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Human nervous system is mainly divided into 3 divisions, which are as follows: 1. Central Nervous System 2. Peripheral Nervous System 3. Autonomic Nervous System.
The nervous system is mainly divided into central nervous system, peripheral nervous system and autonomic nervous system.
But some scientists have classified them into two divisions in which the ANS is included under peripheral nervous system category.
1. Central Nervous System:
Central nervous system consists of brain and spinal cord.
Brain:
It is the highest and the most important nerve centre. It is situated in the skull cavity. It comprises of the cerebrum, cerebellum, thalamus, hypothalamus, pons and medulla oblongata.
The Cerebrum:
It is the largest part of the brain filling the whole of the upper part of the skull. It is divided into left and right hemispheres by a longitudinal fissure. This is covered by a layer of gray matter called cerebral cortex and the inner part by white matter.
Below the central portion of the falx, the cerebral hemispheres are connected by a substantial bridge of white matter called Corpus callosum. The most prominent feature on the surface of each hemisphere is numerous folds called gyri, which greatly increase the surface area of the cerebral cortex.
It is estimated that if this folded surface is spread out, it can occupy about 670 square inches. In lower animals the cerebrum has no folds, whereas the folds begin to appear increasingly in higher animals.
The mental ability of an individual will be proportionate the folds of his cerebrum. It contains nerve centres which control the greater part of our behaviour.
All the important psychological processes like memory, imagination, thinking, reasoning, senses are all controlled by cortex. Figure. 2.3 shows the cross-section of brain and its parts.
Each cerebral hemisphere is divided into four lobes, named for the skull bones overlying them. The frontal lobe is important in voluntary motor functions, motivation, aggression, mood and olfactory reception. The parietal lobe is the centre for the reception and evaluation of most sensory information such as touch, pain, temperature, balances and taste. The frontal and parietal lobes are separated by an intervening groove called ‘central sulcus’ or ‘fissure of Rolando’.
The temporal lobe situated at the lateral sides receives and evaluates olfactory (smell) and auditory (hearing) input and plays an important role in memory. Its anterior and inferior portions are called as the ‘psychic cortex’, and they are associated with functions such as abstract thought and judgement.
This lobe is separated from the rest of the cerebrum by a lateral fissure called ‘lateral sulcus’ or ‘fissure of Sylvius’. Finally the occipital lobe, which functions in the reception and integration of visual sensory input is situated at the back portion of the skull.
Association Cortex:
As stated, in peripheral nervous system the nerves perform two types of functions – sensory and motor. The sensory nerves or the afferent nerves which carry the information from sense organs to the cortex and in turn, motor or efferent nerves carry the instruction from the brain to the muscles of organs in the body.
The sensory nerve tracts which carry the impulses project to specific regions of the cerebral cortex called Primary Sensory areas where sensations are perceived. Cortical areas immediately adjacent to the primary sensory centres are called ‘Association area or Association cortex’.
These portions of the cortex are involved in the process of recognition. For example, the optic nerve fibres from the retina of the eye reach the visual cortex where the image is perceived. These nerve fibres then pass from the visual cortex to the visual association cortex or area where the present visual information is compared with past visual experiences (seen before).
On the basis of this comparison, the visual association cortex decides whether the image is of a known person or not.
The other areas of association cortex include the auditory association area, adjacent to the primary auditory cortex and the somatic sensory association cortex adjacent to the primary somatic sensory cortex.
Earlier it was thought that association areas just connect sensory and motor pathways. Currently it is believed that the association cortex performs the function of processing and integration of sensory information leading to meaningful behaviour.
The primary motor cortex is located in the posterior portion of the frontal lobe, directly anterior to the central sulcus. Efferent nerves located in this area control voluntary movements of skeletal muscles.
These are connected in an upside down system – where the upper portion of the brain controls the lower portion of the body and the head by lower part of cortex. The motivation and the foresight to plan and initiate movements occur in the anterior portion of the frontal lobes called prefrontal area.
