* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Outline14 Efferent NS
Neuroregeneration wikipedia , lookup
Nonsynaptic plasticity wikipedia , lookup
Central pattern generator wikipedia , lookup
Proprioception wikipedia , lookup
Long-term depression wikipedia , lookup
Activity-dependent plasticity wikipedia , lookup
Biological neuron model wikipedia , lookup
Development of the nervous system wikipedia , lookup
Caridoid escape reaction wikipedia , lookup
Haemodynamic response wikipedia , lookup
Neuroanatomy wikipedia , lookup
Embodied language processing wikipedia , lookup
Axon guidance wikipedia , lookup
Synaptic gating wikipedia , lookup
Muscle memory wikipedia , lookup
Premovement neuronal activity wikipedia , lookup
Chemical synapse wikipedia , lookup
Signal transduction wikipedia , lookup
Neurotransmitter wikipedia , lookup
Endocannabinoid system wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Microneurography wikipedia , lookup
Circumventricular organs wikipedia , lookup
Synaptogenesis wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
End-plate potential wikipedia , lookup
Stimulus (physiology) wikipedia , lookup
Biology 219 – Human Physiology Somatic Motor and Autonomic Nervous Systems Clemens Text: Ch. 11 PNS Afferent Division Effectors Efferent Division Somatic Motor → skeletal muscles Autonomic → cardiac muscle, smooth muscle, glands, adipose tissue sympathetic division parasympathetic division A. Somatic Motor Division - somatic motor neurons activate skeletal muscles - voluntary (mostly): control of movement, posture, breathing 1. Somatic Motor Pathway - one motor neuron pathway from CNS to muscle: motor neuron cell bodies located in ventral gray horn of spinal cord axons travel through spinal nerves axon terminals located at the neuromuscular junctions 2. Neuromuscular Junction 3 components: (1) axon terminal of motor neuron (2) synaptic cleft (3) motor end plate - axon terminals secrete ACh into the synaptic cleft nicotinic cholinergic receptors at the motor end plate binding of ACh open cation channels → strong EPSP → exceeds threshold → muscle AP B. Autonomic Division (ANS) - involuntary control of autonomic effectors (visceral organs, blood vessels, etc.) - activated by the hypothalamus, pons & medulla, and spinal cord (autonomic reflexes) - two motor neuron pathway from CNS to effectors: preganglionic fibers from CNS to autonomic ganglia postganglionic fibers from autonomic ganglion to target organ - 2 divisions: sympathetic “fight or flight” parasympathetic “rest and digest” dual innervation of sympathetic and parasympathetic to target organs, usually antagonistic both systems are active, but parasympathetic dominates during normal maintenance states; sympathetic system dominates during short-term stress, exercise, cold, drop in BP 1. ANS Organization a. Sympathetic Division - thoracolumbar outflow - short preganglionic, long postganglionic fibers - ganglia located in sympathetic chain and collateral ganglia - postganglionic neurons secrete norepinephrine (NE) as the neurotransmitter at target cells - adrenal medulla is functionally part of the sympathetic system stimulated directly by preganglionic sympathetic fibers secretes epinephrine (E) and norepinephrine (NE) as hormones b. Parasympathetic Division - craniosacral outflow vagus nerve (cranial nerve X) is the major parasympathetic nerve to visceral organs - long preganglionic, short postganglionic fibers - postganglionic neurons secrete acetylcholine (ACh) as the neurotransmitter at target cells - terminal ganglia located in or near target organs 2. ANS Neurotransmitters and Receptors preganglionic fibers: ACh → nicotinic cholinergic receptors (sympathetic and parasympathetic) postganglionic fibers 1. sympathetic: E, NE → adrenergic receptors a. alpha-adrenergic receptors (α1 → constriction of blood vessels) G-protein coupled receptors, activate phospholipase C second-messenger pathway b. beta-adrenergic receptors (β1 → stimulates heart; β2 → bronchodilation) G-protein coupled receptors, activate cAMP second-messenger pathway 2. parasympathetic: ACh → muscarinic cholinergic receptors G-protein coupled receptors, open or close K+ channels (excitatory or inhibitory) 3. Summary of Sympathetic and Parasympathetic Effects Sympathetic Parasympathetic increases heart rate and contractility decreases heart rate (no effect on contractility) inhibits digestive tract motility and secretion stimulates digestive tract motility and secretion vasoconstriction in peripheral blood vessels vasodilation in skeletal muscles no effect on blood vessels bronchiole dilation bronchiole constriction pupil dilation pupil constriction mobilization of energy reserves (glycogen and lipids) no metabolic effects