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Human Brain

The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head.

The brain is an amazing three-pound organ that controls all functions of the body, interprets information from the outside world, and embodies the essence of the mind and soul. Intelligence, creativity, emotion, and memory are a few of the many things governed by the brain. Protected within the skull, the brain is composed of the cerebrum, cerebellum, and brainstem.

The brain receives information through our five senses: sight, smell, touch, taste, and hearing – often many at one time. It assembles the messages in a way that has meaning for us, and can store that information in our memory. The brain controls our thoughts, memory and speech, movement of the arms and legs, and the function of many organs within our body.

The central nervous system (CNS) is composed of the brain and spinal cord. The peripheral nervous system (PNS) is composed of spinal nerves that branch from the spinal cord and cranial nerves that branch from the brain.

The brain is composed of the cerebrum, cerebellum, and brainstem.

A side view illustration of the human brain, with areas labeled and colored

Cerebrum: is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement.

Cerebellum: is located under the cerebrum. Its function is to coordinate muscle movements, maintain posture, and balance.

Brainstem: acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing.

Right brain – left brain

The cerebrum is divided into two halves: the right and left hemispheres. They are joined by a bundle of fibers called the corpus callosum that transmits messages from one side to the other. Each hemisphere controls the opposite side of the body. If a stroke occurs on the right side of the brain, your left arm or leg may be weak or paralyzed.

Not all functions of the hemispheres are shared. In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.

Left and right hemispheres

The cerebrum is divided into left and right hemispheres. The two sides are connected by the nerve fibers corpus callosum.

Lobes of the brain

The cerebral hemispheres have distinct fissures, which divide the brain into lobes. Each hemisphere has 4 lobes: frontal, temporal, parietal, and occipital. Each lobe may be divided, once again, into areas that serve very specific functions. It’s important to understand that each lobe of the brain does not function alone. There are very complex relationships between the lobes of the brain and between the right and left hemispheres.

Lobes of the brain

Our brains allow us to process the world, understand everything around us, learn new things, and paradoxically, we’re still very unaware of how much of our own brains function. However, modern neuroscience and cognitive sciences have made great strides in understanding the effect our brains have on our everyday functions.

Pineal Gland

The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone from which it derived its name. The pineal gland is located in the epithalamus, near the center of the brain, between the two hemispheres, tucked in a groove where the two halves of the thalamus join. The pineal gland is one of the neuroendocrine secretory circumventricular organs in which there does not exist the blood–brain barrier at the capillary level.

10 Mysterious Facts About the Pineal Gland

1. IT’S BEEN RECOGNIZED AS IMPORTANT SINCE THE ANCIENT GREEKS.

Though the pineal gland wouldn’t be fully understood until the 20th century, descriptions of its anatomical location are included in the writings of Galen (ca. 130-ca. 210 CE), a Greek doctor and philosopher.

2. ITS SHAPE INFLUENCED ITS NAME.

This itty-bitty little gland, located very deep in the center of the brain, gets its name from its pinecone-like shape, most recently from the French (pinéal, or “like a pinecone”), itself from the Latin for pinecone (pinea). However, at about one-third of an inch long in adults, it’s smaller than your average pinecone.

3. THE PINEAL GLAND IS PART OF YOUR ENDOCRINE SYSTEM.

Though located in your brain, the pineal gland is actually a crucial part of your endocrine system, which regulates major bodily processes such as growth, metabolism, and sexual development through the release and control of hormones.

4. IT CONNECTS THE ENDOCRINE AND NERVOUS SYSTEMS.

The gland translates nerve signals from the sympathetic nervous system into hormone signals.

5. THE PINEAL GLAND WAS LONG CONSIDERED MYSTERIOUS.

Because the pineal gland was the last of the endocrine structures to be discovered, scientists considered it a mysterious organ. Today, we know that unlike much of the rest of the brain, the pineal gland is not isolated from the body by the blood-brain barrier system.

6. DESCARTES WAS WRONG ABOUT ITS RELATIONSHIP TO THE MIND, THE SOUL …

The 16th-century French philosopher and mathematician René Descartes was fascinated with the pineal gland, considering it “the place in which all our thoughts are formed.” Scientists now credit that function to the neocortex.

7. …AND TINY ANIMAL SPIRITS IN THE BRAIN.

Descartes thought that within the pineal gland, tiny animal spirits were like “a very fine wind, or rather a very lively and pure flame,” feeding life into the many small arteries that surround the gland. This was likely due to his abysmal understanding of anatomy and physiology.

8. IT’S BEEN CALLED THE “THIRD EYE.”

The pineal gland was commonly dubbed the “third eye” for many reasons, including its location deep in the center of the brain and its connection to light. Mystic and esoteric spiritual traditions suggest it serves as a metaphysical connection between the physical and spiritual worlds.

