1 / 58

Chapter 7: The Nervous System

Chapter 7: The Nervous System. Anatomy & Physiology. Functions of the Nervous System. Nervous System manages body via electrical impulses Sensory input—gathering information Monitor changes occurring inside and outside the body Changes = stimuli Internal vs external Integration

vinaya
Download Presentation

Chapter 7: The Nervous System

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: The Nervous System Anatomy & Physiology

  2. Functions of the Nervous System • Nervous System manages body via electrical impulses • Sensory input—gathering information • Monitor changes occurring inside and outside the body • Changes = stimuli • Internal vs external • Integration • Processes and interprets sensory input • Decide if/what action is needed • Motor output • A response to integrated stimuli • By activating muscles or glands

  3. Functions of the Nervous System

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

  5. Classification of the Peripheral Nervous System • Sensory (afferent) division • Nerve fibers that carry information to the central nervous system • Via sensory fibers found in: • Skin • Skeletal muscles • Joints • Motor (efferent) division • Nerve fibers that carry impulses away from the central nervous system

  6. Motor (Efferent) Division • Somatic nervous system = voluntary • System that we consciously control • I.E. contracting muscles on demand • Autonomic nervous system = involuntary • System that is activated subconsciously • I.E. cardiac muscles, glands, respiratory rate

  7. Organization of the Nervous System

  8. Nervous Tissue: Support Cells • Astrocytes • Abundant, star-shaped cells • Brace neurons • Form barrier between capillaries and neurons • Control the chemical environment of the brain

  9. Nervous Tissue: Support Cells • Microglia • Spiderlike phagocytes • Dispose of debris • i.e. dead brain cells • bacteria

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

  11. Nervous Tissue: Support Cells • Oligodendrocytes • Wrap around nerve fibers in the central nervous system to form myelin sheaths • Schwann cells • Form myelin sheath in the peripheral nervous system • Include neurilemma. • Satellite cells • Protect neuron cell bodies

  12. Nervous Tissue: Neurons • Neurons = nerve cells • transmit messages • Major regions of neurons • Cell body—nucleus and metabolic center of the cell • Processes—fibers that extend from the cell body • Cell body • Nissl substance • Specialized rough endoplasmic reticulum • Neurofibrils • Intermediate cytoskeleton • Maintains cell shape

  13. Nervous Tissue: Neurons • Cell body • Nucleus • Large nucleolus • Projections outside the cell body • Dendrites—conduct impulses toward the cell body • Axons—conduct impulses away from the cell body

  14. Nervous Tissue: Neurons • Axons end in axonal terminals • contain vesicles with neurotransmitters • Neurons don’t touch each other rather are separated by a gap • Synaptic cleft—gap between adjacent neurons • Synapse—junction between nerves

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

  16. Neuron Cell Body Location • Most neuron cell bodies are found in the central nervous system • Gray matter—cell bodies and unmyelinated fibers • Ganglia—collections of cell bodies outside the central nervous system • “Tracts” are nerve fibers traveling through the CNS • “Nerves” nerve fibers traveling through PNS

  17. Functional Classification of Neurons • Sensory (afferent) neurons • Carry impulses from the sensory receptors to the CNS • Receptors • Cutaneous sense organs • Proprioceptors—detect stretch or tension in muscles, tendons, joints • Brain makes adjustments for posture and balance • Motor (efferent) neurons • Carry impulses from the central nervous system to viscera, muscles, or glands to illicit reaction • Interneurons (association neurons) • Found in neural pathways in the CNS • Connect sensory and motor neurons

  18. Structural Classification of Neurons • Multipolar neurons —many extensions (processes) from the cell body • Common Location: Motor neurons

  19. Structural Classification of Neurons • Bipolar neurons —one axon and one dendrite • Rare • Common locations: Special sense organs (i.e. ears, nose, eyes)

  20. Structural Classification of Neurons • Unipolar neurons —have a short single process leaving the cell body • 1 process only • Axon: Includes CNS and PNS extension • Common Location: Sensory Neurons in PNS

  21. Physiology of Nerve Impulses • Neurons function in 2 ways: • Irritability: Respond to stimulus and translate it into a nerve impulse • Conductivity: Transport impulse to necessary location (i.e. other neurons, muscles, glands, organs)

  22. Physiology of Nerve Impulses • Membrane of Neuron • At rest: Membrane is impermeable to sodium ions 1)When activated: sodium ions rush into the neuron cell body. • How are they activitaed? • By external stimulus (i.e. light-eye, smell-nose, sound-ear) • Most commonly by neurotransmitters 2)Depolarization occurs (sodium-potassium pump: more sodium in than out) and results in a graded potential 3) If graded potential is strong enough it leads to…. • Action potential/nerve impulse

