Your brain is the most important organ in your body. It controls everything you do, your movements, your thoughts and your memory. It often does not act directly, but it can control small amounts of blood chemicals, which in turn have a strong effect on another part of the body.Although it seems very simple, the brain is immensely complicated. It is a mass of whitish tissue.The brain and spinal cord form the central nervous system. Along the length of the spinal cord, thread-like nerves come out and divide and connect with almost every part of the body. The nerves carry messages from the sense organs to the brain.
Central Nervous System
The Central Nervous System is made up of the brain and the spinal cord , both involved and protected by three membranes called meninges .
The brain , which weighs approximately 1.5 kilos, is located in the cranial box and has three main organs : the brain, the cerebellum and the brainstem;
It is the most important organ of the nervous system. Considered the most bulky organ, as it occupies most of the brain, the brain is divided into two symmetrical parts: the right hemisphere and the left hemisphere .
Thus, the outermost layer of the brain and full of recesses, is called the cerebral cortex , responsible for thinking, seeing, hearing, touching, tasting, speaking, writing, etc.
he main areas of the brain include the brain, cerebellum and brain stem. Each of these parts has a special function.
- Brain. The brain is the body’s control center by sending messages along nerve fibers. The brain is divided into two halves, the right and left cerebral hemispheres. The cerebral hemispheres control movement, thinking, memory, emotions, senses and speech. Symptoms caused by a tumor in the cerebral hemisphere, depending on its location, can include seizures, speech problems, mood swings, depression, personality changes, weakness or paralysis in part of the body, problems with vision or hearing or other senses .
- Cerebellum. The cerebellum is located below and in the back of the brain. The cerebellum maintains balance and posture, controls muscle tone and voluntary movements. Tumors of the cerebellum can cause problems with movement coordination, loss of balance, decreased tone of skeletal muscle, problems with swallowing or synchronization of eye movements, and changes in speech rhythm.
- Brainstem. The brain stem or brain stem is located between the spinal cord and the brain. It is the area of the CNS responsible for controlling blood pressure, swallowing, breathing and heartbeat. The brainstem has three parts: the spinal bulb, the bridge (protuberance) and the midbrain. It is in the brain stem that the cerebellum is fixed. Tumors in this region can cause weakness, double vision, muscle stiffness, or problems with sensation, eye movement, hearing, facial movement, foot coordination or swallowing.
- Cranial nerves. The cranial nerves are those that connect to the brain. These nerves transmit signals directly between the brain and the face, eyes, tongue, mouth and some other areas. Tumors that affect the cranial nerves can cause vision problems, problems with swallowing, hearing loss, facial paralysis, numbness or pain.
- Spinal cord. The spinal cord is composed of all nerve fibers that descend from the brain. Spinal cord tumors can cause weakness, paralysis or numbness. Some types of brain tumors may have metastasis in the spinal cord. A spinal cord tumor presses on the nerves and can cause different symptoms depending on its location. Spinal cord tumors can cause weakness, paralysis or numbness.
Types of Cells and Tissues of the Central Nervous System
The central nervous system (CNS) is formed by several types of cells: and tissues:
- Neurons. Neurons are the most important cells in the brain. They are responsible for receiving and transmitting stimuli from the internal and external environment, enabling the organism to carry out appropriate actions and responses. Unlike many other types of cells that can grow and divide to repair damage caused by an injury or illness, neurons 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. They are support cells of the brain. Glial cells can become cancerous and grow to form a brain tumor. Tumors that develop in glial cells are called gliomas. There are three types of glial cells, in addition to a fourth type called microglia, which is not really a glial cell, but is part of the immune system:
- Astrocytes. These cells have the function of supporting and nourishing neurons. When the brain is injured, astrocytes form the scar tissue to repair the damage. The main tumors that start in these cells are astrocytomas or glioblastomas.
- Oligodendrocytes. These cells are responsible for the production of the myelin sheath, a fatty substance, which serves as an electrical insulator for the neurons of the CNS. Tumors that start in these cells are called oligodendrogliomas.
- Ependymal Cells. They are columnar epithelial cells that line the ventricles of the brain and the central channel of the spinal cord. In some regions, these cells are ciliated, facilitating the movement of cerebrospinal fluid. Tumors that start in these cells are called ependymomas.
- Microglia. These cells participate in the inflammation and repair process of the CNS, they also secrete several cytokines that regulate the immune process and remove the cell debris that appears in the CNS lesions.
- Neuroectodermal cells. Neuroectodermal cells are primitive cells, probably remnants of embryonic cells, and found throughout the brain. The most common tumor of these cells in the cerebellum is medulloblastoma.
- Meninges. Meninges are connective tissue membranes that line and protect the brain and spinal cord. Despite their protective function, meninges can be the target of important pathologies, such as benign tumors, meningiomas and the known meningitis.
- Choroid plexus. The choroid plexus is the area of the brain located within the ventricles that produces cerebrospinal fluid (CSF) to nourish and protect the brain.
- Pituitary Gland and Hypothalamus. The pituitary gland or pituitary gland is a gland, located in the turkish saddle (bone cavity located at the base of the brain), connected to the hypothalamus by the pituitary peduncle. The pituitary gland is responsible for various functions of the organism such as growth, metabolism, production of natural corticosteroids, menstruation and egg production, sperm production, and milk production in the breasts after the child’s birth. The growth of tumors near the pituitary gland or the hypothalamus, as well as surgery or radiation therapy in these areas can interfere with these functions.
- Pineal gland. The pineal gland is not exactly a part of the brain, in fact it is a small endocrine gland located between the cerebral hemispheres. The pineal gland produces melatonin. This hormone synchronizes the body’s various circadian rhythms with the day / night cycle. The daily changes of melatonin, with its peak being located during the night, act on receptors of the hypothalamus itself, which are in charge of synchronizing the body’s wake / sleep cycle and the functioning of other hormones.
- Blood-brain barrier. The blood-brain barrier (blood-brain barrier) is a structure that acts primarily to protect the central nervous system from chemicals in the blood, while allowing normal brain metabolic function. It is composed of endothelial cells, which are grouped in brain capillaries. This increased density greatly restricts the passage of substances from the bloodstream, much more than the endothelial cells present anywhere in the body. Unfortunately, this barrier also prevents the entry of chemotherapeutic drugs used to destroy cancer cells.