Chapter 16 Flashcards
Autonomic Nervous System (ANS)
Operates without conscious instruction
Control visceral effectors
Coordinated system functions (cardiovascular, respiratory, digestive, urinary, sweating, reproductive)
Controlled by hypothalamus, brainstem, + spinal cord
Sympathetic and Parasympathetic
Somatic Nervous System
Single lower motor neuron w/ long myelinated axon to effector
Cell bodies in CNS
All neurons release Ach (always stimulatory)
Fast
Pre-ganglionic neuron in ANS
Cell body in spinal cord or brainstem
Lightly myelinated axons
Release Ach (always stimulatory)
Synapses on post-ganglionic neuron
Post-ganglionic neuron in ANS
Cell body in autonomic ganglion
Unmyelinated axons from ganglion to visceral effector
Release Ach, norepinephrine, epinephrine
Effects could be inhibitory or stimulatory
Sympathetic Division
Preganglionic neurons between T1-L2 (Thoracolumbar)
Cell bodies form lateral gray horn
Short preganglionic axons exit through ventral root of spinal nerves
3 ganglionic neuron locations and effectors
Sympathetic chain (trunk) ganglia (paravertebral)
Collateral ganglia (prevertebral)
Adrenal medulla (suprarenal medulla)
Sympathetic chain (trunk) ganglia (paravertebral)
Long ganglionic neuron axons control effectors in body wall, inside thoracic cavity, head, limbs
Collateral ganglia (prevertebral)
Long ganglionic neuron axons innervate tissues and organs in abdominopelvic cavity
Adrenal Medulla
Pre-ganglionic neuron goes to adrenal medulla
Neuroendocrine cells in AM release neurotransmitters (EPI, NE) into blood to function as hormones
Sympathetic chain ganglia pathway (preganglion)
Axons from T1-L2 lateral horns ascend/descend to sympathetic ganglia, synapse with ganglionic neuron
Collateral ganglia pathway (preganglion)
Axons pass through sympathetic chain without synapsing form splanchinc nerves, synapse with ganglionic neurons in collateral ganglia (celiac ganglion, superior mesenteric ganglion, inferior mesenteric ganglion)
Sympathetic chain ganglia pathway (post-ganglion)
Axons: Gray ramus communicans, spinal nerves, sympathetic nerves
Collateral ganglia pathway (postganglion)
Axons leave ganglia and innervate abdominopelvic organs via NE release
Release energy stores
Decrease blood flow to non-essential organs
Celiac Ganglion
Celiac artery
Innervates stomach, spleen, pancreas, lover, gallbladder, proximal intestine
Superior Mesenteric Ganglion
Superior mesenteric artery
Innervates distal small intestine, proximal large intestine, kidneys, proximal uterus
Inferior Mesenteric Ganglion
Inferior mesenteric artery
Innervates distal large intestine, rectum, urinary bladder, parts of ureters, reproductive organs
Adrenal Medula Pathway
Preganglionic neurons run in splanchinc nerve to adrenal medulla
Preganglionic axons synapse on many neuroendocrine cells: release hormones to blood, “adrenaline rush”, epinephrine (adrenaline), norepinephrine, effects of NT long lasting
Sympathetic activation
Controlled by hypothalamus
Acheived by release of NE at peripheral synapses or EPI and NE in blood
Sympathetic activation physiological changes
Pupils dilate
Increase HR and BP
Airways dilate
Decrease of blood flow to non-essential organs
Release of stored energy by liver + adipose tissue
Parasympathetic (craniosacral) division (pre-ganglion)
Long axons, not many branches
Cell bodies originate in brainstem + sacrum
Axons in: cranial nerves III, VII, IX, X, splanchinc nerves
Release Ach
Terminal ganglia: close to effector
Intramural ganglia: within organ wall
Parasympathetic (craniosacral) division (post-ganglion)
Short
Release Ach
Activate few effectors each: brief + local response
Parasympathetic cranial nerves (pre-ganglion)
Synapse on terminal ganglia
III (Occulomotor): ciliary
VII (facial): submundibular + pterogopalatine ganglion
IX (glossopharangial): otic ganglion
X (vagus): terminal ganglia or intramural ganglia
Parasympathetic cranial nerves (post-ganglion)
Short
Terminate on effectors resulting in:
Pupillary constriction
Production/secretion of tears, mucus, saliva
Increased mucus production
Increased small muscle activity
Increased secretory activity of digestive organs
Decreased airway diameter
Decreased heart rate
Decreased force of contractions
Sacral preganglionic neurons
Cell bodies in lateral gray horn of S2-S4
Axons form splanchinc nerves and branch to form hypogastric plexus
Synapse on terminal or intramural ganglia
