1. Chapter 2 Neurons and Glia

2. Introduction
“Neurophilosophy”
Brain is the origin of mental abilities
Glia and Neurons
Glia: Insulates, supports, and nourishes neurons
Neurons
Process information
Sense environmental changes
Communicate changes to other neurons
Command body response

3. The Neuron Doctrine
Histology
Study of tissue structure
The Nissl Stain
Facilitates the study of cytoarchitecture in the CNS

4. Franz Nissl – (1860 – 1919) founding father of the study of
eurocytology and neuropathology .

6. Golgi-stain (Developed by Camillo Golgi) shows two parts of neurons:
Soma and perikaryon
Neurites: Axons and dendrites

11. Cajal’s Contributions
Neural circuitry
Neurons communicate by contact, not continuity
Neuron doctrine
Neurons adhere to cell theory
Based in Golgi stain

14. Classification Based on the Number of Neurites
Single neurite
Unipolar
Two or more neurites
Bipolar- two
Multipolar- more than two

15. Classifying Neurons
Classification Based on Dendritic and Somatic Morphologies
Stellate cells (star-shaped) and pyramidal cells (pyramid-shaped)
Spiny or aspinous

16. Further Classification
By connections within the CNS
Primary sensory neurons, motor neurons, interneurons
Based on axonal length
Golgi Type I
Golgi Type II
Based on neurotransmitter type
e.g., – Cholinergic = Acetycholine at synapses

17. Glia
Function of Glia
Supports neuronal functions
Astrocytes
Most numerous glia in the brain
Fill spaces between neurons
Influence neurite growth
Regulate chemical content of extracellular space

21. Myelinating Glia
Oligodendroglia (in CNS)
Schwann cells (in PNS)
Insulate axons

22. Myelinating Glia (Cont’d)
Oligodendroglial cells
Node of Ranvier
Region where the axonal membrane is exposed

23. Other Non-Neuronal Cells
Microglia as phagocytes (immune)

24. The Soma
Cytosol: Watery fluid inside the cell
Organelles: Membrane-enclosed structures within the soma
Cytoplasm: Contents within a cell membrane (e.g., organelles, excluding the nucleus)

26. The Membrane
Barrier that encloses cytoplasm
~5 nm thick
Protein concentration in membrane varies
Structure of discrete membrane regions influences neuronal function

28. The Soma
Mitochondrion
Site of cellular respiration (inhale and exhale)
Krebs cycle
ATP- cell’s energy source

29. The Soma
Major site for protein synthesis
Rough endoplasmic reticulum

30. The Soma
Smooth ER and Golgi Apparatus
Sites for preparing/sorting proteins for delivery to different cell regions (trafficking) and regulating substances

31. The Axon
Axon hillock (beginning)
Axon proper (middle)
Axon terminal (end)
Differences between axon and soma
ER does not extend into axon
Protein composition: Unique

32. The Axon
The Axon Terminal
Differences between the cytoplasm of axon terminal and axon
No microtubules in terminal
Presence of synaptic vesicles
Abundance of membrane proteins
Large number of mitochondria

33. The Axon
Synapse
Synaptic transmission
Electrical-to-chemical-to-electrical transformation
Synaptic transmission dysfunction
Mental disorders

37. Structure Correlates with Function
NEURONS
Soma
Axons
Dendrites
Synapse
Structural characteristics of a neuron tell us about its function
e.g., Dense Nissl stain = protein; suggests specialization
Elaborate structure of dendritic tree = receiver