We are searching data for your request:
Upon completion, a link will appear to access the found materials.
Everywhere I look online says the brain is about 60% fat. But when it comes to water, I see numbers like 70-75%. One webpage even makes both those claims back to back! That doesn't make any sense. So what is it, really?
Whenever you see a percentage, you should think "Percentage of what?". Not doing this is usually at the root of the trouble people get into with percentages.
The water and fat percentages mentioned in the question are certainly not percentages of the same thing. The sources of the figures should make clear what the percentage is of, but non-scientific writing quite often fails to do this.
In the paper "Lipid composition of the normal human brain", there is a table giving percentages of water and lipids (fats), and at the bottom of the table it says:
All values, except water, are expressed as a percentage of dry weight.
This is a common approach, as, for example in this table from a textbook the lipid percentages are also given as percent of dry weight. This is convenient because water is such a large part of most organisms, and also dry weight is what is usually measured in the laboratory.
Thus the water percentages you are seeing are presumably percentages of total weight, and the fat percentages are percentage of dry weight. You can convert the latter to percent of total weight by multiplying by the dry percentage of the brain, which is what is left when you subtract the water percentage from 100%.
Thus, assuming say 73% of total brain weight is water, the 60% fat figure would translate to about 16% of total brain weight is fat.
mgkrebbs is totally right. It's standard in biology to evaporate the water to get the wet/dry weight, and then to see for the rest. This study is old so it may lack accuracy:
Fatty Acids and the Aging Brain
Alyssa Bianca Velasco , Zaldy S. Tan , in Omega-3 Fatty Acids in Brain and Neurological Health , 2014
Fatty Acid Composition of the Brain
The lipid composition of the brain is unique from other tissues in the body. More than half of the solid matter in the brain is composed of membrane lipids ( O’Brien, 1986 ), which in turn are predominantly composed of phospholipids ( Crawford and Sinclair, 1972 ). Svennerholm (1968) studied human brain material from a range of developmental stages in order to understand the changes that occur in brain fatty acid composition throughout the lifespan. The results showed that the concentration of brain phosphoglycerides was age-dependent. The concentration of the linoleate family of fatty acids, which includes omega-6 PUFAs, decreased while the linolenic family of fatty acids, which includes omega-3 PUFAs, increased in aging brains ( Svennerholm, 1968 ).
The alteration of the specific pattern of fatty acid concentration with age likely contributes to the deterioration of central nervous system functions, but whether these changes are a natural component of physiologic aging is unresolved. Some studies have suggested that aging leads to decreased content of PUFAs in the frontal cortex, but others did not find significant age-related differences in fatty acid composition ( Söderberg et al, 1991 ). Further, it has been suggested that changes in brain lipid composition are indicative of pathological brain aging ( Söderberg et al., 1991 ).
Anatomy of fat
Under a microscope, fat cells look like bulbous little spheres. Like other cells in the body, each has a cell membrane and a nucleus, but their bulk is made up of droplets of stored triglycerides, each of which consists of three fatty-acid molecules attached to a single glycerol molecule.
"Human triglyceride looks exactly like olive oil, peanut oil and all the other triglycerides we squeeze out of plant seeds," said Ruben Meerman, a physicist, science communicator and author of "Big Fat Myths: When You Lose Weight, Where Does the Fat Go?" (Ebury Australia, 2016). "It has the same yellowish color, the same energy density and the exact same chemical formula."
But not all adipocytes are the same. The stuff we typically think of as fat is "white fat," which is the main substance used for energy storage. When insulin levels go up — say, after a meal — white adipocytes take in more fatty acids, literally swelling in size, Meerman told Live Science. When insulin drops, fat cells release their stores as a source of quick energy for the body.
Other clusters of adipocytes are used mostly for support, such as the cushion of fat that surrounds the eyes, according to a 2006 paper in the journal Nature. These fat cells probably don't release a lot of energy into the body unless the organism enters starvation mode. The body also stores fat under the skin (subcutaneous fat) and around the internal organs (visceral fat).
"Brown fat" cells, on the other hand, are iron-rich cells with their own unique function. They express genes that alter metabolism to produce heat, making brown adipose tissue pretty important for maintaining body temperature. Specifically, brown-fat cells release something called uncoupling protein-1 (UCP-1), which makes the process of fatty-acid oxidation in the cells' powerhouses (the mitochondria) less efficient. That means more of the energy the mitochondria process is "wasted" as heat, thus warming the body, according to a 2017 paper in the journal Endocrine Connections.
Newborn babies have high levels of brown fat. Those levels drop with age, and in adults, most brown fat clusters around the neck and collarbone.
A third type of fat, "beige fat," is found in white adipose tissue, but unlike white-fat cells, these cells contain UCP-1. Beige-fat cells seem to have the flexibility to act like either white fat or brown fat, depending on the situation, according to the Endocrine Connections paper.
