It coordinates complex processes which take place inside the body , It responds to stimuli coming from the internal or external environment, It facilitates the senses (visual, auditory, taste, tactile, olfactory)

Organ systems would function chaotically, The body’s demands couldn’t be met, Cognitive processes and emotions would cease

It consists of the encephalon (located in the cranial cavity) and the spinal cord (located in the spinal canal), It is the body’s central control centre, Certain CNS components receive the incoming information and release the appropriate reactions

It consists mainly of the axons and dendrites of sensory and motor neurons, Neuronal cellular bodies are located in the central nervous system or close to it (lymph nodes), The PNS informs the CNS about the stimuli coming from the external environment

The 21 pairs of cranial nerves which include 3 pairs of sensory nerves (I, II, VIII), The 31 pairs of spinal nerves which apparently originate in the spinal cord, The 12 pairs of cranial nerves which include 5 pairs of motor nerves (III, IV, VI, XI, XII)

It regulates the activity of involuntary muscles and of glands (endocrine and exocrine), It contains two types of motor nerves: sympathetic and parasympathetic, Parasympathetic nerves ensure the body’s relaxation capacity

They are represented by two types of cells: neurons and glial cells, Glial cells are supporting cells, Neurons receive and transmit biochemical signals

Schwann cells – form the myelin sheath enveloping the neurons located outside the central nervous system, Astrocytes help isolate the damaged nervous tissue, Oligodendrocytes – form myelin sheaths enveloping the projections of the central nervous system neurons

Multipolar, when they have multiple dendrites and a single axon, Pseudounipolar, when they have a single projection which divides to form a dendrite and an axon, Bipolar, when they nave a single axon and a single dendrite

Afferent neurons, efferent neurons and association neurons, Sensory neurons, motor neurons and interneurons, Neurons which send information from receptors to the central nervous system, neurons which send messages from the central nervous system to the muscles, heart and lymph nodes, and interneurons also called association neurons

The cell body represents a small part of the cell’s total size, The surface of dendrites is covered with thousands of spines which help dendrites connect to other neurons, The neuron’s cell body contains the nucleus, mitochondria, Golgi apparatus, lysosomes, Nissl bodies

Axons originating in the lower part of the spinal cord and extend to the foot may reach 1.2 meters, At their distal end, axons have axon terminals with swollen ends called synaptic boutons, Dendrites are specialised in receiving nerve impulses and relaying them to the cell body

It is a stratified membrane produced by two types of cells – oligodendrocytes and Schwann cells, Myelin is a major component of the oligodendrocyte membrane and of Schwann cells, Myelin isolates electrochemical reactions which transmit nervous impulses along axons

The nerve consists of several axon and/or dendrite bundles, In the structure of a nerve, each nerve bundle is surrounded by a sheath called perinerve, Lymph nodes are structures which contain the cell bodies of neurons

Reception means getting information from the surrounding environment, The activity of relaying information refers to information being transmitted to the central nervous system by sensory neurons, Integration is subsequent to transmission and refers to the activity during which the proper response is being determined

The role of the receptor is to detect internal or external alterations, Components are represented in the following order by receptors, sensory neurons, interneurons, motor neurons, effectors (muscle or lymph node), The role of the effector is to respond to the stimulus received from the motor neuron and to produce a reflex action

It can be automatic and unconscious without involving the encephalon or a mental activity, A reflex occurs when a sensory neuron receives a stimulus, A typical example of a reflex act is the patellar reflex

It is polarised because the internal and external surface of its membrane have opposite electrical charges, Its cytoplasm has a negative electric charge, The external surface of its membrane has a positive electric charge

It originates in an electrochemical event triggered by the altered ion distribution in the nerve cell, It is also called action potential, When it is generated, a stimulus (electric, mechanical, chemical) changes the resting potential by opening sodium channels and allowing the passage of sodium ions into the nerve cell

A neuron and an effector (muscle), A neuron and a lymph node, Two neurons (a presynaptic one and a postsynaptic one)

Motor plate, Neuromuscular synapse, Neuromuscular junction

They are chemical substances belonging to different classes of compounds (catecholamines, amino acids etc.), They are released from the terminal buttons of the presynaptic neuron axon and cross the synaptic gap, Their connection to the postsynaptic membrane receptors generates an action potential in the postsynaptic neuron

The neurons which innervate skeletal muscles at the point of the neuromuscular junction, Certain neurons from the vegetative component of the peripheral nervous system, Some of the neurons in the encephalon

It is a neurotransmitter present both in the encephalon and in the spinal cord, It can be involved in certain mental functions or in the circadian rhythm

Gamma aminobutyric acid – in the encephalon, Certain neurotransmitters which keep sodium channels closed, Glycine – mainly in the spinal cord

