Wednesday, August 17, 2022

What Is The Outer Layer Of The Brain Called

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Layers Of The Cerebral Cortex

The Nervous System: Cerebral Cortex

The cerebral cortex contains clearly defined and characteristic brain layers:

  • Lamina molecularis – the surface layer
  • Lamina granularis externa – a well-developed layer in the sensitive region, containing Golgi cells
  • Lamina pyramidalis externa – best developed in the precentral part
  • Lamina granularis internal – consists of tiny Golgi cells
  • Lamina pyramidalis internal – in the motor region and it contains large pyramidal Betz cells which is why it was also named giganto-pyramidalis
  • Lamina multiformis – consists of the spindle cells .

How Does The Brain Work

The brain sends and receives chemical and electrical signals throughout the body. Different signals control different processes, and your brain interprets each. Some make you feel tired, for example, while others make you feel pain.

Some messages are kept within the brain, while others are relayed through the spine and across the bodys vast network of nerves to distant extremities. To do this, the central nervous system relies on billions of neurons .

Lobes Of The Brain And What They Control

Each brain hemisphere has four sections, called lobes: frontal, parietal, temporal and occipital. Each lobe controls specific functions.

  • Frontal lobe. The largest lobe of the brain, located in the front of the head, the frontal lobe is involved in personality characteristics, decision-making and movement. Recognition of smell usually involves parts of the frontal lobe. The frontal lobe contains Brocas area, which is associated with speech ability.
  • Parietal lobe. The middle part of the brain, the parietal lobe helps a person identify objects and understand spatial relationships . The parietal lobe is also involved in interpreting pain and touch in the body. The parietal lobe houses Wernickes area, which helps the brain understand spoken language.
  • Occipital lobe. The occipital lobe is the back part of the brain that is involved with vision.
  • Temporal lobe. The sides of the brain, temporal lobes are involved in short-term memory, speech, musical rhythm and some degree of smell recognition.

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What Is The Brain And Why Does It Matter

The brain is a three-pound organ that serves as headquarters for our bodies. Without it, we wouldn’t be able to process information, move our limbs, or even breathe. Together with the spinal cord, brain structure and function helps control the central nervous systemthe main part of two that make up the human nervous system. The human nervous system is responsible for helping us think, breathe, move, react and feel.

Like any good command center, there is a structure to the brain and its operations that help it carry out its basic functions.

What Are The Layers Of The Cerebrum

Outermost covering of brain is A Piamater B Duramater class 12 biology CBSE

The cerebrum has two layers: one inner and one outer. The outer layer is known as the cerebral cortex . Most times, whenever you see photos of the brain, you are looking at the cerebral cortex. This area houses the brain’s “gray matter,” and is considered the “seat” of human consciousness. Higher brain functions such as thinking, reasoning, planning, emotion, memory, the processing of sensory information and speech all happen in the cerebral cortex. In other words, the cerebral cortex is what sets humans apart from other species.

The cerebral cortex is referred to as “gray matter,” due to its color and is responsible for several vital functions, such as those listed above.

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Information Transport And Boundary Assistants

The gyrus and sulcus are what give the brain its wrinkly appearance. The grooves of the brain are known as the sulci, while the bumps are called the gyri. These folds and ridges help increase how much of the cerebral cortex can fit into the skull. They also create boundaries between the different sections of the brain, such as the two hemispheres and four lobes of the cerebrum.

Albert Kok/Wikimedia Commons

The gyri and sulci create the wrinkles we traditionally associate with the brain./ Bruce Blaus/Wikimedia Commons

Control Centres For Making Sense Of Our Bodies

Apart from the cerebrum, the forebrain also contains several small, but highly important structures located towards the centre of the brain and are included in the limbic system. Collectively these are called the diencephalon and they are involved in regulating things like the bodys sensory perception, motor functions, and hormones.

The thalamus consists of two lobes of grey matter tucked away right under the cerebral cortex. It is a prime processing centre for sensory information, as it links up the relevant parts of the cerebral cortex with the spinal cord and other areas of the brain important for our senses. The thalamus also controls sleep.

The hypothalamus is quite small, only about the size of an almond. As its name suggests, it can be found right underneath the thalamus, and despite its small size it is actually the major control centre of the autonomic motor system. It is involved in some hormonal activity and connects the hormonal and nervous systems. The hypothalamus also works to regulate things like our blood pressure, body temperature, and overall homeostasis.

The pineal gland is even smaller than the hypothalamus – only about the length of a grain of rice – and is tucked between the two lobes of the thalamus. It is actually shaped like a tiny pinecone, and its main job is to produce the hormone melatonin, which regulates our sleep-wake cycles. Just like the hypothalamus, it is also involved in regulating hormonal functions.

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Other Key Parts Of The Brain

Ventricular SystemThe brain is not a solid organ. Instead, there are fluid-filled cavities within the brain called ventricles. The ventricles provide nourishment to the brain. The ventricular system produces and processes cerebrospinal fluid, a clear, watery substance flowing around the brain to cushion and protect it.