Human brain: Facts, functions & anatomy
The human brain is the command center for the human nervous system.
The human brain is the command center for the human nervous system. It receives signals from the body's sensory organs and outputs information to the muscles. The human brain has the same basic structure as other mammal brains but is larger in relation to body size than the brains of many other mammals, such as dolphins, whales and elephants.
How much does a human brain weigh?
The human brain weighs about 3 lbs. (1.4 kilograms) and makes up about 2% of a human's body weight. On average, male brains are about 10% larger than female brains, according to Northwestern Medicine in Illinois. The average male has a brain volume of nearly 78 cubic inches (1,274 cubic centimeters), while the average female brain has a volume of 69 cubic inches (1,131 cubic cm). The cerebrum, which is the main part of the brain located in the front area of the skull, makes up 85% of the brain's weight.
How many brain cells does a human have?
The human brain contains about 86 billion nerve cells (neurons) &mdash called "gray matter," according to a 2012 study published in the Proceedings of the National Academy of Sciences. The brain also has about the same number of non-neuronal cells, such as the oligodendrocytes that insulate neuronal axons with a myelin sheath. This gives axons (thin strands through which electrical impulses are transmitted between neurons) a white appearance, and so these axons are called the brain's "white matter."
Other cool facts about the brain
- The brain can't multitask, according to the Dent Neurologic Institute. Instead, it switches between tasks, which increases errors and makes things take longer.
- The human brain triples in size during the first year of life and reaches full maturity at about age 25.
- Humans use all of the brain all of the time, not just 10% of it.
- The brain is 60% fat, according to Northwestern Medicine.
- The human brain can generate 23 watts of electrical power &mdash enough to fuel a small lightbulb.
Anatomy of the human brain
The largest part of the human brain is the cerebrum, which is divided into two hemispheres, according to the Mayfield Clinic. Each hemisphere consists of four lobes: the frontal, parietal, temporal and occipital. The rippled surface of the cerebrum is called the cortex. Underneath the cerebrum lies the brainstem, and behind that sits the cerebellum.
The frontal lobe is important for cognitive functions, such as thought and planning ahead, and for the control of voluntary movement. The temporal lobe generates memories and emotions. The parietal lobe integrates input from different senses and is important for spatial orientation and navigation. Visual processing takes place in the occipital lobe, near the back of the skull.
The brainstem connects to the spinal cord and consists of the medulla oblongata, pons and midbrain. The primary functions of the brainstem include relaying information between the brain and the body supplying most of the cranial nerves to the face and head and performing critical functions in controlling the heart, breathing and levels of consciousness (it's involved in controlling wake and sleep cycles).
Between the cerebrum and brainstem lie the thalamus and hypothalamus. The thalamus relays sensory and motor signals to the cortex. Except for olfaction (sense of smell), every sensory system sends information through the thalamus to the cortex, according to the online textbook, "Neuroanatomy, Thalamus" (StatPublishing, 2020). The hypothalamus connects the nervous system to the endocrine system &mdash where hormones are produced &mdash via the pituitary gland.
The cerebellum lies beneath the cerebrum and has important functions in motor control. It plays a role in coordination and balance and may also have some cognitive functions.
The brain also has four interconnected cavities, called ventricles, which produce what's called cerebrospinal fluid (CSF). This fluid circulates around the brain and spinal cord, cushioning it from injury, and is eventually absorbed into the bloodstream.
In addition to cushioning the central nervous system, CSF clears waste from the brain. In what's called the glymphatic system, waste products from the interstitial fluid surrounding brain cells move into the CSF and away from the brain, according to the Society for Neuroscience. Studies suggest this waste clearance process mostly happens during sleep. In a 2013 Science paper, researchers reported that when mice were asleep, their interstitial spaces expanded by 60%, and the brain's glymphatic system cleared beta-amyloid (the protein that makes up Alzheimer's disease's hallmark plaques) faster than when the rodents were awake. Clearing potentially neurotoxic waste from the brain or "taking out the trash" through the glymphatic system could be one reason that sleep is so important, the authors suggested in their paper.
Is brain size linked to intelligence?
Overall brain size doesn't correlate with level of intelligence for non-human animals. For instance, the brain of a sperm whale is more than five times heavier than the human brain, but humans are considered to be of higher intelligence than sperm whales. A more accurate measure of an animal's likely intelligence is the ratio between the size of the brain and body size, although not even that measure puts humans in first place: The tree shrew has the highest brain-to-body ratio of any mammal, according to BrainFacts.org, a website produced by the Society for Neuroscience.
Among humans, brain size doesn't indicate a person's level of intelligence. Some geniuses in their field have smaller-than-average brains, while others have brains that are larger than average, according to Christof Koch, a neuroscientist and president of the Allen Institute for Brain Science in Seattle. For example, compare the brains of two highly acclaimed writers. The Russian novelist Ivan Turgenev's brain was found to weigh 71 ounces (2,021 grams), while the brain of French writer Anatole France weighed only 36 ounces (1,017 g).
