Nervous system

Hello friends.. you can use these notes for your convenience as they are taken from many other standard books.. Thank you..

1. NERVOUS SYSTEM Dr. Vibhash Kumar Vaidya Department of Anatomy

2. Introduction:- Nervous system is the chief controlling and coordinating system of the body. It control and regulates all activities of the body, whether voluntary or involuntary. This is based on the special properties:- Sensitivity Conductivity responsiveness Dr. Vibhash

3. General Functions of the Nervous System Sensory :- The sensory impulses are transmitted by the sensory (afferent) nerves from periphery ( skin, mucous membranes, muscles, tendons, joints, and special sense organs) to the central nervous system (CNS). Motor :- The motor impulses are transmitted by the motor (efferent) nerves from the central nervous system to the periphery (muscle and glands) Dr. Vibhash

4. Classification of Nervous system Central nervous system (CNS) composed of:- B rain S pinal cord Peripheral Nervous System Spinal nerves 12 pairs of cranial nerves. 31 pairs of spinal nerves. Autonomic N.S . Somatic N.S . Sympathetic Parasympathetic Dr. Vibhash

5. Central nervous system The central nervous system (CNS) is composed of the brain and spinal cord . These neurons cannot regenerate if damaged. Dr. Vibhash

6. Peripheral nervous system (PNS ) is made up of peripheral nerves that connect the CNS to the rest of the body. These neurons can regenerate if damaged. 12 pairs of cranial nerves. 31 pairs of spinal nerves. Dr. Vibhash

7. Peripheral nervous system… PNS can be subdivided into 2 divisions : (1) Somatic Cranial & spinal nerves connecting CNS to skin & skeletal muscles Oversees conscious activities Dr. Vibhash

8. Peripheral nervous system… (2) Autonomic Cranial & spinal nerves connecting CNS to heart, stomach, intestines, glands. It controls unconscious activities. ANS divided into 2 part:- Sympathetic:- Acts in emergency Parasympathetic:- Counter acts the sympathetic ns after the emergency. Dr. Vibhash

9. (1) Parasympathetic Decreases heart rate, bronchiole dilation, blood glucose, blood to skeletal muscle Increases digestion, pupil size, urinary output “rest and digest” (2) Sympathetic Decreases digestion, pupil size, urinary output Increases heart rate, bronchiole dilation, blood glucose, blood to skeletal muscle “fight or flight” Dr. Vibhash

10. Parasympathetic vs. Sympathetic Divisions Dr. Vibhash

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12. Cell type of Nervous System Nervous Tissue is composed of two major cell types: neurons and neuroglial cells . Dr. Vibhash

13. Neurons Neurons are made up of a cell body, dendrites , and axons. Dendrites receive information. Axons send information. Larger axons are enclosed by sheaths of myelin produced by Schwann cells . Narrow gaps in the myelin sheath between Schwann cells are called nodes of Ranvier . Dr. Vibhash

14. Neuroglial cells Provide physical support , insulation (myelin), and nutrients for neurons. Dr. Vibhash

15. Structural Classification of Neurons ( 1) Multipolar Many processes arising from cell body Brain or spinal cord (2) Bipolar 2 processes (1 from each end of cell body) Ear, eyes, nose (3) Unipolar Single process extends from cell body Outside of brain & spinal cord Dr. Vibhash

16. Functional Classification of Neurons Sensory Neurons – ( afferent ) have specialized receptor ends that sense stimuli and then carry impulses from peripheral body parts to brain or spinal cord. Can be unipolar or bipolar . Interneurons – lie entirely within the brain or spinal cord; direct incoming sensory impulses to appropriate parts for processing and interpreting. Motor Neurons – ( efferent ) carry impulses out of the brain or spinal cord to effectors (muscles, glands). Interneurons and motor neurons are multipolar . Dr. Vibhash

17. Dr. Vibhash

18. Thank you…!