1 / 79

Nervous System – Part I

Chapter 7 BIO 160 Kelly Trainor. Nervous System – Part I. 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

garron
Télécharger la présentation

Nervous System – Part I

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 7 BIO 160 Kelly Trainor Nervous System – Part I

  2. 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 • Motor output • A response to integrated stimuli • The response activates muscles or glands

  3. Structural Classification • Central nervous system (CNS) • Brain • Spinal cord • Peripheral nervous system (PNS) • Nerves outside the brain and spinal cord • Spinal nerves • Cranial nerves

  4. 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 • Two subdivisions • Somatic nervous system = voluntary • Autonomic nervous system = involuntary

  5. Nervous Tissue: Support Cells • Support cells in the CNS are grouped together as “neuroglia” • Function: to support, insulate, and protect neurons • Astrocytes • Abundant, star-shaped cells • Brace neurons • Form barrier between capillaries and neurons • Control the chemical environment of the brain

  6. Nervous Tissue: Support Cells • Microglia • Spiderlike phagocytes • Dispose of debris

  7. Nervous Tissue: Support Cells • Ependymal cells • Line cavities of the brain and spinal cord • Circulate cerebrospinal fluid

  8. Nervous Tissue: Support Cells • Oligodendrocytes • Wrap around nerve fibers in the central nervous system • Produce myelin sheaths

  9. Nervous Tissue: Support Cells • Satellite cells • Protect neuron cell bodies • Schwann cells • Form myelin sheath in the peripheral nervous system

  10. Nervous Tissue: Neurons • Neurons = nerve cells • Cells specialized to transmit messages • Major regions of neurons • Cell body—nucleus and metabolic center of the cell • Processes—fibers that extend from the cell body • Dendrites—conduct impulses toward the cell body • Axons—conduct impulses away from the cell body

  11. Nervous Tissue: Neurons • Axons end in axonal terminals • Axonal terminals contain vesicles with neurotransmitters • Axonal terminals are separated from the next neuron by a gap • Synaptic cleft—gap between adjacent neurons • Synapse—junction between nerves

  12. Nervous Tissue: Neurons • Myelin sheath—whitish, fatty material covering axons • Schwann cells—produce myelin sheaths in jelly roll–like fashion • Nodes of Ranvier—gaps in myelin sheath along the axon

  13. Neuron Cell Body Location • Most neuron cell bodies are found in the central nervous system • Gray matter—cell bodies and unmyelinated fibers • Nuclei—clusters of cell bodies within the white matter of the central nervous system • Ganglia—collections of cell bodies outside the central nervous system

  14. Functional Classification of Neurons • Sensory (afferent) neurons • Carry impulses from the sensory receptors to the CNS • Cutaneous sense organs • Proprioceptors—detect stretch or tension • Motor (efferent) neurons • Carry impulses from the central nervous system to viscera, muscles, or glands

  15. Functional Classification of Neurons Figure 7.7

  16. Neuron Classification • Interneurons (association neurons) • Found in neural pathways in the central nervous system • Connect sensory and motor neurons

  17. Chapter 7 BIO 160 Kelly Trainor Nervous System – Part II

  18. Functional Properties of Neurons • Irritability • Ability to respond to stimuli • Conductivity • Ability to transmit an impulse

  19. Nerve Impulses • Resting neuron • The plasma membrane at rest is polarized • Fewer positive ions are inside the cell than outside the cell • Depolarization • A stimulus depolarizes the neuron’s membrane • A depolarized membrane allows sodium (Na+) to flow inside the membrane • The exchange of ions initiates an action potential in the neuron

  20. Nerve Impulses Figure 7.9a–b

  21. Nerve Impulses • Action potential • If the action potential (nerve impulse) starts, it is propagated over the entire axon • Impulses travel faster when fibers have a myelin sheath

  22. Nerve Impulses Figure 7.9c–d

  23. Nerve Impulses • Repolarization • Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane • The sodium-potassium pump, using ATP, restores the original configuration

  24. Nerve Impulses Figure 7.9e–f

  25. Transmission of a Signal at Synapse • Impulses are able to cross the synapse to another nerve • Neurotransmitter is released from a nerve’s axon terminal • The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter • An action potential is started in the dendrite

  26. Transmitting neuron Axonterminal Actionpotentialarrives Axon oftransmittingneuron Vesiclefuses withplasmamembrane Neurotrans-mitter is re-leased intosynaptic cleft Vesicles Neurotransmittermolecules Synaptic cleft Ion channels Synapticcleft Receiving neuron Receivingneuron Synapse Transmission of a Signal at Synapses

