Functional Anatomy of the Central Nervous System Essay
After studying the material of the chapter, the student must:
• the basic concepts, the classification of the departments of the nervous system according to the topographic-anatomical and functional principles;
• features of the structure of nerve cells;
• classification of nerve cells;
• the structure of the synapses and their classification;
be able to
• schematically depict various forms of nerve cells;
• define them in a form, giving them a functional characteristic;
• by the conceptual apparatus used in neuromorphology. Functional Anatomy of the Central Nervous System Essay.
The nervous system is a collection of anatomically and functionally interrelated structures that provide for the regulation and coordination of the organism’s activity as a whole and its interaction with the surrounding environment. It plays the role of an apparatus that perceives irritations, analyzing incoming information and providing a response of the organism.
The nervous system appeared in the course of evolution as an integrative system, carrying out the consistency of the functions of all organs and adaptation of the organism to conditions of existence. At the same time, from the moment of occurrence of stimulation to its sensation, hundredths of a second pass. After elimination of the action of the stimulus, the response ceases immediately.
The topographic-anatomical principle divides the nervous system into central and peripheral. The central nervous system includes the brain and spinal cord, peripheral – all nerve structures located outside the brain and spinal cord.
The central nervous system consists of billions of highly specialized cells – neurocytes and glial cells. Glial cells provide the activity of neurons (support, protect and fulfill a trophic role). The task of the central nervous system is to obtain a rating after taking the information within a fraction of a second and make an appropriate decision. In the implementation of the latter, the ability of the brain to store and reproduce, at the right time, previously received information is invaluable. Functional Anatomy of the Central Nervous System Essay. The greatest achievement of the evolution of the nervous system is the thinking ability. It is realized as a result of the analysis and synthesis of nerve impulses in the higher centers of the brain and constitutes the higher nervous activity of the human body.
The structures associated with the spinal cord are the spinal cord of the peripheral nervous system. It includes sensitive nodes of spinal nerves, roots of spinal nerves, trunks and branches of spinal nerves, plexus, sympathetic nerve nodes, regional and organ nerves and nerve endings. The spinal column provides innervation of the trunk, extremities, partially – the neck and internal organs.
The structures associated with the brain form the cranial section of the peripheral nervous system. It includes sensitive nodes of cranial nerves, cranial nerves, branches of cranial nerves, parasympathetic nerve nodes and nerve endings. The cranial department provides innervation of the head, partly – of the neck and internal organs.
The peripheral nervous system connects the spinal cord and the brain with receptors (sensitive nerve endings) and with effectors (apparatuses that transmit nerve impulses to the working organs). The working organs respond to external and internal stimulation with adaptive reactions of the body, such as muscle contraction or secretion of glands.
It should be noted that the division of the nervous system into central and peripheral is conditional, as in anatomical and functional relations these departments are closely interrelated.
By function the nervous system is divided into somatic ( abnormal ) and autonomic ( autonomous ) . The somatic nervous system responds for the innervation of the body (soma) – skin, muscles and skeleton. The autonomic nervous system provides innervation of internal organs, glands and blood vessels. In turn, it includessympathetic and parasympathetic departments.
The somatic nervous system innervates the skin, muscles, skeleton, some internal organs (tongue, throat, larynx, etc.), carries out the connection of the organism as an integral system with the external environment. She perceives irritations from the external environment, analyzes them and provides a response – controls the skeletal (striated) muscles. Functional Anatomy of the Central Nervous System Essay.
The vegetative nervous system innervates internal organs and blood vessels, controls smooth muscles and glands. It unites individual parts of the body in a single integrated system and carries out an adaptive-trophic function in the body.
Before proceeding to the study of the morphology of the spinal cord and brain, it is advisable to consider the general principles of the structure of the nervous system.
In addition to the anatomical divisions listed above, the nervous system can also be divided on the basis of its functions. The nervous system is involved in receiving information about the environment around us (sensory functions, sensation) and generating responses to that information (motor functions, responses) and coordinating the two (integration).
Sensation. Sensation refers to receiving information about the environment, either what is happening outside (ie: heat from the sun) or inside the body (ie: heat from muscle activity). These sensations are known as stimuli (singular = stimulus) and different sensory receptors are responsible for detecting different stimuli. Sensory information travels towards the CNS through the PNS nerves in the specific division known as the afferent (sensory) branch of the PNS. When information arises from sensory receptors in the skin, skeletal muscles, or joints this is known as somatic sensory information; when information arises from sensory receptors in the blood vessels or internal organs, this is known as visceral sensory information.
Response. The nervous system produces a response in effector organs (such as muscles or glands) due to the sensory stimuli. The motor (efferent) branch of the PNS carries signals away from the CNS to the effector organs. When the effector organ is a skeletal muscle, the information is called somatic motor; when the effector organ is cardiac or smooth muscle or glandular tissue, the information is called visceral (autonomic) motor. Voluntary responses are governed by the somatic nervous system and involuntary responses are governed by the autonomic nervous system, which are discussed in the next section.
Integration. Stimuli that are received by sensory structures are communicated to the nervous system where that information is processed. This is called integration (see Figure 12.1.2 below). In the CNS, stimuli are compared with, or integrated with, other stimuli, memories of previous stimuli, or the state of a person at a particular time. This leads to the specific response that will be generated. Functional Anatomy of the Central Nervous System Essay.