1. Chapter 48: The Nervous System The nervous system & endocrine system work to regulate the organism & maintain homeostasis. Nervous system Involves: Involves: Sensory reception Sensory reception Stimulus (change in environment) triggers a response Stimulus (change in environment) triggers a response concentrated in sense organs concentrated in sense organs Sensitivity determined by density of receptors Sensitivity determined by density of receptors Integration Integration Interneurons or associative neurons within the CNS relay message Interneurons or associative neurons within the CNS relay message Motor response Motor response A reaction or behavior resulting in response to a stimulus A reaction or behavior resulting in response to a stimulus Effecter- muscle or gland which carries out a response Effecter- muscle or gland which carries out a response

2. Neurons Neurons Nerve cells Nerve cells Structure similar in all organisms Structure similar in all organisms Organization of cells varies among organisms Organization of cells varies among organisms Parts Parts Dendrites Dendrites receive signal receive signal Cell body Cell body contains nucleus & other organelles contains nucleus & other organelles Axon Axon transmits signal transmits signal Myelin sheath Myelin sheath encloses axon, insulating signal encloses axon, insulating signal aids in speed of action potential aids in speed of action potential Terminal branches Terminal branches may contain neurotransmitters may contain neurotransmitters Synaptic gap Synaptic gap site of communication between 2 neurons via neurotransmitters site of communication between 2 neurons via neurotransmitters *Impulse enters via dendrites & exits via terminal branches Glia= supporting cells Glia= supporting cells Types Types Astrocytes Astrocytes regulate ion & neurotransmitter concentration; dilation of blood vessels regulate ion & neurotransmitter concentration; dilation of blood vessels Radial glia Radial glia act as stem cells act as stem cells Oligodendrocytes (CNS) & Schwann cells (PNS) Oligodendrocytes (CNS) & Schwann cells (PNS) form myelin sheath form myelin sheath

3. Reflexes Reflexes Automatic, inborn, unlearned Automatic, inborn, unlearned Protective responses to stimulation Protective responses to stimulation Examples: blinking, sneezing, coughing Examples: blinking, sneezing, coughing Reflex arc Reflex arc Stimulus (receptors on sense organ)  sensory neuron  interneuron within CNS (analyze & interpret)  motor neuron  effectors at neuromuscular junction Instincts- automatic & inborn like reflexes but not necessarily protective in function Instincts- automatic & inborn like reflexes but not necessarily protective in function Habits Habits Automatic, learned behaviors Automatic, learned behaviors Examples: smoking, tying shoe laces, using profanity, writing Examples: smoking, tying shoe laces, using profanity, writing

4. Response of neurons Response of neurons Graded potentials Graded potentials Magnitude of depolarization or hyper-polarization varies with stimulus strength Magnitude of depolarization or hyper-polarization varies with stimulus strength Bigger stimuli= bigger change Bigger stimuli= bigger change Action potentials Action potentials All or none depolarization All or none depolarization Same strength regardless of stimulus Same strength regardless of stimulus Nerve impulse Nerve impulse Electrochemical signal; speeds of 100 meters/second Electrochemical signal; speeds of 100 meters/second Resting state Resting state both Na + & K + activation gate channels are closed both Na + & K + activation gate channels are closed Resting potential- membrane more permeable to K + so more K + moves out than Na + moves in. Resting potential- membrane more permeable to K + so more K + moves out than Na + moves in. Ion permeability must change to send an impulse Ion permeability must change to send an impulse Threshold must be achieved to depolarize neuron membrane & produce an action potential Threshold must be achieved to depolarize neuron membrane & produce an action potential Depolarization: Na+ channels open & Na+ flows into neuron reversing polarity Depolarization: Na+ channels open & Na+ flows into neuron reversing polarity Re-polarization: K+ ions allowed into neuron as Na+ is blocked Re-polarization: K+ ions allowed into neuron as Na+ is blocked Refractory: brief period of time when cell can not be stimulated to carry an impulse Refractory: brief period of time when cell can not be stimulated to carry an impulse

5. The Synapse The Synapse Types Types Electrical synapses Electrical synapses Gap junctions allow action potential to travel cell to cell Gap junctions allow action potential to travel cell to cell Chemical synapses Chemical synapses Neurotransmitters released from synaptic vesicles & bind to dendrites of next neuron to start a new action potential Neurotransmitters released from synaptic vesicles & bind to dendrites of next neuron to start a new action potential **Majority of synapses Neurotransmitters Neurotransmitters Chemicals released into synaptic gap that diffuse & bind to next neuron Chemicals released into synaptic gap that diffuse & bind to next neuron Ca +2 required for release Ca +2 required for release Excitatory neurotransmitters Excitatory neurotransmitters Transmit impulses Transmit impulses Examples: acetylcholine (to skeletal muscle), norepinephrine, dopamine, glutamate, aspartate Examples: acetylcholine (to skeletal muscle), norepinephrine, dopamine, glutamate, aspartate Inhibitory neurotransmitters Inhibitory neurotransmitters Block impulse transmission Block impulse transmission Examples: acetylcholine (to cardiac muscle), serotonin, epinephrine, glycine, GABA, endorphins Examples: acetylcholine (to cardiac muscle), serotonin, epinephrine, glycine, GABA, endorphins