9. IN REALITY, IT PRODUCES A SINGLE—BUT KEY—HORMONE.

As scientists have learned more about the functions of the pineal gland, they’ve learned it synthesizes the hormone melatonin from the neurotransmitter serotonin. Melatonin production determines your sleep-wake cycles and is purely determined by the detection of light and dark. The retina sends these signals to a brain region known as the hypothalamus, which passes them on to the pineal gland. The more light your brain detects, the less melatonin it produces, and vice versa. Melatonin levels are highest at night to help us sleep.

10. MELATONIN IS ALSO CRITICALLY INVOLVED IN REPRODUCTION.

Melatonin inhibits the release of pituitary reproductive hormones, known as gonadotropins, from the pituitary gland, affecting male and female reproductive organs. In this way, melatonin—and therefore the pineal gland—regulates sexual development.

Here are 49 interesting facts and stories about the human brain that are sure to blow your mind

1. Nearly all colors have a physical wavelength associated with it, but the color Magenta doesn’t. Rather, your brain is simply processing the color as “not green.”

2. When you find yourself sleeping in a new environment for the first time, the brain processes danger and remains half-awake in order to be more aware.

3. According to researchers at UCLA, humans have been observed to have their first bout with anxiety or depression right after stomach illnesses. Utilizing brain scans, they found that patients who ate probiotics had their brains directly affected by the bacteria. All of their research suggests that stomach microbial health has a much greater effect on your brain than once thought.

4. A man by the name of Bruce Bridgeman spent nearly his entire life, 67 years, without the ability of depth perception, called stereoblindness. However, after being forced to purchase 3D glasses to watch the movie Hugo in theaters, his brain clicked and he was able to experience 3D vision.

5. A man in the UK had chronic hiccups for 2.5 years of his life and was told that it was likely caused by heartburn. After a Japanese TV show picked up the strange phenomena and paid for medical testing, a brain tumor was discovered. Once the man had the tumor removed, his chronic hiccups went away for good.

6. Blacking out from drinking is actually caused by the effect of alcohol on the hippocampus, the part of your brain responsible for memory. You’re not physically forgetting anything, rather your brain becomes incapable of storing and recording new memories.

7. We cry when we are very happy because our hypothalamus in our brain can’t distinguish the difference between strong happiness and strong sadness.

8. We get chills when we listen to music as a result of our brain releasing dopamine. When a song “moves” you, the anticipation from a peak moment in the song triggers this release.

9. Solitary confinement can actually cause extreme neurological damage to human brains. So much so that it can be seen on EEG scans and the brains of solitary prisoners have the same indicators as people who have had traumatic injuries.

10. While we sleep, our spinal fluid flows through the brain on the outside of the brain’s blood vessels. This removes brain cell waste, specific buildups of amyloid-beta protein. This only occurs during sleep and a buildup of the proteins that get cleaned has been linked to greater risks of Alzheimer’s.

11. A scientist by the name of Theodor Erismann created goggles that completely flip his vision. At first, he struggled with the flipped perception, but within just 5 days, his brain adapted to the change and he saw everything as normal. This type of adaptation is also well demonstrated by YouTuber “Smarter Every Day” who forgot how to ride a bike and relearned flipped his bike steering around, causing him to forget how to ride a bike and relearn in a reverse manner.

12. Alzheimer’s disease is caused by a resistance to insulin in the brain, causing many to refer to it as type 3 diabetes.

13. The world’s fastest supercomputer requires 24 million Watts of power to operate, but our brains only require 20 Watts and operate about 100,000 times faster.

14. Exercise slows our brains’ cognitive decline and increased physical activity over the norm can slow our brain’s aging by 10 years.

15. Human brains receive 20% of the total oxygen from our bodies even though they only represent 2% of our bodies’ weight.

16. Certain languages do not have terms for Left, Right, Front, Back, and rather use the terms North, South, East, West. People raised in these languages have been found to always know what direction they are oriented, resulting in a type of compass brain.

17. 73% of your brain is just water, which means that if you get dehydrated by more than 2%, you can suffer from a loss in attention, cognitive skills, and memory.

18. Babies’ brains grow rapidly. A 2-year-old baby will have an 80% fully grown brain. This rapid development is why paying close attention to your child’s development in the early years is so impactful to their ability as an adult.

19. Information transfer in our brain occurs at a rate equivalent to 260 miles per hour.

20. Yawning is actually a reaction that sends more oxygen to your brain. Reptiles, birds, and mammals all yawn and it’s controlled by neurotransmitters in the brain.

21. The cerebellum is the part of the brain responsible for posture, walking, and movement coordination. It is located in the back of the brain and weighs 150 grams.

