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