The reason behind humans' intelligence, in part, is neurons and folds. Humans have more neurons per unit volume than other animals, and the only way they can all fit within the brain's layered structure is to make folds in the outer layer, or cortex, said Dr. Eric Holland, a neurosurgeon and cancer biologist at the Fred Hutchinson Cancer Research Center and the University of Washington.
"The more complicated a brain gets, the more gyri and sulci, or wiggly hills and valleys, it has," Holland told Live Science. Other intelligent animals, such as monkeys and dolphins, also have these folds in their cortex, whereas mice have smooth brains, he said.
How the brain is integrated also seems to matter when it comes to intelligence. A genius among geniuses, Albert Einstein had an average size brain researchers suspect his mind-boggling cognitive abilities may have stemmed from its high connectivity, with several pathways connecting distant regions of his brain, Live Science previously reported.
Humans also have the largest frontal lobes of any animal, Holland said. The frontal lobes are associated with higher-level functions such as self-control, planning, logic and abstract thought &mdash basically, "the things that make us particularly human," he said.
What's the difference between the left brain and right brain?
The human brain is divided into two hemispheres, the left and right, connected by a bundle of nerve fibers called the corpus callosum. The hemispheres are strongly, though not entirely, symmetrical. Generally, the left brain controls the muscles on the right side of the body, and the right brain controls the left side. One hemisphere may be slightly dominant, as with left- or right-handedness.
The popular notions about "left brain" and "right brain" qualities are generalizations that are not well supported by evidence. However, there are some important differences between these areas. The left brain contains regions that are involved in language production and comprehension (called Broca's area and Wernicke's area, respectively) and is also associated with mathematical calculation and fact retrieval, Holland said. The right brain plays a role in visual and auditory processing, spatial skills and artistic ability &mdash more instinctive or creative things, Holland said &mdash though these functions involve both hemispheres. "Everyone uses both halves all the time," he said.
In April 2013, President Barack Obama announced a scientific grand challenge known as the BRAIN Initiative, short for Brain Research through Advancing Innovative Neurotechnologies. The $100-million-plus effort aimed to develop new technologies to produce a dynamic picture of the human brain, from the level of individual cells to complex circuits.
Like other major science efforts, such as the Human Genome Project, the significant expense is usually worth the investment, Holland said. Scientists hope the increased understanding will lead to new ways to treat, cure and prevent brain disorders.
The project contains members from several government agencies, including the National Institutes of Health (NIH), the National Science Foundation (NSF) and the Defense Advanced Research Projects Agency (DARPA), as well as private research organizations, including the Allen Institute for Brain Science and the Howard Hughes Medical Institute.
In May 2013, the project's backers outlined their goals in the journal Science. In September 2014, the NIH announced $46 million in BRAIN Initiative grants. Industry members pledged another $30 million to support the effort, and major foundations and universities also agreed to apply more than $240 million of their own research toward BRAIN Initiative goals.
When the project was announced, President Obama convened a commission to evaluate the ethical issues involved in research on the brain. In May 2014, the commission released the first half of its report, calling for ethics to be integrated early and explicitly in neuroscience research, Live Science previously reported. In March 2015, the commission released the second half of the report, which focused on issues of cognitive enhancement, informed consent and using neuroscience in the legal system, Live Science reported.
The Brain Initiative has achieved several of its goals. As of 2018, the NIH has "invested more than $559 million in the research of more than 500 scientists," and Congress appropriated "close to $400 million in NIH funding for fiscal year 2018," according to the initiative's website. The research funding facilitated the development of new brain-imaging and brain-mapping tools, and helped create the BRAIN Initiative Cell Census Network (BICCN) &mdash an effort to catalog the brain's "parts' list." The BICCN released its first results in November 2018.
Beyond a parts list, the BRAIN Initiative is working to develop a detailed picture of the circuits in the brain. For example, in 2020, BRAIN Initiative researchers published a study in the journal Neuron, reporting that they had developed a system, tested in mice, to control and monitor circuit activity at any depth in the brain. Previous efforts could only examine circuits close to the surface of the brain. Also in 2020, the initiative's Machine Intelligence from Cortical Networks (MICrONS) program, an effort to map circuits in the cortex, launched a website where researchers can share their data, including electron microscopy images of circuits.
Since 2019, the initiative has sponsored a photo and video contest in which initiative researchers are invited to submit eye-catching depictions of the brain. Check out the 2020 winners on the Brain Initiative website.
Does the brain stay alive after a person dies?
