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The Nervous System

7. The Nervous System. Overview OF THE NERVOUS SYSTEM. Functions of the Nervous System. Sensory input — gathering information To monitor changes occurring inside and outside the body Changes = stimuli Integration To process and interpret sensory input and decide if action is needed.

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The Nervous System

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  1. 7 The Nervous System

  2. Overview OF THE NERVOUS SYSTEM

  3. Functions of the Nervous System Sensory input — gathering information To monitor changes occurring inside and outside the body Changes = stimuli Integration To process and interpret sensory input and decide if action is needed

  4. Functions of the Nervous System Motor output A response to integrated stimuli The response activates muscles or glands

  5. Figure 7.1

  6. Figure 7.2

  7. Central Nervous System • https://www.youtube.com/watch?v=q8NtmDrb_qo&index=11&list=PL8dPuuaLjXtOAKed_MxxWBNaPno5h3Zs8

  8. Structural Classification of the Nervous System Central nervous system (CNS) Organs Brain Spinal cord Function Integration; command center Interpretincoming sensory information Issues outgoing instructions

  9. Figure 7.2

  10. Peripheral Nervous System • https://www.youtube.com/watch?v=QY9NTVh-Awo&index=12&list=PL8dPuuaLjXtOAKed_MxxWBNaPno5h3Zs8

  11. Structural Classification of the Nervous System Peripheral nervous system (PNS) Nerves extending from the brain and spinal cord Spinal nerves — carry impulses to and from the spinal cord Cranial nerves — carry impulses to and from the brain Functions Serve as communication lines among sensory organs, the brain and spinal cord, and glands or muscles

  12. Figure 7.2

  13. Functional Classification of the Peripheral Nervous System Sensory (afferent) division Nerve fibers that carry information to the central nervous system Motor (efferent) division Nerve fibers that carry impulses away from the central nervous system

  14. Figure 7.2

  15. Functional Classification of the Peripheral Nervous System Motor (efferent) division (continued) Two subdivisions Somatic nervous system = voluntary Consciously controls skeletal muscles Autonomic nervous system = involuntary Automatically controls smooth and cardiac muscles and glands Further divided into the sympathetic and parasympathetic nervous systems

  16. The Reflex Arc Somatic reflexes Reflexes that stimulate the skeletal muscles Example: pull your hand away from a hot object Autonomic reflexes Regulate the activity of smooth muscles, the heart, and glands Example: Regulation of smooth muscles, heart and blood pressure, glands, digestive system

  17. The Reflex Arc Five elements of a reflex: Sensory receptor – reacts to a stimulus Sensory neuron – carries message to the integration center Integration center (CNS) – processes information and directs motor output Motor neuron – carries message to an effector Effector organ – is the muscle or gland to be stimulated

  18. Skin Stimulus at distal end of neuron Receptor 1 Figure 7.11a, step 1

  19. Skin Spinal cord (in cross section) Stimulus at distal end of neuron Sensory neuron 2 Receptor 1 Interneuron Figure 7.11a, step 2

  20. Skin Spinal cord (in cross section) Stimulus at distal end of neuron Sensory neuron 2 Integration center 3 Receptor 1 Interneuron Figure 7.11a, step 3

  21. Skin Spinal cord (in cross section) Stimulus at distal end of neuron Sensory neuron 2 Integration center 3 Receptor 1 Motor neuron 4 Interneuron Figure 7.11a, step 4

  22. Skin Spinal cord (in cross section) Stimulus at distal end of neuron Sensory neuron 2 Integration center 3 Receptor 1 Motor neuron 4 Interneuron Effector 5 Figure 7.11a, step 5

  23. Central Nervous System (CNS) CNS develops from the embryonic neural tube The neural tube becomes the brain and spinal cord The opening of the neural tube becomes the ventricles Four chambers within the brain Filled with cerebrospinal fluid

  24. Spinal Cord Extends from the base of the brain stem to the first or second lumbar vertebra Provides a two-way conduction pathway to and from the brain 31 pairs of spinal nerves arise from the spinal cord

  25. Cervical spinal nerves Cervical enlargement C8 Dura and arachnoid mater Thoracic spinal nerves Figure 7.20 (1 of 2)

  26. Lumbar enlargement T12 End of spinal cord Lumbar spinal nerves Cauda equina L5 End of meningeal coverings S1 Sacral spinal nerves S5 S5 S5 Figure 7.20 (2 of 2)

  27. Dorsal (posterior) horn of gray matter White matter Central canal Dorsal root ganglion Lateral horn of gray matter Spinal nerve Ventral (anterior) horn of gray matter Dorsal root of spinal nerve Ventral root of spinal nerve Pia mater Arachnoid mater Dura mater Spinal Cord Anatomy Figure 7.21

  28. Spinal Cord Anatomy Meninges cover the spinal cord Spinal nerves leave at the level of each vertebrae Dorsal root Ventral root