6. Regulation in invertebrates Regulation in invertebrates Protists Protists Sensitive to light, chemicals, temperature Sensitive to light, chemicals, temperature Cnideria (hydra) Cnideria (hydra) Nerve net Nerve net Whole organism responds to stimulus Whole organism responds to stimulus Annelida (earthworm) Annelida (earthworm) Ventral nerve cord Ventral nerve cord Fused ganglia (clusters of neurons) acting as brain Fused ganglia (clusters of neurons) acting as brain Arthropoda (insects) Arthropoda (insects) Ventral nerve cord Ventral nerve cord Sensory organs Sensory organs Antennae Antennae Tympanum Tympanum Compound eyes Compound eyes

7. Mammalian Nervous System Central Nervous System Central Nervous System Cerebrospinal fluid Cerebrospinal fluid helps supply nutrients & hormones to brain & removes waste helps supply nutrients & hormones to brain & removes waste cushions brain & spinal cord cushions brain & spinal cord Meninges- protective layers surrounding brain & spinal cord Meninges- protective layers surrounding brain & spinal cord Brain Brain Cerebrum Cerebrum Largest, upper portion of brain Largest, upper portion of brain thinking, memory, body awareness, social behavior, language thinking, memory, body awareness, social behavior, language EEG (electroencephalogram) detects brain wave activity EEG (electroencephalogram) detects brain wave activity Convolutions- folds in brain Convolutions- folds in brain Limbic system- lower part of brain that interacts with cerebral cortex to produce emotions, complex reasoning, & personality Limbic system- lower part of brain that interacts with cerebral cortex to produce emotions, complex reasoning, & personality Includes: Includes: Amygdala- emotional memories Amygdala- emotional memories Hippocampus- emotional events, long term memories Hippocampus- emotional events, long term memories Olfactory bulb Olfactory bulb Corpus callosum- axons that enable communication between hemispheres of cerebrum Corpus callosum- axons that enable communication between hemispheres of cerebrum Lobes: Lobes: Frontal- speech, motor function Frontal- speech, motor function Temporal- smell, hearing, auditory association Temporal- smell, hearing, auditory association Occipital- vision Occipital- vision Parietal- reading, somatosensory association, speech, taste Parietal- reading, somatosensory association, speech, taste

8. Cerebellum Cerebellum Lower, posterior portion of brain Lower, posterior portion of brain Regulates muscle balance, tone, coordination, & error checking during motor, perceptual, & cognitive functions Regulates muscle balance, tone, coordination, & error checking during motor, perceptual, & cognitive functions Brainstem Brainstem Primitive brain controlling involuntary activities includes: Primitive brain controlling involuntary activities includes: Midbrain Midbrain Pons- heart beat, swallowing, vomiting, digestion Pons- heart beat, swallowing, vomiting, digestion Medulla oblongata- breathing Medulla oblongata- breathing Reticular formation Reticular formation network of neurons in the brainstem which selects information being sent to cerebral cortex network of neurons in the brainstem which selects information being sent to cerebral cortex affects alertness affects alertness Diencephalon Diencephalon Includes Includes Epithalamus- pineal gland & choroid plexus Epithalamus- pineal gland & choroid plexus Thalamus- input center for sensory info & output center for motor info & emotions Thalamus- input center for sensory info & output center for motor info & emotions Hypothalamus- homeostatic regulation; connection between nervous & endocrine systems; regulates circadian rhythms Hypothalamus- homeostatic regulation; connection between nervous & endocrine systems; regulates circadian rhythms

9. Spinal cord- connects the brain to the peripheral nervous system Spinal cord- connects the brain to the peripheral nervous system Peripheral nervous system Peripheral nervous system System of branching nerves linking CNS to body tissues & organs System of branching nerves linking CNS to body tissues & organs Consists of: Consists of: Somatic nervous system Somatic nervous system Voluntary control or awareness of muscles, sense organs, & skin Voluntary control or awareness of muscles, sense organs, & skin Allows for conscious control in response to external stimulation Allows for conscious control in response to external stimulation Autonomic nervous system Autonomic nervous system Automatic, unconscious or involuntary regulation Automatic, unconscious or involuntary regulation Regulates internal environment by controlling smooth & cardiac muscle & organs Regulates internal environment by controlling smooth & cardiac muscle & organs Includes Includes Sympathetic nervous system- increased heart beat, blood vessel constriction, bronchi open, pupils dilate, peristalsis slows, bladder relaxes Sympathetic nervous system- increased heart beat, blood vessel constriction, bronchi open, pupils dilate, peristalsis slows, bladder relaxes Parasympatheic nervous system- reverse reactions of sympathetic nervous system Parasympatheic nervous system- reverse reactions of sympathetic nervous system Enteric nervous system- network of neurons to control organ secretions & smooth muscles; regulated through the sympathetic & parasympatheic nervous systems Enteric nervous system- network of neurons to control organ secretions & smooth muscles; regulated through the sympathetic & parasympatheic nervous systems

10. Diseases & Disorders Schizophrenia Schizophrenia Bipolar disorder/Manic depressive disorder Bipolar disorder/Manic depressive disorder Major depression Major depression Alzheimer’s disease Alzheimer’s disease Parkinson’s disease Parkinson’s disease