What is the Brain?

Consciousness

Consciousness is a constellation of attributes of mind such as subjectivity, self-awareness, sentience, and the ability to perceive a relationship between oneself and one’s environment.

Unconsciousness

Unconsciousness is an alteration of mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is an illustration of unconsciousness.

Fainting due to a drop in blood pressure and a decrease of the oxygen supply to the brain is an illustration of a temporary loss of consciousness.

How and why do we dream?

Dreams have fascinated nearly everyone for thousands of years. There are two different schools of thought as to why we dream: the physiological school, and the psychological school. While many theories have been proposed, not single consensus has emerged as to why we dream.

Some researchers suggest that dreams serve no real purpose, while other believe that dreaming is essential to mental, emotional and physical well-being. One theory for dreaming suggests dreams serve to clean up clutter from the mind.

How does the brain control body temperature?

The Hypothalamus part of the brain regulates body temperature much like a thermostat. The hypothalamus knows what temperature your body should be (about 98.6 Fahrenheit or 37 Celsius), and if your body is too hot, the hypothalamus tells it to sweat. If you’re too cold, the hypothalamus makes you start shivering. Shivering and sweating helps get your body’s temperature back to normal.

Are humans born with all their brain cells?

Babies are born with around a 100 billion brain cells, but only a small number of neurons are actually connected. By three years of age a child’s brain has formed about 1,000 trillion connections, about twice as many as adults have. At around 11 years, the brain begins to prune unused connections. Connections that are used repeatedly in the early years become permanent; those that are not are eliminated. Hence the saying:“Use it, or lose it.”

How and why do we sleep?

We still don’t fully understand the importance of sleep. However, we do know that sleep is the time when the body does most of its repair work; muscle tissue is rebuilt and restored and tissue-building growth hormone is secreted during sleep. A good way to understand the role of sleep is to look at what happens when we don’t get enough sleep.

Are IQ tests accurate measures of intelligence?

First you need to define intelligence, a very hard task, think about it. Intelligence is an encompassing term. “We cannot measure intelligence when we have not defined it,” said journalist Walter Lippmann in the early 1920s.

According to most current definitions intelligence is made up of the skills of logical reasoning, problem solving, critical thinking, and adaptation.

IQ tests are not very reliable and the scores may vary as much as 15 points from one test to another. The average IQ scores for many populations have been rising at an average rate of three points per decade since the early 20th century with most of the increase in the lower half of the IQ range.

When is the brain considered dead?

Brain death is the irreversible end of all brain activity (including involuntary activity necessary to sustain life) due to total necrosis of the cerebral neurons following loss of blood flow and oxygenation. A brain-dead individual has no clinical evidence of brain function upon physical examination. This includes no response to pain and no cranial nerve reflexes.

Reflexes include pupillary response (fixed pupils), oculocephalic reflex, corneal reflex, no response to the caloric reflex test and no spontaneous respirations. The diagnosis of brain death needs to be rigorous to determine whether the condition is irreversible.

Legal criteria vary, but it generally requires neurological exams by two independent physicians. The exams must show complete absence of brain function, and may include two isoelectric (flat-line) EEGs 24 hours apart.

If tests show brain activity, the patient may be in a coma or vegetative state. A brain dead person doesn’t show brain activity. It is important to distinguish between brain death and states that may mimic brain death. Some comatose patients can recover, and some patients with severe irreversible neurologic dysfunction will nonetheless retain some lower brain functions such as spontaneous respiration, despite the losses of both cortex and brainstem functionality.

Thus, anencephaly, in which there is no higher brain present, is generally not considered brain death, though it is certainly an irreversible condition in which it may be appropriate to withdraw life support.

Today, both the legal and medical communities use ‘brain death’ as a legal definition of death. Using brain-death criteria, the medical community can declare a person legally dead even if life-support equipment keeps the body’s metabolic processes working.

Do brain supplements work in enhancing memory and brain power?

As we age our brain is more susceptible to memory loss and diseases such as Alzheimer’s disease. The functionality of the human brain can also be affected due to problems in nervous system or inadequate blood supply to the brain.

Interesting Brain Facts:

• The diameter of an individual brain neuron is just 4 microns thick, you could fit 30,000 neurons on the head of a pin.

• Your brain generates nearly 25 watts of power while you’re awake, which is enough to light up a light bulb.

• Alcohol interferes with brain processes by weakening connections between neurons.

• Every time you have a new thought, or recall a memory, a new brain connection is made between two or more brain cells.

• A living brain is so soft you could cut it with a table knife.

• Loss of oxygen for just 5 to 10 minutes can cause serious brain damage. The brain can stay alive for 4 to 6 minutes without oxygen. After that cells begin die.

• The average adult’s brain weighs 3 – 4 lbs. but consumes 20% of the bodys oxygen supply.

• The human brain contains around 400 miles of blood vessels.

• There is no sense of pain within the brain itself which explains why brain surgeons can probe areas of the brain even when the patient is awake.

• The left side of your brain (left hemisphere) controls the right side of your body; and, the right side of your brain (right hemisphere) controls the left side of your body.

• Your cerebral cortex is about as thick as a doctors tongue depressor and it grows thicker as you learn more.

• You will lose consciousness in 10 seconds after the loss of blood supply to the brain.

• Of all creatures on earth humans have the most complex brain.

• Differences in brain weight and size do not equal differences in mental ability.

• If stretched out the cerebral cortex would be 0.23 sq. m or 2.5 sq.ft.

• Average surface area of the cerebral cortex is 2,500 cm2 or 2.69 sq.ft.

• There are about 100 billion neurons in the human brain, the same number of stars in our galaxy.

[Courtesy: http://www.disabled-world.com/artman/publish/brain-facts.shtml]