April 2019 marked a milestone for both the initiative and neuroscience research at large: BRAIN Initiative researcher Nenad Sestan, of the Yale School of Medicine, published a report in the journal Nature, revealing that his research team had restored circulation and some cellular functions to pig brains four hours after the animals' deaths, Live Science previously reported. The results challenged the prevailing view that brain cells are suddenly and irreversibly damaged shortly after the heart stops beating. The researchers did not observe any signs of consciousness in the brains, nor were they trying to on the contrary, the researchers injected pig brains with chemicals that mimicked blood flow and also blocked neurons from firing. The researchers emphasized that they did not bring the pig brains back to life. They did, however, restore some of their cellular activity.
- "Evolution of the brain and intelligence," by Gerhard Roth and Ursula Dicke, in Trends in Cognitive Sciences (May 2005)
- NIH: The BRAIN Initiative
- NSF: Understanding the brain
This article was updated on May 28, 2021 by Live Science contributor Ashley P. Taylor.
How Much of Your Brain Is Water?
The human brain is comprised of 77 to 78 percent water. Lipids, or fats, contribute 10 to 12 percent to brain mass, proteins make up 8 percent, 2 percent is composed of soluble organic substances, and carbohydrates and inorganic salts each contribute 1 percent.
Although composed primarily of water, the brain requires a sufficient daily intake of water to function properly. Brain cells that are deprived of too much water lose efficiency. Dehydration can cause impairment to the attention span, short-term memory, long-term memory and mathematical abilities.
The medical condition hydrocephalus, commonly referred to as water on the brain, is not actually caused by the presence of too much water in the brain. Rather, it is caused by a buildup of cerebrospinal fluid, the clear, colorless liquid that surrounds the brain and spinal cord. Hydrocephalus can occur at any time during human development and may be caused by birth defects, infections, brain hemorrhage, strokes, tumors or trauma to the head. Hydrocephalus is typically treated by one of two surgical procedures: the insertion of a drainage system called a shunt or a procedure known as endoscopic third ventriculostomy, in which tiny holes are made in the brain's ventricles to drain the fluid.
What is the water and fat composition of the human brain? - Biology
% brain of total body weight (150 pound human) = 2%
Average brain width = 140 mm
Average brain length = 167 mm
Average brain height = 93 mm
Intracranial contents by volume (1,700 ml, 100%): brain = 1,400 ml (80%) blood = 150 ml (10%) cerebrospinal fluid = 150 ml (10%) (from Rengachary, S.S. and Ellenbogen, R.G., editors, Principles of Neurosurgery, Edinburgh: Elsevier Mosby, 2005)
Average number of neurons in the brain = 86 billion ( Frederico Azevedo et al., Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain. J. Comp. Neurol., 513: 532-541, 2009. )
The octopus nervous system has about 500,000,000 neurons, with two-thirds of these neurons located in the arms of the octopus. ( Hochner, B. et al., The octopus: a model for a comparative analysis of the evolution of learning and memory mechanisms, Biol Bull., 210:308-317, 2006. )
Number of neurons in honey bee brain = 950,000 ( from Menzel, R. and Giurfa, M., Cognitive architecture of a mini-brain: the honeybee, Trd. Cog. Sci., 5:62-71, 2001.)
Number of neurons in Aplysia nervous system = 18,000-20,000
Number of neurons in each segmental ganglia in the leech = 350
Volume of the brain of a locust = 6mm 3 (from The Neurobiology of the Insect Brain, Burrows, M., 1996)
Ratio of the volume of grey matter to white matter in the cerebral hemipheres (20 yrs. old) = 1.3 (Miller, A.K., Alston, R.L. and Corsellis, J.A., Variation with age in the volumes of grey and white matter in the cerebral hemispheres of man: measurements with an image analyser, Neuropathol Appl Neurobiol., 6:119-132, 1980)
Ratio of the volume of grey matter to white matter in the cerebral hemipheres (50 yrs. old) = 1.1 (Miller et al., 1980)
Ratio of the volume of grey matter to white matter in the cerebral hemipheres (100 yrs. old) = 1.5 (Miller et al., 1980)
% of cerebral oxygen consumption by white matter = 6%
% of cerebral oxygen consumption by gray matter = 94%
Ratio of glial cells to neurons in the brain = 1:1 (Reference 1 and Reference 2)
(For more information about the number of neurons in the brain, see R.W. Williams and K. Herrup, Ann. Review Neuroscience, 11:423-453, 1988)
Number of neocortical neurons (females) = 19.3 billion (Pakkenberg, B. et al., Aging and the human neocortex, Exp. Gerontology, 38:95-99, 2003 and Pakkenberg, B. and Gundersen, H.J.G. Neocortical neuron number in humans: effect of sex and age. J. Comp. Neurology, 384:312-320, 1997.)
