Autonomic Nervous System Ch 14

The ANS and Visceral Sensory Neurons Figure 15.1

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 2nd motor neuron, the ganglionic neuron, in a peripheral autonomic ganglion Postganglionic fiber (axon) of the ganglionic neuron extends to the visceral organs

Anatomical Differences 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)

Comparison of Somatic & Autonomic Nervous System

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

Autonomic Nervous System 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

Autonomic Nervous System Biofeedback: Conscious control of ANS Ex. Yoga, meditation Monitoring devices useful for: epilepsy digestive problems chronic headaches high blood pressure generalized stress anxiety insomnia The Beginnings of Biofeedback The word "biofeedback" was coined in the late 1960s to describe laboratory procedures then being used to train experimental research subjects to alter brain activity, blood pressure, heart rate, and other bodily functions that normally are not controlled voluntarily. At the time, many scientists looked forward to the day when biofeedback would give us a major degree of control over our bodies. They thought, for instance, that we might be able to "will" ourselves to be more creative by changing the patterns of our brainwaves. Some believed that biofeedback would one day make it possible to do away with drug treatments that often cause uncomfortable side effects in patients with high blood pressure and other serious conditions. Today, most scientists agree that such high hopes were not realistic. Research has demonstrated that biofeedback can help in the treatment of many diseases and painful conditions. It has shown that we have more control over so-called involuntary bodily fun ction than we once though possible. But it has also shown that nature limits the extent of such control. Scientists are now trying to determine just how much voluntary control we can exert. How is Biofeedback Used Today? Clinical biofeedback techniques that grew out of the early laboratory procedures are now widely used to treat an ever-lengthening list of conditions. These include: ·Migraine headaches, tension headaches, and many other types of pain ·Disorders of the digestive system ·High blood pressure and its opposite, low blood pressure ·Cardiac arrhythmias (abnormalities, sometimes dangerous, in the rhythm of the heartbeat) ·Raynaud's disease (a circulatory disorder that causes uncomfortably cold hands) ·Epilepsy ·Paralysis and other movement disorders Specialists who provide biofeedback training range from psychiatrists and psychologists to dentists, internists, nurses, and physical therapists. Most rely on many other techniques in addition to biofeedback. Patients usually are taught some form of relaxation exercise. Some learn to identify the circumstances that trigger their symptoms. They may also be taught how to avoid or cope with these stressful events. Most are encouraged to change their habits, and some are trained in special techniques for gaining such self-control. Biofeedback is not magic. It cannot cure disease or by itself make a person healthy. It is a tool, one of many available to health care professionals. It reminds physicians that behavior, thoughts, and feelings profoundly influence physical health. And it helps both patients and doctors understand that they must work together as a team.

Autonomic Nervous System Sympathetic Parasympathetic Work antagonistically Myelinated motor neuron Unmyelinated motor neuron CNS ganglion effector The output (motor) part of ANS has 2 principle branches sympathetic and parasympathetic Ganglion- a collection of neuronal cell bodies outside the CNS

Neurotransmitter is norepinephrine “fight or flight” Sympathetic Division Neurotransmitter is norepinephrine “fight or flight” E = exercise, excitement, emergency, and embarrassment The output (motor) part of ANS has 2 principle branches sympathetic and parasympathetic

Sympathetic Division 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. The output (motor) part of ANS has 2 principle branches sympathetic and parasympathetic Fight or flight adaptive effects include:   a) increased cardiac activity, increased blood pressure, dilation of skeletal muscle blood vessels - provides increased perfusion of vital organs and muscles b) constriction of blood vessels in skin - limits bleeding from wounds c) dilation of pupil - letting more light into the eye d) inhibition of gut and urinary bladder contractions - inhibit defecation and urination e) increase in blood glucose and free fatty acid levels - supply more energy f) dilation of bronchial smooth muscle - easier flow of air g) secretion of viscous saliva - possibly to avoid choking h) sweating i) lower threshold for reticular formation activation - reinforcing the alert state j) liver produces glucose to provide energy for muscle contraction.

Parasympathetic Division 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 The output (motor) part of ANS has 2 principle branches sympathetic and parasympathetic

Sympathetic Ganglia 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 The output (motor) part of ANS has 2 principle branches sympathetic and parasympathetic

Parasympathetic Ganglia Site of synapses between pre and post parasympathetic ganglia terminal ganglia Located close to or within the wall of a visceral organ The output (motor) part of ANS has 2 principle branches sympathetic and parasympathetic

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

Sympathetic

Parasympathetic

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

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

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

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