28. Nerve & Nerve Cells ppt.pptx presentation

28. Nerve & Nerve Cells ppt.pptx presentation

1. GOOD MORNING

2. NERVE AND NERVE CELLS Presented By: TANISHA DAS Submitted to: Dr. Ashish Shrestha Dr. Vinay Marla

3. Objectives: Introduction about Nerve And Nerve Cells The Nervous System The Nerve The Neurons and its parts Nerve Fibre and its Types Clinical Considerations Summary

4. Introductio n Neurons are the functional unit in CNS and PNS. A nerve is a cordlike structure that contain many axons of a neuron , also called nerve fibers. Conveys information in the form of electrochemical impulse carried by indivisual neurons. Site of inter-communication between two neuron are called as Synapses . Ganglia are the group of nerve cells outside CNS.

5. Nervous System It is a chief controlling and coordinating system of body. Nervous system is divided into two main parts : a. Central Nervous System (CNS) - Brain - Spinal cord b. Peripheral Nervous System (PNS) - cranial, spinal, peripheral nerves conducting impulse from CNS and ganglia.

6. The Nerve Bundle of axon present in CNS and PNS. Classified in two types : Sensory Nerves – from periphery to CNS Motor Nerves – from CNS to periphery

7. The Neurons [ Nerve Cells ] Despite variations in shape and size in different part of nervous system they all have same basic structures. Cell Body [ Perikaryone ] - large - contain nucleus surrounding cytoplasm. Axon - long, slender projection from the cell body that conducts electric away from the neuron’s cell body.

8. Dendrites - highly branched - short afferent process - acts to propagate electrochemical stimulation Axon Hillock - cone shaped portion of the cell body from where the axon arise. Terminal Boutons - small swelling at the end of axon through which axon terminates to the other neurons.

9. Figure : Neuron

10. Types of Neurons

11. Ultra structure of Neuron Nucleus in large, round, centrally located. Cytoplasm consist of aggregation of RER Nissl substances. Golgi apparatus found adjacent to nucleus. Mitochondria, At cell body oval At axons slender and elongated Intermediate filament and microtubules arranged in bundles throughout the cell body and along the length of axon and dendrites.

12. Nerve Fibers Nerve fiber is an axon with its covering. Larger axons are covered with myelin sheath so called as myelinated nerve fibers. Where as, smaller axons of less than 1µ diameter do not have these sheath and are called as non myelinated nerve fibers. Fatty nature of this myelin is responsible for glistening whiteness of the peripheral nerve trunk and white matter of CNS.

13. Myelinated Nerve Fibers Enclosed in a myelin sheath. Myelin sheath consist of compressed layer of Schwann cells surrounded around the axon in spiral fashion. - rich in cholesterol, glycolipid, phospholipids. Interrupted at regular interval nodes of Ranvier. Insulator so impulse cannot pass. Saltatory condition - 2 major advantages a. for a given diameter it has a higher conduction velocity. b. conserve energy

14. Figure : Myelinated Nerve Fibers

15. Non myelinated Nerve Fibers Comprise of smaller axon. Structurally, it consist of group of small axon without any spiral of mesaxon Example : Olfactory Nerve, C fibers of skin, muscle and viscera.

16. Staining Special staining is required for structural detail of nervous system: Heavy metal impregnate technique Spread preparation Immunohistochemistry H & E - no detail of cytoplasmic process seen. - Evenly distributed chromatophilic substances. Nissl method - stains RNA Figure : Immunohistochemistry Figure : Gold Method

17. Figure : Spread Preparation Figure : Nissl Method

18. Dendrites Chromatophilic substances Nucleus Cell Body Axon hillock Axon Figure : H & E stain Figure : H & E stain × 100

19. Clinical Consideration Epilepsy : Abnormal regulation of neuronal excitability within brain leading to an uncontrolled spread of seizures. Neurodegenerative Disease : Series of disease that is seen specially old age due to degeneration and death of nerve cells. - Alzheimer’s Disease - Parkinson’s Disease

20. Dysphagia : Difficulty in swallowing - actually a neuromuscular disorder - may occurs when patient have a history of spinal cord injury, stroke, Parkinson’s disease.

21. Bell’s Palsy : Form of facial paralysis due to dysfunction of Cranial Nerve VII - Loss of taste sensation in anterior 2/3 rd of the tongue in affected side.

22. Nerve Injury

23. SUMMARY

24. Figure : Types Of Nerve Cells

25. Clinical Consideration - Dysphagia - Epilepsy - Neurodegenerative Disease - Bells Palsy Nerve Injury - Neuropraxia - Axonotmesis - Neurotmesis

26. REFRENCES WWW.PHOTOBUCKET.COM WHEATER’S FUNCTIONAL HISTOLOGY [ FIFTH EDITION ] JUNQUEIRA’S BASIC HISTOLOGY [ 11 TH & 12 TH EDITION ] UNDERSTANDING MEDICAL PHYSIOLOGY BIJLANI [ FOURTH EDITION ]