Number of neocortical neurons (males) = 22.8 billion (Pakkenberg et al., 1997 2003)
Average loss of neocortical neurons = 85,000 per day (
31 million per year) (Pakkenberg et al., 1997 2003)
Average loss of neocortical neurons = 1 per second (Pakkenberg et al., 1997 2003)
Average number of neocortical glial cells (young adults ) = 39 billion (Pakkenberg et al., 1997 2003)
Average number of neocortical glial cells (older adults) =36 billion (Pakkenberg et al., 1997 2003)
Number of neurons in cerebral cortex (rat) = 21 million (Korbo, L., et al., J. Neurosci Methods, 31:93-100, 1990)
Length of myelinated nerve fibers in brain = 150,000-180,000 km (Pakkenberg et al., 1997 2003)
Number of synapses in cortex = 0.15 quadrillion (Pakkenberg et al., 1997 2003)
Difference number of neurons in the right and left hemispheres = 186 million MORE neurons on left side than right side (Pakkenberg et al., 1997 2003)
|Proportion by Volume (%)|
|(Reference: Trends in Neurosciences, 18:471-474, 1995)|
|Composition of Brain and Muscle|
|Skeletal Muscle (%)||Whole Brain (%)|
|Water||75||77 to 78|
|Lipids||5||10 to 12|
|Protein||18 to 20||8|
|Soluble organic substances||3 to 5||2|
|(Reference: McIlwain, H. and Bachelard, H.S., Biochemistry and the Central Nervous System, Edinburgh: Churchill Livingstone, 1985)|
Total surface area of the cerebral cortex = 2,500 cm 2 (2.5 ft 2 A. Peters, and E.G. Jones, Cerebral Cortex, 1984 )
Total surface area of the cerebral cortex (lesser shrew) = 0.8 cm 2
Total surface area of the cerebral cortex (rat) = 6 cm 2
Total surface area of the cerebral cortex (cat) = 83 cm 2
Total surface area of the cerebral cortex (African elephant) = 6,300 cm 2
Total surface area of the cerebral cortex (Bottlenosed dolphin) = 3,745 cm 2 (S.H. Ridgway, The Cetacean Central Nervous System, p. 221)
Total surface area of the cerebral cortex (pilot whale) = 5,800 cm 2
Total surface area of the cerebral cortex (false killer whale) = 7,400 cm 2
(Reference for surface area figures: Nieuwenhuys, R., Ten Donkelaar, H.J. and Nicholson, C., The Central nervous System of Vertebrates, Vol. 3, Berlin: Springer, 1998)
Total number of neurons in cerebral cortex = 10 billion ( from G.M. Shepherd, The Synaptic Organization of the Brain, 1998, p. 6) . However, C. Koch lists the total number of neurons in the cerebral cortex at 20 billion (Biophysics of Computation. Information Processing in Single Neurons, New York: Oxford Univ. Press, 1999, page 87).
Total number of synapses in cerebral cortex = 60 trillion (yes, trillion) (from G.M. Shepherd, The Synaptic Organization of the Brain, 1998, p. 6). However, C. Koch lists the total synapses in the cerebral cortex at 240 trillion (Biophysics of Computation. Information Processing in Single Neurons, New York: Oxford Univ. Press, 1999, page 87).
Percentage of total cerebral cortex volume (human): frontal lobe = 41% temporal lobe = 22% parietal lobe = 19% occipital lobe = 18%. (Kennedy et al., Cerebral Cortex, 8:372-384, 1998.)
Number of cortical layers = 6
Thickness of cerebral cortex = 1.5-4.5 mm
Thickness of cerebral cortex (Bottlenosed dolphin) = 1.3-1.8 mm (S.H. Ridgway, The Cetacean Central Nervous System, p. 221)
EEG - beta wave frequency = 13 to 30 Hz
EEG - alpha wave frequency = 8 to 13 Hz
EEG - theta wave frequency = 4 to 7 Hz
EEG - delta wave frequency = 0.5 to 4 Hz
World record, time without sleep = 264 hours (11 days) by Randy Gardner in 1965. Note: In Biopsychology (by J.P.J. Pinel, Boston: Allyn and Bacon, 2000, p. 322), the record for time awake is attributed to Mrs. Maureen Weston. She apparently spent 449 hours [18 days, 17 hours] awake in a rocking chair. The Guinness Book of World Records  has the record belonging to Robert McDonald who spent 453 hours, 40 min in a rocking chair.
