Brain: Difference between revisions

Latest revision as of 11:55, 1 April 2025

Brain is the central organ of the nervous system that enables animals to interpret sensory input and coordinate bodily functions. It processes information from the sense organs and produces responses that affect behavior. In humans, the brain also facilitates the use of language and enables abstract thought. The brain is composed of a specialized type of cell known as neurons, which communicate with each other and with the nervous system through synapses. The brain is protected by the skull in vertebrates, including humans, and by other mechanisms in animals without skulls.

Function[edit]

The brain is responsible for a wide array of activities, including thinking, learning, emotion regulation, and the body's basic functions such as breathing, heartbeat, and digestion. In humans, the brain is also the center of consciousness, although it is unclear whether other mammals possess consciousness in the same way.<ref>We do not know whether other mammals have consciousness.</ref>

The brain processes sensory information and interprets it, turning it into experiences like images, sounds, and tactile sensations. For example, when we see something, the brain interprets visual data to create a mental image. In addition, the brain coordinates actions by sending signals via the nervous system to muscles, organs, and other parts of the body, directing movement and controlling bodily functions. While most body functions are under the control of the brain, some actions, such as reflexes, occur directly in the spinal cord without involving the brain.

In simple organisms like sponges, there is no brain. However, more complex animals, especially vertebrates, have evolved highly specialized and intricate brains, making their behavior more complex.

Parts of the Brain[edit]

In mammals, the brain is divided into three main parts: the cerebrum, the cerebellum, and the brainstem. The surface of the cerebrum is known as the cerebral cortex, which all vertebrates have. Mammals, however, have an additional layer called the neocortex, which is important for advanced behavior, especially in humans.

Cerebral Cortex[edit]

The cerebral cortex is the outer layer of the cerebrum and is involved in many complex brain functions, such as perception, thought, and reasoning. It contains:

Sensory areas: These regions process information from the senses.
Motor areas: These regions control voluntary muscle movements, such as fine motor skills like hand movement.
Association areas: These areas integrate sensory and motor information to create meaningful experiences and support abstract thinking, including language processing. For example, the left hemisphere is primarily involved in language functions.

The motor area of the cortex is organized such that the right hemisphere controls the left side of the body, and the left hemisphere controls the right side.

Cerebellum[edit]

The cerebellum is located beneath the cerebrum and is responsible for coordinating muscle movements, balance, and posture. It plays a vital role in fine-tuning motor actions, helping to maintain smooth and coordinated body movements. This is important for motor skills such as walking, writing, and playing musical instruments.

Neural signaling in the human brain. Small electrical charges go from one neuron to the next

Brainstem[edit]

The brainstem is the lowest part of the brain and connects the brain to the spinal cord. It controls many basic life functions such as breathing, heartbeat, and swallowing. The brainstem also manages unconscious actions like sneezing, eye blinking, and regulating body temperature. This area of the brain is crucial for survival as it governs essential functions that occur automatically.

Size and Structure[edit]

The human brain is relatively large compared to the size of the body, especially when considering its surface area. The cerebral cortex, which is the outermost layer, is highly folded, allowing for more surface area to fit into the limited space inside the skull. If the human cortex were unfolded, it would cover an area of nearly one square meter. Other animals, such as dolphins and elephants, also have highly folded brains, but the human brain remains one of the most advanced in terms of complexity and size.

The size of the brain generally correlates with the size of the animal, but human brains, and especially the neocortex, have evolved to be much larger compared to other species. Over the past several million years, the human brain has increased in size by approximately fourfold, which is thought to be linked to the development of complex social behavior, advanced language skills, and problem-solving abilities.

Glial Cells[edit]

Although the human brain accounts for about 2% of the body's weight, it consumes about 20% of the body's energy. The brain contains approximately 50 to 100 billion neurons, which are the primary cells responsible for transmitting information throughout the nervous system. Alongside neurons, there are also an equal number of support cells known as glial cells or glia. These cells provide nutrients, remove waste products, and assist with the maintenance of neuronal function.

