Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 49 Nervous Systems

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Animal Nervous Systems Nervous systems consist of circuits of neurons and supporting cells All animals except sponges – Have some type of nervous system What distinguishes the nervous systems of different animal groups – Is how the neurons are organized into circuits

Fig – Nervous System Organization (e) Insect (arthropod) Segmental ganglia Ventral nerve cord Brain (a) Hydra (cnidarian) Nerve net Nerve ring Radial nerve (b) Sea star (echinoderm) Anterior nerve ring Longitudinal nerve cords (f) Chiton (mollusc)(g) Squid (mollusc) Ganglia Brain Ganglia (c) Planarian (flatworm) Nerve cords Transverse nerve Brain Eyespot Brain (d) Leech (annelid) Segmental ganglia Ventral nerve cord Brain Spinal cord (dorsal nerve cord) Sensory ganglia (h) Salamander (vertebrate)

Fig Peripheral nervous system (PNS) Cranial nerves Brain Central nervous system (CNS) Ganglia outside CNS Spinal nerves Spinal cord

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The spinal cord conveys information from the brain to the PNS The spinal cord also produces reflexes independently of the brain A reflex is the body’s automatic response to a stimulus – For example, a doctor uses a mallet to trigger a knee-jerk reflex Organization of the Vertebrate Nervous System

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Three Stages of Information Processing Nervous systems process information in three stages: 1.sensory input; 2.integration; 3.motor output Figure 48.3 Sensor Effector Motor output Integration Sensory input Peripheral nervous system (PNS) Central nervous system (CNS)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Three Stages of Information Processing Figure 48.4 Sensory neurons from the quadriceps also communicate with interneurons in the spinal cord. The interneurons inhibit motor neurons that supply the hamstring (flexor) muscle. This inhibition prevents the hamstring from contracting, which would resist the action of the quadriceps. The sensory neurons communicate with motor neurons that supply the quadriceps. The motor neurons convey signals to the quadriceps, causing it to contract and jerking the lower leg forward The reflex is initiated by tapping the tendon connected to the quadriceps (extensor) muscle. 1 Sensors detect a sudden stretch in the quadriceps. 2 Sensory neurons convey the information to the spinal cord. 3 Quadriceps muscle Hamstring muscle Spinal cord (cross section) Gray matter White matter Cell body of sensory neuron in dorsal root ganglion Sensory neuron Motor neuron Interneuron

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The central canal of the spinal cord and the ventricles of the brain are hollow and filled with cerebrospinal fluid The cerebrospinal fluid is filtered from blood and functions to cushion the brain and spinal cord The brain and spinal cord contain – Gray matter, which consists of neuron cell bodies, dendrites, and unmyelinated axons – White matter, which consists of bundles of myelinated axons Organization of the Vertebrate Nervous System

Fig Oligodendrocyte Microglial cell Schwann cells Ependy- mal cell Neuron Astrocyte CNS PNS Capillary (a) Glia in vertebrates (b) Astrocytes (LM) VENTRICLE 50 µm

Fig Efferent neurons Locomotion Motor system Autonomic nervous system Afferent (sensory) neurons PNS Hearing CirculationGas exchangeDigestion Hormone action Enteric division Sympathetic division Parasympathetic division

Fig Stimulates glucose release from liver; inhibits gallbladder Dilates pupil of eye Parasympathetic division Sympathetic division Action on target organs: Inhibits salivary gland secretion Accelerates heart Relaxes bronchi in lungs Inhibits activity of stomach and intestines Inhibits activity of pancreas Stimulates adrenal medulla Inhibits emptying of bladder Promotes ejaculation and vaginal contractions Constricts pupil of eye Stimulates salivary gland secretion Constricts bronchi in lungs Slows heart Stimulates activity of stomach and intestines Stimulates activity of pancreas Stimulates gallbladder Promotes emptying of bladder Promotes erection of genitals Action on target organs: Cervical Sympathetic ganglia Thoracic Lumbar Synapse Sacral

Table 49-1

Fig. 49-UN5 Cerebrum Thalamus Hypothalamus Pituitary gland Forebrain Cerebral cortex Midbrain Hindbrain Pons Medulla oblongata Cerebellum Spinal cord

Fig. 49-UN1

Fig. 49-UN2

Fig. 49-UN3

Fig. 49-UN4

Fig Corpus callosum Thalamus Left cerebral hemisphere Right cerebral hemisphere Cerebral cortex Basal nuclei

Fig Speech Occipital lobe Vision Temporal lobe Frontal lobe Parietal lobe Somatosensory association area Frontal association area Visual association area Reading Taste Hearing Auditory association area Speech Smell Motor cortex Somatosensory cortex

Fig Primary somatosensory cortex Frontal lobe Pharynx Parietal lobe Teeth Gums Jaw Tongue Lips Face Nose Eye Thumb Fingers Hand Forearm Elbow Upper arm Head Neck Trunk Hip Leg Genitals Abdominal organs Primary motor cortex Tongue Toes Jaw Lips Face Eye Brow Neck Fingers Hand Wrist Forearm Elbow Shoulder Trunk Hip Knee Thumb

Fig Thalamus Hypothalamus Prefrontal cortex Olfactory bulb Amygdala Hippocampus

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Memory and Learning Learning can occur when neurons make new connections or when the strength of existing neural connections changes Short-term memory is accessed via the hippocampus The hippocampus also plays a role in forming long-term memory, which is stored in the cerebral cortex

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 49.5: Nervous System Disorders Nervous system disorders can be explained in molecular terms Disorders of the nervous system include schizophrenia, depression, Alzheimer’s disease, and Parkinson’s disease Genetic and environmental factors contribute to diseases of the nervous system

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Schizophrenia About 1% of the world’s population suffers from schizophrenia Schizophrenia is characterized by hallucinations, delusions, blunted emotions, and other symptoms Available treatments focus on brain pathways that use dopamine as a neurotransmitter

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Depression Two broad forms of depressive illness are known: major depressive disorder and bipolar disorder In major depressive disorder, patients have a persistent lack of interest or pleasure in most activities Bipolar disorder is characterized by manic (high-mood) and depressive (low-mood) phases Treatments for these types of depression include drugs such as Prozac and lithium

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Drug Addiction and the Brain Reward System The brain’s reward system rewards motivation with pleasure Some drugs are addictive because they increase activity of the brain’s reward system These drugs include cocaine, amphetamine, heroin, alcohol, and tobacco Drug addiction is characterized by compulsive consumption and an inability to control intake

Fig Nicotine stimulates dopamine- releasing VTA neuron. Cerebral neuron of reward pathway Opium and heroin decrease activity of inhibitory neuron. Cocaine and amphetamines block removal of dopamine. Reward system response

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Alzheimer’s Disease Alzheimer’s disease is a mental deterioration characterized by confusion, memory loss, and other symptoms Alzheimer’s disease is caused by the formation of neurofibrillary tangles and amyloid plaques in the brain A successful treatment in humans may hinge on early detection of amyloid plaques There is no cure for this disease though some drugs are effective at relieving symptoms

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Parkinson’s Disease Parkinson’s disease is a motor disorder caused by death of dopamine-secreting neurons in the midbrain It is characterized by difficulty in initiating movements, muscle tremors, slowness of movement, and rigidity There is no cure, although drugs and various other approaches are used to manage symptoms