Time until unconsciousness after loss of blood supply to brain = 8-10 sec
Time until reflex loss after loss of blood supply to brain = 40-110 sec
Rate of neuron growth (early pregnancy) = 250,000 neurons/minute
Length of spiny terminals of a Purkinje cell = 40,700 micron
Number spines on a Purkinje cell dendritic branchlet = 61,000
Surface area of cerebellar cortex = 1,590 cm 2 ( from Sereno et al., The human cerebellum has almost 80% of the surface area of the neocortex, PNAS, 117:19538-19543, 2020
Weight of adult cerebellum = 150 grams (Afifi, A.K. and Bergman, R.A., Functional Neuroanatomy, New York: McGraw-Hill, 1998)
Number of Purkinje cells = 15-26 million
Number of synapses made on a Purkinje cell = up to 200,000
Weight of hypothalamus = 4 g
Volume of suprachiasmatic nucleus = 0.3 mm 3
Number of fibers in pyramidal tract above decussation = 1,100,000
Number of fibers in corpus callosum = 200,000,000 (Lunders, E., Thompson, P.M. and Toga, A.W., The Development of the Corpus Callosum in the Healthy Human Brain, The Journal of Neuroscience, 30:10985-10990, 2010.)
Area of the corpus callosum (midsagittal section) = 6.2 cm 2
|Species||Cerebellum Weight (grams)||Body Weight (grams)|
|Sultan, F. and Braitenberg, V. Shapes and sizes of different mammalian cerebella. A study in quantitative comparative neuroanatomy. J. Hirnforsch., 34:79-92, 1993.|
Total volume of cerebrospinal fluid (adult) = 125-150 ml
Total volume of cerebrospinal fluid (infant) = 50 ml (Aghababian, R., Essentials of Emergency Medicine, 2006)
Turnover of entire volume of cerebrospinal fluid = 3 to 4 times per day (from Kandel et al., 2000, p. 1296)
Rate of production of CSF = 0.35 ml/min (500 ml/day) (from Kandel et al., 2000, p. 1296)
pH of cerebrospinal fluid = 7.33 (from Kandel et al., 2000, p. 1296)
Specific gravity of cerebrospinal fluid = 1.007
Color of normal CSF = clear and colorless
White blood cell count in CSF = 0-3 per mm 3
Red blood cell count in CSF = 0-5 per mm 3
Normal intracranial pressure = 150 - 180 mm of water
The Skinny on Brain Fats
Fats are vital to a healthy diet. Fats help carry, absorb, and store the fat-soluble vitamins (A, D, E, and K) in your bloodstream. Fats also help regulate your body temperature. Having some body fat cushions your organs and protects them from injury. However, as your probably already know, there are good fats and bad fats for your body . . . and your brain.
The good fats, or lipids, that work so beautifully in your body-and your brain-are called fatty acids. Essential fatty acids cannot be manufactured in your body so must come from the foods you eat (or supplements you take, although food sourcing is highly preferable). As far as your body, fatty acids are primarily used to produce hormone-like substances that regulate a wide range of functions, including blood pressure, blood clotting, blood lipid levels, the immune response, and the inflammation response to injury or infection.
Approximately 60 percent of your brain matter consists of fats that create all the cell membranes in your body. Let's review: The good fat in your brain matter creates all the cell membranes in your body! If your diet is loaded with bad fats, your brain can only make low-quality nerve cell membranes that don't function well if your diet provides the essential, good fats, your brain cells can manufacture higher-quality nerve cell membranes and influence positively your nerve cells' ability to function at their peak capacity. (Magnesium also plays a critical role in nerve cell development and optimal functioning.)
Thus, it's important to choose foods that offer the essential fatty acids your body and brain need. Unfortunately, even good fats are a very concentrated source of energy, providing more than double the amount of calories in one gram of carbohydrate or protein, which is why it's important to choose the healthy fats and to eat them in moderation.
Omega-3 Fatty Acids Are Good for Your Brain
Omega-3 fatty acids are great for mental clarity, concentration, and focus. They play an essential role throughout your life and should be at the top of your shopping list in terms of positive value for your brain. However, they are fattening so maximizing the sources in terms of benefits as opposed to caloric content is a wise move. Certain foods containing omega-3 fatty acids are especially good for your brain. These include:
- Certain cold-water fish (bluefish, herring, mackerel, rainbow trout, salmon, sardines, tuna, and whitefish)
- Olive oil
- Flaxseed oil
- Peanut oil
- Canola oil
Studies have revealed that Omega-3 fatty acids, which are essential for maintaining normal cognitive function, have additional advantages in the brain. For example, DHA and EPA, the Omega-3 fatty acids found in fish, particularly salmon, albacore tuna, sardines, and swordfish, are vital for a sharp mind.
They're Good for Your Heart
Omega-3 fatty acids may also decrease the risk of stroke and heart attack, as well as protect against abnormal heart rhythms, the leading cause of death after heart attacks. Omega-3 fatty acids may provide protection by enhancing the stability of the heart cells and increasing their resistance to becoming overexcited. Eating fish just one to two times per week has shown a 40 percent reduction in sudden deaths from cardiac arrhythmias.
