1. Nervous Tissue 2007

2. Cellular Components of Nervous System Nerve Cells and Glia Nerve Cells and Glia Nerve cells ≈ 100 billion cells in the body Nerve cells ≈ 100 billion cells in the body Glia ≈ 10 – 50 times as many as there are nerve cells Glia ≈ 10 – 50 times as many as there are nerve cells Analogy = Chocolate chip cookie where the glia are the dough and the neurons are the chips Analogy = Chocolate chip cookie where the glia are the dough and the neurons are the chips

3. Neuroglia: Provide structural and metabolic support for neurons Provide structural and metabolic support for neurons Can divide and reproduce when injured (unlike neurons) Can divide and reproduce when injured (unlike neurons) Cannot conduct action potentials so cannot transmit information Cannot conduct action potentials so cannot transmit information

4. Schwann cell: Major glial cell in the PNS Major glial cell in the PNS Quick anatomy reminder – CNS vs. PNS Quick anatomy reminder – CNS vs. PNS Produce myelin sheaths in the PNS – Wraps cell membrane around the axon (50 times) Produce myelin sheaths in the PNS – Wraps cell membrane around the axon (50 times) Cytoplasm gets squished out (details on this in lab) Cytoplasm gets squished out (details on this in lab) Each Schwann cell wraps only one axon; many cells in series along an axon Each Schwann cell wraps only one axon; many cells in series along an axon

5. Myelination

6. Glia in the CNS 1. Oligodendrocytes: form myelin in the CNS 2. Astrocytes: provide structural support; divide wildly when CNS is damaged, forming glial scars. divide wildly when CNS is damaged, forming glial scars. - astrocytic end-feet form part of the blood-brain barrier types of astros: types of astros: a. Fibrous – white matter of the CNS a. Fibrous – white matter of the CNS b. Protoplasmic – grey matter of the CNS. b. Protoplasmic – grey matter of the CNS. 3. Microglia – function as macrophages to remove dead or foreign tissue 3. Microglia – function as macrophages to remove dead or foreign tissue

7. Ependymal Cells - cuboidal epithelial cells that line the ventricles of the brain & central canal of spinal cord. - have cilia to circulate CSF.

8. Neurons: Conduct action potentials = nerve impulses; thus transmit information Conduct action potentials = nerve impulses; thus transmit information Generally cannot divide when injured Generally cannot divide when injured

9. Components of a Neuron: Components of a Neuron: dendrites cell body (soma) axon node of Ranvier (if myelinated) Nerve terminals

10. Parts of a Neuron Dendrites: receive signals from other neurons; branched, tapered, many per neuron. Dendrites: receive signals from other neurons; branched, tapered, many per neuron. Cell body (soma; perikaryon): nucleus large and euchromatic; prominent nucleolus; Nissl substance = clumps of RER; thus lots of protein synthesis. Cell body (soma; perikaryon): nucleus large and euchromatic; prominent nucleolus; Nissl substance = clumps of RER; thus lots of protein synthesis. Axon: output process of neuron; one axon per neuron; thinner than dendrites; constant diameter; no RER or ribosomes (so doesn’t routinely stain) Axon: output process of neuron; one axon per neuron; thinner than dendrites; constant diameter; no RER or ribosomes (so doesn’t routinely stain)

11. Node of Ranvier in myelinated axons – teased preparation

12. Nervous System Central Nervous System (CNS): Central Nervous System (CNS): brain and spinal cord brain and spinal cord Peripheral Nervous System: Peripheral Nervous System: peripheral nerves, cranial nerves and their associated ganglia peripheral nerves, cranial nerves and their associated ganglia

13. CNS = brain + spinal cord

14. Development of Leukocytes Myeloblast Promyelocyte Eosinophilic myeolocyte Eosinophilic Metamyelocyte Eosinophil Motor end plate Dorsal root ganglion White matter Gray matter central canal  -motor neuron A SPINAL CORD (sensory neurons)

15. Dorsal Root Ganglion

16. DRG Nerve Cell Bodies with Euchromatic nucleus and Prominent nucleolus

17. Peripheral Nerve in Cross-section

18. Neurovascular Bundle

19. Nerve Fascicles in the Skin (longitudinal section)

20. Node of Ranvier in myelinated axons

21. Development of Leukocytes Myeloblast Promyelocyte Eosinophilic myeolocyte Eosinophilic Metamyelocyte Eosinophil Motor end plate Dorsal root ganglion (sensory) White matter Gray matter central canal  -motor neuron SPINAL CORD interneuron Dorsal horn Ventral horn

22. Motor End Plates

23. Intestinal Wall

24. Nerve cells of the Parasympathetic Ganglia in the Intestinal Wall

25. Nerve cells of the Parasympathetic Ganglia – Myenteric Plexus