Cranial NervesThe brain also contains 12 pairs of cranial nerves. Each is responsible for specific body functions.

  • Olfactory nerve: Sense of smell
  • Optic nerve: Vision

How Does The Nervous System Work

Dura mater – Function, Location & Layers – Neuroanatomy | Kenhub

The basic workings of the nervous system depend a lot on tiny cells called neurons. The brain has billions of them, and they have many specialized jobs. For example, sensory neurons send information from the eyes, ears, nose, tongue, and skin to the brain. Motor neurons carry messages away from the brain to the rest of the body.

All neurons, however, relay information to each other through a complex electrochemical process, making connections that affect the way we think, learn, move, and behave.

Intelligence, learning, and memory. As we grow and learn, messages travel from one neuron to another over and over, creating connections, or pathways, in the brain. It’s why driving takes so much concentration when someone first learns it, but later is second nature: The pathway became established.

In young children, the brain is highly adaptable. In fact, when one part of a young child’s brain is injured, another part often can learn to take over some of the lost function. But as we age, the brain has to work harder to make new neural pathways, making it harder to master new tasks or change set behavior patterns. That’s why many scientists believe it’s important to keep challenging the brain to learn new things and make new connections it helps keeps the brain active over the course of a lifetime.

The Senses

Smell. Olfactory cells in the mucous membranes lining each nostril react to chemicals we breathe in and send messages along specific nerves to the brain.

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Blood Vessels In The Brain

The oxygen supply for the brain comes from 4 major arteries, two vertebral arteries and two carotid arteries. The two vertebral arteries supply blood to the back of the brain. The two carotid arteries branch and supply oxygen to the front and middle of the brain. The front and back arteries interconnect at the circle of Willis at the base of the brain. The circle of Willis ensures a continuous blood supply to the brain.

The Cerebrum: Front Part Of The Brain

The largest part of the brain, located in the front, is called the cerebrum. The cerebrum is responsible for:

  • Movement
  • Emotions
  • Learning

The cerebrum is made up of the right and left cerebral hemispheres. The hemispheres are connected at the bottom and have a deep groove running between them. In general, the right cerebral hemisphere controls the left side of the body, and the left cerebral hemisphere controls the right. The right side is involved with creativity and artistic abilities. The left side is important for logic and rational thinking.

The cerebral hemispheres are divided into lobes . Each lobe is responsible for a variety of bodily functions. Frontal lobes are involved with personality, speech, and motor development. Temporal lobes are responsible for memory, language and speech function. Parietal lobes are involved with sensation, while the occipital lobes are the primary vision centers.

The surface of the cerebrum appears wrinkled and is made up of deep grooves and bumps or folds . The outer part of the cerebrum is called gray matter and contains nerve cells. The inner part is called white matter and contains connections of nerves.

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What Are The Parts Of The Nervous System

The nervous system is made up of the central nervous system and the peripheral nervous system:

  • The brain and the spinal cord are the central nervous system.
  • The nerves that go through the whole body make up the peripheral nervous system.

The human brain is incredibly compact, weighing just 3 pounds. It has many folds and grooves, though. These give it the added surface area needed for storing the body’s important information.

The spinal cord is a long bundle of nerve tissue about 18 inches long and 1/2-inch thick. It extends from the lower part of the brain down through spine. Along the way, nerves branch out to the entire body.

Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull, and the spinal cord by a set of ring-shaped bones called vertebrae. They’re both cushioned by layers of membranes called meninges and a special fluid called cerebrospinal fluid. This fluid helps protect the nerve tissue, keep it healthy, and remove waste products.

The Cerebellum’s Left And Right Hemispheres

Brain &  Cranial Nerves

The cerebellum also has two hemispheres: the left cerebellar hemisphere and the right cerebellar hemisphere. Just as the longitudinal fissure divides the cerebrum’s hemispheres, the “vermis” separates the cerebellum’s hemispheres.

Cerebellar hemispheres seen from front and back / The Database Center for Life Science/Wikimedia Commons

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The Cranium: Covering Of The Brain

The brain is protected by a bony covering called the cranium. The cranium and the bones of the face make up the skull. Inside the cranium, the brain is surrounded by three layers of tissue called the meninges. The meninges include:

  • Pia mater: The layer closest to the surface of the brain
  • Arachnoid membrane: The middle layer of tissue
  • Dura mater: The outer-most layer

Cerebrum And The Cerebral Cortex

When you picture the iconic shape of the human brain, the majority of whats visible is the cerebrum with its wrinkly, pinkish-grey outer appearance. It makes up around 85% of the brain and consists primarily of grey matter, divided into two hemispheres.

The cerebrum is where most of the important brain functions happen, such as thinking, planning, reasoning, language processing, and interpreting and processing inputs from our senses, such as vision, touch, hearing, taste and smell.

The outer layer of the cerebrum is called the cerebral cortex, and in each hemisphere it is traditionally divided into four lobes – frontal, parietal, occipital and temporal. Communications between the two hemispheres are maintained by a fibrous bridge called the corpus callosum, which is formed in utero.

