Chapter 11 Efferent Division Autonomic and Somatic Motor Control 2013 Pearson Education Inc About This Chapter The autonomic division The somatic motor division 2013 Pearson Education Inc Efferent Division of the Peripheral Nervous System Somatic motor neurons Control skeletal muscles Mostly voluntary Autonomic neurons Control smooth and cardiac muscle many glands lymphoid and some adipose tissues Mostly involuntary Sympathetic branch is fight or flight Parasympathetic branch is rest and digest Works with endocrine and behavioral state systems to maintain homeostasis 2013 Pearson Education Inc Figure 11 1 THE AUTONOMIC DIVISION Homeostasis is a dynamic balance between the autonomic branches Parasympathetic ti c e h t a y m p S Rest and digest Parasympathetic activity dominates Fight or flight Sympathetic activity dominates Figure 11 2 The hypothalamus pons and medulla initiate autonomic endocrine and behavioral responses Sensory input Hypothalamic sensors Somatic and visceral sensory neurons Pons medulla hypo thalamus Limbic system cerebral cortex Autonomic response Endocrine response Behavioral response Figure 11 3 AUTONOMIC CONTROL CENTERS Temperature control Water balance Eating behavior Hypothalamus Pons Medulla Urinary bladder control Secondary respiratory center Blood pressure control Respiratory center Antagonistic Control of the Autonomic Division Most internal organs are under antagonistic control One autonomic branch is excitatory and the other branch is inhibitory Example Effector organ heart Sympathetic response increases heart rate Parasympathetic response slows rate 2013 Pearson Education Inc Figure 11 5 3 3 of 4 EFFECTOR ORGAN SYMPATHETIC RESPONSE ADRENERGIC RECEPTOR PARASYMPATHETIC RESPONSE Pupil of eye Dilates Constricts Mucus enzymes and 2 Watery secretion Salivary glands Heart Increases rate and force of contraction Arterioles and veins Constricts Dilates Lungs Digestive tract Exocrine pancreas Bronchioles dilate Decreases motility and secretion Decreases enzyme secretion Endocrine pancreas Inhibits insulin secretion 1 2 2 2 Hormonal epinephrine only Slows rate Bronchioles constrict Increases motility and secretion Increases enzyme secretion Stimulates insulin secretion All parasympathetic responses are mediated by muscarinic receptors Figure 11 4 Autonomic pathways consist of two neurons that synapse in an autonomic ganglion Preganglionic neuron Postganglionic neuron CNS Autonomic ganglion Target tissue Figure 11 5 SYMPATHETIC Hypothalamus Reticular formation Ganglion Eye Pupil constricts PARASYMPATHETIC Hypothalamus Reticular formation Pupil dilates Mucus and enzymes secreted Increases heart rate and contractility Heart Relaxes airways Salivary glands Watery secretion Slows heart rate Constricts airways Vagus nerve Lungs Stomach Intestines Increases bile secretion Increases motility and secretion Increases motility and secretion Inhibits digestion Liver Ganglion Decreases enzymes and insulin Inhibits digestion Inhibits digestion Pancreas Release enzymes and insulin Adrenal medulla secretes catecholamines Release of urine Increases renin secretion Kidney Relaxes bladder Urinary bladder Induces ejaculation Penis Stimulates contraction Sympathetic chain Testes Induces erection Engorgement and secretions Uterus Pons Medulla Spinal cord C12 3 4 5 6 7 8 T1 2 3 4 5 6 7 8 9 10 11 12 L1 2 3 4 5 S1 2 3 4 5 Co1 Pons Medulla Spinal cord Pelvic nerves KEY Sympathetic Parasympathetic FIGURE QUESTIONS 1 Name the regions of the CNS where the two branches originate 2 Describe where the ganglia for the two branches are located relative to the spinal cord 3 What is an advantage of having ganglia in the sympathetic chain linked to each other Vagus Nerve Contains about 75 of all parasympathetic fibers Sensory information from internal organs to brain Output from brain to organs 2013 Pearson Education Inc Figure 11 6 Sympathetic and parasympathetic neurotransmitters and receptors Parasympathetic pathways use acetylcholine Sympathetic pathways use acetylcholine and norepinephrine CNS CNS ACh Nicotinic receptor Autonomic ganglion FIGURE QUESTIONS 1 Identify all cholinergic neurons adrenergic neurons preganglionic neurons postganglionic neurons 2 Which pathway will have longer preganglionic neurons Hint See Fig 11 5 Adrenergic receptor Norepinephrine ACh T Target tissue T Muscarinic receptor Figure 11 7a 1 of 10 Axon of postganglionic autonomic neuron Varicosities Autonomic varicosities release neurotransmitter over the surface of target cells Vesicle containing neurotransmitter Varicosity Mitochondrion Smooth muscle cells Figure 11 7b 2 of 10 Norepinephrine NE release and removal at a sympathetic neuroeffector junction Axon varicosity Tyrosine MAO Axon Action potential Voltage gated Ca2 channel Ca2 Diffuses away Blood vessel NE Exocytosis NE G Response Adrenergic receptor Target cell Active transport Action potential arrives at the varicosity Depolarization opens voltage gated Ca2 channels Ca2 entry triggers exocytosis of synaptic vesicles NE binds to adrenergic receptor on target Receptor activation ceases when NE diffuses away from the synapse NE is removed from the synapse NE can be taken back into synaptic vesicles for re release NE is metabolized by monoamine oxidase MAO Figure 11 7b Slide 1 Action potential arrives at the varicosity Tyrosine NE Axon Action potential Blood vessel Target cell 2013 Pearson Education Inc Figure 11 7b Slide 2 Action potential arrives at the varicosity Depolarization opens voltage gated Ca2 channels Tyrosine NE Axon Action potential Voltage gated Ca2 channel Ca2 Blood vessel Target cell 2013 Pearson Education Inc Figure 11 7b Slide 3 Action potential arrives at the varicosity Depolarization opens voltage gated Ca2 channels Ca2 entry triggers exocytosis of synaptic vesicles Axon Action potential Tyrosine NE Exocytosis Voltage gated Ca2 channel Ca2 Blood vessel NE Target cell 2013 Pearson Education Inc Figure 11 7b Slide 4 Action potential arrives at the varicosity Depolarization opens voltage gated Ca2 channels Ca2 entry triggers exocytosis of synaptic vesicles NE binds to adrenergic receptor on target Axon Action potential Tyrosine NE Exocytosis Voltage gated Ca2 channel Ca2 Blood vessel NE G Response Adrenergic receptor Target cell 2013 Pearson Education Inc Figure 11 7b Slide 5 Action potential arrives at the varicosity Depolarization opens voltage gated Ca2 channels Ca2 entry triggers exocytosis of synaptic vesicles NE binds to adrenergic