This is a region of association cortex that is well developed only in primates, especially in humans. It is involved in motivation and regulation of emotional behaviour and mood. The motor speech area called Broca’s area (named after Dr. Paul Broca who recognised this area) situated in left hemisphere in majority of people and rarely in right hemisphere also, performs its function in the same manner like – sensory input —> association areas —> motor output.
Cerebellum:
This is also called hind brain. It regulates the muscles and their movements. It is mainly responsible for co-ordination of the muscular movements and maintenance of the body equilibrium.
The Thalamus:
It acts like a telephone exchange or a relay station. All sensory impulses pass through this centre before they reach higher centre of the brain.
Hypothalamus:
Situated below the thalamus and is mainly responsible for the control of emotional behaviour, metabolism and sexual activities.
Pons:
This is a way station for tracts running between the cerebrum and the cerebellum.
Medulla Oblongata:
This is situated at the base of the skull. It connects the brain and spinal cord. All nerve impulses to and from brain pass through this. It controls the vital functions like heart beat, blood pressure, blood circulation and respiration.
It also controls the reflexes like papillary reflex, sneezing and winking reflexes. If the upper portion of the medulla is damaged, the connection of cerebrum with rest of the body is broken, if lower portion is damaged, the vital functions are affected and person may die immediately.
Spinal Cord:
This is the continuation of the medulla oblongata and runs through the canal of the vertebral column. Both sensory and motor nerves pass through this, to and from the brain.
This is also the centre for reflex actions (reflex action- is receiving the impressions from different parts of the body through sensory nerves and sending back instruction through motor nerve for suitable action on its own authority without consulting the brain, this structure is called Reflex Arc). If any damage takes place to spinal cord the area below that part will get paralysed.
2. Peripheral Nervous System:
This system consists of all the neuron cell bodies and processes located outside the brain and spinal cord. This system can be classified into 2 parts: 12 pairs of cranial nerves and 31 pairs of spinal nerves.
The cranial nerves are divided into 3 types:
(a) Afferent or sensory nerves which carry the information from inside and on the surface of the individual and relay the same to the central nervous system where it is evaluated,
(b) Efferent or motor nerves relay the information from central nervous system to muscles and glands in various parts of the body to regulate activity of those structures,
(c) Mixed nerves perform both afferent and efferent functions. Though there is difference in functions, structure of all the nerves remain the same.
The spinal nerves arise along the spinal cord. All of them are mixed nerves. Some of them are also sympathetic and parasympathetic, influencing the behaviour.
3. Autonomic Nervous System:
The autonomic nervous system (ANS) plays a very important role in controlling the muscular and glandular functions which are directly related with our behaviour. This system controls the emotional activities of a person.
If this system is affected, the individual’s experiencing of emotions will also be disturbed. The ANS not only controls the emotional behaviour, but also helps to manage the biochemical balances and metabolic activities. This system is responsible for all the physiological and psychological changes during emotions.
The ANS is composed of sympathetic and parasympathetic divisions. Increased activity of sympathetic divisions generally prepares the individual for physical activity, whereas the parasympathetic stimulation generally activates vegetative (growth) functions such as digestion, normally associated with body at rest.
The sympathetic division of ANS prepares a person for physical activity by increasing heart rate and blood pressure, by dilating the respiration passages and by stimulating perspiration. It also stimulates the release of glucose from liver for energy, at the same time inhibits digestive activities and diverts all energy to the concerned part of the body during emergency.
In other words, it prepares the person for “fight or flight”, because it prepares the individual either to stand and face the threat or escape from that situation as quickly as possible.
The parasympathetic division stimulates the vegetative activities such as digestion, defecation and urination, at the same time slows down heart rate and respiration. It also causes the pupil of the eye to constrict and the lens to thicken. In this way increased activity of sympathetic division generally prepares the individual for physical activity, whereas parasympathetic division generally activates vegetative function.
Most organs that receive autonomic motor neurons are innervated by both sympathetic and parasympathetic divisions. However, the sweat glands and blood vessels are innervated exclusively by sympathetic neurons. But smooth muscles associated with lens of the eye are innervated by parasympathetic neurons.
