Chapter 28 - BIOL1320
Chapter 28 - BIOL1320 BIOL 1320
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This 5 page Class Notes was uploaded by Ailia Owen on Friday April 3, 2015. The Class Notes belongs to BIOL 1320 at University of Houston taught by Brian C Mahon in Spring2015. Since its upload, it has received 226 views. For similar materials see General Biology in Natural Sciences and Mathematics at University of Houston.
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Date Created: 04/03/15
Chapter 28 The Nervous System 4315 544 PM Spinal cord injuries 0 distrupt communication between the 0 Central nervous system brain and spinal cord 0 Rest of the body 0 Happen more often in men 0 Teens and 205 Caused by vehicle accident gunshots falls 0 Permanent spinal cord cannot be repaired NERVOUS SYSTEM STRUCTURE AND FUNCTION 0 Sensory input information o Sensory neurons convey signals from receptors to CNS 0 Integration processing of sensory information o Interneurons only in CNS integrate gt to motor neurons 0 Motor output sends commands to effector cells muscles that carry out responses 0 Motor neurons convey signals to effector cells 0 Central nervous system CNS brain and spinal cord 0 Peripheral nervous system PNS outside CNS 0 Nerves bundles of nerves wrapped in connective tissue 0 Ganglia clusters of neuron cell bodies Neurons functional units of nervous system 0 Specialized cells for carrying out signals 0 Cell body nucleus and organelles o 2 extensions for conducting signals Dendrites receive signals Axons transmits signals a Myelin sheaths enclose axons 0 Cellular insulation 0 Speed transmission 0 Synapse junction of nerve cell where signals are transmitted between 2 neurons or neurons and effector cells Presynaptic sending signal across Postsynaptic receiving signal NERVE SIGNALS AND THEIR TRANSMISSION Membrane potential energy potential of a plasma membrane at rest 0 Just inside cell slightly negative 0 Just outside cell slightly positive 0 Resting potential voltage across plasma membrane of a resting neuron o Exists because of differences in ion concentration of fluids inside and outside a neuron Inside K high NA low Outside K low NA high 0 Stimulus any factor that causes a nerve signal to be generated 0 Alters the permeability of a portion of the membrane 0 Allows ions to pass through 0 Changes membrane s voltage 0 Action potential nerve signal that is o A change from membrane voltage gt from the resting potential gt to a maximum level gt back to resting potential 0 Self propagated in a oneway chain reaction along a neuron o All or none event 0 Frequency not strength changes with strength of signal 0 Electrical synapse electrical signals pass between cells 0 Chemical synapse o Neurotransmitter chemical signal secreted by presynaptic cell the ending Some excite a receiving cell Others inhibit a receiving cells activity by decreasing its ability to develop an action potential 0 Synaptic cleft Neurotransmitter crosses to bind to a receptor on the surface of the postsynaptic cell receiving 0 Receiving neurons membrane receive signals that are Both excitatory and inhibitory From many different sending neurons Determines if a neuron will transmit a nerve signal 0 Psychoactive drugs act at synapses and affect neurotransmitter ac on o Caffeine counter effect of inhibitory neurotransmitter o Nicotine acts as stimulant by binding to acetylcholine receptors 0 Alcohol depressant ANIMAL NERVOUS SYSTEMS Bilaterally symmetrical o Cephalization concentration of NS at head end 0 Centralization CNS distinct from PNS Vertebrates o CNS Brain and spinal cord Spaces filled with cerebrospinal fluid a Ventricles in the brain a Central canal of spinal cord n Surrounding brain 0 PNS cranial nerves spinal cord ganglia Motor mostly voluntary n Signals to and from skeletal muscles n Responds to external stimuli Autonomic mostly involuntary n Regulates internal environment a Controls smooth and cardiac muscle organs and glands of digestive cardiovascular excretory and endocrine system a 3 divisions Parasympathetic rest and digest primes body for activities that gain and conserve energy Sympathetic fight or flight prepares body for intense energyconsuming activities Enteric network of neurons in digestive tract pancreas gallbladder that control secretion and peristalsis THE HUMAN BRAIN Forebrain o Cerebrum sophisticated integration major role in memory learning speech emotions forms complex behavioral responses Largest and most complex Cerebral hemispheres most of the integrative power is in the cerebral cortex of the 2 n Cerebral cortex less than 5mm thick 0 80 of total human brain mass 0 specialized integrative regions 0 somatosensory cortex 0 centers for vision hearing taste smell 0 Motor cortex directs responses Association areas make up most of cerebrum n Concerned with higher mental activities reasoning and language Lateralization right and left cerebral hemispheres specialize in different mental tasks 0 Thalamus input center for sensory data going to cerebrum output center for motor responses leaving cerebrum sorts data 0 Hypothalamus homeostatic control center controls pituitary biological clock Midbrain subdivisions of the hindbrain thalamus and hypothalamus 0 Conduct information to and from higher brain centers 0 Regulate homeostatic function 0 Keep track of body position 0 Sort sensory information auditory visual reflexes Hindbrain o Pons controls breathing o Medulla oblongata controls breathing circulation swallowing digestion o Cerebellum coordinates body movement role in learning and remembering motor responses Disease 0 Alzheimer s confusion memory loss personality changes Difficult to diagnose o Parkinson s motor disorder difficulty in initiating movement slowness rigidity
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