Introduction
The nervous system is the central communication and decision-making center in the body. It relays messages to all body parts; to and from the brain. The whole system uses neurons and other specialized cells called glial cells to pass messages. It is divided into two sections; the central nervous system (CNS) and the peripheral nervous system (PNS). The two systems communicate via neurons through the generation of impulses. The central nervous system primarily comprises the spinal cord and the brain. The PNS is made of somatic and efferent nervous systems. Coordination between these two systems controls all body functions (Farebee, 2007, Para. 1-6).
General description
The collection of information from the environment is the central role of sensory nerves. This information is relayed to the brain, and feedback is sent via motor neurons on actions to be taken by the body (Serendip, 2005, Para. 1-3).
The cerebral cortex has millions of neurons, each with thousands of synaptic connections. Communications by brain neurons are done via protoplasmic fibers called axons. The brain controls behavior through two means; muscle activation or hormonal secretions. Many connective tissue membranes surround the brain hence, separating it from the skull. This helps in cushioning and protecting the brain with help of the cerebrospinal fluid. The separating layers are the arachnoid mater, Pia mater, and Dura mater.
Three sections make the human brain namely: the midbrain (tectum and tegmentum), forebrain (hypothalamus, cerebrum, and thalamus), and the hindbrain (the cerebellum, medulla, and pons).
The five swellings
During the development of a vertebrae embryo, a fluid-filled tube develops into the CNS. The first signs of a developing brain are swellings that develop at the tube end. These swellings later develop into three main sections in an adult’s brain. The swellings (three), as the fetus develops multiply to five due to the division of the hind and forebrain into two. The five swellings that develop are Telencephalon, metencephalon, Diencephalon, Mesencephalon, and myelencephalon. The telencephalon and the diencephalons form the forebrain, the mesencephalon forms the midbrain and the metencephalon, and the myelencephalon from the hindbrain (Rice University, 2000, Para 2)
Myelencephalon (or medulla) forms the posterior section of the human brain stem. It contains neurons that carry signals communicated from the body to the brain and vice versa. In addition, it contains the reticular formations that occupy the middle part of the brain stem, from the back of the myelencephalon to the front section of the midbrain. The Myelencephalon controls main body activities that include: sleep, attention, respiratory, cardiac, and circulatory reflexes in addition to the movement (Rice university-Myelencephalon, 2000, Para. 1)
The mesencephalon forms the midbrain. It contains two divisions namely: the tegmentum and tectum. The tectum forms the upper cover of the mid-brain. It has two pairs of bumps called colliculi. These two pairs’ work is to control the auditory and the visual systems. The tegmentum has three structures namely: the periaqueductal gray, red nucleus, and substantia nigra. The periaqueductal gray helps in offsetting effects resulting from opiate drugs. On the other hand, the substantial nigra in collaboration with the red nucleus helps the sensory-motor system in conveying messages to and from the brain (Rice university- mesencephalon, 2000, Para. 1).
The telencephalon is the largest of all divisions of the brain. It is made up of the cerebral cortex, Amygdaloidal Nucleus, Basal forebrain nuclei, and basal ganglia. The amygdala is also found in this section. It is a component of the limbic system, positioned in the temporal lobe. It helps in controlling fear and emotional levels (Rice university- telencephalon, 2000, Para. 1). The basal ganglion controls the body motor system, speech development, emotions, and helps the brain to store data (mainly done by the cerebral cortex). In addition to the amygdala, the telencephalon has another component called the hippocampus. This section of the brain is important in learning and memorization of content (Serendip, 2005, Para 11).
The metencephalon takes the biggest proportion of the hindbrain. It has two parts, the cerebellum, and the pons. This portion of the brain houses tracts and portions of the reticular formations. The pons acts as a bridge to the cerebellum with millions of fibers. Many of these fibers cross the bottom of the brain stem hence, connecting to places in the cerebellum. The cerebellum has two divisions that have ten smaller lobules. Its major function is to organize motor movements, muscle tone, and ensuring balance during movements. In addition to movement, it also helps in language development through controlling tongue movements (Sodicoff, 2004, Para. 2).
The last division of the brain is the Diencephalon. It is made up of two structures: the hypothalamus and the thalamus. The thalamus is lobe-shaped and found on the brain stem. Its surface is covered with white lamina, made up of myelinated axons. It forms the main pathway for neuron transfer of information to the cerebral cortex hence helping the sensory and motor body systems. The hypothalamus is near the thalamus. It is involved in homeostasis, emotional, hunger, and thirst control. In addition, it helps the body to coordinate the autonomic nervous system and circadian patterns (Serendip, 2005, Para. 12).
Conclusion
In conclusion, the brain is a very vital organ in the human body. This is because through the brain human beings can move, and “read” their environment hence coordinate body functions to meet their needs.
Reference
Farebee, M. J. (2007). The nervous system: the brain. 2009. Web.
Rice University. (2000). Language and brain: neurocognitive linguistics. 2009. Web.
Serendip. (2005). Brain Structures and their Functions. 2009. Web.
Sordicoff, M. (2004). Neuronatomy resource appendices: Neuroembryology. 2009. Web.