In most cases the influence of two divisions of ANS is opposite on the organs that receive both innervations. For example, sympathetic division increases the heart rate whereas the parasympathetic division decreases the heart rate.
Though ANS is also a part of central nervous system, the control of brain is less on the functions of this system, hence it is called ANS. But this system is controlled by mid-brain and hypothalamus. It has direct relationship with many muscles and glands of the body and thereby controls both internal and external behaviour.
Home ›› Human Nervous System
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FAQs
What are 3 divisions of the nervous system and what do they do? ›
The brain and spinal cord make up the central nervous system. The peripheral nervous system is comprised of the somatic and autonomic nervous systems. The somatic nervous system transmits sensory and motor signals to and from the central nervous system.
What are the functions of the main divisions of the nervous system? ›The nervous system is involved in receiving information about the environment around us (sensation) and generating responses to that information (motor responses). The nervous system can be divided into regions that are responsible for sensation (sensory functions) and for the response (motor functions).
What are the divisions of the nervous system in psychology? ›The nervous system can be divided into two major subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS), shown in Figure 3.13. The CNS is comprised of the brain and spinal cord; the PNS connects the CNS to the rest of the body.
What are the 3 main nervous system called? ›The ANS can be further subdivided into the sympathetic, parasympathetic, and enteric nervous systems.
What are the 4 types of nerves in the nervous system? ›Axons, cord-like groups of fibers in the center of your nerve. Dendrites, branches that carry electrical impulses. Endoneurium, a layer of connective tissue surrounding axons. Perineurium, a layer of connective tissue that surrounds groups of axons called fascicles.
What are the 6 divisions of the nervous system? ›The central nervous system (defined as the brain and spinal cord) is usually considered to have seven basic parts: the spinal cord, the medulla, the pons, the cerebellum, the midbrain, the diencephalon, and the cerebral hemispheres (Figure 1.10; see also Figure 1.8).
What are the major divisions of the human nervous system quizlet? ›The structures of the nervous system are described in terms of 2 principal divisions-the central nervous system (CNS) and the peripheral nervous system (PNS).
What are the 3 divisions of the autonomic nervous system? ›The autonomic nervous system is a component of the peripheral nervous system that regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal. It contains three anatomically distinct divisions: sympathetic, parasympathetic, and enteric.
How do you differentiate the function of the divisions of the nervous system? ›Functionally, the nervous system can be divided into those regions that are responsible for sensation, those that are responsible for integration, and those that are responsible for generating responses.
What are the sympathetic and parasympathetic divisions of the nervous system? ›The autonomic nervous system comprises two parts- the sympathetic and parasympathetic nervous systems. The sympathetic nervous system activates the fight or flight response during a threat or perceived danger, and the parasympathetic nervous system restores the body to a state of calm.
Which division of nervous system serves as the main processing? ›
The central nervous system is composed of the brain and spinal cord. Your brain and spinal cord serve as the main "processing center" for your entire nervous system. They control all the workings of your body.
How many parts is the nervous system divided into quizlet? ›The Nervous System is divided into two parts. What are they? 1) The CNS (Central Nervous System) and 2) The PNS (Peripheral Nervous System. The CNS consists of only two parts - name them.
What are the 3 functions of the central nervous system? ›The central nervous system (CNS) is comprised of the brain and spinal cord. The three broad functions of the CNS are to take in sensory information, process information, and send out motor signals.
What is nervous system with diagram? ›...
Nervous system.
| Definition | A network of neurons that sends, receives and modulates neural impulses between different body parts. |
|---|---|
| Divisions | Central nervous system Peripheral nervous system |
| Central nervous system | Brain and spinal cord |
The cerebrum is the thinking part of the brain and it controls your voluntary muscles — the ones that move when you want them to.
What are the 5 major organs of the nervous system? ›The nervous system consists of the brain, spinal cord, sensory organs, and all of the nerves that connect these organs with the rest of the body. Together, these organs are responsible for the control of the body and communication among its parts.
