What Is The Gray Matter And White Matter
Gray and white matter are two different regions of the central nervous system. In the brain, gray matter refers to the darker, outer portion, while white matter describes the lighter, inner section underneath. In the spinal cord, this order is reversed: The white matter is on the outside, and the gray matter sits within.
Gray matter is primarily composed of neuron somas , and white matter is mostly made of axons wrapped in myelin . The different composition of neuron parts is why the two appear as separate shades on certain scans.
Each region serves a different role. Gray matter is primarily responsible for processing and interpreting information, while white matter transmits that information to other parts of the nervous system.
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 Does The Blood Brain Barrier Do
But the barrier also keeps out many substances that are meant to help the brain, including drugs designed to treat brain cancer. For instance, chemotherapy drugs, designed to kill fast-growing cells like cancer cells, may also kill fast-growing cells elsewhere in the body. The cells of the blood-brain barrier may consider these drugs too toxic to be allowed access to the brain, preventing them from reaching the cancer. Cells in the barrier also have large amounts of a protein called P-glycoprotein , which helps flush toxins out of cells.
So even if a chemotherapy drug were to penetrate a brain cell, P-gp may promptly remove it. “No matter what drugs you use systemically, there is a blood-brain barrier,” says Shayma Master Kazmi, MD, RPh, Hematologist-Oncologist and Medical Oncologist at our hospital in Philadelphia. “So a lot of chemotherapy drugs or immunotherapy drugs dont get close to 100 percent penetration into the central nervous system. If the drug isnt getting to where it needs to go, that’s problem No 1.”
What Is The Blood Brain Barrier
Each person has a protective blood barrier lining the blood vessels in the brain to restrict the passage of large toxic substances from the bloodstream into the brain.
You can imagine the barrier acting like plastic wrap around the small blood vessels. In most areas of the body, there is no plastic wrap and whatever is in the bloodstream can get into the various tissues of the body, such as muscle, etc.
In the brain, all of the blood vessels have this plastic wrap around them that only allows very select molecules to get through.
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Protection For The Brain: Meninges Csf Blood
The brain is protected from injury by the skull, meninges, cerebrospinal fluid and the blood-brain barrier. In this post we will explore them all in detail, well, except for the skull since that was already discussed in other posts about the bones.
The function of the meninges is to cover and protect the brain itself.; It encloses and protects the vessels that supply the brain and contains CSF between the pia mater and arachnoid maters.; Immediately deep to the periosteum is the periosteal and meningeal which create the dura mater.; The dura mater is found all around the brain and its 2 layers separate and create spaces called dural sinuses.; See the blue triangle below?; The meningeal separates from the periosteal and goes down into the longitudinal fissure.; The space that is firmed is a sinus.
Deep to the dura mater is the potentialsubdural space and deep to that is the arachnoid mater and its named arachnoid because of its spider-leggy appearance.; Deep to the arachnoid mater is the potential subarachnoid space.; Our deepest layer is the pia mater which is a very delicate connective tissue.; It literally means soft mother as opposed to dura mater which means durable mother.
Falx Cerebelli is a small triangular process of dura mater, received into the posterior cerebellar notch and runs along the vermis
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:
- Sensory relay
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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 .
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
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Parts Of The Brain Not Protected By The Blood
The blood-brain barrier prevents toxic substances, large molecules, and neurotransmitters released in the blood from entering the brain. Four areas of the brain are not protected by the blood-brain barrier. These areas include the posterior pituitary gland, pineal gland, the median eminence of the hypothalamus and the area postrema.
Right Brain Left Brain
The cerebrum is divided into two halves: the right and left hemispheres They are joined by a bundle of fibers called the corpus callosum that transmits messages from one side to the other. Each hemisphere controls the opposite side of the body. If a stroke occurs on the right side of the brain, your left arm or leg may be weak or paralyzed.
Not all functions of the hemispheres are shared. In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.
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How Is Brain Protected From Shock And Injury
Brain is protected from shock and injury due to Cerebrospinal Fluid. It absorbs all the injuries and shocks.
Skull protects the brain from shock and injury. ;
Inside the skull, the brain is enclosed by structure called as cranial meninges. It is a three layered structure and each layer is known by different name as :
- Dura meter The outer most layers next to the skull.
- Arachnoid The middle layer and it is very thin.
- Pia mater The innermost layer which is in contact with the tissues of the brain.
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.
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Gene And Protein Expression
Bioinformatics is a field of study that includes the creation and advancement of databases, and computational and statistical techniques, that can be used in studies of the human brain, particularly in the areas of gene and protein expression. Bioinformatics and studies in genomics, and functional genomics, generated the need for DNA annotation, a transcriptome technology, identifying genes, their locations and functions.GeneCards is a major database.
As of 2017, just under 20,000 protein-coding genes are seen to be expressed in the human, and some 400 of these genes are brain-specific. The data that has been provided on gene expression in the brain has fuelled further research into a number of disorders. The long term use of alcohol for example, has shown altered gene expression in the brain, and cell-type specific changes that may relate to alcohol use disorder. These changes have been noted in the synaptictranscriptome in the prefrontal cortex, and are seen as a factor causing the drive to alcohol dependence, and also to other substance abuses.
