The Basics of the Brain – Anatomy and Physiology

THE BRAIN

Majid Ali, M.D.

(Also see Mental Health and Disorders)

The brain is generally regarded as the most important organ in the human body. I consider this to be an unlightened view of those who do not reflect on the functions of the body organs which create the conditions in which either the brain either develops and flourishes or suffers serious functional handicaps. In The Canary and Chronic Fatigue (1994), I described the cases of brain-fogged teenagers and young adults with serious problems of mood, memory, and mentation created by toxicities in the bowel and the liver.


Structure of the Brain

The adult human brain weighs about 3 pounds. It is protected by skull, a bony structure called the cranium. The brain is surrounded by and further protected by sheets of tissue called the meninges composed of of the following three layers:

* Pia mater – the layer closest to the surface of the brain

* Arachnoid membrane – the middle layer of tissue

* Dura mater – the outer-most layer


The Anatomy of the Brain

The brain has a very comples structure. Following are its major anatomical divisions:

* Cerebrum – the front of the brain

* Cerebellum – the back of the brain

* The brainstem – the middle of the brain

The cerebrum – the front of the brain

This is the largest part of the brain and is located in the front part of the cranium. It has two parts: the right cerebral hemisphere and the left cerebral hemisphere connected with each other but separated by a deep groove. Each hemisphere has the following major lobes :

* Frontal lobes are involved with personality, speech, and motor development

* Temporal lobes are responsible for memory, language and speech functions

* Parietal lobes are involved with sensation

* Occipital lobes are the primary vision centers


The functional centers in the cerebrum regulate the following functions:

* Touch

* Vision

* Hearing

* Movement

* Body temperature

* Judgment

* Reasoning

* Problem solving

* Emotions

* Learning

The cerebellum

The term cerebellum is dereived from a Latin root meaning “little brain.” Amazingly, the cerebellum has a larger population of neurons than cerebral hemispheres combined. It is primarily a movement control part of the brain and is responsible for:

* Voluntary muscle movements

* Fine motor skills

* Maintaining balance, posture, and equilibrium


Neurons

The human brains brain contains 15–33 billion cells called neurons. Each neuron is connected by delicate fibers called axons to a large number of other neurons through structures called synapses. Neuronal communications occur through electrical pulses called action potentials.

Neurones are cells located in the gray matter and are either aggregated in nuclei, in layers as in six-layered cerebral cortex, or in columns. Neuronal reactions to injury occur as: (1) axonal reaction, after the axon is cut or otherwise injured, represents a healing response characterized by rounding and enlargement of the cell, enlargement of the nucleus, and dispersion of the Nissl substance; (2) acute cell necrosis (red neurone) due to anoxia or dysoxygenosis; (3) atrophy of cells surrounded by areas of gliosis (proliferation of the connective tissue of the brain parenchyma); (4) neuronal degeneration surrounded by areas of gliosis; and (5) accumulation of oxidized and denatured lipid, protein, and carbohydrate complexes (i.e., lipofuscin) indicating mild degenerative changes associated with aging.


The Oxygen Model of Brain Injury

The brain parenchyma is a highly aerobic tissue and yet does not hold any oxygen reserve. The brain draws about 15% of the resting cardiac output and 20% of the total body consumption of oxygen. Unlike in many other body tissues, oxygen availability is the rate-limiting factor in brain metabolism. For those reasons, neuronal metabolism begins to be impaired within 8 to 10 seconds of oxygen deficiency and irreversible damage occurs within 6 to 8 minutes. By contrast, neuronal glucose reserves can maintain metabolism for 30 to 60 minutes after glucose supply is turned off. Hence, even severe hypoglycemia in most clinical situations can be effectively managed without irreversible neuronal injury.


Oxidative-Dysoxygenative Perspective on Neuronal Injury and Repair

In RDA: Rats, Drug, and Assumption (1996) I proposed a model of brain injury that held at oxidative injury and oxygen dysfunction as the two primary mechanisms of injury. In Recognized that the molecular underpinnings of all types of toxic, metabolic, ischemic, degenerative, and infectious injuries to brain parenchyma involve oxidative-dysoxygenative phenomena. I draw this conclusion from the examination of experimental and clinical observations reported about the various clinicopathologic entities concerning the central nervous system. For example, the genetic locus on chromosome 21 in familial AML appears to be the Cu/Zn-binding superoxide dismutase. Monoamine oxidase inhibitors are of limited benefits in the early stages. As for the common stroke, Alzheimer’s disease, and heavy metal toxicity, the oxidative-dysoxygenative nature of the nature is self-evident. From the standpoint of integrative medicine, this is of paramount importance since it means all effective integrative therapies for brain disorders must be sharply focused on issues of oxidosis and dysoxygenosis.


