1. RHPT-472 PT NEURO INTRODUCTION TO NERVOUS SYSTEM

2. Objectives By the end of this class the students must have an understanding about Definition & function of NS Different cells present in NS & their basic function Parts of Brain & its function Parts of NS Major division of NS & their function.

3. Nervous System The human nervous system consists of the central nervous system (CNS) and peripheral nervous system (PNS). The primary functions of the nervous system are to monitor, integrate (process) and respond to information inside and outside the body.

4. Nervous System The human nervous system is comprised of two kinds of cells: – Neurons – Glia The human brain contains approximately 100 billion individual neurons. BEHAVIOUR depends upon the communication between neurons.

5. The Cells of the Nervous System Neuron cells are similar to other cells of the body but have a distinctive shape. A motor neuron has its soma in the spinal cord and receives excitation from other neurons and conducts impulses along it axon to a muscle. A sensory neuron is specialized at one end to be highly sensitive to a particular type of stimulation (touch, temperature, odor etc.)

6. The Cells of the Nervous System All neurons have the following major components: – Dendrites. – Soma/ cell body. – Axon

7. The Cells of the Nervous System Terms used to describe the neuron include the following: – Afferent axon - refers to bringing information into a structure. – Efferent axon - refers to carrying information away from a structure. – Interneurons or Intrinsic neurons are those whose dendrites and axons are completely contained within a structure.

8. Fig. 2-8, p. 34

9. The Cells of the Nervous System Glia are the other major component of the nervous system and include the following: – Astrocytes helps synchronize the activity of the axon by wrapping around the presynaptic terminal and taking up chemicals released by the axon. – Microglia - remove waste material and other microorganisms that could prove harmful to the neuron.

10. Fig. 2-10, p. 35

11. Fig. 2-11, p. 36

12. The Cells of the Nervous System (Types of glia continued) – Oligdendrocytes & Schwann cells- build the myelin sheath that surrounds the axon of some neurons. – Radial glia- guide the migration of neurons and the growth of their axons and dendrites during embryonic development.

13. The Nerve Impulse A nerve impulse is the electrical message that is transmitted down the axon of a neuron. The impulse does not travel directly down the axon but is regenerated at points along the axon. The speed of nerve impulses ranges from approximately 1 m/s to 100 m/s.

14. The Nervous System Major division - Central vs. Peripheral Central or CNS- brain and spinal cord Peripheral- nerves connecting CNS to muscles and organs Central Nervous System Peripheral Nervous System

15. 3 kinds of neurons connect CNS to the body – sensory – motor – interneurons Motor - CNS to muscles and organs Sensory - sensory receptors to CNS Interneurons: Connections Within CNS Spinal Cord Brain Nerves

16. Peripheral Nervous System Skeletal (Somatic) SympatheticParasympathetic Autonomic Peripheral Nervous System

17. Somatic System Nerves to/from spinal cord – control muscle movements – somatosensory inputs Both Voluntary and reflex movements Skeletal Reflexes – simplest is spinal reflex arc Muscle Motor Neuron Interneuron Skin receptors Sensory Neuron Brain

18. Autonomic System Two divisions: – sympathetic – Parasympatheitic Control involuntary functions – heartbeat – blood pressure – respiration – perspiration – digestion Can be influenced by thought and emotion

19. Sympathetic “ Fight or flight” response Release adrenaline and noradrenaline Increases heart rate and blood pressure Increases blood flow to skeletal muscles Inhibits digestive functions CENTRAL NERVOUS SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney

20. Parasympathetic “ Rest and digest ” system Calms body to conserve and maintain energy Lowers heartbeat, breathing rate, blood pressure CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil

21. Summary of autonomic differences Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Parasympathetic division (calming) Pupils dilate EYES Pupils contract Decreases SALVATION Increases Perspires SKIN Dries Increases RESPERATION Decreases Accelerates HEART Slows Inhibits DIGESTION Activates Secrete stress hormones ADRENAL GLANDS Decrease secretion of stress hormones

22. Central Nervous System Brain and Spinal Cord Spinal Cord Brain

23. Brain has 2 Hemispheres Left & Right sides are separate Corpus Callosum : major pathway between hemispheres Some functions are ‘lateralized’ – language on left – math, music on right Lateralization is never 100% Left Hemisphere Corpus Callosum Right Hemisphere

24. Each hemisphere is divided into 4 lobes Frontal Parietal Occipital Temporal

25. Sensory Information sent to opposite hemisphere Principle is Contralateral Organization Sensory data crosses over in pathways leading to the cortex Visual Crossover – left visual field to right hemisphere – right field to left Other senses similar Left visual field Right visual field Optic nerves Corpus Callosum Left Visual Cortex Right Visual Cortex

26. Contralateral Motor Control Movements controled by motor area Right hemisphere controls left side of body Left hemisphere controls right side Motor nerves cross sides in spinal cord Somatosensory CortexMotor Cortex

27. Corpus Callosum Major ( but not only) pathway between sides Connects comparable structures on each side Permits data received on one side to be processed in both hemispheres Aids motor coordination of left and right side Corpus Callosum Medial surface of right hemisphere

28. Corpus Callosum What happens when the corpus callosum is cut? Sensory inputs are still crossed Motor outputs are still crossed Hemispheres can’t exchange data

29. Localization of function Frontal Parietal Occipital Temporal

30. Occipital Lobe Input from Optic nerve Contains primary visual cortex – most is on surface inside central fissure Outputs to parietal and temporal lobes Occipital Lobe Visual Lobe

31. Temporal Lobe Inputs are auditory, visual patterns – speech recognition – face recognition – word recognition – memory formation Outputs to limbic System, basal Ganglia, and brainstem z Contains primary auditory cortex Temporal Lobe Temporal Lobe Auditory Cortex

32. Parietal Lobe Somatosensory Cortex Parietal Lobe Inputs from multiple senses z contains primary somatosensory cortex z borders visual & auditory cortex z Outputs to Frontal lobe z hand-eye coordination z eye movements z attention

33. Frontal Lobe Frontal Lobe Contains primary motor cortex Motor Cortex Motor Cortex Broca’s Area Motor Cortex Working Memory zNo direct sensory input zImportant planning and sequencing areas  Broca’s area for speech zPrefrontal area for working memory

34. Frontal Lobe Disorders Broca’s area – productive aphasia Prefrontal area – lose track of ongoing context – fail to inhibit inappropriate responses Often measured with the Wisconsin Card Sorting Task

35. The Nervous System: Summary Major structures of the nervous – CNS, Somatic, Autonomic – Two hemispheres & 4 lobes Organization – contralateral input & output – primary sensory areas – motor areas – Commissure Localization of functions Central Nervous System Peripheral Nervous System