  27. Axonterminal Axon oftransmittingneuron Actionpotentialarrives Vesicles Synapticcleft Receivingneuron Synapse Transmitting neuron Neurotrans-mitter bindsto receptoron receivingneuron’smembrane Vesiclefuses withplasmamembrane Neurotrans-mitter is re-leased intosynaptic cleft Neurotransmittermolecules Synaptic cleft Ion channels Receiving neuron Neurotransmitterbroken downand released Neurotransmitter Receptor Na+ Na+ Ion channel opens Ion channel closes Transmission of a Signal at Synapses

  28. Skin Spinal cord (in cross section) Stimulus at distalend of neuron Sensory neuron Integrationcenter Receptor Motor neuron Interneuron Effector (a) The Reflex Arc • Reflex—rapid, predictable, and involuntary response to a stimulus • Occurs over pathways called reflex arcs • Reflex arc—direct route from a sensory neuron, to an interneuron, to an effector

  29. Types of Reflexes and Regulation • Somatic reflexes • Activation of skeletal muscles • Example: When you move your hand away from a hot stove • Autonomic reflexes • Smooth muscle regulation • Heart and blood pressure regulation • Regulation of glands • Digestive system regulation

  30. Chapter 7 BIO 160 Kelly Trainor Nervous System – Part III

  31. Regions of the Brain • Cerebral hemispheres (cerebrum) • Diencephalon • Brain stem • Cerebellum

  32. Regions of the Brain: Cerebrum • Cerebral Hemispheres (Cerebrum) • Paired (left and right) superior parts of the brain • Includes more than half of the brain mass • The surface is made of ridges (gyri) and grooves (sulci)

  33. Regions of the Brain: Cerebrum Figure 7.13a

  34. Regions of the Brain: Cerebrum • Lobes of the cerebrum • Fissures (deep grooves) divide the cerebrum into lobes • Surface lobes of the cerebrum • Frontal lobe • Parietal lobe • Occipital lobe • Temporal lobe

  35. Regions of the Brain: Cerebrum Figure 7.13b

  36. Regions of the Brain: Cerebrum • Specialized areas of the cerebrum • Primary somatic sensory area • Receives impulses from the body’s sensory receptors • Located in parietal lobe • Primary motor area • Sends impulses to skeletal muscles • Located in frontal lobe • Broca’s area • Involved in our ability to speak

  37. Regions of the Brain: Cerebrum Figure 7.13c

  38. Regions of the Brain: Cerebrum Figure 7.14

  39. Regions of the Brain: Cerebrum • Cerebral areas involved in special senses • Gustatory area (taste) • Visual area • Auditory area • Olfactory area • Interpretation areas of the cerebrum • Speech/language region • Language comprehension region • General interpretation area

  40. Regions of the Brain: Cerebrum Figure 7.13c

  41. Regions of the Brain: Cerebrum • Layers of the cerebrum • Gray matter—outer layer in the cerebral cortex composed mostly of neuron cell bodies • White matter—fiber tracts deep to the gray matter • Corpus callosum connects hemispheres • Basal nuclei—islands of gray matter buried within the white matter

  42. Regions of the Brain: Diencephalon • Sits on top of the brain stem • Enclosed by the cerebral hemispheres • Made of three parts • Thalamus • Hypothalamus • Epithalamus

  43. Regions of the Brain: Diencephalon • Thalamus • Surrounds the third ventricle • The relay station for sensory impulses • Transfers impulses to the correct part of the cortex for localization and interpretation

  44. Regions of the Brain: Diencephalon • Hypothalamus • Under the thalamus • Important autonomic nervous system center • Helps regulate body temperature • Controls water balance • Regulates metabolism • An important part of the limbic system (emotions) • The pituitary gland is attached to the hypothalamus • Epithalamus • Forms the roof of the third ventricle • Houses the pineal body (an endocrine gland) • Includes the choroid plexus—forms cerebrospinal fluid

  45. Regions of the Brain: Brain Stem • Attaches to the spinal cord • Parts of the brain stem • Midbrain • Pons • Medulla oblongata

  46. Regions of the Brain: Brain Stem Figure 7.16a

  47. Regions of the Brain: Brain Stem • Midbrain • Mostly composed of tracts of nerve fibers • Has two bulging fiber tracts—cerebral peduncles • Has four rounded protrusions—corpora quadrigemina • Reflex centers for vision and hearing • Pons • The bulging center part of the brain stem • Mostly composed of fiber tracts • Includes nuclei involved in the control of breathing

  48. Regions of the Brain: Brain Stem • Medulla Oblongata • The lowest part of the brain stem • Merges into the spinal cord • Includes important fiber tracts • Contains important control centers • Heart rate control • Blood pressure regulation • Breathing • Swallowing • Vomiting

  49. Regions of the Brain: Brain Stem • Reticular Formation • Diffuse mass of gray matter along the brain stem • Involved in motor control of visceral organs • Reticular activating system (RAS) plays a role in awake/sleep cycles and consciousness

More Related