They May Tamp Down Mood Swings
Researchers at Harvard University suggest that omega-3 fats (which are also available in supplements, though food sources are preferred) may disrupt the brain signals that trigger the characteristic mood swings seen with bipolar disorder. If these findings hold true in future studies, omega-3 fatty acids may have implications for successfully treating other psychiatric disorders such as depression and schizophrenia. Caution: No one with these disorders should attempt to self-medicate. Always consult with your doctors before adding supplements.
Limit Saturated and Hydrogenated Fats
Essential fatty acids are the most important nutrients for your brain, but most American diets are sadly lacking in these "good" essential fats (found in flaxseed oil, olive oil, and fish oil) and way over the top when it comes to saturated, hydrogenated, and partially hydrogenated trans fats. You can easily recognize the "bad" fats (saturated and processed fats), as they're the ones that have been processed or hydrogenated and remain solid when refrigerated. They are typically found in:
- Commercial baked goods: pies, cakes, doughnuts, cookies, etc.
- Processed foods and fast foods
- Fatty cuts of beef, pork, and lamb
- Butter, margarines
- Whole milk, ice cream
- Crackers, potato chips, corn chips, cheese puffs, pretzels, etc.
- Mayonnaise and some salad dressings
- Palm, palm kernel, and coconut oils
When unsaturated fats are heated for a long time, in metal pots and pans, they form altered or trans fatty acids. In contrast to healthy fatty acids (whose soft pliability helps nerve cell membranes function smoothly), these trans fatty acids become double-bonded, rigid, and thus tend to gum up synaptic or electrical nerve cell communication. Besides greatly increasing your chance of gaining too much weight on foods that contain little to zero nutritional value, here's a short list of the damage trans fats can do to your brain:
- Alter the synthesis of neurotransmitters, such as dopamine.
- Increase LDL (bad) cholesterol and decrease HDL (good) cholesterol.
- Increase the amount of plaque in blood vessels and increase the possibility of blood clots forming, both of which puts your heart-and your brain-at risk.
- Increase the amount of triglycerides in your system, which slows down the amount of oxygen going to your brain, and the excess of which has been linked to depression.
One reason America has become a nation of overweight people is that our consumption of essential fatty acids has declined by more than 80 percent while our consumption of trans fats has skyrocketed more than 2,500 percent! If you want your brain to be healthy and happy, severely limit saturated and hydrogenated fats.
Two More, Huge Reasons to Ban Trans Fats
Trans fats may be even more harmful than saturated and hydrogenated fats. Saturated fats tend to raise cholesterol levels and thus endanger your heart and your brain, but trans fats can be far worse. Here are two reasons you may want to ban trans fats from your diet:
The forebrain is the division of the brain that is responsible for a variety of functions including receiving and processing sensory information, thinking, perceiving, producing and understanding language, and controlling motor function. There are two major divisions of forebrain: the diencephalon and the telencephalon. The diencephalon contains structures such as the thalamus and hypothalamus which are responsible for such functions as motor control, relaying sensory information, and controlling autonomic functions. The telencephalon contains the largest part of the brain, the cerebrum. Most of the actual information processing in the brain takes place in the cerebral cortex.
The midbrain and the hindbrain together make up the brainstem. The midbrain or mesencephalon, is the portion of the brainstem that connects the hindbrain and the forebrain. This region of the brain is involved in auditory and visual responses as well as motor function.
The hindbrain extends from the spinal cord and is composed of the metencephalon and myelencephalon. The metencephalon contains structures such as the pons and cerebellum. These regions assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The myelencephalon is composed of the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion.
Our editors will review what you’ve submitted and determine whether to revise the article.
Brain, the mass of nerve tissue in the anterior end of an organism. The brain integrates sensory information and directs motor responses in higher vertebrates it is also the centre of learning. The human brain weighs approximately 1.4 kg (3 pounds) and is made up of billions of cells called neurons. Junctions between neurons, known as synapses, enable electrical and chemical messages to be transmitted from one neuron to the next in the brain, a process that underlies basic sensory functions and that is critical to learning, memory and thought formation, and other cognitive activities.
In lower vertebrates the brain is tubular and resembles an early developmental stage of the brain in higher vertebrates. It consists of three distinct regions: the hindbrain, the midbrain, and the forebrain. Although the brain of higher vertebrates undergoes considerable modification during embryonic development, these three regions are still discernible.
The hindbrain is composed of the medulla oblongata and the pons. The medulla transmits signals between the spinal cord and the higher parts of the brain it also controls such autonomic functions as heartbeat and respiration. The pons is partly made up of tracts connecting the spinal cord with higher brain levels, and it also contains cell groups that transfer information from the cerebrum to the cerebellum.
The midbrain, the upper portion of which evolved from the optic lobes, is the main centre of sensory integration in fish and amphibians. It also is involved with integration in reptiles and birds. In mammals the midbrain is greatly reduced, serving primarily as a connecting link between the hindbrain and the forebrain.