Patterns of Glial Reactions

Glia is the stroma (the connective tissue scaffolding) of the brain parenchyma. It includes four types of cells: (1) astrocytes are large cells with round to ova nuclei; (2) oligodendrocytes are smaller denser cells; (3) ependymal cells are columnar in shape, have ciliate borders, and line the inner surfaces of ventricles; and (4) microglial cells that are elongated and contain irregular nuclei.

In neuropathology and neurology texts, glia is delegated a largely structurally supportive role with participation in repair reactions. In my view, such thinking is very limited and is wholly inconsistent with the profound regulatory roles of the matrix in other tissues. In my view, glia asserts foundational regulatory roles in health as well as in all pathophysiologic phenomena affecting the brain parenchyma. Though at this time I base my view largely on the many established roles of matrix in other tissues. It seems safe to predict that future research will clearly show that to be the case.

Patterns of Neuronal Regeneration

Until recently, the prevailing belief in neurology was that human neuronal death results in permanent loss of the function of those cells. Indeed, of all the body’s cells, neurones seem least capable of repair and regeneration when injured by neurotoxins, infectious diseases, stroke, or degenerative disorders. A spate of recent studies have clearly demonstrated the ability of neurones to regenerate. Still, neurones of neocortex—the region of the brain of greatest interest from the standpoint of functions involving mood, memory, and mentation—appeared not to participate in repair and regenerative functions. Now that also is changing. Consider the following:

“…when they induced certain neurones in the neocortex of adult mice to self-destruct, the loss triggered the formation of replacement neurons by brain stem cells. What’s more, the newly formed neurones migrated to the same position as their deceased predecessors.”

In the experimental cited above, opoptosis of neocortex cells was selectively induced with light-activated compound. The death of neocortical cells then triggered the multipotential neural precursor (stem) cells located in the subventricular zones to produce new neurons which then traveled to find their home in the area of dead cells and replaced them. The tracking of the new neurons was done by labeling those cells with a tracer chemical (5-bromodeoxyuridine). Further experiments with a dye demonstrated that the newly formed neocortical cells established the same functional axon connections to thalamus as the original cells.

Related Articles

*Rising Prevalence of Autism Spectrum

* Brain Edema

* Cerebral Ischemia and Infarction

* Brain Aneurysms

* Multiple Sclerosis (MS) and Demyelinating Diseases

* Parkinson’s Disease

* Pick’s Disease

* The Oxygen Model Alzheimer’s Disease

* Anatomy of the Parasympathetic Nervous System

* Alzheimer’s, Oxygen, and Tau Protein

* The Oxygen Model Alzheimer’s Disease

* Alzheimer’s, Oxygen, and Tau Protein

*Rising Prevalence of Autism Spectrum

* Brain Edema

* Cerebral Ischemia and Infarction

* Brain Aneurysms

* Multiple Sclerosis (MS) and Demyelinating Diseases

* Parkinson’s Disease

* Pick’s Disease

* Anatomy of the Parasympathetic Nervous System

Articles and YouTube Segments on Alzheimer’s disease

☞ Alzheimer’s Disease
http://www.majidali.com/memory_problems.htm
☞ Oxygen, Genes, Memory, and Alzheimer’s Disease – The incidence of Alzheimer’s disease (AD)—a problem of
http://www.majidali.com/alzheimers_disease.htm
☞ The Grease and Detergent Model of Alzheimer’s Disease
http://vuim.org/alzheimers_disease_1.htm
☞ Oxygen, Alzheimer’s disease, and Lapdog Joes
http://www.wiki-medical.org/adrefog.htm
☞ YouTube: Alzheimer’s Disease Part Two * Ali Academy

☞ YouTube: Brain Nutrients Part Two * Ali Academy

☞ YouTube: Alzheimer’s – You Have It? Really? * Ali Academy

☞ YouTube: Presidents’ Wars on Cancer and Alzheimer’s * Ali Academy

Additional Related Articles

Suggested Readings

1. Ali M. Darwin, oxidosis, dysoxygenosis, and integration. J Integrative Medicine 1999;3:11-16.

2. Lasley EN. Death leads to brain neuron birth. Science 2000;288:2111-2.

3. Magavi S, Leavit B, Macklis J. Nature June 22, 2000

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