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Lab 08 Neuron Histology & Brain

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Text of Lab 08 Neuron Histology & Brain

Histology of the Nervous System

Lab 8

Lab 8 Activities1.

2.

3.

4.

identify neuron, pyramidal cell, Purkinje cell, and peripheral nerve slides identify boldfaced structures on brain models identify specified parts in lab manual on sheep brain dissection identify cranial nerves (by name + number)

Histology of Nervous Tissue

Parts of a Neuron

Neuron Structure Cell Body (= Soma)

contains the usual cellular organelles synthesis & metabolism occurs primarily in the soma the outer cell membrane contains the receptors for incoming information (stimuli) most cell bodies are located within the CNS

clusters of neuron cell bodies in the CNS are called nuclei clusters of neuron cell bodies in the PNS are called ganglia

Neuron Structure - Processes

dendrites

short, tapering, highly branched processes or extensions from soma not myelinated the location for some cell organelles sites of receptive or input regions transfer information to the cell body transmit graded potentials - not action potentials

Neuron Structure - Processes

axons

a long thin cylindrical cytoplasmic projection starts at a cone-shaped region the axon hillock may be long (1 meter) or short (1 mm) a long axon is called a nerve fiber transmit information away from the soma ends in many branches

known as axonal terminals may be 10,000 on one nerve form synapses (junctions) with neighboring neurons or with effector cells (muscles or glands)

Neuron Structure - Axons (continued)

filled with axoplasm and surrounded by an axolemma action potentials start at the axon hillock (trigger zone); travel along the axon to the axon terminal axon terminal has the secretory component

Action Potential (nerve impulse) arrival causes the release of stored neurotransmitters neurotransmitters transfer the message across a synapse to the next neuron or to an effector neurotransmitters can excite or inhibit the action of the next cell in the pathway

Histology of Neurons Myelin Sheath

the myelin sheath

lipid-rich, segmented covering on an axon primarily along the larger, longer axons dendrites are never myelinated myelin protects & electrically insulates axon increases the speed of nerve impulses

myelinated fibers conduct impulses 10-150x faster than unmyelinated fibers 150 m/sec vs. 1 m/sec

Nervous Tissue (slide # 24)

Unipolar Neuron

Bipolar Neuron

Multipolar Neuron

Pyramidal Cells (slide #29)

Pyramidal Cells, 2

Pyramidal Cells 3

Purkinje Cells of Cerebellum, slide # 30)

Purkinje Cells, 2

Purkinje Cells, 3

Purkinje Cells, 4

cytoskeleton stain

Spinal Cord with Dorsal Root

Sensory Neurons of Dorsal Root

Dorsal Root, Sensory Neurons

Dorsal Root, Sensory Neurons

Dorsal Root, Sensory Neurons with Satellite Cells

Peripheral Nerve

Nerve, cross-section (slide #28)

Nerve, cross section, Fascicles

Nerve, cross section, Myelinated Fibers

Myelinated Axons, cross-section

Myelinated Axons, cross-section

Nerve, Long Section, 40X (slide # 28)

Nerve, long section

Neurofibrilar Node Nerve, 400X

Neurofibrilar Node

Sheep Brain Dissection

Sheep Brain Dissection

and pia mater

Sheep Brain Dissection

Sheep Brain Dissection

Sheep Brain Dissection

Sheep Brain in Cross Section

Key to Sheep Brain in Cross Section

1. 2. 3. 4. 5. 6. 7. 8.

Gray Matter White Matter Corpus Callosum Lateral Ventricle Caudate Nucleus Septum Pellucidum Fornix Optic Chiasm

9. Third Ventricle 10. Thalamus 11. Corona Radiata 12. Hippocampus 13. Cerebral Aqueduct 14. Pituitary Gland 15. Pineal Gland

Human Cranial Nerves

Human Cranial Nerves

End of Lab 8 Presentation