Nervous tissue

The nervous system controls and integrates the organism. The basic function is fast and accurate transfer of information. Transmitted information (excitement) is the main code of the nervous system.

Nervous tissue is adapted to receive stimuli, organize them and conduct them. In nerve centers, signals from different nerve pathways are collected and processed. One neuron can be connected to several thousand neurons thanks to synapses .

Transmission of nerve impulse[edit | edit source]

Electrical transmission: when spreading through a cell
Chemical transfer : from one cell to another

1.dendrite, 2. axon, 3. notches of Ranvier, 4. terminal end;, 5. myelin sheath, 6. cell body, 7. nucleus

New signals[edit | edit source]

New signals lead to executive bodies, namely:

CNS = Brain + Spinal Cord
PNS = Paired nerves exiting the brain and spinal cord

Importance of Neuronal Structures[edit | edit source]

Dendrites: short projections of the neuron (output + receptive field of the neuron), input membranes give rise to a local graded electrical response dependent on the intensity of the stimulus
Cell body (soma): nucleus + neuroplasm + organelles (transport and production of neurotransmitters and proteins)
Dendrosomatic membrane: membrane of dendrites + soma (if it has the function of an input membrane)
Axon (nerve fibre, neurite): conducts excitation and is a conductive component of transmission, hascytoplasm and a membrane , can be covered by glial cells in the CNS and Schwann cells in the PNS, so-called myelin sheaths (axons are not covered in invertebrates)
Dendrites + body: = signal input
Initial segment: it is between the connection of the axon with the body and the beginning of the myelin sheath, the place where the excitation occurs is called the axon bump - the immediate transition between the body and the axon
Nerve endings (telodendria): the final, output section of the axon, specialized for the release of synaptic mediators
Collatelars : lateral processes, they can branch from the axon at different places

Types of neurons[edit | edit source]

Afferent (ascending, sensitive): information from receptors to the spinal cord or brain
Efferent (descending, motor): carry signals from the CNS to effectors (muscles/glands), motoneurons innervate skeletal muscles
Interneurons (association): mainly in the CNS (97%), the more complex the function, the more interneurons are involved

A simplified CNS phylogeny procedure[edit | edit source]

Diffuse nervous system: small animals
Ganglion Nervous System: Molluscs
Ladder nervous system: arthropods
Tubular Nervous System: Vertebrates

This was followed by corticalization, i.e. the cerebral cortex developed, the multiplication, improvement and specialization of neurons took place.

Links[edit | edit source]

References[edit | edit source]

LANGMEIER, Miloš. Basics of medical physiology. 1. edition. Prague : Grada Publishing, a.s, 2009. 320 pp. ISBN 978-80-247-2526-0.

MYSLIVEČEK, Jaromír. Basics of neuroscience. 2. edition. Prague : Triton, 2009. 0 pp. ISBN 978-80-7387-088-1.

L. Janský, I. Novotný: Animal and human physiology, 1981, edition. Avicenum, 1. edition, 08-085-80