Topic List for Chapter 6 – Neuronal Signaling and Structure of the Nervous SystemKnow the examples of how certain drugs and diseases/toxins act on synapses.- Diseaseso Clostridium tetani- prevents vesicle fusion with the membrane, inhibiting neurotransmitter release and causes increased muscle contractiono Clostridium botulinum- interferes with actions of SNARE proteins at excitatory synapses that activate muscles; botulism characterized by muscle paralysiso Botox- injected therapeutically to treat a number of conditions, including facial wrinkles,severe sweating, uncontrollable blinking, and misalignment of the eyes- Drugso Act by interfering with or stimulating normal processes in the neuron involved with neurotransmitter synthesis, storage, and releaseKnow the difference between a neurotransmitter and a neuromodulator.- Neurotransmitter- involved in rapid communicationo Receptors affect ion channels that directly affect excitation or inhibition of the postsynaptic cello Operate within milliseconds- Neuromodulator- associated with slower events such as learning, development, motivational states, and some sensory and motor activitieso Receptors bring about changes in metabolic processes in neuronso Can occur over minutes, hours, or daysKnow what a neuroeffector junction is and how it works.- Neurons synapse on muscle and gland cellso Neurotransmitter is released from the efferent neuron, diffuses to the surface of the effector cell, where it binds to receptors on that cell’s plasma membraneo Receptors on the effector cell may be either ionotropic or metabotropic (metabolic)Know the major classes of neurotransmitters/neuromodulators important facts about each (Table 6-6).- Actetylcholine – important neurotransmitter in the PNS especially at neuromuscular junctionso Neurons that release ACh are called cholinergic neurons. ACh is broken down by the enzyme acetylcholine esterase in the synaptic cleft.  Altzheimer disease is associated with the degeneration of cholinergic neurons.o Receptors for ACh are called nicotinic and muscarinic. - Biogenic Amines – synthesized from amino acids. o Examles are dopamine, epinephrine, norepinephrine, serotonin, and histamine. o Norepinephrine(NE) and epinephrine (Epi or adrenaline) are secreted from the adrenal gland. NE and Epi stimulate “fight or flight” response. Cells that produce these are called adrenergic.  In group called catecholamines which also includes dopamineo Seratonin – affects food intake, reproductive behavior, mood and anxiety.  Main location is CNS in the brainstem Antidepressants called SSRI (selective serotonin reuptake inhibitors) act to prevent the reuptake of serotonin from the synapse and keep its concentration there high.o Histamine- CNS neurotransmitter located in hypothalamus; known for paracrine actions Involved in allergic reactions, nerve sensitization, and acid production in stomach Make you stay awake Antihistamine- make you sleepy- Amino acid neurotransmitters – some neurotransmitters are made of amino acids. o Glutamate and Aspartate- excitatory Glutamate is an excitatory neurotransmitter used by 50% of the excitatory synapses in the brain. o Glycine and GABA- inhibitory Alcohol activates GABA inhibitor; xanax and ethanol act on these receptors- Neuropeptides – made of short chains of amino acids. o Neurons that produce these are called peptidergic. o endogenous opioids- beta-endorphins and dynorphins that are probably involved in regulating pain and in runner’s “second wind.”  The receptors for these are acted upon by morphine, heroin etc and are analgesics.- Gases – nitric oxide, carbon monoxide, and hydrogen sulfide act as neurotransmitters. o Not released by exocytosis and don’t have receptors. o Diffuse from the axon terminal into the cytoplasm of the postsynaptic cell. o Nitric Oxide- learning, development, and drug toleranceKnow the major divisions of the nervous system (Figure 6-37). Central Nervous systemo Brain and spinal cord Peripheral Nervous systemo Afferent division- going into the CNS Somatic sensory- consciously experienced Visceral sensory- don’t consciously experience it Special sensory- eyes, ears, tasteo Efferent division- leaving the CNS Somatic motor- conscious movement Autonomic motor- non conscious movement (blood pressure, heart rate)- Sympathetic- fight or flight; respiratory functions- Parasympathetic- calming, rest and digest, sexual behavior- Enteric- autonomic neurons innervate a nerve network in the wall of theintestinal tractKnow the major anatomical structures of the brain and their general functions (see Table 6-7).- Forebraino Cerebral hemispheres Cerebral cortex- perception, skilled movements, reasoning, learning and memory- Outer shell of gray matter and inner layer of white matter- Ridges=gyri, grooves=sulci Contain subcortical nuclei- participate in coordination of skeletal muscle activity Contain interconnecting fiber pathways (gray matter internal) Corpus callosum- massive branch of nerve fiberso Thalamus Synaptic relay station for sensory pathways on their way to the cerebral cortex Participates in control of skeletal muscle Plays a key role in awarenesso Hypothalamus Single most important control area for homeostatic regulation of internal environment (body temp, water balance, eating and drinking behavior, etc) Connected to pituitary gland o Limbic system- thalamus, hypothalamus, portions of frontal and temporal lobes Generation of emotions and emotional behavior Plays essential role in most kinds of learning- Cerebellumo Coordinates movements including those for posture and balanceo Participates in some forms of learning- Brainstemo Contains all fibers passing between spinal cord, forebrain, and cerebellumo Contains reticular formation (absolutely essential for life) and integrating centerso Contains nuclei for cranial nerves 3-12Know the anatomy of the spinal cord including the dorsal and ventral roots and ganglia. What are the functions of each? (Fig.6-41). Spinal cord- slender cylinder of soft tissue about as big as the little finger Dorsal horns- gray matter projecting towards the back of the body Ventral horns- gray matter projecting towards the front of the body Gray matter surrounded by white matter, which consists of myelinated axons (opposite of brain) Dorsal root- where afferent fibers enter from peripheral nerveso Dorsal