion neurons, along with cells called glia, which support the neurons and help them do what they do.

Each neuron consists of a cell body, a long tendril called an axon, which is the “cable” down which the neurons sends signals to other neurons, and dendrites, which are “antennas” through which the neurons receives signals from other neurons.

Gray matter is where the neuron bodies live. White matter is where the axons run. White matter is white because the axons are wrapped in a fatty tissue called myelin, which insulates the axons electrically and helps them conduct signals. A variety of diseases, the most familiar being multiple sclerosis, can result when the myelin is disrupted.

 The lower parts of the brain are responsible for “housekeeping” functions such as regulating breathing, body temperature, and so forth. The outermost portion of the brain, called the cerebral cortex, is in charge of all “higher functions.” The right side of the brain controls the left side of the body, and vice versa. In right-handed people speech is run by the left side of the brain. The hypothalamus, one of those “lower” brain centers, controls the “4 Fs”: flight, fighting, feeding, and … reproduction.

Stroke is the third most common cause of death, and the leading cause of disability in the Western world. Stroke comes in two varieties: ischemic and hemorrhagic. Ischemic stroke (about 85% of all strokes are of this type) occurs when a blood vessel supplying blood to the brain gets blocked by a blood clot, and the tissue which depends on that blood for oxygen and glucose dies. Hemorrhagic stroke happens when a blood vessel bursts (usually at a weak point called an aneurysm) and blood spills into the brain. Symptoms of a stroke include paralysis, numbness, loss of speech, and loss of other senses such as vision. If someone has symptoms which suggest a stroke, it is vital to get them to the hospital as soon as possible because 1) the only real treatment that exists for ischemic stroke now has to be given within 4.5 hours of onset if it is to do more good than harm and 2) every minute, about 1.9 million neurons are dying.

Neurons talk to each other by releasing small bursts of chemicals called neurotransmitters. Some of the well known ones are serotonin, dopamine, GABA, glutamate, norepinephrine, and acetylcholine. Many of the drugs that affect our minds, both of the recreational variety and the pharmaceutical variety, have their effects by changing the way that neurotransmitters are handled – they may cause them to hang around longer, or amplify their effect in some other way.

The study of the brain, called neuroscience, is a very diverse field, and uses anatomy, genetics, physiology, and other methods. The largest conference in this field, the Society for Neuroscience, draws an annual crowd of tens of thousands of scientists.

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