  29. Interneuron carrying sensory information to cerebral cortex Integration (processing and interpretation of sensory input) occurs Cerebral cortex (gray matter) Interneuron carrying response to motor neurons White matter Thalamus Cerebrum Interneuron carrying response to motor neuron Brain stem Cell body of sensory neuron in sensory ganglion Interneuron carrying sensory information to cerebral cortex Nerve Skin Sensory receptors Cervical spinal cord Muscle White matter Gray matter Motor output Interneuron Motor neuron cell body Figure 7.22

  30. Peripheral Nervous System (PNS) Nerves and ganglia outside the central nervous system Nerve = bundle of neuron fibers Neuron fibers are bundled by connective tissue

  31. Axon Myelin sheath Endoneurium Perineurium Epineurium PNS: Structure of a Nerve Fascicle Blood vessels Figure 7.23

  32. PNS: Classification of Nerves Mixed nerves Both sensory and motor fibers Sensory (afferent) nerves Carry impulses toward the CNS Motor (efferent) nerves Carry impulses away from the CNS

  33. PNS: Cranial Nerves Twelve pairs of nerves that mostly serve the head and neck Only the pair of vagus nerves extend to thoracic and abdominal cavities Most are mixed nerves, but three are sensory only

  34. PNS: Cranial Nerves Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal

  35. PNS: Cranial Nerves Device Oh Oh Oh To Touch And Feel Very Green Vegetables A H

  36. PNS: Cranial Nerves Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal

  37. PNS: Cranial Nerves I Olfactory nerve — sensory for smell II Optic nerve — sensory for vision III Oculomotor nerve — motor fibers to eye muscles IV Trochlear — motor fiber to one eye muscle

  38. PNS: Cranial Nerves V Trigeminal nerve — sensory for the face; motor fibers to chewing muscles VI Abducens nerve — motor fibers to eye muscles VII Facial nerve — sensory for taste; motor fibers to the face VIII Vestibulocochlear nerve — sensory for balance and hearing

  39. PNS: Cranial Nerves IX Glossopharyngeal nerve — sensory for taste; motor fibers to the pharynx X Vagus nerves — sensory and motor fibers for pharynx, larynx, and viscera XI Accessory nerve — motor fibers to neck and upper back XII Hypoglossal nerve — motor fibers to tongue

  40. Cranial Nerve FUNCTION • https://www.youtube.com/watch?v=FtJtYMRVw7A Cranial nerves SONG https://www.youtube.com/watch?v=0lbwshg_Kj4

  41. PNS: Spinal Nerves There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Formed by the combination of the ventral and dorsal roots of the spinal cord Named for the region from which they arise

  42. C1 2 3 Ventral rami form cervical plexus (C1 – C5) Cervical nerves 4 5 6 7 Ventral rami form brachial plexus (C5 – C8; T1) 8 T1 2 3 4 5 Thoracic nerves 6 7 No plexus formed (intercostal nerves) (T1 – T12) 8 9 10 11 Lumbar nerves 12 L1 Sacral nerves 2 Ventral rami form lumbar plexus (L1 – L4) 3 4 5 S1 Ventral rami form sacral plexus (L4 – L5; S1 – S4) 2 3 4 (a) Figure 7.25a

  43. PNS: Spinal Nerve Plexuses Plexus–networks of nerves serving motor and sensory needs of the limbs Form from ventral rami of spinal nerves in the cervical, lumbar, and sacral regions Four plexuses: Cervical Brachial Lumbar Sacral

  44. These nerves arise from the BRACHIAL PLEXUS Axillary nerve Humerus Radial nerve Musculocutaneous nerve Ulna Radius Ulnar nerve Radial nerve (superficial branch) Median nerve (a) The major nerves of the upper limb Figure 7.26a

  45. These nerves arise from the LUMBAR PLEXUS Femoral Lateral femoral cutaneous Obturator Anterior femoral cutaneous Saphenous (b) Lumbar plexus, anterior view Figure 7.26b

  46. These nerves arise from the SACRAL PLEXUS Superior gluteal Inferior gluteal Sciatic Posterior femoral cutaneous Common fibular Tibial Sural (cut) Deep fibular Superficial fibular Plantar branches (c) Sacral plexus, posterior view Figure 7.26c

  47. Figure 7.2

  48. PNS: Autonomic Nervous System Motor subdivision of the PNS Consists only of motor nerves Also known as the involuntary nervous system Regulates activities of cardiac and smooth muscles and glands Two subdivisions Sympathetic division Parasympathetic division

  49. Parasympathetic Sympathetic Eye Eye Brain stem Salivary glands Skin Cranial nerves Salivary glands Sympathetic ganglia Heart Cervical Lungs Lungs T1 Heart Stomach Thoracic Stomach Pancreas Liver and gall- bladder Pancreas L1 Liver and gall- bladder Adrenal gland Lumbar Bladder Bladder Pelvic splanchnic nerves Genitals Genitals Sacral nerves (S2 – S4) Figure 7.28

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