Neuroanatomy II: The Nervous System and The Brain

The Parts of the Nervous System

The nervous system is split into two main parts: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The CNS consists of the brain and spinal cord. These two parts of our body are responsible for integrating information and responding to sensory stimuli. The PNS consists of all the nerves and ganglia that branch out from the CNS. Similarly, it is responsible for connecting all limbs and organs to the CNS, so physical and behavioural actions can be performed as a result of stimuli. Furthermore, the PNS is split into two subdivisions known as the Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS). The Somatic Nervous System controls all voluntary movements such as walking, clapping and other actions that need genuine instruction to function. The Autonomic Nervous system is the opposite; it controls involuntary actions such as the heartbeat, breathing and more. The SNS and the ANS both consist of two types of nerves that contribute to their functions. Similar to the PNS, the ANS can also be split into two more subsections known as the Sympathetic Nervous System and the Parasympathetic Nervous System. The Sympathetic Nervous System is responsible for controlling the body’s fight or flight response to stressful situations, such as inducing extreme sweating and increasing heart rate. In contrast, the Parasympathetic Nervous System is responsible for generating rest and digestion functions such as relaxing muscles, slowing down the heart rate and increasing nutritional digestion.

Earlier in the passage, there were mentions of ganglia and nerves. So, what are they? To get a better understanding of them, we will have to look at the two different types of tissue in the nervous system: grey matter and white matter. Grey matter consists of the cell bodies of neurons while white matter is made up of axons. The location of these tissues contributes insights into their function. Ganglia and nerves are initially bundles of such tissues that help with transporting signals across the PNS. Figure 2 provides a general overview of the classification of different types of matter.

The Brain

The brain is the center of the nervous system and where all of the processing of electric and chemical impulses takes place. The brain can be split into three main subsections: the cerebrum, the cerebellum and the brain stem. The cerebellum plays an important role in maintaining balance, coordination and timing of motor functions. The brain stem, on the other hand, is made up of three parts: the medulla oblongata, the pons and the midbrain. The medulla oblongata is responsible for controlling a majority of the autonomic nervous system’s functions from breathing to digestion. The pons is also involved in breathing along with inter-regional brain communication. The midbrain is crucial to communication, and the control of the motor system, vision and hearing, and a large variety of other reflexes. The largest subsection of the brain is the cerebrum, which is key in receiving and processing visual, auditory, somatosensory and olfactory information.

The cerebral cortex is the surface of the cerebrum, and it has four regions, each of which is responsible for controlling a specific function or group of functions. The lobe shaded in blue is known as the Frontal lobe. This lobe is responsible for critical thinking, problem-solving and performing all cognitive tasks. The Parietal lobe (the yellow region of Figure 3) processes and integrates sensory information such as sensation and perception. The Occipital lobe is located at the back of the brain, which is represented by the pink region, and it processes visual information provided by the visual system. Finally, the Temporal lobe is shown in green and is responsible for memory, recognition and auditory perception. Conclusively, the Nervous System forms a vast network of connections in which every Neural circuit and cell is able to manifest significance and contribute to making humans the people that we are.

References

The Neuronal Membrane. (n.d.). Retrieved October 13, 2020, from https://youthneuro.org/media/myelin/slides/1.06__Introduction_to_Neuroanatomy.pdf

Introduction to Neuroanatomy. (n.d.). Retrieved October 13, 2020, from https://youthneuro.org/media/myelin/slides/1.06__Introduction_to_Neuroanatomy.pdf