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Identify neurons, pyramidal cells, Purkinje cells, and peripheral nerve slides. Identify specified parts in lab manual on sheep brain dissection. Learn about the parts of a neuron and cranial nerves.
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Lab 9 Histology and Gross Anatomy of the Nervous System
Lab 9 Activities • 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 I - XII)
Parts of a Neuron • Soma • Dendrites • Axon
Cell Body (Soma) • Contains the usual cellular organelles • Primary site of synthesis & metabolism • Cell membrane contains receptors to respond to stimuli • Cell membrane transmits graded potentials • 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
Dendrites • Short, tapering, highly branched processes • Not myelinated • Contain some cell organelles • Cell membrane contains receptors to respond to stimuli • Transmit graded potentialstowards the soma
Axons (nerve fiber) • Originate at a cone-shaped region – the axon hillock • A single process that transmits action potentialsaway from the soma • May be long (1 meter) or short (1 mm) • May branch (=collaterals) • Collaterals end at • axonal terminals • synapse with neurons or effector cells (muscles or glands)
The Myelin Sheath • Lipid-rich, covering of axons • Oligodendrocytes in CNS • Neurilemmocytes in PNS • Dendrites are never myelinated • Protects & electrically insulates • Increases speed of nerve impulses • 10-150x faster than unmyelinated fibers
Neurons structural Classifications
Multipolar Neuron (slide #24) Many processes originate from soma
Bipolar Neuron Two processes originate from soma
Unipolar Neuron • A single process originates from soma
Neurons Specific types
Purkinje Cells • cytoskeleton stain
Peripheral Nerve • Connective tissue elements: • Epineurium (wraps nerve) • Perineurium (wraps fascicle) • Endoneurium (wraps axon & myelin sheath)
Nerve, cross-section (slide #28) Epineurium Perineurium Endoneurium
Nerve, cross section, Fascicles Epineurium Perineurium Endoneurium
Sheep Brain Dissection Dura mater partially removed
Sheep Brain Dissection and pia mater
Sheep Brain Dissection Note: pituitary removed
1. Gray Matter 2. White Matter 3. Corpus Callosum 4. Lateral Ventricle 5. Caudate Nucleus 6. Septum Pellucidum 7. Fornix 8. Optic Chiasm 9. Third Ventricle 10. Thalamus 11. Corona Radiata 12. Hippocampus 13. Cerebral Aqueduct 14. Pituitary Gland 15. Pineal Gland Key to Sheep Brain in Cross Section