1 / 18

Chapter 48 Nervous System

Chapter 48 Nervous System. http://youtube.com/watch?v=NqVeH26i7Kg&feature=related. Nervous systems. Effector cells~ muscle or gland cells Nerves~ bundles of neurons wrapped in connective tissue Central nervous system (CNS)~ brain and spinal cord

mweisman
Download Presentation

Chapter 48 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 48 Nervous System http://youtube.com/watch?v=NqVeH26i7Kg&feature=related

  2. Nervous systems • Effector cells~ muscle or gland cells • Nerves~ bundles of neurons wrapped in connective tissue • Central nervous system (CNS)~ brain and spinal cord • Peripheral nervous system (PNS)~ sensory and motor neurons

  3. Structural Unit of Nervous System • Neuron~ structural and functional unit • Cell body~ nucelus and organelles • Dendrites~ impulses from tips to neuron • Axons~ impulses toward tips

  4. Structural Unit of Nervous System • Myelin sheath~ supporting, insulating layer • Schwann cells~PNS support cells • Synaptic terminals~ neurotransmitter releaser • Synapse~ neuron junction

  5. Simple Nerve Circuit • Sensory neuron: convey information to spinal cord • Interneurons: information integration • Motor neurons: convey signals to effector cell (muscle or gland) • Reflex: simple response; sensory to motor neurons • Ganglion (ganglia): cluster of nerve cell bodies in the PNS • Supporting cells/glia: nonconductiong cell that provides support, insulation, and protection

  6. The Resting Potential • http://bcs.whfreeman.com/thelifewire/content/chp44/4402001.html • http://youtube.com/watch?v=iA-Gdkje6pg&feature=related

  7. Resting potential • Membrane potential (voltage differences across the plasma membrane) • Intracellular/extracellular ionic concentration difference • K+ diffuses out (Na+ in); large anions cannot follow….selective permeability of the plasma membrane • Net negative charge of about -70mV

  8. The Action Potential • http://youtube.com/watch?v=SCasruJT-DU&feature=related • http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120107/bio_d.swf::Action Potential Propagation in an Unmyelinated Axon • http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf

  9. Neural signaling - 1 • Excitable cells~ cells that can change membrane potentials (neurons, muscle) • Resting potential~ the unexcited state of excitable cells • Gated ion channels (open/close response to stimuli): photoreceptors; vibrations in air (sound receptors); chemical (neurotransmitters) & voltage (membrane potential changes)

  10. Neural signaling - 2 • Graded Potentials (depend on strength of stimulus): • 1- Hyperpolarization (outflow of K+); increase in electrical gradient; cell becomes more negative • 2- Depolarization (inflow of Na+); reduction in electrical gradient; cell becomes less negative

  11. Neural signaling - 3

  12. Neural signaling - 3 • Threshold potential: if stimulus reaches a certain voltage (-50 to -55 mV)…. • The action potential is triggered…. • Voltage-gated ion channels (Na+; K+) • 1-Resting state •both channels closed • 2-Threshold •a stimulus opens some Na+ channels • 3-Depolarization•action potential generated •Na+ channels open; cell becomes positive (K+ channels closed) • 4-Repolarization•Na+ channels close, K+ channels open; K+ leaves •cell becomes negative • 5-Undershoot•both gates close, but K+ channel is slow; resting state restored • Refractory period~ insensitive to depolarization due to closing of Na+ gates

  13. Neural signaling - 4 • “Travel” of the action potential is self-propagating • Regeneration of “new” action potentials only after refractory period • Forward direction only • Action potential speed: • 1. Axon diameter (larger = faster; 100m/sec) • 2. Nodes of Ranvier (concentration of ion channels); saltatory conduction; 150m/sec

  14. Synaptic communication • Presynaptic cell: transmitting cell • Postsynaptic cell: receiving cell • Synaptic cleft: separation gap • Synaptic vesicles: neurotransmitter releasers • Ca+ influx: caused by action potential; vesicles fuse with presynaptic membrane and release…. • Neurotransmitter

  15. Signal transmission • http://youtube.com/watch?v=90cj4NX87Yk&feature=related • http://youtube.com/watch?v=HXx9qlJetSU&feature=related • http://youtube.com/watch?v=CiZLnbKVIhM&feature=related

  16. Neurotransmitters • Acetylcholine (most common) •skeletal muscle • Biogenic amines(derived from amino acids) •norepinephrine •dopamine •serotonin • Amino acids • Neuropeptides(short chains of amino acids) •endorphin

  17. Vertebrate PNS • Cranial nerves (brain origin) • Spinal nerves (spine origin) • Sensory division • Motor division •somatic system voluntary, conscious control •autonomic system parasympathetic conservation of energy sympathetic increase energy consumption

  18. The Vertebrate Brain • Forebrain•cerebrum~memory, learning, emotion •cerebral cortex~sensory and motor nerve cell bodies •corpus callosum~connects left and right hemispheres•thalamus; hypothalamus • Midbrain •inferior (auditory) and superior (visual) colliculi • Hindbrain•cerebellum~coordination of movement•medulla oblongata/ pons~autonomic, homeostatic functions

More Related