Figure 15.1 The ANS and Visceral Sensory Neurons

Terms Synapse – junction between 2 neurons that communicates the message from the presynaptic neuron to the postsynaptic neuron Ganglion (pl. ganglia) – a cluster of neuronal cell bodies in the PNS Preganglionic neuron – cell body lies within the CNS - its axon, the preganglionic fiber synapses with the 2 nd motor neuron, the ganglionic neuron, in a peripheral autonomic ganglion Postganglionic fiber (axon) of the ganglionic neuron extends to the visceral organs

Issue from different regions of the CNS Sympathetic - aka the thoracolumbar division Parasympathetic – aka the craniosacral division Figure 15.3 Anatomical Differences

Length of postganglionic fibers: sympathetic are long and parasympathetic are short Branching of axons: sympathetic axons are highly branched to influence many organs while parasympathetic axons have few branches so have a localized effect Sympathetic release norepinephrine (adrenergic) Parasympathetic release acetylcholine (cholinergic)

Anatomical Differences Figure 15.4a

Anatomical Differences Figure 15.4b

Neurotransmitters Cholinergic fibers release the neurotransmitter ACh –All ANS preganglionic axons –All parasympathetic postganglionic axons Adrenergic fibers release the neurotransmitter NE –Most sympathetic postganglionic axons –Exceptions: sympathetic postganglionic fibers secrete ACh at sweat glands and some blood vessels in skeletal muscles

Parasympathetic and Sympathetic Nervous System: A subdivision of the PNS Not under conscious control Controlled by medulla oblongata and hypothalamus PNS supplies stimulation via motor nerves to smooth and cardiac muscle and to glands

Biofeedback: Conscious control of ANS Ex. Yoga, meditation Monitoring devices useful for: -epilepsy -digestive problems -chronic headaches -high blood pressure -generalized stress -anxiety -insomnia

Sympathetic Parasympathetic CNS ganglion Unmyelinated motor neuron Myelinated motor neuron effector Work antagonistically

Neurotransmitter is norepinephrine “fight or flight” E = exercise, excitement, emergency, and embarrassment

Fight or flight adaptive effects include: increased cardiac activity, increased blood pressure, dilation of skeletal muscle blood vessels constriction of blood vessels in skin dilation of pupil inhibition of gut and urinary bladder contractions increase in blood glucose and free fatty acid levels dilation of bronchial smooth muscle secretion of viscous saliva sweating lower threshold for reticular formation activation liver produces glucose to provide energy for muscle contraction.

neurotransmitter is acetylcholine D = digestion, defecation, diuresis (urinating) Parasympathetic activation results in: decreased cardiac activity secretion of watery saliva and stimulation of GI secretions contraction of urinary bladder increased insulin and glucagon secretion bronchiole constriction

Sites of synapses between pre and postsympathetic ganglia sympathetic trunk ganglia -located from base of skull to coccyx prevertebral ganglia -innervates organs below the diaphragm

Site of synapses between pre and post parasympathetic ganglia terminal ganglia -Located close to or within the wall of a visceral organ

when there is no escape route or no way to win – causes massive activation of parasympathetic division – loss of control over urination and defecation Paradoxical fear

Parasympathetic Cranial Nerves Oculomotor nerve – ciliary ganglion in orbit – ciliary muscle & pupillary constrictor muscle inside eyeball Facial nerve – pterygopalatine and submandibular ganglions – supply tears, salivary & nasal secretions Glossopharyngeal – otic ganglion supplies parotid salivary gland Vagus nerve – many brs supply heart, pulmonary and GI tract as far as the midpoint of the colon

Autonomic Plexuses in the Thorax, Abdomen & Pelvis

Types of connections bwtn ganglia & postganglia neurons in the sympathetic division

Examples: Digestion Blood pressure Defecation Urination Components of an Autonomic Reflex: 1.Receptor 2.Sensory neuron 3.Integration center 4.Motor neuron 5.Effector (smooth or cardiac muscle, or a gland)

Hypothalamus & Medulla Major control and integration center of the ANS Medulla oblongata

1.What neurotransmitter is produces from the Somatic nervous system, Sympathetic, and Parasympathetic nervous system? 2.What effector organs are targeted from the ANS? 3. Where does sensory input for the ANS come from? 4.List the components of an autonomic reflex arc. 5.What part of the brain is the major control and integration center of the ANS? 6.What effect does the parasympathetic nervous system have on the digestive system? 7.What effect does the sympathetic nervous system have on the liver?