Each neuron can form connections with as many as 10,000 other neurons through structures known as synapses, enabling the brain to process vast amounts of information efficiently.

Related pages[edit]

References[edit]

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-The '''brain''' is the part of the body which lets animals make sense of things. It gets input from [[sense organs]], and changes [[behaviour]] in response to this information. In humans, the brain also controls our use of [[language]], and is capable of [[wikt:abstract|abstract]] [[thought]].<ref name=Calvin>Calvin, William H. [1996] 1998. ''How brains think: evolving intelligence, then & now''. Phoenix, London. {{ISBN|0-75380-200-7}}</ref> The brain is the main control centre of the whole body.<ref>''Encyclopedia of discovery: science''. Weldon Owen, 2001, 30{{ndash}}31. {{ISBN|1740893298}}</ref> The brain is made up of a special type of [[cell]]s. They are connected with each other and with the [[nerve]]s in our body. In all animals the delicate brain is protected in some way. In ourselves, and all [[vertebrates]], it is protected by the [[bone]]s of the [[skull]].
+'''Brain''' is the central organ of the nervous system that enables animals to interpret sensory input and coordinate bodily functions. It processes information from the [[sense organs]] and produces responses that affect behavior. In humans, the brain also facilitates the use of [[language]] and enables [[abstract thought]]. The brain is composed of a specialized type of [[cell]] known as neurons, which communicate with each other and with the [[nervous system]] through synapses. The brain is protected by the [[skull]] in vertebrates, including humans, and by other mechanisms in animals without skulls.
+[[File:Chimp Brain in a jar.jpg|Brain|thumb]]
 [[File:Brain-en.png|Brain|thumb]]
 == Function ==
-The brain does the [[thinking]], learning, and feeling for the body. For humans, it is the source of [[consciousness]].<ref>We do not know whether other mammals have consciousness.</ref> The brain also controls basic [[autonomic]] body actions, like [[breathing]], [[digestion]], [[heartbeat]], that happen automatically. These activities, and much else, are governed by [[unconscious]] functions of the brain and [[nervous system]]. All the information about the world gathered by our [[senses]] is sent through nerves into the brain, allowing us to see, hear, smell, taste and feel things. The brain processes this information, and we experience it as pictures, sounds, and so on. The brain also uses nerves to tell the body what to do, for example by telling muscles to move or our [[heart]] to beat faster.
+The brain is responsible for a wide array of activities, including [[thinking]], [[learning]], [[emotion]] regulation, and the body's basic functions such as [[breathing]], [[heartbeat]], and [[digestion]]. In humans, the brain is also the center of [[consciousness]], although it is unclear whether other mammals possess consciousness in the same way.<ref>We do not know whether other mammals have consciousness.</ref>
+The brain processes sensory information and interprets it, turning it into experiences like images, sounds, and tactile sensations. For example, when we see something, the brain interprets visual data to create a mental image. In addition, the brain coordinates actions by sending signals via the [[nervous system]] to muscles, organs, and other parts of the body, directing movement and controlling bodily functions. While most body functions are under the control of the brain, some actions, such as [[reflex]]es, occur directly in the [[spinal cord]] without involving the brain.
+In simple organisms like [[sponges]], there is no brain. However, more complex animals, especially [[vertebrates]], have evolved highly specialized and intricate brains, making their behavior more complex.
-[[File:Brain-ALZH.png|Brain cross section|thumb]]
+== Parts of the Brain ==
-This is generally true but some activity is caused by the [[spinal cord]] directly, for example, [[reflex]] actions do not involve the brain. In lower animals, a good deal is done without their brain being involved.
