Download presentation
Presentation is loading. Please wait.
1
Nervous tissue Neurons and Glial Cells
Anna L. Kiss Department of Human Morphology and Developmental Biology Semmelweis University 2015
2
Nervous tissue Function: stimulus transmission Origin: ectoderm
Structure: neurons + glial cells
3
Nervous tissue Neurons: unipolar bipolar pseudounipolar multipolar
4
Functions of neuronal compartments
Dendrites receive input from other neurons. The axon transmits information over distance. The termini send information to other neurons. The soma (cell body) synthesizes proteins and membrane components.
5
Soma: perikaryon: cell body
In the soma of the cells:cell nucleus (containing the DNA, i.e genetic code); rER: synthesis of the proteins (Nissle bodies (ribosomes and endoplasmatic reticulum) mitochondria: ATP production
6
Nerve cells (neurons)
7
Processes: short: dendrites long: axon
8
Dendrites receive input from other neurons
Highly branched dendrites provide a large postsynaptic surface area. The soma also receives synapses.
9
Axons transmit excitation over distance
Axons are electrically excitable. The axon begins with a trigger zone, the axon hillock. Bigger axons conduct faster. Most axons are insulated by myelin.
10
Structure of neurons - Axon
The axon transmits the information electrically from the soma to the synapses – it is surrounded by myelin sheath that insulate the axon, provided by glial cells
11
Terminals transmit signals to other cells
Presynaptic terminals release neurotransmitter onto target cells. The target may be a neuron or some other effector. Neuroendocrine cells release transmitter into the blood.
12
General structure of the synapses
presynapses synaptic cleft postsynapses
13
Synapse – Communication between neurons
14
Electrical synapses synaptic cleft: narrow work faster
impulse transmission: bidirectional
15
Chemical synapses synaptic cleft: wider work slower
impulse conduction: unidirectional
16
Resting potential aniqual ion distribution: - extracellular space: Na+
- intracellular space: K+ + negatively charged proteins
17
Action potential: depolarization
18
repolarization
20
Synapses Axo-dendritic Axo-somatic the most ommon Axo-axonic
Dendro-dendritic the most ommon
21
Chemical synapses Excitatory: cholinergic: acetylcholine
adrenergic: adrenalin, noradrenalin peptidergic: dopamin, serotonine Inhibitory: GABA
22
Nervous tissue Glial cells The principal glia: Schwann cells
oligodendrocytes, astrocytes, ependymal cells: lining layer (central canal+ventricles microglial cells: phagocytotic cells
23
Sheath In the peripheral nervous system: Schwann cell
Schwann sheath myelin sheath In the central nervous system: oligodendroglial cells myelin sheath ONLY
24
Principal glial cell types
25
Formation of myelin sheth in a peripheral axon.
26
Myelin sheath Ranvier’s node axon hillock Shwann cells
27
Axons are sheathed in myelin
28
Oligodendrocytes Oligodendrocytes sheat the axons of the neurons to increase conductance of action potential
29
Oligodendrocytes
30
Glial cells astrocytes
31
Astrocytes Astrocytes connect the extraneuronal space with the blood vessels
32
Comparison of neurons and glia
33
References Wikipaedia
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.