22. The human brain is split into two sides, with each interacting with the opposite side of the body. While this interaction is known, the reason for it is still not understood.

23. Within your brain, there are 150,000 miles of blood vessels that carry blood and oxygen to various parts of the organ.

24. You can actually improve your memory if you choose to eat seafood regularly. The fatty acids in these foods improve the memory storing parts of your brain.

25. The human brain continues to develop until your late 40s. It is the only organ in the body that develops for this long of a time – and it sees more changes than any other organ as well.

26. Every second, there are 100,000 chemical reactions happening in the human brain.

27. Babies lose about half of their neurons before they are born. Referred to as pruning, this eliminates any brain neurons that don’t receive sufficient input from other areas of the brain.

28. Studies have found that when mothers speak to their babies, the children learned, on average, 300 more words by the age of 2.

29. EEGs or electroencephalograms is a non-invasive imaging technique that is used to record small changes of electrical activity in the brain. Utilizing surface electrodes on the scalp, scientists can study many aspects of the brain utilizing this technique. Tiny fluctuations in the EEG signals indicate whether a person is asleep, aroused, or somewhere in-between.

30. Researchers from Baylor University have discovered that children who are deprived of touch, play, and interaction with others have 20-30% smaller brains than what is normal for their age. Child abuse can thus inhibit brain development in a child and negatively affect their lifetime brain development.

31. The brain cannot experience pain. This allows neurosurgeons to probe areas within the brain while patients are awake. They can then get real-time feedback from each patient, allowing them to pinpoint particular regions, like for speech or movement.

32. The reaction of our pupils constricting when they are exposed to bright light is called the pupillary light reflex. This reflex is used by doctors to determine whether the reflex pathway to the brain has been disrupted. If one or both of your eyes fail to produce this reflex, then doctors can work to pinpoint the exact location of the disconnect.

33. 5% of the population of the world has epilepsy. However, it’s estimated that 1 in 10 people will have a seizure within their lifetime.

34. Scratching an itch is actually a strange biological response from a medical perspective. It seems to hinder the healing process rather than help it. Researchers believe that we itch because it stimulates the release of endorphins and natural opiates that block pain. Because scratching thus damages the skin, it causes a fresh rush of endorphins to help the pain.

35. Every time that you remember something, you, in turn, strengthen that memory in your brain. Whenever the neural pathways of a memory are exercised, your brain makes new connections. The older and more times a memory has been remembered, the stronger that memory is.

36. During sleep, your body produces a hormone that prevents you from getting up and acting out your dreams. Five minutes after a dream, your body has already forgotten half of it and ten minutes later it is 90% gone from your memory.

37. Our brains can compute 10 to the 13th and 10 to the 16th operations per second. That is equivalent to 1 million times the people on earth. In theory, brains are capable of solving problems faster than any computer in the world, perhaps better than any computer that will ever exist.

38. Good nutrition is incredibly important to brain health. Dieting can force the brain to start eating itself and malnourished fetuses or infants can suffer from cognitive and behavioral deficits. Babies need proper nourishment because their brains use up to 50% of their total glucose supply, another reason why they may need so much sleep.

39. Humans experience 70,000 thoughts each day.

40. Our sense of smell is the only sense that is directly linked to our limbic system. This part of the brain specializes in physical, emotional, and psychological responses. This all means that good smells can change our moods drastically in a snap.

41. A group of researchers studied London Taxi drivers and found that they had a larger hippocampus, the part of the brain responsible for memory. This suggests that the more you are forced to memorize, the larger this part of your brain grows.

42. Making music may actually have a quantifiable effect on our brain. When you hook up guitar players to electrodes, researchers discovered that brainwaves of musicians synchronize when they play duets.

43. The average weight of brains for men is 2.9 pounds and for women 2.6 pounds. However, that doesn’t correlate to higher intelligence. For example, Einstein’s brain weighed 2.7 pounds.

44. The brain is the only object in the world that can contemplate itself.

45. Chronic exposer to stress actually overloads your brain with hormones that are only intended for short-term emergency functions. In turn, that means that long-term exposure can kill brain cells.

46. Of people ages 1 to 44, traumatic brain injury is the leading cause of disability and death. Most commonly involved are falls, motor vehicle crashes, and assaults.

47. The average size of the human brain has decreased by 9 cubic inches over a period of the last 5000 years. Scientists aren’t exactly sure why.

48. Déjà vu hasn’t been fully explained. Scientists think that it’s actually a neurological glitch caused by something being registered in memory before conscious thought.

49. What seems like random light when you hit your head, is actually just jolts to brain cells responsible for vision. These visual “hallucinations” are just simple responses.

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