+In mammals, the brain is divided into three main parts: the [[cerebrum]], the [[cerebellum]], and the [[brainstem]]. The surface of the cerebrum is known as the [[cerebral cortex]], which all vertebrates have. Mammals, however, have an additional layer called the [[neocortex]], which is important for advanced behavior, especially in humans.
-All [[vertebrates]] have brains and, over time, their brains have [[evolved]] to become more complex. Some simple animals, however, like [[sponge]]s, do not have anything like a brain. [[Segmented]] [[invertebrates]] have [[ganglion]]s in each segment, and a ring of nervous tissue around the [[alimentary canal]] at the front. This acts to bring [[sense data]] from the front into play with the movement of the body.
+=== Cerebral Cortex ===
+The cerebral cortex is the outer layer of the cerebrum and is involved in many complex brain functions, such as perception, thought, and reasoning. It contains:
-== Parts ==
+* '''Sensory areas''': These regions process information from the senses.
-In [[mammal]]s, the brain is made of three main parts: the [[cerebrum]], the [[cerebellum]] and the [[brainstem]]. The surface of the cerebrum is the [[cerebral cortex]], which all vertebrates have. Mammals also have an extra layer, the [[neocortex]]. This is the key to the behaviour which is typical of mammals, especially humans.
+* '''Motor areas''': These regions control voluntary muscle movements, such as fine motor skills like hand movement.
+* '''Association areas''': These areas integrate sensory and motor information to create meaningful experiences and support abstract thinking, including language processing. For example, the left hemisphere is primarily involved in language functions.
-=== Cerebral cortex ===
+The motor area of the cortex is organized such that the right hemisphere controls the left side of the body, and the left hemisphere controls the right side.
-The cortex has [[Sensory system|sensory]], [[Motor system|motor]], and association areas. The sensory areas are the areas that receive and process information from the senses. The motor areas control voluntary movements, especially fine movements performed by the hand. The right half of the motor area controls the left side of the body, and vice versa. Association areas produce a meaningful experience of the world, and supports abstract thinking and language. This enables us to interact effectively. Most connections are from one area of the cortex to another, rather than to subcortical areas; The figure may be as high as 99%.<ref>Braitenberg V. and Schüz A. 1991. ''Anatomy of the cortex: statistics and geometry''. NY: Springer-Verlag.</ref>
 [[File:CT of a normal brain, sagittal 11.png|CT of a normal brain, sagittal|thumb]]
 === Cerebellum ===
-The cerebellum coordinates [[muscle]]s so they work together.<ref name=igcse>{{cite book|title=Edexcel IGCSE Biology: Student Book|page=75|date=2009|publisher=Pearson Education|first1=Phil|last1=Bradfield|first2=Steve|last2=Potter|isbn=9780435966881}}</ref> It is also the centre of maintaining position and balance, a vital part of movement helping with simple motor skills.
+The cerebellum is located beneath the cerebrum and is responsible for coordinating muscle movements, balance, and posture. It plays a vital role in fine-tuning motor actions, helping to maintain smooth and coordinated body movements. This is important for motor skills such as walking, writing, and playing musical instruments.
 [[File:Neural signaling-human brain.gif|thumb|Neural signaling in the human brain. Small electrical charges go from one neuron to the next]]
-=== Brain stem ===
-The [[brain stem]] is at the back of the brain (actually underneath it in humans). It joins the rest of the brain with the [[spinal cord]]. It has lots of different parts that control different jobs in the body: for instance, the brain stem controls breathing, [[heart]]beat, sneezing, [[eye]] blinking, and swallowing. Body temperature and hunger are also controlled by parts of the brain stem.
-== Size ==
+=== Brainstem ===