What is the largest nerve in the body? ›The sciatic nerve is the longest, largest nerve in your body. Your sciatic nerve roots start in your lower back and run down the back of each leg. Sciatica is the pain or discomfort if your sciatic nerve gets compressed or pinched.
How do you remember the divisions of the nervous system? ›- On old Olympus's towering top, a Finn and German viewed some hops.
- Ooh, ooh, ooh to touch and feel very good velvet. Such heaven!
Several stages of neuron development have been identified- neuron production (or proliferation), migration, differentiation, synaptogenesis (increased connectivity), myelination, and synaptic pruning.
What are the major and minor divisions of the nervous system? ›The human nervous system consists of two distinct parts: the first being the central nervous system (CNS) which refers to the brain and spinal cord together and the second is the peripheral nervous system (PNS) which refers to the cervical, thoracic, lumbar, and sacral nerve trunks leading away from the spine to the ...
What are the functions of the nervous system's main divisions quizlet? ›
The central nervous system (CNS)—the brain and the spinal cord—is the nervous system's decision maker. The peripheral nervous system (PNS), which connects the CNS to the rest of the body by means of nerves, gathers information and transmits CNS decisions to the rest of the body.
What are the two major divisions of the nervous system _______________ and __________________? ›- The brain and the spinal cord are the central nervous system.
- The nerves that go through the whole body make up the peripheral nervous system.
The parasympathetic nervous system is part of the body's autonomic nervous system. Its partner is the sympathetic nervous system, which control's the body's fight or flight response. The parasympathetic nervous system controls the body's ability to relax. It's sometimes called the "rest and digest" state.
What are the somatic and autonomic nervous systems divisions of? ›The peripheral nervous system is further subdivided into the somatic nervous system and the autonomic nervous system.
What is the role of the sympathetic division? ›sympathetic nervous system, division of the nervous system that functions to produce localized adjustments (such as sweating as a response to an increase in temperature) and reflex adjustments of the cardiovascular system.
What are the 3 types of nervous system What is the difference between nerve and neuron? ›A group of neurons form a nerve. Neurons are the structural and functional units of the nervous system. Nerve is an enclosed, cable-like bundle of axons and nerve fibres found in the peripheral nervous system. There are three types of nerves autonomic nerves, motor nerves, and sensory nerves.
What is the main difference between sympathetic and parasympathetic nervous system? ›The parasympathetic part of your autonomic nervous system balances your sympathetic nervous system. While your sympathetic nervous system controls your body's “fight or flight” response, your parasympathetic nervous system helps to control your body's response during times of rest.
What are the four parasympathetic nerves? ›Parasympathetic ganglia which innervate targets in the head are located in four main ganglia: the ciliary, pterygopalatine, submandibular and otic ganglia.
How to remember difference between sympathetic and parasympathetic? ›- A.
- The sympathetic nervous system prepares the body for “fight or flight,” whereas the parasympathetic nervous system allows the body to “rest and digest.” Sympathetic neurons release norepinephrine onto target organs; parasympathetic neurons release acetylcholine.
The parasympathetic nervous system, also known as “rest and digest,” can be thought of as functioning in opposition to the sympathetic nervous system. Its functions include: A decrease in heart rate and contractility of cardiac muscle. Constriction of the ciliary muscle and the pupil for near vision.
Which nervous system drives the fight or flight response? ›
The sympathetic nervous system functions like a gas pedal in a car. It triggers the fight-or-flight response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathetic nervous system acts like a brake.
What is the main function of the medulla? ›Your medulla oblongata is the bottom-most part of your brain. Its location means it's where your brain and spinal cord connect, making it a key conduit for nerve signals to and from your body. It also helps control vital processes like your heartbeat, breathing and blood pressure.
What are the two types of cells found in the nervous system? ›Although the nervous system is very complex, there are only two main types of cells in nerve tissue. The actual nerve cell is the neuron. It is the "conducting" cell that transmits impulses and the structural unit of the nervous system. The other type of cell is neuroglia, or glial, cell.