Beneath the surface of the hemispheres are large knots of neurons called basal ganglia, which specialise in programming and executing our motor functions. When basal ganglia are affected by diseases such as Parkinsons, patients have tremors and uncontrolled movements.

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What Is The Top Layer Of Brain

  • The cerebrum sits at the topmost part of the brain and is the source of intellectual activities. It holds your memories, allows you to plan, enables you to imagine and think. It allows you to recognize friends, read books, and play games. The cerebrum is split into two halves by a deep fissure.

What Medical Conditions Affect The Meninges

Meninges of the Brain | 3D Anatomy Tutorial

Two of the more common conditions that affect your meninges are:

  • Meningitis. This is an infection of your meninges. The infection can be caused by bacteria, fungus or viruses. A lumbar puncture to get a cerebrospinal fluid sample is usually required to diagnose this condition. Rarely, meningitis can occur by non-infectious causes such as cancers, inflammatory disease, brain surgery or certain medicines.
  • Subdural hematoma. This is bleeding that occurs between your dura mater and arachnoid mater due to a tear in a blood vessel.
  • Bleeding within other meningeal layers. Many blood vessels travel through your meninges. Trauma to your head can cause bleeding between any of the layers of meninges, especially in people who take blood thinners or have bleeding disorders.

Other medical conditions affecting your meninges include:

  • Meningiomas. These are tumors that grow in your meninges. Theyre usually not cancerous, but can grow large enough to be life-threatening and may require surgical treatment.
  • Meningeal carcinomatoses. This is cancer that has spread from its original tumor site to your meninges.

There are many other conditions that can affect each specific meningeal layer. Because of the important role of your meninges in protecting your brain, conditions that affect your meninges can be potentially life-threatening.

A note from Cleveland Clinic

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What Does The Brain Do

The brain controls what we think and feel, how we learn and remember, and the way we move and talk. But it also controls things we’re less aware of like the beating of our hearts and the digestion of our food.

Think of the brain as a central computer that controls all the body’s functions. The rest of the nervous system is like a network that relays messages back and forth from the brain to different parts of the body. It does this via the spinal cord, which runs from the brain down through the back. It contains threadlike nerves that branch out to every organ and body part.

When a message comes into the brain from anywhere in the body, the brain tells the body how to react. For example, if you touch a hot stove, the nerves in your skin shoot a message of pain to your brain. The brain then sends a message back telling the muscles in your hand to pull away. Luckily, this neurological relay race happens in an instant.

The Brainstem: Middle Of The Brain

The brainstem is located in front of the cerebellum. Think of the brainstem like a computer hard-drive. It is the bodys main control panel and is responsible for conveying messages between the brain and other parts of the body. The cerebrum, the cerebellum and the spinal cord are all connected to the brainstem. The brainstem has three main parts: the midbrain, the pons and the medulla oblongata.

The brain stem controls these vital body functions:

  • Breathing
  • Sensory relay
  • Hunger

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What Is In Frontal Lobe

The frontal lobe is the most anterior part of the brain. It extends from the area behind the forehead back to the precentral gyrus. As a whole, the frontal lobe is responsible for higher cognitive functions such as memory, emotions, impulse control, problem solving, social interaction, and motor function.


Lipid Extraction And Thin

Cerebral Cortex

Cerebra from several rats are dissected and homogenized initially in a small volume of chloroform/methanol , with several brains pooled into one homogenate, and equal fractions are taken for each sample. This is carried out to reduce the variation in myo-inositol incorporation between the individual animals. The lipids are extracted essentially according to the method of Hauser and Eichberg or Schacht . Prior to use, it is essential to wash each test tube three times with chloroform/methanol to remove possible contaminants. The initial neutral extraction removes primarily PI. In addition, during each step of the lipid extraction, the samples are kept under nitrogen using test tubes with Teflon-lined caps. After the acidified chloroform/methanol extraction step, the lipid phases are mixed with 0.2 volume of 1 M HCl, with each phase neutralized immediately with ammonia. The first acidified chloroform/methanol lipid extract is used for all lipid determinations, as this fraction contains most of the polyphosphoinositides.

D. Gupta, in, 2017

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What Is The Outer Membrane That Covers The Brain

  • Meningitis is inflamation of the protective membranes, the meninges, that cover the brain and the spinal cord. It is a dangerous disease not least as it develops very fast within hours. The brain is surrounded by three membranes. The outer ultra hard membrane called dura, the mid membrane called araknoidea and the inner, soft membrane called pia.

The Cell Structure Of The Brain

The brain is made up of two types of cells: neurons and glial cells, also known as neuroglia or glia. The neuron is responsible for sending and receiving nerve impulses or signals. Glial cells are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin and facilitate signal transmission in the nervous system. In the human brain, glial cells outnumber neurons by about 50 to one. Glial cells are the most common cells found in primary brain tumors.

When a person is diagnosed with a brain tumor, a biopsy may be done, in which tissue is removed from the tumor for identification purposes by a pathologist. Pathologists identify the type of cells that are present in this brain tissue, and brain tumors are named based on this association. The type of brain tumor and cells involved impact patient prognosis and treatment.

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