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 anequal ion distribution: - extracellular space: Na+
- intracellular space: K+
+ negatively charged proteins

17. Action potential: depolarization

18. Synapses Axo-dendritic Axo-somatic the most ommon Axo-axonic
Dendro-dendritic
the most ommon

19. Chemical synapses Excitatory: cholinergic: acetylcholine
adrenergic: adrenalin, noradrenalin
peptidergic: dopamin, serotonine
Inhibitory: GABA

20. Nervous tissue Glial cells The principal glia: Schwann cells
oligodendrocytes,
astrocytes,
ependymal cells: lining layer (central canal+ventricles
microglial cells: phagocytotic cells

21. Sheath In the peripheral nervous system: Schwann cell
Schwann sheath
myelin sheath
In the central nervous system: oligodendroglial cells
myelin sheath ONLY

22. Principal glial cell types

23. Formation of myelin sheth in a peripheral axon.

24. Myelin sheath
Ranvier’s node
axon hillock
Shwann cells

25. Axons are sheathed in myelin

26. Oligodendrocytes
Oligodendrocytes sheat the axons of the neurons to increase conductance of action potential

27. Oligodendrocytes

28. Glial cells
astrocytes

29. Astrocytes
Astrocytes connect the extraneuronal space with the blood vessels:
blood/brain barrier

30. Comparison of neurons and glia

31. References
Wikipaedia