A&P II Ch. 11 Narrated.pptx PDF

PowerPoint® Lecture Presentations prepared by Donal Skinner, University of Wyoming CHAPTER 11 The Nervous System: Autonomic and Motor Systems © 2013 Pearson Education, Inc.  Dual Innervation of the Autonomic Nervous System Both divisions of the autonomic nervou...

PowerPoint® Lecture Presentations prepared by Donal Skinner, University of Wyoming CHAPTER 11 The Nervous System: Autonomic and Motor Systems © 2013 Pearson Education, Inc.  Dual Innervation of the Autonomic Nervous System Both divisions of the autonomic nervous system innervate most effector organs Primary function: regulate organs to maintain homeostasis Parasympathetic and sympathetic activities tend to be antagonistic Parasympathetic nervous system: rest Sympathetic nervous system: fight-or-flight response © 2013 Pearson Education, Inc.  Figure 11.1 Dual innervation in the autonomic nervous system. Sympathetic Parasympathetic Eye Cranial nerve III Lacrimal and salivary glands Lungs Pons Cranial nerve VII Parasympathetic Cranial nerve IX Medulla ganglion Cranial nerve X C1 C2 C3 C4 Cervical C5 C6 Heart C7 C8 Vagus nerve T1 Liver (cranial nerve X) T2 Stomach T3 T4 T5 Spleen T6 Pancreas Thoracic T7 T8 Kidney T9 Large T10 intestine T11 Small intestine T12 L1 L2 Lumbar L3 Collateral L4 ganglion Rectum L5 S1 S2 S2 Sacral S3 S3 S4 S4 Bladder S5 Coccygeal Co1 Sympathetic chain © 2013 Pearson Education, Inc. Genitalia  Anatomy of the Autonomic Nervous System Two types of neurons from CNS to effector organs: Preganglionic neurons Postganglionic neurons Autonomic ganglia Communication from preganglionic to postganglionic neuron Intrinsic neurons © 2013 Pearson Education, Inc.  Anatomy of the Autonomic Nervous System Effector organs Cardiac muscle Smooth muscle Glands Adipose tissue © 2013 Pearson Education, Inc.  Figure 11.2 Anatomy of autonomic pathways. CNS PNS Effector organs: Preganglionic Postganglionic Cardiac muscle neuron neuron Smooth muscle Glands Adipose tissue Autonomic ganglion © 2013 Pearson Education, Inc.  Anatomy of Parasympathetic Nervous System Parasympathetic nerves Cranial nerves Cranial nerve X = vagus nerve Cranial nerve III = oculomotor Cranial nerve VII = facial nerve Cranial nerve IX = glossopharyngeal nerve Spinal nerves Pelvic nerves are distinct from somatic spinal nerves © 2013 Pearson Education, Inc.  The Mixed Composition of Autonomic Nerves Efferent fibers Autonomic nervous system Afferent fibers Transmit information from visceral receptors to CNS Important in maintaining homeostasis © 2013 Pearson Education, Inc.  Autonomic Neurotransmitters and Receptors Cholinergic receptors – more common; bind acetylcholine Adrenergic receptors – bind norepinephrine © 2013 Pearson Education, Inc.  Types of Cholinergic Receptors Nicotinic cholinergic receptors (ionotropic) Cause cation channels to open Channel opening results in depolarization Muscarinic cholinergic receptors (metabotropic) G protein coupled Effect depends on target cell © 2013 Pearson Education, Inc.  Types of Adrenergic Receptors Two main classes: alpha and beta Each has subclasses All are coupled to G proteins © 2013 Pearson Education, Inc.  Types of Adrenergic Receptors Properties of  adrenergic receptors Located in effector organs of sympathetic nervous system Most common Usually excitatory Affinity greater for norepinephrine than epinephrine © 2013 Pearson Education, Inc.  Types of Adrenergic Receptors Properties of  adrenergic receptors All activate cAMP Affinities for norepinephrine and epinephrine vary © 2013 Pearson Education, Inc.  Types of Adrenergic Receptors Properties of 1 adrenergic receptors Located in cardiac muscle and kidneys Usually excitatory Equal affinity for norepinephrine and epinephrine Properties of 2 adrenergic receptors Located in some blood vessels and smooth muscle Usually inhibitory Greater affinity for epinephrine than norepinephrine © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.  Autonomic Neuroeffector Junctions Synapses between efferent and effector organ in the autonomic nervous system Neuroeffector junction Between postganglionic neuron and effector organ Neurotransmitter stored in axon swellings Varicosities Released in response to action potential in postganglionic neuron © 2013 Pearson Education, Inc.  Figure 11.9 Neuroeffector junctions of the autonomic nervous system. Postganglionic neuron Varicosity Effector organ Varicosity Synaptic vesicle Neurotransmitter (acetylcholine or norepinephrine) Axon Axon Voltage- Voltage- gated gated Na+ K+ channel channel Voltage-gated Ca2+ channel © 2013 Pearson Education, Inc.  