What is a collection of neurons called? ›In the central nervous system, a collection of neuron cell bodies is called a nucleus. In the peripheral nervous system, a collection of neuron cell bodies is called a ganglion (plural: ganglia). The one exception to this rule that you may have encountered is the basal ganglia in the brain.
What is the difference between central nervous system and autonomic nervous system? ›CNS (central nervous system) refers to the part of the nervous system, consisting of the brain and the spinal cord, while ANS (autonomic nervous system) refers to the part of the nervous system responsible for the coordination of involuntary functions of the body.
What are the two types of nervous systems and what do they do? ›The nervous system is made up of the central nervous system and the peripheral nervous system: The central nervous system includes the brain and spinal cord. The peripheral nervous system includes the nerves that run throughout the whole body.
What division is the sympathetic nervous system? ›Introduction. The sympathetic nervous system (SNS) is one of the two divisions of the autonomic nervous system (ANS), along with the parasympathetic nervous system (PNS), These systems primarily work unconsciously in opposite ways to regulate many functions and parts of the body.
What are the 7 nervous system? ›The central nervous system (defined as the brain and spinal cord) is usually considered to have seven basic parts: the spinal cord, the medulla, the pons, the cerebellum, the midbrain, the diencephalon, and the cerebral hemispheres (Figure 1.10; see also Figure 1.8).
What are the divisions of the nervous system quizlet? ›The structures of the nervous system are described in terms of 2 principal divisions-the central nervous system (CNS) and the peripheral nervous system (PNS).
What are the 8 divisions of the nervous system? ›- Learning Objectives.
- Central Nervous System.
- Gray Matter and White Matter.
- Peripheral Nervous System.
- Autonomic and Somatic Nervous Systems.
- Parasympathetic and Sympathetic Nervous Systems.
What are the five senses of the nervous system? ›
Nerves relay the signals to the brain, which interprets them as sight (vision), sound (hearing), smell (olfaction), taste (gustation), and touch (tactile perception).
What are the major divisions of the nervous system what are their functions quizlet? ›The nervous system is divided into two main parts: the central and the peripheral nervous system. The central nervous system can be further divided into the brain and the spinal cord. The peripheral nervous system can further be divided into the autonomic and the somatic nervous system.
Which division of the nervous system is divided into the sympathetic and the parasympathetic? ›The two divisions of the autonomic nervous system are the sympathetic division and the parasympathetic division. The sympathetic system is associated with the fight-or-flight response, and parasympathetic activity is referred to by the epithet of rest and digest. Homeostasis is the balance between the two systems.
What is the difference between the sympathetic and parasympathetic nervous systems? ›The sympathetic system controls “fight-or-flight” responses. In other words, this system prepares the body for strenuous physical activity. The events that we would expect to occur within the body to allow this to happen do, in fact, occur. The parasympathetic system regulates “rest and digest” functions.
What does the parasympathetic division do? ›The parasympathetic part of your autonomic nervous system balances your sympathetic nervous system. While your sympathetic nervous system controls your body's “fight or flight” response, your parasympathetic nervous system helps to control your body's response during times of rest.
What are sympathetic and parasympathetic nerves? ›Your sympathetic and parasympathetic nervous systems have opposite roles. While your sympathetic nervous system carries signals that put your body's systems on alert, your parasympathetic carries signals that relax those systems. The two systems work together to keep your body in balance.
What are the 3 most important organs in the nervous system? ›The nervous system includes the brain, spinal cord, and a complex network of nerves. This system sends messages back and forth between the brain and the body. The brain is what controls all the body's functions. The spinal cord runs from the brain down through the back.
What are 10 functions of the nervous system? ›- maintaining homeostasis.
- interpreting sensory information.
- creating motor responses (movement)
- learning.
- thinking.
- talking.
The cranial nerves are a set of 12 paired nerves in the back of your brain. Cranial nerves send electrical signals between your brain, face, neck and torso. Your cranial nerves help you taste, smell, hear and feel sensations. They also help you make facial expressions, blink your eyes and move your tongue.