brain
Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.
More about the experts All content is checked by medical journalists.The brain (encephalon) is the control center of our body. It consists of a huge number of brain cells that are linked together. The brain is very metabolically active and therefore needs a lot of oxygen and blood sugar (glucose). It is extremely sensitive to an insufficient supply. Read everything you need to know about: What is the brain anatomy like? How does the brain work? How big is the storage capacity (brain)? What are the most important diseases and injuries?
What is the brain
The brain (encephalon) is the part of the central nervous system that lies within and fills the bony skull. It consists of innumerable nerve cells that are connected to and control the organism via incoming and outgoing nerve pathways.
The brain volume (human) is around 20 to 22 grams per kilogram of body mass. The weight (brain) makes up about three percent of the body weight at 1.5 to two kilograms.
How many brain cells does a person have?
A person has around 100 billion brain cells that make up the central nervous system, our brain, and are interconnected. The number of these links is estimated at 100 trillion.
Glial cells
The nerve cells in the brain are embedded in a supporting tissue made of glial cells. You can read about the tasks of these cells and how they are structured in the article Glial cells.
Meninges
The brain is surrounded by three meninges: dura mater, arachnoid and pia mater. You can find out everything you need to know about the three protective covers and their function in the article Meninges.
Brain Structure: Five Sections
The human brain can be roughly divided into five sections:
- Cerebrum (telencephalon)
- Diencephalon
- Midbrain (mesencephalon)
- Cerebellum
- Afterbrain (myelencephalon, medulla oblongata)
Cerebrum (telencephalon)
The cerebrum is the largest and heaviest part of the brain and, with its folds and furrows, resembles a walnut kernel. Read more about its anatomy and function in the post Cerebrum.
Diencephalon
The diencephalon consists, among other things, of the thalamus and the hypothalamus. You can read more information about the structure and function of the diencephalon in the article Diencephalon.
In the lower skull area is the brain base, which - corresponding to the bony skull base - is more heavily modeled. This is where the brain stem lies.
Brain stem
The brain stem is the oldest part of the brain in phylogenetic terms and consists of the midbrain, medulla oblongata and bridge (pons). Read more in the article on the brain stem.
Midbrain (mesencephalon)
The mesencephalon is the smallest section of the brain. You can find out everything you need to know about its structure and function in the midbrain article.
Medulla oblongata (myelencephalon)
The meyelencephalon, also known as the afterbrain, represents the transition between the brain and the spinal cord. You can read more about this section of the brain in the article Medulla oblongata.
Cerebellum
The cerebellum sits above the brain stem and below the two cerebral hemispheres. You can read more about its tasks and its anatomy in the article cerebellum.
Gray matter
The gray matter in the brain consists primarily of nerve cell bodies. The name comes from the fact that the nerve cells in the living organism are pink, but turn gray after its death. The cerebral cortex, basal ganglia, cerebellar cortex and cranial nerve nuclei consist of gray matter. About 80 percent of the cerebral blood flow is necessary for the supply of gray matter.
Basal ganglia
The basal ganglia are a group of cerebral and diencephalic nuclei made of gray matter. You can read more about them and their functions in the article Basal ganglia.
White matter
In addition to the gray matter, there is also the white matter, which consists of the nerve cell processes, the nerve fibers (axons). The white matter is found in the marrow of the cerebrum and cerebellum.
Cranial nerves
Twelve paired nerves originate in the brain and supply the head, neck and organs in the trunk. You can read more about these important nerve pathways in the article Cranial Nerves.
The blood supply (brain)
About 800 milliliters of blood flow through the brain every minute. This amount can fluctuate slightly up to the age of 50, but decreases afterwards (along with the consumption of oxygen and glucose). The blood supply to the brain accounts for between 15 and 20 percent of the cardiac output.
In the sleeping and waking phases, the brain is always supplied with approximately the same amount of blood. Even with increases in blood pressure, drops in blood pressure, vigorous physical exertion or even an irregular heartbeat, the blood flow to the brain hardly changes - except when the systolic blood pressure drops sharply (below 70 mmHg) or increases sharply (over 180 mmHg).
The brain is supplied with blood via the right and left internal carotid arteries (internal carotid arteries), which arise from the common carotid artery (communal arteries), and via the vertebral artery, which comes from the vertebral bodies and enters the cranial cavity through the occipital opening. These are closed by additional arteries to form a vascular ring (Circulus arteriosus cerebri), which encompasses the base of the diencephalon.
This vascular ring ensures that the blood demand of the sensitive brain is always sufficient, even with fluctuations in the blood supply. The vascular ring and its branches lie between two meninges (the spider tissue skin and the inner meninges) in the so-called subarachnoid space and are there surrounded by liquor (cerebral spinal fluid), which protects the thin-walled vessels.
Liquor
The liquor is the liquid that protects the brain and the spinal cord. You can read more about cerebrospinal fluid in the article Liquor.
Ventricular system
The brain has several cavities (cerebral chambers) in which the liquor circulates and which together form the ventricular system. You can read more about this in the article Ventricular System.
The blood-brain barrier
The sensitive tissue in the brain is shielded from harmful substances in the blood (such as poisons, pathogens, certain drugs, etc.) by the blood-brain barrier. You can find out everything you need to know about this protective mechanism in the article Blood-Brain Barrier.
