1. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings C h a p t e r 16 Neural Integration II: The Autonomic Nervous System and Higher-Order Functions PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

2. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings An Introduction to the ANS Autonomic Nervous System (ANS)  coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions  Two subdivisions  Sympathetic division  Parasympathetic division

3. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  Sympathetic Division  Prepares the body for heightened levels of somatic activity  Produces the “fight or flight” response –heightened mental alertness –increased metabolic rate –reduced digestive and urinary functions –activation of energy reserves –increased respiratory rate –increased heart rate –activation of sweat glands

4. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  Preganglionic fibers are short and the postganglionic fibers are long  preganglionic fibers from the thoracic and superior lumbar segments (T1 to L2) of the spinal cord synapse in ganglia near the spinal cord  The cell bodies of the preganglionic neurons are situated in the lateral gray horns, and their axons enter the ventral roots of these segments.

5. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  The ganglionic neurons occur in three locations: Sympathetic Chain Ganglia –Lie on both sides of the vertebral column –These neurons control effectors in the body wall, inside the thoracic cavity, and in the head and limbs Collateral Ganglia –Anterior to the vertebral bodies –These neurons innervate tissues and organs in the abdominopelvic cavity –Preganglionic fibers that innervate the collateral ganglia form the splanchnic nerves. They originate as a paired ganglia but typically fuse together as one in adults –The splanchnic nerves innervate three collateral ganglia: »celiac ganglion »superior mesenteric ganglion »inferior mesenteric ganglion

6. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division Adrenal Medullae –Center of each adrenal gland (adrenal medulla) is a modified sympathetic ganglion –These neurons release the neurotransmitters epinephrine (E) and norepinephrine (NE) into the bloodstream when stimulated –Function as hormones that affect target cells throughout the body

7. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  Sympathetic Activation  Occurs in a crisis so the person can cope with a stressful situation  Controlled by sympathetic centers in the hypothalamus  The following changes occur when activated:  increased alertness causing the person to feel “on edge”  a feeling of energy and euphoria which is associated with a disregard for danger and a temporary insensitivity to painful stimuli  elevations in blood pressure, heart rate, and breathing  general elevation in muscle tone  mobilization of energy reserves

8. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  The sympathetic division releases:  Acetylcholine  Syapses that release ACh are called cholinergic  has an excitatory effect on the ganglionic neurons which leads to the release of neurotransmitters at specific target organs  Instead of fording synaptic knobs, telodendria form a branch network. Each branch contains swollen segments called varicosities that are packed with neurotransmitter vesicles.  Norepinephrine  Neurons that use NE as a neurotransmitter are called adrenergic  NE released by varicosities affect its targets united it is reabsorbed or inactivated by the enzymes MAO and COMT when it diffuses out of the area

9. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  There are two classes of sympathetic receptors:  Alpha receptors  Activates enzymes on the inside of the cell membrane  Two types of alpha receptors –a1 »more common type of alpha receptor »function is the release of intracellular calcium ions from reserves in the endoplasmic reticulum »has an excitatory effect on the target cell –a2 »results in a lowering of cAMP in the cytoplasm »inhibitory effect on the cell

10. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Sympathetic Division  Beta receptors  located on the membranes of cells in many organs (skeletal muscles, lungs, heart, liver)  stimulation triggers changes in the metabolic activity of the target cell  three types of beta receptors:  B1 –Stimulation leads to an increase in metabolic activity  B2 –Stimulation causes inhibition, triggering a relaxation of smooth muscles along the respiratory tract –This response accounts for the effectiveness of inhalers used to treat asthma  B3 –Found in adipose tissue –Stimulation leads to lipolysis – breakdown of triglycerides stored within adipocytes

11. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Parasympathetic Division  Parasympathetic Division  Preganglionic fibers are long and the postganglionic fibers are short because they synapse in ganglia very close to the target organ  Stimulates visceral activity  Produces the “rest and repose” response that follows a big meal –decreased metabolic rate –decreased heart rate and blood pressure –increased secretion by salivary and digestive glands –increased motility and blood flow in the digestive tract –stimulation of urination and defecation

12. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Parasympathetic Division  All parasympathetic neurons release ACh as a neurotransmitter, but there are two types:  Nicotinic Receptors  Bind nicotine  Causes excitation of the ganglionic neuron or muscle fiber by the opening of chemically gated channels in the postsynaptic membrane  Muscarinic Receptors  Stimulated by muscarine  G proteins whose stimulation produces longer-lasting effects than does the stimulation of nicotinic receptors  Response can be inhibitory or excitatory

13. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Dual Innervation  Although some organs are innervated by just one division, most vital organs receive instructions from both the sympathetic and parasympathetic divisions (dual innervation).  Where dual innervation exists, the two divisions commonly have opposing effects.

14. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Autonomic Tone  Autonomic Tone  Even in the absence of stimuli, autonomic motor neurons show a resting level of spontaneous activity. The background level of activation determines an individual’s autonomic tone.  If a nerve is absolutely inactive under normal conditions, then all it can do is increase its activity on demand. But if the nerve maintains a background level of activity, it can increase or decrease its activity, producing a greater range of control options.

15. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Integration and Control of Autonomic Functions  Integration and Control of Autonomic Functions  The ANS is organized into a series of interacting levels. At the bottom are visceral motor neurons in the lower brain stem and spinal cord that are involved in cranial and spinal visceral reflexes.  Visceral reflexes provide automatic motor responses that can be modified, facilitated, or inhibited by higher center, especially those of the hypothalamus.

16. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Visceral reflexes  Visceral reflexes  Each visceral reflex arc consists of a receptor, a sensory neuron, a processing center (one or more interneurons), and two visceral motor neurons.  All are polysynaptic  They are either:  1. long reflexes –the autonomic equivalents of the polysynaptic reflexes –visceral sensory neurons deliver information to the CNS along the dorsal roots of spinal nerves, within the autonomic nerves that innervate visceral effectors. –Control activities of an entire organ  2. short reflexes –bypass the CNS entirely –they involve sensory neurons and interneurons whose cell bodies are located within autonomic ganglia –control very simple motorized responses with localized effects –control patterns of activity in one small part of a target organ

17. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions  Share three functions:  The cerebral cortex is required for their performance, and they involve complex interactions among areas of the cortex and between the cerebral cortex and other areas of the brain.  They involve both conscious and unconscious information processing.  They are not part of the programmed “wiring” of the brain; therefore, the functions are subject to modification and adjustment over time.

18. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions A. Memory  Stored bits of information gathered through experience  There are two types of memories:  Fact memories – specific bits of information, such as the color of a stop sign or the smell of perfume  Skill memories – learned motor behaviors, such as lighting a match

19. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions  There are two classes of memories:  short-term memories –primary memories –they do not last long, but can be recalled immediately –contain small bits of information –repetition promotes retention  long-term memories  last much longer than short-term memories  short-term memories are converted to long-term memories through memory consolidation  two types of long-term memories: –secondary memories – fade with time and may require considerable effort to recall –tertiary memories – memories with you for a lifetime

20. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions  The amygdaloid body and the hippocampus are essential to memory consolidation. Damage to the hippocampus leads to an inability to convert short-term memories to long-term memories.  The nucleus basalis, a cerebral nucleus near the diencephalon, plays an uncertain role in memory storage and retrieval. Damage to this nucleus is associated with changes in emotional states, memory, and intellectual function.  Most long-term memories are stored in the cerebral cortex

21. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions  Memory consolidation at the cellular level involves anatomical and physiological changes in neurons and synapses. Research on animals has indicated that the following mechanisms may be involved:  Increased neurotransmitter release  Facilitation at synapses  The formation of additional synaptic connections  These processes create anatomical changes that facilitate communication along a specific neural circuit. This facilitated communication is thought to be the basis of memory storage. A single circuit that corresponds to a single memory is called a memory engram.  Amnesia is the loss of memory as a result of disease or trauma. The type of memory loss depends on the specific regions of the brain affected.

22. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions B. States of Consciousness  1. conscious  implies an awareness of and attention to external events and stimuli  Examples include: nearly asleep, wide awake, or high-strung and jumpy  2. unconscious  refer to conditions ranging from the deep, unresponsive stated induced by anesthesia before major surgery, to deep sleep, to light sleep.

23. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions  Sleep  There are two general levels of sleep:  a. deep sleep –also called slow wave or non-REM sleep –your entire body relaxes, and activity at the cerebral cortex is at a minimum –heart rate, blood pressure, respiratory rate, and energy utilization decline by up to 30%  b. rapid eye movement (REM) sleep –active dreaming occurs accompanied by changed in blood pressure and respiratory rate –become less receptive to outside stimuli –muscle tone decreases markedly –eyes move rapidly as dream unfolds

24. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Higher-Order Functions  Periods of REM and deep sleep alternate throughout the night. People spend less than two hours dreaming each night. REM sleep periods average from 5 to 20 minutes in length over a typical 8 hour sleeping cycle.  Awakening from sleep (arousal) is one of the functions of the reticular formation. It has extensive interconnections with the sensory, motor, and integrative nuclei and pathways along the brain stem. All of these interconnections make it the “watchdog”. The reticular activating system (RAS) is a network in the reticular formation that is most important to arousal and the maintenance of consciousness.  The regulation of awake-sleep cycles involves an interplay between brain stem nuclei that use different neurotransmitters. One group of nuclei stimulates the RAS (reticular activating system) with norepinephrine and maintains the awake, alert state. The other group, which depresses RAS activity with serotonin, promotes deep sleep.