№ 2 дәріс Тақырып: Physiology and hygiene of nervous system, its age peculiarities
Жоспар: 1. Physiology of nervous system. 2. Development of nervous system.
1. Physiology of nervous system. The nervous system is the part of animal's body that coordinates its voluntary and involuntary actions and transmits signals to and from different parts of its body. In vertebrate species it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS contains the brain and spinal cord.
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CNS PNS NS central nervous system brain spinal cord peripheral nervous system nervous neural networks
nervous system of the person somatic system touch department (perceives information from environment) motive department (provides with Managements of movements) vegetative system sympathetic department (mobilization of the person to vigorous activity) parasympathetic department (restoration of the spent resources)
At the cellular level, the nervous system is defined by the presence of a special type of cell, called the neuron, also known as a "nerve cell". Neurons have special structures that allow them to send signals rapidly and precisely to other cells. They send these signals in the form of electrochemical waves traveling along thin fibers called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses. A cell that receives a synaptic signal from a neuron may be excited, inhibited, or otherwise modulated. The connections between neurons can form neural circuits and also neural networks that generate an organism's perception of the world and determine its behavior. Along with neurons, the nervous system contains other specialized cells called glial cells (or simply glia), which provide structural and metabolic support.
A typical neuron consists of a cell body (soma), dendrites, and an axon. The term neurite is used to describe either a dendrite or an axon, particularly in its undifferentiated stage. Dendrites are thin structures that arise from the cell body, often extending for hundreds of micrometres and branching multiple times, giving rise to a complex "dendritic tree". An axon is a special cellular extension that arises from the cell body at a site called the axon hillock and travels for a distance, as far as 1 meter in humans or even more in other species.
A typical neuron consists of a cell body (soma), dendrites, and an axon.
Types of neurones
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron. Some authors generalize this concept to include the communication from a neuron to any other cell type, although such non-neuronal contacts may be referred to as junctions (a historically older term). The word "synapse" – from the Greek synapsis, meaning "conjunction", in turn from συνάπτεὶν (συν ("together") and ἅπτειν ("to fasten"))
Synapse (A place of contact of one neuron with another or an axon with working body) mitochondrion axon synoptic crack synoptic bubble postsynaptic membrane dendrite receptor for a mediator
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. The brain and spinal cord together make up the central nervous system (CNS). The spinal cord begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column. It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. Also, the spinal cord has a varying width, ranging from 13 mm (1⁄2 in) thick in the cervical and lumbar regions to 6. 4 mm (1⁄4 in) thick in the thoracic area. The enclosing bony vertebral column protects the relatively shorter spinal cord. The spinal cord functions primarily in the transmission of neural signals between the brain and the rest of the body but also contains neural circuits that can independently control numerous reflexes and central pattern generators. The spinal cord has three major functions: as a conduit for motor information, which travels down the spinal cord, as a conduit for sensory information in the reverse direction, and
Physiology of the Nervous System Neuron physiology neuron body Aksosomatichesky synapse dendrite aksodendritichesky synapse aksonalny synapse axon
Internal structure of a spinal cord. The spinal cord has a segmentary structure. A segment call such piece which gives rise to two couples backs. Back backs of a spinal cord are sensitive, and lobbies — motive. The spinal cord consists of gray and white substance. In chest and top lumbar departments. there also side ledges of gray substance. Thus, in a spinal cord distinguish three pair columns of a gray substance : forward, side and back which on a cross-section of a spinal cord carry the name of forward, side and back horns. The white substance of a spinal cord makes forward, side and back ropes and is formed is mainly longitudinal the going nervous fibers united in bunches — the carrying-out ways. Physiology of a spinal cord. – two functions are inherent in a spinal cord: reflex and conduction.
The spinal cord can be anatomically divided into 31 spinal segments based on the origins of the spinal nerves. The grey column, (as three regions of grey columns), in the center of the cord, is shaped like a butterfly and consists of cell bodies of interneurons, motor neurons, neuroglia cells and unmyelinated axons. The anterior and posterior grey column present as projections of the grey matter and are also known as the horns of the spinal cord. Together, the grey columns and the gray commissure form the "grey H. " The white matter is located outside of the grey matter and consists almost totally of myelinated motor and sensory axons.
