These sophisticated cells that conduct electrical signals depend on a number of organs.
These organs are:
The bulb is the body that is in direct contact with the spinal cord , it is the passageway for the nerves to the organs located higher.
In the bulb are the neuronal cell bodies that control vital functions such as the heartbeat, respiration rate, and blood pressure. It also contains cell bodies of neurons related to the control of swallowing, coughing and vomiting.
Body that regulates balance and posture in the environment. It is connected to peripheral receptors, located in the inner ear (labyrinth), which send messages to the balance control center located in the cerebellum. The success of a tightrope walker crossing two buildings, supported by a simple thread stretched between them, depends on good cerebellar activity.
Brain organ formed mainly by the thalamus and the hypothalamus. The hypothalamus contains the control centers for body temperature, appetite, thirst, sleep, and certain emotions. It is the main intermediate between the nervous system and the hormonal system, the hypothalamus is linked to the pituitary, the main endocrine gland.
When the hypothalamus detects changes in the body, it releases neurotransmitters that act on the pituitary. For its part, it releases or inhibits the secretion of its own hormones that regulate various metabolic activities.
It is the center of intelligence, memory, consciousness and language. Control our sensations and motor functions. About 70% of the nerve cells of the brain are located in the brain, the most developed part of our nervous system and which is separated into two hemispheres, joined to each other by a region known as the corpus callosum.
Each cerebral hemisphere, in turn, has innumerable invaginations called sulci.
The deepest sulci divide each hemisphere into four regions called lobes: the frontal, the parietal, the temporal, and the occipital. The central sulcus is the most pronounced and separates the frontal and parietal lobes.
The surface of the brain, 2 mm to 4 mm thick, is known as the cerebral cortex and is made up of multiple layers of the cell bodies of millions of neurons, giving the region a gray color, hence the one that dominates gray matter. of the brain.
The fibers (axons and dendrites), the neurons that leave and reach the cerebral cortex are located more internally and form the white matter of the brain, due to the existence of myelin fibers.
Most of the nervous system is a tissue made up of two classes of cells: neurons and neuroglia .
Neurons, also known as nerve cells, communicate within the body by transmitting electrochemical signals. Neurons look quite different from other cells in the body due to the many long cellular processes that extend from their central cell body.
The cell body is the roughly round part of a neuron that contains the nucleus, mitochondria, and most of the cellular organelles. Tiny tree-like structures called dendrites extend from the cell body to pick up stimuli from the environment, other neurons, or sensory receptor cells.
Long transmission processes called axons extend from the cell body to send forward signals to other neurons or effector cells in the body.
There are 3 basic classes of neurons: afferent neurons, efferent neurons, and interneurons:
- Afferent neurons: Also known as sensory neurons, afferent neurons transmit sensory signals to the central nervous system from receptors in the body.
- Efferent neurons: Also known as motor neurons, efferent neurons transmit signals from the central nervous system to effectors in the body, such as muscles and glands.
- Interneurons: Interneurons form complex networks within the central nervous system to integrate information received from afferent neurons and direct the body’s function through efferent neurons.
The glia, also known as glial cells, act as “helper” cells of the nervous system. Each neuron in the body is surrounded by 6 to 60 glia that protect, feed, and isolate the neuron.
Because neurons are extremely specialized cells that are essential for body function and rarely reproduce, glia are vital to maintaining a functional nervous system.
The spinal cord is a long, thin mass of clustered neurons that carries information through the vertebral cavity of the spinal column that begins in the brainstem at its upper end and continues into the lower lumbar region of the spine. vertebral.
In the lumbar region, the spinal cord separates into a bundle of individual nerves called the cauda equina that continues into the lower part of the sacrum and coccyx. The white matter of the spinal cord functions as the main conduit for nerve signals to the body from the brain. The gray matter of the spinal cord integrates reflexes to stimuli.
The meninges are the protective coverings of the central nervous system (CNS). They consist of three layers: the dura mater, the arachnoid mater, and the pia mater.
Dura mater : Dura mater, which means “hard mother,” is the thickest, hardest, and most superficial layer of meninges. Made of dense irregular connective tissue, it contains many collagen fibers and strong blood vessels. Dura mater protects the CNS from external damage, contains the cerebrospinal fluid that surrounds the CNS, and supplies blood to the nervous tissue of the CNS.
Arachnoid: The arachnoid, which means “spider mother,” is much thinner and more delicate than the dura. It thickens the interior of the dura and contains many fine fibers that connect it to the underlying pia mater. These fibers cross a fluid-filled space called the subarachnoid space between the arachnoid and the pia mater.
Pia mater : The pia mater, which means “tender mother,” is a thin, delicate layer of tissue that rests on the outside of the brain and spinal cord. Containing many blood vessels that feed the nervous tissue of the CNS, the pia mater penetrates the valleys of the sulci and fissures of the brain, as it covers the entire surface of the CNS.
The space around the CNS organs is filled with a clear fluid known as cerebrospinal fluid (CSF). CSF is formed from blood plasma by special structures called choroid plexuses.
The choroid plexuses contain many capillaries lined with epithelial tissue that filter blood plasma and allow filtered fluid to enter the space around the brain.
All the sense organs of many bodies are components of the nervous system. What are known as the special senses – vision, taste, smell, hearing, and balance – are all sensed by specialized organs such as the eyes, taste buds, and olfactory epithelium.
Sensory receptors for the general senses such as touch, temperature, and pain are found throughout most of the body. All of the body’s sensory receptors are connected to afferent neurons that carry their sensory information to the CNS to be processed and integrated.