Energy consumption (brain) and brain capacity
The energy consumption in the brain is enormous. The brain accounts for almost a quarter of the body's total energy requirements. Up to two thirds of the amount of glucose that is ingested with food is used by the brain.
The brain capacity is significantly greater than that which we actually use in everyday life. That means: A large part of our brain capacity is unused.
Brain development
The embryonic development of the brain from the neural tube is characterized on the one hand by a particular growth in size, on the other hand by an uneven growth in thickness of the wall and special kinks. This divides the brain into several sections at an early stage.
From the cerebral anlage, three consecutive sections (primary cerebral vesicles) develop, which then form the forebrain, the midbrain and the hindbrain. In the further development, five additional, secondary cerebral vesicles arise from this: The cerebrum and diencephalon develop from the forebrain. The medulla oblongata, the bridge and the cerebellum emerge from the hindbrain.
What is the function of the brain?
The functional areas of the brain are diverse. The brain stem, the oldest part of the brain in terms of evolution, is responsible for the basic life functions. It controls the heart rate, blood pressure and breathing as well as reflexes such as the blinking, swallowing or coughing reflex.
The diencephalon has several sections, including the thalamus and the hypothalamus: In the thalamus, sensory impressions are processed; The hypothalamus controls the sleep-wake cycle, hunger and thirst, the pain and temperature sensation and the sex drive.
Thalamus
You can find out everything you need to know about this important part of the diencephalon, which is the “gateway to consciousness”, in the article Thalamus.
Hypothalamus
You can read more about the structure and tasks of the hypothalamus in the article Hypothalamus.
Pituitary gland
The pituitary gland is connected to the hypothalamus by a stalk. You can read more about the anatomy and function of this endocrine gland in the article Pituitary Gland.
The cerebellum coordinates our movements and balance and stores learned movements.
In the cerebrum there is language and logic on the one hand, and creativity and a sense of direction on the other.
In the cerebral cortex - the outer area of the cerebrum - the ability to learn, speak and think as well as awareness and memory are anchored. This is where the information from the sensory organs converges, is processed and finally stored in the memory.
Limbic system
The limbic system regulates the affect and drive behavior and its links with vegetative organ functions. You can read more about this very old area of the brain in the article Limbic System.
Two important areas within the limbic system are the amygdala (tonsil nucleus) and the hippocampus:
Amygdala
You can find out what tasks the almond kernel has in the article Amygdala.
Hippocampus
The hippocampus is the working memory of our brain and the switching point between short and long-term memory. You can read more about this in the article Hippocampus.
memory
A very important function of the brain is memory - from ultra-short-term to short-term to long-term memory. You can read more about this in the article Memory.
How does the brain work?
A smooth functioning of all organs and tissues in the body as well as a meaningful behavior are only possible if all organ functions are coordinated and controlled by a superordinate supervisory authority and all information that the environment provides is recorded, processed and answered. This task is performed by our brain, the network of billions of nerve cells (neurons).
The brain cells are connected to one another by synapses, contact points between the cells. These contact points play an important role in processing the messages. Information from the body or the environment reaches the brain in the form of hormones, for example, or as electrical impulses from the sensory cells via nerve tracts. There they are evaluated and processed. In response, appropriate signals are sent back from the brain - for example to muscles to move, to glands to produce and release secretions, or to sensory organs to respond to stimuli from the environment.
Where is the brain located?
The brain is located in the bony skull, fills it completely and continues through the occipital opening as the spinal cord in the spine.
What problems can the brain cause?
Since the brain is a very complex and highly sensitive system, it can be disturbed or damaged by various influences (from inside or outside the body) - although it is relatively well protected by the bony skull.
The easiest form of traumatic brain injury is a concussion. It is usually accompanied by unconsciousness from a few seconds to hours, but can also only consist of a short twilight. Short memory gaps of up to an hour are possible.
A more serious injury is a bruised skull, which means damage to the brain substance. The impaired consciousness can then last longer than an hour. Paralysis and epileptic seizures are also possible.
Any head trauma - no matter how minor, such as bumping your head when getting out of the car - can cause an epidural hematoma. Here, bleeding occurs between the hard meninges and the skull bone through a vascular tear. The addictive bruise can cause clouding of consciousness and hemiplegia within minutes to hours.
Subdural hematomas in the brain are bruises between the outer and middle meninges, i.e. between the dura mater and the arachnoid. They arise from torn bridge veins, usually in connection with severe brain contusions.
An epileptic seizure that occurs before the age of 25 is caused by early childhood brain damage. Seizures occurring later in life can be caused by tumors or other brain or cerebral vascular diseases.
Multiple sclerosis is an inflammatory disease of the central nervous system (brain and spinal cord). The medullary sheaths, the insulating layer of the nerve fibers, dissolve in the form of a focal point. Nerve conduction is no longer possible without a medullary sheath. Depending on the location, there may be corresponding failures.
Tumors in the brain can occur at any age and can be benign and malignant.
A stroke is an acute circulatory disorder in the brain. The sudden interruption of the oxygen supply causes the nerve cells in the affected brain area to die.
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