What Are The Different Kinds Of Stroke
A transient ischemic attack is often called a mini stroke. Its a brief interruption of blood flow to part of the brain, spinal cord or retina, which may cause temporary stroke-like symptoms but does not damage brain cells or cause permanent disability. Symptoms of TIA usually last only a few minutes but may persist for up to 24 hours. The risk of stroke is especially high within 48 hours after a TIA.
An ischemic stroke is the most common type of stroke. It happens when blood flow through the artery that supplies oxygen-rich blood to the brain becomes blocked. Blood clots often cause the blockages that lead to ischemic strokes. The effects of a stroke vary, and can depend on which part of the brain was injured and how long it took to get medical attention.
The most common effects from stroke include cognitive difficulties, paralysis, weakness, as well as difficulty with language, vision, and swallowing.
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How Is A Craniectomy Done
Before deciding to do a craniectomy, doctors will order an MRI or other imaging to get an idea of what is happening inside the skull. They will want to know where any injuries or blood clots are located so they can target the areas with the highest pressure when they operate.
You will be under general anesthesia during the surgery. Doctors need to carefully cut the skin to expose the bone of your skull. Theyâll use a specialized drill to make holes in the skull so they can make boundaries around the section of bone they will remove. Theyâll use a bone saw to cut from hole to hole, then lift the segment of the skull away.
Once the doctors can see the brain, they may remove blood clots or clear any excess fluid. They donât replace the bone right away. Instead, they will give you a special helmet to protect your brain. The hole in the skull will stay open until the swelling and pressure have gone down. This procedure is different from another surgery called a craniotomy. For a craniotomy, doctors open the skull the same way. However, they replace the bone when they have finished operating.
What Is The Smallest Human Brain
A model of Einsteins brain is included in the exhibition and there is footage of the worlds smallest known brain the nematode worm C. elegans, a 1mm-long worm which has just 302 neurons compared to the estimated 86 billion neurons of a human brain. It is the only brain to be fully mapped by scientists.
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Parts Of The Brain And Spinal Cord
The main areas of the brain include the cerebrum, cerebellum, and brain stem. Each part has a special function.
Cerebrum: The cerebrum is the large, outer part of the brain. It is divided into left and right hemispheres and controls reasoning, thought, emotion, and language. It is also responsible for planned muscle movements and for taking in and interpreting sensory information such as vision, hearing, smell, touch, and pain.
Cerebellum: The cerebellum lies under the cerebrum at the back part of the brain. It helps coordinate movement.
Brain stem: The brain stem is the lower part of the brain that connects to the spinal cord. It contains bundles of very long nerve fibers that carry signals controlling muscles and sensation or feeling between the cerebrum and the rest the body. Special centers in the brain stem also help control breathing and the beating of the heart. Also, most cranial nerves start in the brain stem.
The brain stem is divided into 3 main parts: the midbrain, pons, and medulla oblongata.
Because the brain stem is a small area that is so essential for life, it might not be possible to surgically remove tumors in this area.
Cranial nerves: The cranial nerves extend directly out of the base of the brain . These nerves carry signals directly between the brain and the face, eyes, ears, tongue, mouth, and some other areas.
Choroid plexus:Â;The choroid plexus is the area of the brain within the ventricles that makes CSF, which nourishes and protects the brain.
Types Of Cells And Body Tissues In The Brain And Spinal Cord
The brain and spinal cord have many kinds of tissues and cells, which can develop into different types of tumors.
Neurons : These are the cells in the brain that help determine thought, memory, emotion, speech, muscle movement, sensation, and just about everything else that the brain and spinal cord do.
Unlike many other types of cells that can grow and divide to repair damage from injury or disease, neurons in the brain and spinal cord largely stop dividing about a year after birth . Neurons do not usually form tumors, but they are often damaged by tumors that start nearby.
Glial cells: Glial cells are the supporting cells of the brain. Most brain and spinal cord tumors develop from glial cells. These tumors are sometimes referred to as gliomas.
There are 3 main types of glial cells:
- Astrocytes help support and nourish neurons. When the brain is injured, astrocytes form scar tissue that helps repair the damage. The main tumors starting in these cells are called astrocytomas or glioblastomas.
- Oligodendrocytes make myelin, a fatty substance that surrounds and insulates the nerve cell axons of the brain and spinal cord. This helps neurons send electric signals through the axons. Tumors starting in these cells are called oligodendrogliomas.
- Ependymal cells line the ventricles within the brain and form part of the pathway through which CSF flows. Tumors starting in these cells are called ependymomas.
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Illustration Of The Spinal Cord And Central Nervous System
The brain and the spinal cord together are called the central nervous system .
The brain and spinal cord are also covered and protected by three layers of tissue . These are called the meninges. The three layers are:
- the dura mater
- the arachnoid
- the pia mater .
The area between two of these layers is called the subarachnoid space. This space contains a liquid called cerebrospinal fluid .
CSF also fills spaces inside the brain called ventricles. CSF makes a protective cushion for the brain. It also takes nutrients to the brain and removes waste products.