1 / 28

The Nervous System

The Nervous System . Introduction. Nervous control vs. endocrine control of the body What does the nervous system do?. Receive, process, store sensory information Integrate and interpret Stimulation of skeletal muscle Stimulation/inhibition of smooth and cardiac muscle

yessica
Download Presentation

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. The Nervous System Introduction • Nervous control vs. endocrine control of the body • What does the nervous system do? • Receive, process, store sensory information • Integrate and interpret • Stimulation of skeletal muscle • Stimulation/inhibition of smooth and cardiac muscle • Stimulation/inhibition of glands • cognition

  2. The Nervous System Introduction • 3. Why is the nervous system of prime importance to understanding aging effects on the body? • It controls virtually all body functions • Neurons are postmitotic – why is this important?

  3. The Nervous System B. Cells of the nervous system • Neurons • Basic structure • Cell body • Dendrites • Axon • Fiber vs. nerve • What is myelin?

  4. The Nervous System B. Cells of the nervous system • Neurons • d. Types of neurons • Motor • Sensory • Association (interneuron) • What is a center? • What is a ganglion?

  5. The Nervous System B. Cells of the nervous system • 2. Neuroglia (glial cells) • Support cells of the nervous system • Greatly outnumber neurons • Types of cells • Astrocytes (CNS) • Oligodendrocytes (CNS) • Microglial cells (CNS) • Ependymal cells (CNS) • Neurolemmocytes (Schwann cells) (PNS)

  6. The Nervous System C. Membrane potentials • What is a polarized membrane? • How is it formed? • What are voltage-gated channels? • Resting potential vs. action potential • Continuous conduction • Saltatory conduction

  7. The Nervous System D. The synapse • Presynaptic neuron • Synaptic cleft • Postsynaptic neuron • Excitatory neurotransmitters • Acetylcholine • Norepinephrine • c. Dopamine • d. Serotonin • 5. Inhibitory neurotransmitters • Gamma aminobutyric acid (GABA) • Glutamate

  8. The Nervous System E. Organization of the nervous system • Sensory • peripheral nervous system • Motor • peripheral nervous system • Central nervous system • Brain • Spinal cord • Somatic motor neurons (voluntary) to skeletal muscles • Somatic receptors • Visceral receptors • Special sensory receptors • Sympathetic and parasympathetic nervous systems • Autonomic motor neurons (involuntary) to smooth muscle, cardiac muscle, and glands • Sensory receptors and neurons in the gut • Enteric motor neurons (involuntary) in gut to smooth muscle and glands

  9. The Nervous System F. Central nervous system • Brain and spinal cord • Meninges • Dura mater • Arachnoid membrane • Pia mater

  10. The Nervous System F. Central nervous system • 3. Cerebrospinal fluid • Subarachnoid space • Ventricles and central canal • Flow pattern

  11. The Nervous System F. Central nervous system • 4. Cerebrum (white and gray matter) • Hemispheres and lobes • Gyrus – sulcus – fissure • Cerebral cortex • Functional areas • Primary sensory areas • Primary motor areas • Association areas • f. Basal ganglia (cerebral nuclei)

  12. The Nervous System F. Central nervous system • Cerebellum (white and gray matter) • Diencephalon (gray matter) • Thalamus • Hypothalamus • Epithalamus • 7. Brainstem (white and gray matter) • Midbrain • Pons • Medulla oblongata

  13. The Nervous System F. Central nervous system • 8. Spinal cord (white and gray matter) • Regions • Cervical • Thoracic • Lumbar • Sacral • Coccygeal

  14. The Nervous System F. Central nervous system • 8. Spinal cord • b. Cross-sectional anatomy • Horns • Dorsal = sensory nuclei • Ventral = motor nuclei • ii. Roots • Dorsal = sensory axons • Ventral = motor axons • iii. Tracts • Ascending • Descending

  15. The Nervous System F. Central nervous system • 8. Spinal cord • c. What is a reflex? • Inborn • Unconscious • Unlearned • d. Reflex arc components • receptor  sensory neuron  • integration center  • motor neuron  effector

