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

2. Copyright © 2010 Pearson Education, Inc. 21.1 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

3. Copyright © 2010 Pearson Education, Inc. 21.1 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)

4. Copyright © 2010 Pearson Education, Inc. 21.1 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

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

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

7. Copyright © 2010 Pearson Education, Inc. 21.1 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

8. Copyright © 2010 Pearson Education, Inc. 21.1 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

9. Copyright © 2010 Pearson Education, Inc. 21.1 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

10. Copyright © 2010 Pearson Education, Inc. 21.1 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’

11. Copyright © 2010 Pearson Education, Inc. 21.1 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

12. Copyright © 2010 Pearson Education, Inc. 21.2 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 100-200 billion neurons 2.Glial cells support neurons by providing protection & nutrients  Almost 10 times as many glial cells as neurons Figure 21.6

13. Copyright © 2010 Pearson Education, Inc. 21.2 The Brain The brain is divided into 5 regions 1.Cerebrum 2.Cerebellum 3.Thalamus 4.Hypothalamus 5.Brain stem

14. Copyright © 2010 Pearson Education, Inc. 21.2 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

15. Copyright © 2010 Pearson Education, Inc. 21.2 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

16. Copyright © 2010 Pearson Education, Inc. 21.2 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.

17. Copyright © 2010 Pearson Education, Inc. 21.2 The Brain - Cerebellum Cerebellum  Control of balance  Coordination of muscular movement  Damage to the cerebellum results in jerky, awkward movements

18. Copyright © 2010 Pearson Education, Inc. 21.2 The Brain - Brainstem Brainstem  Controls involuntary activity.  The brainstem is composed of the midbrain, pons, and medulla oblongata Figure 21.8

19. Copyright © 2010 Pearson Education, Inc. 21.2 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

20. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons Neurons  Neurons are highly specialized cells Parts of Neuron  Dendrites  Cell Body  Axon  Terminal Boutons Figure 21.9

21. Copyright © 2010 Pearson Education, Inc. 21.3 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

22. Copyright © 2010 Pearson Education, Inc. 21.3 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

23. Copyright © 2010 Pearson Education, Inc. 21.3 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

24. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons - Neuron Function Animation—Communication Within Neurons: The Axon PLAY

25. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons - Neuron Function How Neurons Work

26. Copyright © 2010 Pearson Education, Inc. 21.3 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

27. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons - Neuron Function Figure 21.12 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

28. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons - Neuron Function Figure 21.12 Two ways to stop synaptic transmission 1.Neurotransmitter is digested by enzymes 2.Reuptake of neurotransmitters by presynatpic cell

29. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons - Neuron Function Animation—Communication Within Neurons: The Synapse PLAY

30. Copyright © 2010 Pearson Education, Inc. 21.3 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.

31. Copyright © 2010 Pearson Education, Inc. 21.3 Neurons - ADD Perscription Drug Action Figure 21.13 Ritalin Blocks reuptake receptors on presynaptic cells Increases dopamine in synapse Adderall & Dexedrine Both are amphetamines Increase levels of dopamine in synapse