Copyright © 2010 Pearson Education, Inc. Chapter 21 Brain Structure and Function Attention Deficit Disorder

Copyright © 2010 Pearson Education, Inc The Nervous System The nervous system  Neurons carry electrical and chemical messages to and from the brain  Neurons receive, process, and respond to stimuli. Three general categories of neurons 1.Sensory neurons 2.Interneurons 3.Motor neurons

Copyright © 2010 Pearson Education, Inc The Nervous System Figure 21.2 See and smell cookies Smile and salivate Sensory neurons (to brain) Interneurons (within brain or spinal cord) Motor neurons (from brain)

Copyright © 2010 Pearson Education, Inc The Nervous System Table 21.1 Sensory detectors can be either: 1.Sensory neurons 2.Specialized cells that communicate with neurons General Senses Temperature Pain Pressure Touch Proprioception

Copyright © 2010 Pearson Education, Inc The Nervous System Table 21.1 Special Senses Smell Taste Vision Hearing Equilibrium

Copyright © 2010 Pearson Education, Inc The Nervous System Table 21.1 Special Senses Smell Taste Vision Hearing Equilibrium

Copyright © 2010 Pearson Education, Inc The Nervous System The nervous system is divided into two parts: 1.Central nervous system  brain and spinal cord 2.Peripheral nervous system  nerves extending from vertebrae out to body Reflex arc  sensory neuron that synapses to an interneuron and then motor neuron  action without higher processing (e.g., knee jerk reflex) Figure 21.4 Hot stimulus Motor neuron withdraws hand from heat Sensory neuron senses heat Interneuron relays signal

Copyright © 2010 Pearson Education, Inc The Nervous System Focus on Evolution  Muscle & Nervous tissue is unique to the animal kingdom  Enables animals to sense environment & move in search of food  All animal nervous systems have similar properties. Figure 21.1 Brain Sense organs Spinal cord Nerves

Copyright © 2010 Pearson Education, Inc The Nervous System - Focus on Evolution Figure E21.2 Primitive Animal Nervous System Nerve Nets Found in hydras, sea anemones & jellyfish Limited travel through environment No brain

Copyright © 2010 Pearson Education, Inc The Nervous System - Focus on Evolution Figure E21.2 Nerve Cords Found in insects Processing of information centralized in CNS Simple brain plus many enlarged ‘ganglia’

Copyright © 2010 Pearson Education, Inc The Nervous System - Focus on Evolution Figure E21.3 Vertebrate Nervous Systems Greater degree of centralization Single large brain Regions of brain become specialized for specific tasks

Copyright © 2010 Pearson Education, Inc The Brain Human Brain  The brain rests in the skull in cerebrospinal fluid, which bathes and cushions it. Two major cell types in the brain 1.Neurons transmit nervous impulses  Brain has billion neurons 2.Glial cells support neurons by providing protection & nutrients  Almost 10 times as many glial cells as neurons Figure 21.6

Copyright © 2010 Pearson Education, Inc The Brain The brain is divided into 5 regions 1.Cerebrum 2.Cerebellum 3.Thalamus 4.Hypothalamus 5.Brain stem

Copyright © 2010 Pearson Education, Inc The Brain - Cerebrum Figure 21.7 Lobes of the Cerebrum 1.Frontal lobe 2.Temporal lobe 3.Parietal lobe 4.Occipital lobe Other Important Structures Right & Left Hemispheres Central fissure Corpus callosum Caudate nuclei

Copyright © 2010 Pearson Education, Inc The Brain - Cerebrum Figure 21.7 Brain Hemispheres Many nerves cross over, so left brain controls right side of body, and visa versa Left Hemispheres Controls speech, reading, & solving math Right Hemispheres Interprets spatial relationships, music & art

Copyright © 2010 Pearson Education, Inc The Brain - Thalamus and Hypothalamus Thalamus and hypothalamus  lie deep in the brain between the hemispheres and act as control center.  Thalamus relays information from spinal cord to brain.  Thalamus suppresses some information and enhances other.  Hypothalamus is the control center for sex drive, pleasure, pain, hunger, and other basic drives.

Copyright © 2010 Pearson Education, Inc The Brain - Cerebellum Cerebellum  Control of balance  Coordination of muscular movement  Damage to the cerebellum results in jerky, awkward movements

Copyright © 2010 Pearson Education, Inc The Brain - Brainstem Brainstem  Controls involuntary activity.  The brainstem is composed of the midbrain, pons, and medulla oblongata Figure 21.8

Copyright © 2010 Pearson Education, Inc The Brain ADD and Brain Structure and Function  Some researchers suggest there are differences between brains of people with ADD and people without.  Corpus callosum smaller in individuals with ADD  Decreased folding on cerebrum in ADD individuals  Differences could be a result of genetics, or development and life experiences

Copyright © 2010 Pearson Education, Inc Neurons Neurons  Neurons are highly specialized cells Parts of Neuron  Dendrites  Cell Body  Axon  Terminal Boutons Figure 21.9

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Structure Myelin speeds up nervous impulses  Many neurons have their axons covered by a myelin sheath made by Schwann cells  the unmyelinated patches are the nodes of Ranvier. Figure 21.10

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Neuron Function  Cell accumulates K + ions inside and Na + ions outside Figure 21.11a Nerve cell All channels are closed. The inside of the cell has a more negative charge than the outside of the cell. Nodes of Ranvier Outside cellInside cell (a) Resting nerve cell K + channel Na + channel

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Nervous Impulse = Action Potential  Stimulation of a neuron causes ion gates to open, and Na + rushes in, changing polarity (depolarization)  Action potential (nervous Impulse) – a brief change in polarity of the surface membrane, which moves down the length of an axon Figure 21.11b

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Animation—Communication Within Neurons: The Axon PLAY

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function How Neurons Work

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Synapse = junction between neurons  Terminal boutons, space, & dendrites or cell body Synaptic transmission = Transmission of impulses between neurons  neurons use neurotransmitters to communicate chemically across the synapse

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Figure Synaptic Transmission 1.Action potential reaches terminal bouton of presynaptic cell 2.Calcium gates open, allowing Ca 2+ to rush in 3.Ca 2+ causes synaptic vesicles to release neurotransmitters 4.Neurotransmitter binds to receptors on postsynaptic cell 5.Opening or ion channels triggers action potential in postsynpatic cell

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Figure Two ways to stop synaptic transmission 1.Neurotransmitter is digested by enzymes 2.Reuptake of neurotransmitters by presynatpic cell

Copyright © 2010 Pearson Education, Inc Neurons - Neuron Function Animation—Communication Within Neurons: The Synapse PLAY

Copyright © 2010 Pearson Education, Inc Neurons Alzheimer’s, Depression, Parkinson’s, and ADD  Many mental diseases are linked to problems with neurotransmitters.  Alzheimer’s and Parkinson’s diseases seem to be related to impaired neurotransmitter production.  Depression appears to be related to an imbalance in several neurotransmitters, but its unclear if this is a cause or a result of depression.  ADD may be result of lower levels of neurotransmitter dopamine.

Copyright © 2010 Pearson Education, Inc Neurons - ADD Perscription Drug Action Figure Ritalin Blocks reuptake receptors on presynaptic cells Increases dopamine in synapse Adderall & Dexedrine Both are amphetamines Increase levels of dopamine in synapse