  23. Physiology of Nerve Impulses 4) Repolarization: • Membrane becomes impermeable again • Sodium goes outside cell body, potassium goes inside • Restores natural state • Another impulse cannot be initiated until repolarizationoccurs • Uses what energy? • Myelin sheaths role: • Causes impulse to travel faster by… • Nerve impulse leaps OVER sheaths because it can’t travel through fat

  24. Physiology of Nerve Impulses • How does nerve impulse travel throughout neurons? • Electrical chemical event: • Impulse cannot go past axon terminals • Vesicles release neurotransmitters • They travel across synaptic cleft • Bind to receptors on the dendrites of the next neuron • Initiate process of nerve impulse all over again https://www.youtube.com/results?search_query=nerve+impulse

  25. Axonterminal Actionpotentialarrives Axon oftransmittingneuron Vesicles Synapticcleft Receivingneuron Synapse

  26. The Reflex Arc • Reflex: A programmed, rapid, involuntary response to stimuli • Reflex arcs: Neural pathways that reflexes travel • 2 types of Reflexes: • Somatic: Reflexes involving skeletal muscle • i.e. removing hand from hot iron • Autonomic: Regulate smooth muscles organs, breathing rate, BP

  27. The Reflex Arc • Reflex arcs made up of a minimum of 5 steps • Sensory Receptor • Sensory Neuron • Integration Center • Motor Neuron • Effector

  28. Skin Spinal cord (in cross section) Stimulus at distalend of neuron Sensory neuron Integrationcenter Receptor Motor neuron Interneuron Effector (a)

  29. Regions of the Brain • Cerebrum (Cerebral Hemispheres) • Diencephalon • Brain Stem • Cerebellum

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

  31. 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

  32. Regions of the Brain-CEREBRUM • Specialized areas of the cerebrum • Primary somatic sensory area • Receives impulses from the body’s sensory receptors • (i.e. cold, pain, touch) • Located in parietal lobe • Primary motor area • Sends impulses to skeletal muscles • Located in frontal lobe • Broca’s Area • Involved in our area to speak

  33. Regions of the Brain-CEREBRUM • Çerebral areas involved in special senses • Gustatory area (taste) • Location: Parietal lobe • Helps detect different tastes in foods • Visual area • Location: Occipital lobe • Recognition based on past experiences • Auditory area • Location: Temporal Lobe • Recognition/perception of sounds • Olfactory area • Location: Medial Temporal Lobe • Conscious awareness of scents

  34. Regions of the Brain-CEREBRUM • Interpretation areas of the cerebrum • Located across both hemispheres (temporal, occipital, parietal lobes) • Speech/language region • Helps with understanding written/spoken language • Language comprehension region • Language/Reading comprehension • General interpretation area • Stores complex memories • Recognizes different senses/signals and puts them into a cognitive thought

  35. 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 • Allows communication between them • Basal nuclei • sections of gray matter buried within the white matter • Adapts voluntary motor movements to changes

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

  37. Diencephalon THALAMUS HYPOTHALAMUS • FUNCTIONS: • Transports all sensory signals/impulses to the cerebral cortex (cerebrum) • Deals with sensations such as pain and temperature • FUNCTIONS: • Transports and receives signals/impulses from the cerebrum and thalamus • Works closely with the pituitary gland • Helps produce hormones to regulate activity of organs • Hunger • Metabolism • Body Temperature • Sleep • Emotions

  38. Diencephalon • EPITHALAMUS • Houses the pineal body (an endocrine gland) • Includes the choroid plexus—forms cerebrospinal fluid

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

  40. Regions of the Brain: Brain Stem MIDBRAIN PONS • Location: • Between pons and diencephalon • Nerve fibers join brain stem and spinal cord to cerebrum • Functions: • Controls vision and hearing • Rounded bulge on brain stem • Between midbrain and medulla oblongata • Functions: • Control swallowing CN: V • Helps in facial movement CN VII

  41. Regions of the Brain: Brain Stem • MEDULLA OBLONGATA • LOCATION: • Between pons and spinal cord • Functions: • Receives and interprets signals from spinal cord • Controls vital signs • Respiration (breathing rate) • Circulation • Blood pressure • Coughing • Heart beat (Beats per minute)

  42. Regions of the Brain: Brain Stem • Reticular Formation • Diffuse mass of gray matter along the brain stem • Plays a role in awake/sleep cycles and consciousness

  43. Regions of the Brain: CEREBELUM • Cerebellum a.k.a. “little brain” • Location: Attaches to brainstem and behind pons • Functions: • Center for balance • Motor control • Activates receptors in muscles, tendons, and joints

  44. Protection of the Central Nervous System • Structures that offer protection: • Scalp and skin • Skull and vertebral column • Meninges • Cerebrospinal fluid (CSF) • Blood-brain barrier

More Related