Adrenaline and noradrenaline, Noradrenaline and dopamine

Excite the postsynaptic neuron, Induce postsynaptic-neuron-membrane depolarisation, Open sodium channels, allowing sodium ions to penetrate the cell

Inhibit the occurrence of nervous impulses in the postsynaptic neuron, Keep sodium channels closed

It lies in the bony canal formed by the vertebrae, It originates in the large opening (foramen magnum) of the occipital bone, extending downwards through the bony canal formed by the vertebrae

The nervous tissue enveloped by three meningeal layers, The central canal also called ependymar canal, A grey matter on the inside consisting of horns, A white mater on the outside consisting of myelinated nerve fibres

The dura mater, fibrous, resistant connective tissue, The arachnoid, network-like thin layer, The pia mater, richly-vascularised very thin layer

Cannot be found outside the dura mater, Whenever a disorder of the nervous system is suspected, a sample can be collected by spinal tap (lumbar puncture) for lab analysis, Its function is to ensure the necessary nutrients required by the nerve cells of the central nervous system

Their apparent origin is the base of the encephalon (cranial nerves) and the spinal cord (spinal nerves), Spinal nerves and some of the cranial nerves contain both sensory fibres and motor fibres, Some cranial nerves contain fibres belonging to the vegetative nervous system (the vagus nerve), The spinal nerves innervate several structures such as the skin, skeletal muscles, joints, blood vessels, mucosae, sweat glands (with the exception of the head and the neck)

The bulb hosts the centres which regulate cardiac activity and blood pressure, The bridge functions as a relay between the two cerebellar hemispheres, The mesencephalon controls the reflex movements of the head and trunk as response to auditory stimuli

They belong to the peripheral nervous system, together with the spinal nerves, They are designated by numbers (I – XII) and a different name for each, Their apparent origin is described – the place where the nerve becomes visible

Nerves I, II and VII are sensory nerves, nerves III, IV, VI, VII and XI are motor nerves, Nerves I, II and VII are mixed nerves

They represent most of the encephalon and control complex mental functions, The insular lobe or insula is a deep area of the cerebral hemispheres, Each hemisphere contains the frontal, parietal, temporal and occipital lobe, They represent the centre of reasoning and memory and greatly determine the intelligence of an individual

They are joined by a bridge called corpus callosum, made of nerve fibres, The frontal lobe lies anterior to each cerebral hemisphere, Their surface is crossed by several grooves and gyri

They contain neurons which interpret the nervous impulses coming from sense organs, They contain neurons which initiate voluntary responses to stimuli, Certain areas of the parietal lobes are responsible for understanding speech and expressing ideas

They are cavities containing a fluid which serves as nutrient for nerve cells, They contain cerebrospinal fluid, which is also located in the ependymal canal of the spinal cord, Two of them (the lateral ventricles) lie inside the cerebral hemispheres

The frontal lobe is anterior to the central sulcus, The parietal lobe is posterior to the frontal lobe and separated from it by the central sulcus, Below the frontal lobe and separated from it by the lateral sulcus, lies the temporal lobe, Posterior to each hemisphere, lies the occipital lobe

The basal nuclei – control muscle tone, The limbic system – centres if pleasure and of punishment, The reticular formation (bulb, pons and mesencephalon) – stimulation of cognitive processes

They are responsible for sensations, feelings and emotions, The area responsible for the sense of smell is located deep inside the cerebral hemispheres, The areas for the sense of hearing are located in the temporal lobe, which is also responsible for the auditory and visual memory

It is situated in the frontal lobe, Contains large pyramidal neurons which generate impulses transmitted along the corticospinal tract, The frontal lobe, in Broca’s area, is responsible for the motor activity connected to speech and language processing, Due to the crossing over of the corticospinal tracts, the impulses received from the left hemisphere control the motor activity of the body’s right side

It acts involuntarily without conscious control, It coordinates the homeostatic functions of certain viscera, such as the heart, Parasympathetic nerves relax the body after a situation of stress or danger

Activate the body for fight or flight („fight or flight” reaction), Its neurotransmitter is represented by noradrenalin released from postganglionic fibres, Prepares the body for emergency situations

Induces the relaxation of the body after a situation of stress or danger, Contains cholinergic postganglionic fibres (which use acetylcholine as neurotransmitter), Its preganglionic neurons are located at cranio-sacral level (in the cerebral trunk, respectively in the sacral spinal cord)

Acceleration of the heart rate, Relaxation of the bronchi, Decreased stimulation of salivation

Slowing down of the heart rate and dilatation of the arteries, Constriction of the pupil, Stimulation of the digestion, Contraction of the urinary bladder