Autonomic Nervous System Chapter 11 Comparison Somatic systems

Autonomic Nervous System Chapter 11

Comparison �Somatic systems- conscious awareness �Autonomic sensory - not consciously perceived ◦ Monitors internal conditions- blood gasses, viscera operation, etc �Autonomic motor- cardiac muscle, smooth muscle & glands ◦ Often adjustment of internal controls in relation to whole body needs

Motor pathways �Somatic motor neurons go directly from spinal cord to skeletal muscle �Autonomic motor systems includes two motor neurons: �Preganglionic neuron from CNS to autonomic neuron from cell body in ganglion to effector

Divisions � Sympathetic division � Parasympathetic division � both divisions often innervate the same effector � They have opposite effects � E. g. sympathetic stimulates heart rate and parasympathetic slows it

Figure 11. 1 a

Figure 11. 1 b

Sympathetic division � Thoracolumbar division- ◦ outflow from thoracic & lumbar segments of spinal cord � Preganglionic fibers – � From lateral horns via ventral roots � to sympathetic ganglia � synapse with postganglionic cells in ganglia

Preganglionic Routing

Parasympathetic Neurons

Neurotransmitters �Acetylcholine- ◦ ◦ All preganglionic fibers terminals parasympathetic postganglionic terminals A few postganglionic sympathetic terminals Short-lived effects �Norepinephrine- ◦ Most postganglioic sympathetic terminals ◦ Longer effects ◦ Amplified by adrenal release with epinephrine

ANS Activity � Balance between sympathetic & parasympathetic “tone” regulated through hypothalamus � Only sympathetic to: ◦ Sweat glands, arrrector pili muscles, kidneys, spleen, blood vessels & adrenal medulla

Sympathetic Effects � fight-or-flight activities Dilate pupils Increase HR, heart contraction & BP Dilate airways Constrict blood vessels to non essential organs: kidneys, GI tract ◦ Dilate vessels to muscles, cardiac muscle, liver & adipose ◦ Mobilize nutrients: glucose & fats ◦ ◦

Parasympathetic Effects �Rest-and–digest �SLUDD act ivies ◦ Salvation ◦ Lacrimation ◦ Urination ◦ Digestion ◦ Defecation ◦ Decrease- HR, airway diameter, pupil diameter

Wrap UP!! What have we learned? � Differentiation of the ANS vs the SNS � Divisions of the Parasympathetic vs Sympathetic systems � Nerve pathway for each system along with the associated neurotransmitters and effects. � This content fulfills some of the requirements for TCOs: ◦ 1, 6 and 7