There are 31 spinal cord nerve segments in a human spinal cord: 8 cervical segments forming 8 pairs of cervical nerves (C 1 spinal nerves exit spinal column between occiput and C 1 vertebra; C 2 nerves exit between posterior arch of C 1 vertebra and lamina of C 2 vertebra; C 3–C 8 spinal nerves through IVF above corresponding cervica vertebra, with the exception of C 8 pair which exit via IVF between C 7 and T 1 vertebra) 12 thoracic segments forming 12 pairs of thoracic nerves (exit spinal column through IVF below corresponding vertebra T 1–T 12) 5 lumbar segments forming 5 pairs of lumbar nerves (exit spinal column through IVF, below corresponding vertebra L 1–L 5) 5 sacral segments forming 5 pairs of sacral nerves (exit spinal column through IVF, below corresponding vertebra S 1–S 5) 1 coccygeal segments
Cross-section of a spinal cord gray substance white substance the spinal channel is filled with cerebrospinal fluid
The brain is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain is the most complex organ in a vertebrate's body. In a typical human, the cerebral cortex (the largest part) is estimated to contain 15– 33 billion neurons, [1] each connected by synapses to several thousand other neurons.
Neuroanatomists usually divide the vertebrate brain into six main regions: the telencephalon (cerebral hemispheres), diencephalon (thalamus and hypothalamus), mesencephalon (midbrain), cerebellum, pons, and medulla oblongata. In a brain distinguish hemispheres of a big brain (the newest part in evolutionary development) and a trunk with a cerebellum. Mass of a brain of the newborn on average 330 — 340 g. And in the first years of life the brain intensively grows in the embryonic period, but only by 20 years reaches final size.
The medulla, along with the spinal cord, contains many small nuclei involved in a wide variety of sensory and involuntary motor functions such as vomiting, heart rate and digestive processes. The medulla oblongata (or medulla) is located in the hindbrain, anterior to the cerebellum. The medulla oblongata is a cone-shaped neuronal mass responsible for multiple autonomic functions ranging from vomiting to involuntary functions such as sneezing. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and therefore deals with the autonomic (involuntary) functions of breathing, heart rate and blood pressure.
Frontal section of a brain gray substance white substance internal capsule bazalny kernels thalamus visual path
The pons lies in the brainstem directly above the medulla. Among other things, it contains nuclei that control often voluntary but simple acts such as sleep, respiration, swallowing, bladder function, equilibrium, eye movement, facial expressions, and posture.
The hypothalamus is a small region at the base of the forebrain, whose complexity and importance belies its size. It is composed of numerous small nuclei, each with distinct connections and neurochemistry. The hypothalamus is engaged in additional involuntary or partially voluntary acts such as sleep and wake cycles, eating and drinking, and the release of some hormones.
Thalamus Нypothalamus
The hypothalamus is a small region at the base of the forebrain, whose complexity and importance belies its size. It is composed of numerous small nuclei, each with distinct connections and neurochemistry. The hypothalamus is engaged in additional involuntary or partially voluntary acts such as sleep and wake cycles, eating and drinking, and the release of some hormones. The thalamus is a collection of nuclei with diverse functions: some are involved in relaying information to and from the cerebral hemispheres, while others are involved in motivation. The subthalamic area (zona incerta) seems to contain action-generating systems for several types of "consummatory" behaviors such as eating, drinking, defecation, and copulation.
The cerebellum modulates the outputs of other brain systems, whether motor related or thought related, to make them certain and precise. Removal of the cerebellum does not prevent an animal from doing anything in particular, but it makes actions hesitant and clumsy. This precision is not built-in, but learned by trial and error. The muscle coordination learned while riding a bicycle is an example of a type of neural plasticity that may take place largely within the cerebellum. [7] 10% of the brain's total volume consists of the cerebellum and 50% of all neurons are held within its structure
Scheme of education unconditional (A) and conditional (B) reflex А B ear food center of bark acoustical nerve food center of bark flavoring receptor food center of a medulla salivary gland tongue acoustical center of bark centripetal nerve tongue salivary gland
Types of higher nervous activity the strong the balanced 1. strong balanced mobile (sanguine) 4. weak (melancholic) 3. strong unbalanced (choleric) 2. strong balanced inert (flegmaticheskiya)
choleric person Phlegmatic person melancholiac sanguine person
3. Formation of the cognitive activity of the child perception thinking feeling imagination memory sensual step of knowledge logical step of knowledge practical activities of the person