-The [[volume]] of the human brain (relative to the size of the whole body) is very large, compared to that of most other animals. The human brain also has a very large surface (called [[Cerebral cortex|cortex]]) for its size, which is possible because it is very wrinkled. If the human cortex were flattened, it would be close to a square [[metre|meter]] in area. Some other animals also have very wrinkled brains, such as [[dolphin]]s and [[elephant]]s. Here is a [[rule of thumb]]: the larger an animal is, the larger its brain will be.<ref name=Calvin/><sup>p15</sup> Even allowing for that, the human brain, and in particular the neocortex, is very large. We know it increased in size four-fold over the last several million years of [[evolution]].<ref name=Calvin/><sup>p79</sup> There are ideas about why this happened, but no-one is quite sure. Most theories suggest complex social activity and the evolution of [[language]] would make a larger brain advantageous.<ref name=Calvin/><sup>p80</sup><ref>Pinker, Stephen 1994. ''The language instinct''. Morrow. p363</ref> As an additional note, [[Einstein]]'s brain weighed only 1,230 grams, which is less than the average adult male brain (about 1,400 grams).<ref>{{cite web|url=http://faculty.washington.edu/chudler/ein.html|title=Neuroscience For Kids - einstein's brain|website=faculty.washington.edu}}</ref> The detailed organisation of a brain obviously matters, but in ways which are not understood at present.
+The brainstem is the lowest part of the brain and connects the brain to the spinal cord. It controls many basic life functions such as [[breathing]], heartbeat, and swallowing. The brainstem also manages unconscious actions like sneezing, eye blinking, and regulating body temperature. This area of the brain is crucial for survival as it governs essential functions that occur automatically.
+== Size and Structure ==
+The human brain is relatively large compared to the size of the body, especially when considering its surface area. The cerebral cortex, which is the outermost layer, is highly folded, allowing for more surface area to fit into the limited space inside the skull. If the human cortex were unfolded, it would cover an area of nearly one square meter. Other animals, such as [[dolphins]] and [[elephants]], also have highly folded brains, but the human brain remains one of the most advanced in terms of complexity and size.
+The size of the brain generally correlates with the size of the animal, but human brains, and especially the neocortex, have evolved to be much larger compared to other species. Over the past several million years, the human brain has increased in size by approximately fourfold, which is thought to be linked to the development of complex social behavior, advanced language skills, and problem-solving abilities.
+=== Glial Cells ===
+Although the human brain accounts for about 2% of the body's weight, it consumes about 20% of the body's energy. The brain contains approximately 50 to 100 billion [[neurons]], which are the primary cells responsible for transmitting information throughout the nervous system. Alongside neurons, there are also an equal number of support cells known as [[glial cells]] or glia. These cells provide nutrients, remove waste products, and assist with the maintenance of neuronal function.
-=== Glial cells ===
+Each neuron can form connections with as many as 10,000 other neurons through structures known as [[synapses]], enabling the brain to process vast amounts of information efficiently.
-A human brain accounts for about 2% of the body's weight, but it uses about 20% of its energy. It has about 50–100 [[billion]] nerve [[cell]]s (also called [[neuron]]s), and roughly the same number of support cells, called ''glia''. The job of neurons is to receive and send [[information]] to and from the rest of the body, while glia provide [[nutrients]] and guide blood flow to the neurons, allowing them to do their job. Each nerve [[cell]] has contact with as many as 10,000 other [[nerve]] cells through connections called [[synapse]]s.
 == Related pages ==
-*[[Spinal cord]]
+* [[Spinal cord]]
-*[[Vertebrate brain]]
+* [[Vertebrate brain]]
-*[[Human Connectome Project]]
+* [[Human Connectome Project]]
+* [[Neuron]]
+* [[Nervous system]]
 == References ==
-{{reflist}}
+<references />
-{{stub}}
-{{Nervous system}}
+[[Category:Brain]]
-{{Portal bar|Philosophy}}
-[[Category:Brain| ]]
 [[Category:Organs (anatomy)]]
 [[Category:Human anatomy by organ]]
 [[Category:Animal anatomy]]
-[[Category:Basic English 850 words]]
+[[Category:Neurobiology]]
-<gallery>
+[[Category:Neuroscience]]
-File:Chimp Brain in a jar.jpg|Brain
+{{stub}}
-</gallery>
+{{Nervous system}}
+{{Medicine}}
+{{Human anatomy}}