  16. The Nervous System G. Peripheral nervous system • Cranial nerves (12 pairs) • Spinal nerves (31 pairs)

  17. The Nervous System G. Peripheral nervous system • 3. subdivisions • Afferent • Somatic sensory from skin, joints, skeletal muscles • Visceral sensory from organs • b. Efferent • Somatic (voluntary) motor to skeletal muscles • Autonomic (involuntary) motor to cardiac muscle, smooth muscle, glands • Sympathetic nervous system • Parasympathetic nervous system

  18. The Nervous System G. Peripheral nervous system • 4. Autonomic nervous system sympathetic parasympathetic • Dual innervation • Antagonistic • Sympathetics • Thoracolumbar • Fight-or-flight • d. Parasympathetic • Craniosacral • Feed- and-breed

  19. The Nervous System H. Age-related changes • Nerve cells die with aging (~10,000 per day) • Neurons do not undergo mitosis • Therefore, lost neurons are not replaced • Nervous tissue is gradually reduced • 2. Other neuronal changes • Axons swell • Myelin diminishes • Cytoskeleton decreases in abundance

  20. The Nervous System H. Age-related changes • Why does routine loss of neurons not affect function until very late in life? • Loss of neurons + loss of myelin = decreased brain mass • Decrease isn’t uniform throughout brain • 25% loss of cerebellum; other areas lose nothing • Decline is size begins slowly at age 30, much faster at age 60; 10% gone by age 90 • Ventricles enlarge, gyri become smaller, sulci widen

  21. The Nervous System H. Age-related changes • 5. Loss of brain mass = loss of learning new skills • What functions tend to have greater decline? • Response times in reflexes • Integration of things observed • Alertness (brain reactivity time) • b. What functions do not decline as quickly? • Verbal ability • Memory

  22. The Nervous System H. Age-related changes • 6. Some neurons sprout new axons and establish new synapses • New synapses = net increase in connections • Learning requires development of new synapses • 7. However, there is age-related decline in IQ test scores • Thought to be associated with neuronal loss • Elderly may have as much as 25% loss in verbal ability • Wide range of individual variability

  23. The Nervous System H. Age-related changes • 8. Memory is affected by age • Long-term memory least affected • Higher intellects retain better memory • Active brains retain memory longer • Decreased rate of nerve impulse conduction • Increased synaptic delay • Decreased neurotransmitter released • Decreased postsynaptic receptors

  24. The Nervous System H. Age-related changes • Reduced dendrites and dendritic spines • Intracellular neuronal changes • Decreased Nissl substance (ribosomes) • In the hippocampus, particularly: • Neurofibrillary tangles • Neuritic plaques • 13. Glial cell changes

  25. The Nervous System H. Age-related changes • 14. Changes in sympathetic nervous system activity • Increased norepinephrine secretion + • Decreased removal of norepinephrine at the synapse + • Decreased norepinephrine receptor sensitivity • 15. Changes in parasympathetic nervous system activity

  26. The Nervous System I. Age-related dysfunctions • Decreased somatic reflex responses • Declining autonomic reflex responses • Body temperature control • Blood pressure control • Urethral and anal internal sphincter control • 3. Insomnia • REM vs. non-REM sleep • Difficulty falling asleep + frequent awakenings • Reticular activating system dysfunction

  27. The Nervous System I. Age-related dysfunctions • 4. Dementia (organic brain syndrome) • What is it? • Reversible vs. irreversible • Categories • Alzheimer’s disease • Non-Alzheimer’s disease • Multi-infarctional dementia • Parkinson’s disease • Cerebrovascular accident (stroke)

  28. The Nervous System J. Take home messages • What are the divisions of the nervous system and how are they communicated together? • What is the basic structure and function of the neuron? • Neurons die with aging and aren’t replaced • Conduction velocities decrease with aging • Synaptic delay increases with aging • Reflex times increase with aging • Many intracellular changes with aging • What are dementias? end

More Related