Lecture Human anatomy and physiology - Chapter 12: The central nervous system (part c)

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Chapter 12 - The central nervous system (part c), in this chapter you will learn about the following: Functional brain systems, limbic system, limbic system: emotion and cognition, reticular formation, reticular formation: RAS and motor function, electroencephalogram (EEG), brain waves,...and other contents.

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Nội dung Text: Lecture Human anatomy and physiology - Chapter 12: The central nervous system (part c)

PowerPoint® Lecture Slides prepared by Vince Austin, Bluegrass Technical and Community College CHAPTER 12 The Central Nervous System: Part C Copyright © 2010 Pearson Education, Inc.
Functional Brain Systems • Networks of neurons that work together and span wide areas of the brain • Limbic system • Reticular formation Copyright © 2010 Pearson Education, Inc.
Limbic System • Structures on the medial aspects of cerebral hemispheres and diencephalon • Includes parts of the diencephalon and some cerebral structures that encircle the brain stem Copyright © 2010 Pearson Education, Inc.
Septum pellucidum Fiber tracts connecting limbic Diencephalic structures system structures Corpus callosum of the limbic system •Fornix •Anterior thalamic •Anterior commissure nuclei (flanking 3rd ventricle) Cerebral struc- tures of the •Hypothalamus limbic system •Mammillary body •Cingulate gyrus •Septal nuclei •Amygdala •Hippocampus •Dentate gyrus •Parahippocampal gyrus Olfactory bulb Copyright © 2010 Pearson Education, Inc. Figure 12.18
Limbic System • Emotional or affective brain • Amygdala—recognizes angry or fearful facial expressions, assesses danger, and elicits the fear response • Cingulate gyrus—plays a role in expressing emotions via gestures, and resolves mental conflict • Puts emotional responses to odors • Example: skunks smell bad Copyright © 2010 Pearson Education, Inc.
Limbic System: Emotion and Cognition • The limbic system interacts with the prefrontal lobes, therefore: • We can react emotionally to things we consciously understand to be happening • We are consciously aware of emotional richness in our lives • Hippocampus and amygdala—play a role in memory Copyright © 2010 Pearson Education, Inc.
Reticular Formation • Three broad columns along the length of the brain stem • Raphe nuclei • Medial (large cell) group of nuclei • Lateral (small cell) group of nuclei • Has far-flung axonal connections with hypothalamus, thalamus, cerebral cortex, cerebellum, and spinal cord Copyright © 2010 Pearson Education, Inc.
Reticular Formation: RAS and Motor Function • RAS (reticular activating system) • Sends impulses to the cerebral cortex to keep it conscious and alert • Filters out repetitive and weak stimuli (~99% of all stimuli!) • Severe injury results in permanent unconsciousness (coma) Copyright © 2010 Pearson Education, Inc.
Reticular Formation: RAS and Motor Function • Motor function • Helps control coarse limb movements • Reticular autonomic centers regulate visceral motor functions • Vasomotor • Cardiac • Respiratory centers Copyright © 2010 Pearson Education, Inc.
Radiations to cerebral cortex Visual impulses Auditory impulses Reticular formation Ascending general Descending sensory tracts motor projections (touch, pain, temperature) to spinal cord Copyright © 2010 Pearson Education, Inc. Figure 12.19
Electroencephalogram (EEG) • Records electrical activity that accompanies brain function • Measures electrical potential differences between various cortical areas Copyright © 2010 Pearson Education, Inc.
(a) Scalp electrodes are used to record brain wave activity (EEG). Copyright © 2010 Pearson Education, Inc. Figure 12.20a
Brain Waves • Patterns of neuronal electrical activity • Generated by synaptic activity in the cortex • Each person’s brain waves are unique • Can be grouped into four classes based on frequency measured as Hertz (Hz) Copyright © 2010 Pearson Education, Inc.
Types of Brain Waves • Alpha waves (8–13 Hz)—regular and rhythmic, low- amplitude, synchronous waves indicating an “idling” brain • Beta waves (14–30 Hz)—rhythmic, less regular waves occurring when mentally alert • Theta waves (4–7 Hz)—more irregular; common in children and uncommon in adults • Delta waves (4 Hz or less)—high-amplitude waves seen in deep sleep and when reticular activating system is damped, or during anesthesia; may indicate brain damage Copyright © 2010 Pearson Education, Inc.
1-second interval Alpha waves—awake but relaxed Beta waves—awake, alert Theta waves—common in children Delta waves—deep sleep (b) Brain waves shown in EEGs fall into four general classes. Copyright © 2010 Pearson Education, Inc. Figure 12.20b
Brain Waves: State of the Brain • Change with age, sensory stimuli, brain disease, and the chemical state of the body • EEGs used to diagnose and localize brain lesions, tumors, infarcts, infections, abscesses, and epileptic lesions • A flat EEG (no electrical activity) is clinical evidence of death Copyright © 2010 Pearson Education, Inc.
Epilepsy • A victim of epilepsy may lose consciousness, fall stiffly, and have uncontrollable jerking • Epilepsy is not associated with intellectual impairments • Epilepsy occurs in 1% of the population Copyright © 2010 Pearson Education, Inc.
Epileptic Seizures • Absence seizures, or petit mal • Mild seizures seen in young children where the expression goes blank • Tonic-clonic (grand mal) seizures • Victim loses consciousness, bones are often broken due to intense contractions, may experience loss of bowel and bladder control, and severe biting of the tongue Copyright © 2010 Pearson Education, Inc.
Control of Epilepsy • Anticonvulsive drugs • Vagus nerve stimulators implanted under the skin of the chest can keep electrical activity of the brain from becoming chaotic Copyright © 2010 Pearson Education, Inc.
Consciousness • Conscious perception of sensation • Voluntary initiation and control of movement • Capabilities associated with higher mental processing (memory, logic, judgment, etc.) • Loss of consciousness (e.g., fainting or syncopy) is a signal that brain function is impaired Copyright © 2010 Pearson Education, Inc.