Autonomic Neuroeffector Junctions Events at the neuroeffector junction 1. Action potential arrives at varicosity 2. Voltage-gated Ca2+ channels open 3. Ca2+ triggers exocytosis of neurotransmitter 4. Neurotransmitter binds with receptors on effector organ 5. Response in effector organ occurs 6. Neurotransmitter is degraded and diffuses away; reuptake occurs © 2013 Pearson Education, Inc.  Figure 11.10 Neurotransmitter release from varicosities. Varicosity Action potential ACh Ca2+ Choline Choline + Acetate Muscarinic cholinergic receptor ACh G protein Amplifier enzyme Effector cell Acetylcholinesterase Acetylcholine release from postganglionic neuron Varicosity Action Mitochondrion potential with MAO NE Ca2+ NE Adrenergic receptor Effector cell G protein Amplifier enzyme Norepinephrine release from postganglionic neuron © 2013 Pearson Education, Inc.  Regulation of Autonomic Function Dual innervation of organs Balance between parasympathetic and sympathetic activity Parasympathetic: rest Sympathetic: excitation Increases in parasympathetic activity are coupled with decreases in sympathetic activity Increases in sympathetic activity are coupled with decreases in parasympathetic activity © 2013 Pearson Education, Inc.  Figure 11.11 Autonomic reflex response that controls blood pressure when a person stands up. Person stands up Lower limbs Force of gravity causes blood to pool Systemic arteries Blood pressure Visceral receptors Detect decrease in blood pressure Afferent pathway Frequency of action Negative potentials feedback Cardiovascular control center in medulla oblongata Integration Efferent pathway Sympathetic Parasympathetic activity activity Heart and blood vessels Blood pressure Initial stimulus Physiological response © 2013 Pearson Education, Inc. Result  Regulation of Autonomic Function Parasympathetic activity Quiet, relaxed states Active in "rest and digest" Increases gastrointestinal activities Decreases heart rate and blood pressure © 2013 Pearson Education, Inc.  Regulation of Autonomic Function Sympathetic activity Fight-or-flight response Prepares for emergency, stress, and exercise Increases heart rate and blood pressure Mobilizes energy stores Dilates pupils Decreases gastrointestinal and urinary functions © 2013 Pearson Education, Inc.  Tonic Activity at Rest Both branches active Parasympathetic nervous system dominates © 2013 Pearson Education, Inc.  Figure 11.12 Areas of the brain that regulate autonomic function. Hypothalamus Pons Respiratory Cardiovascular centers centers Medulla oblongata © 2013 Pearson Education, Inc.  Anatomy of the Somatic Nervous System Motor neurons Innervate skeletal muscle Neurotransmitter = acetylcholine Receptors in skeletal muscle = nicotinic cholinergic © 2013 Pearson Education, Inc.  Anatomy of the Somatic Nervous System Motor unit One motor neuron plus all of the muscle fibers it innervates Somatic motor neurons innervate skeletal muscle One motor neuron innervates many muscle fibers Each muscle fiber is innervated by only one motor neuron © 2013 Pearson Education, Inc.  Figure 11.14 Motor units. Motor neuron 1 Motor neuron 2 Motor neuron 3 Spinal cord Muscle Muscle fiber © 2013 Pearson Education, Inc.  The Neuromuscular Junction Synapse between a motor neuron and a muscle fiber Anatomy of the neuromuscular junction Terminal bouton = axon terminal Motor end plate = specialized muscle membrane at junction All motor neurons release acetylcholine Nicotinic cholinergic receptors Synapses are excitatory Acetylcholinesterase © 2013 Pearson Education, Inc.  The Neuromuscular Junction Activities of the neuromuscular junction Action potential in motor neuron triggers release of acetylcholine at neuromuscular junction End-plate potential occurs at motor end plate Always excitatory © 2013 Pearson Education, Inc.  The Neuromuscular Junction Communication at the neuromuscular junction 1. Action potential arrives at terminal bouton 2. Voltage-gated calcium channels open 3. Calcium enters cell, triggering release of ACh 4. ACh diffuses across cleft and binds to nicotinic receptors on motor end plate 5. ACh triggers opening of channels for the small cations sodium and potassium © 2013 Pearson Education, Inc.  Communication at the Neuromuscular Junction 6. Net movement of positive charge in depolarization End-plate potential (EPP) EPP > EPSP 7. EPP causes action potential in muscle cell 8. Action potential spreads through muscle, causing contraction © 2013 Pearson Education, Inc.  Figure 11.15 Functional anatomy of the neuromuscular junction. Action potential Terminal bouton of motor neuron Skeletal muscle Synaptic ACh cell membrane vesicle 1 Motor end plate of 8 Action skeletal muscle cell potential 3 Choline 6 2 Acetyl- ACh 7 cholines- K+ terase 4 Ca2+ Voltage- 5 gated Current Ca2+ channel Na+ Nicotinic 5 cholinergic Current receptor © 2013 Pearson Education, Inc. © 2013 Pearson Education, Inc.