Connected to the medulla, pons, and midbrain by large bundles of fibres is the cerebellum. Relatively large in humans, this “little brain” controls balance and coordination by producing smooth, coordinated movements of muscle groups.
The forebrain includes the cerebral hemispheres and, under these, the brainstem, which contains the thalamus and hypothalamus. The thalamus is the main relay centre between the medulla and the cerebrum the hypothalamus is an important control centre for sex drive, pleasure, pain, hunger, thirst, blood pressure, body temperature, and other visceral functions. The hypothalamus produces hormones that control the secretions of the anterior pituitary gland, and it also produces oxytocin and antidiuretic hormone, which are stored in and released by the posterior pituitary gland.
The cerebrum, originally functioning as part of the olfactory lobes, is involved with the more complex functions of the human brain. In humans and other advanced vertebrates, the cerebrum has grown over the rest of the brain, forming a convoluted (wrinkled) layer of gray matter. The degree of convolution is partly dependent on the size of the body. Small mammals (e.g., lesser anteater, marmoset) generally have smooth brains, and large mammals (e.g., whale, elephant, dolphin) generally have highly convoluted ones.
The cerebral hemispheres are separated by a deep groove, the longitudinal cerebral fissure. At the base of this fissure lies a thick bundle of nerve fibres, called the corpus callosum, which provides a communication link between the hemispheres. The left hemisphere controls the right half of the body, and vice versa, because of a crossing of the nerve fibres in the medulla or, less commonly, in the spinal cord. Although the right and left hemispheres are mirror images of one another in many ways, there are important functional distinctions. In most people, for example, the areas that control speech are located in the left hemisphere, while areas that control spatial perceptions are located in the right hemisphere.
What is the water and fat composition of the human brain? - Biology
3041 days since
National Science Day
- The brain is the third largest organ in the human body.
- The brain controls all of the body parts.
- Albert Einstein's brain was similar in size to other humans except in the region that is responsible for math and spatial perception. In that region, his brain was 35% wider than average.
- Those who are left-handed or ambidextrous have a corpus collosum (the part of the brain that bridges the two halves ) that is about 11% larger than those who are right-handed.
- Your skin weighs twice as much as your brain.
- The brain is made up of about 75% water.
- There are no pain receptors in the brain, so the brain can feel no pain.
- The human brain is the fattest organ in the body and consists of at least 60% fat.
- A newborn baby's brain grows about three times its size in the first year.
- Your brain uses 20% of the total oxygen in your body.
- If your brain loses blood for 8 to 10 seconds, you will lose consciousness.
- The brain can live for 4 to 6 minutes without oxygen, and then it begins to die. No oxygen for 5 to 10 minutes will result in permanent brain damage.
- You can't tickle yourself because your brain distinguished between unexpected external touch and your own touch.
- Every time you recall a memory or have a new thought, you are creating a new connection in your brain.
- Juggling has shown to change the brain in as little as seven days. The study indicates that learning new things helps the brain to change very quickly.
· Thalamus: a large mass of gray matter deeply situated in the forebrain at the topmost portion of the diencephalon. The structure has sensory and motor functions. Almost all sensory information enters this structure where neurons send that information to the overlying cortex. Axons from every sensory system (except olfaction) synapse here as the last relay site before the information reaches the cerebral cortex.
· Hypothalamus: part of the diencephalon, ventral to the thalamus. The structure is involved in functions including: homeostasis, emotion, thirst, hunger, circadian rhythms, and control of the autonomic nervous system. It controls the pituitary.
· Amygdala: part of the telencephalon, located in the temporal lobe. Involved in memory, emotion, and fear. The amygdala is both large and just beneath the surface of the front, medial part of the temporal lobe where it causes to bulge on the surface called the uncus. This is a component of the limbic system.
· Hippocampus: the portion of the cerebral hemispheres in basal medial part of the temporal lobe. This part of the brain is important for learning and memory. For converting short term memory to more permanent memory, and for recalling spatial relationships in the world about us.
Brain Stem: Underneath the limbic system is the brain stem. This structure is responsible for basic vital life functions such as breathing, heartbeat, and blood pressure.
· Midbrain/Mesencephalon: the rostral part of the brain stem, which includes the tectum and tegmentum. It is involved in functions such as vision, hearing, eye movement, and body movement. The anterior part has the cerebral peduncle, which is a huge bundle of axons traveling from the cerebral cortex through the brain stem and these fibers are important for voluntary motor function.
· Pons: part of the metencephalon in the hindbrain. It is involved in motor control and sensory analysis. For example, information from the ear first enters the brain in the pons. It has parts that are important for the level of consciousness and for sleep. Some structures within the pons are linked to the cerebellum, then they are involved in movement and posture.
· Medulla: this structure is the caudal most part of the brain stem, between the pons and spinal cord. It is responsible for maintaining vital body functions, such as breathing and heart rate.