1. Autonomic Nervous System

2. Introduction Autonomic Nervous System Auto (self) nom (govern) We are not in control of the functions that are performed by the ANS It is the involuntary nervous system

3. Levels of Organization

4. ANS Motor division of peripheral nervous system (PNS) Controls visceral activities, goal = maintaining internal homeostasis

5. Two motor division systems ANS = involuntary Somatic = voluntary Efferent pathway (nerve impulses) ANS (from CNS to cardiac & smooth muscles, glands) Somatic (from CNS to skeletal muscles)

6. ANS (Comparison)

7. Somatic Nervous System (SNS) Single neuron fron CNS to effector organs Heavily myelinated = rapid nerve impulse conduction Ach is the main neurotransmitter ANS (two-neuron chain) Preganglionic neuron (in brain or spinal cord) Preganglionic axon (from CNS) synapses with ganglionic neuron then, Postganglionic axon extends to the effector organ Preganglionic axons are lightly myelinated Postganglionic axons are unmyelinated

10. Comparison

12. Constantly active at a basal level to maintain homeostasis

13. Two kinds of neurons involved in the transmission of any signal through the sympathetic system

14. Preganglion

15. Postganglion

16. Preganglionic fibers are located in the spinal cord (T1-L2) known as the “Thoracolumbar Division”

18. Cranial Outflow Preganglion fibers come from the cranial and sacral division Oculomotor Nerves (CIII) Smooth muslces in the eyes (pupil constriction) Facial Nerves (CVII) Nasal glands Lacrimal glands Superior salivatory nuclei Glossopharyngeal nerves (CIX) Inferior salivatory nuclei Vagus Nerves (CX) Fibers to neck and nerve plexuses

19. Sacral Outflow Most of the large intestine and pelvic organs Distal half of large intestine Urinary bladder Ureters Reproductive organs

21. Neurotransmitters

22. Neurotrasmitters Substances released from neurons that influences the likelihood that an action potential in the presynaptic terminal will result in the postsynaptic cell Effects of autonomic activity lies in knowing which neurotransmitters are released by the autonomic fibers and what kind of receptors occur on the target cells

23. Axon terminals of autonomic neurons release two neurotransmitters Norepinephrine (adrenergic fibers) Acetylcholine (cholinergic fibers) Majority of sympathetic postganglionic fibers are adrenergic Cholinergic fibers include all preganglionic fibers of both division Postganglionic fibers of parasympathetic Few sympathetic postganglionic fibers

24. Receptor Type Norepinephrine affects visceral effectors by first binding to adrenergic receptors in their plasma Adrenergic receptor types Alpha ( ) Beta ()βα Subtypes of alpha and beta receptors include (B1, B2, B3, A1, A2)

25. ACh binds to cholinergic receptors Nicotinic Muscarinic Subtypes Nicotinic-1, Nicotinic-2 Muscarinic-1, Muscarinic-2, Muscarinic-3 All Ach receptors are either nicotinic or muscarinic

26. Autonomic Disorders Most reflect exaggerated or deficient control of smooth muscle activity Hypertension (high blood pressure) Results from an overactive sympathetic vasoconstrictor response Makes the heart work harder to pump blood to the body Contributes to arthrosclerosis (hardening of arteries) Factors that contribute to hypertension; smoking, weight, genetics, chronic kidney disease, thyroid disorders

28. Damage to SNS

29. Major sign is drooping of the upper eyelid

30. Due to loss of sympathetic innervation to the eye (superior tarsal muscle)

31. RaynaudsDisease (Body limits blood flow to hands and feet)Exaggerated vasoconstriction response Provoked by exposure to cold or emotional stress In severe cases, blood circulation to fingers and toes diminish leading to skin ulcers or gangrene Vasodilators are used as treatment

32. Autonomic neuropathy Common complication of diabetes mellitus Nerve damage occurs due to high blood glucose Symptoms include dizziness and urinary discontinance Autonomic Dysreflexia(hyperreflexia) Dangerous complication of spinal cord injury Uncontrolled activation of autonomic neurons Spinal cord injuries at T6 or higher are at rish Trigger is painful stimulus to the skin or overfilling of visceral organs Elevated blood pressure can lead to stroke

33. Biofeedback The use of instrumentation to monitor and feedback to the patient Originally thought that the ANS could not be controlled voluntarily Voluntary cortical control of visceral activities is possible through biofeedback Physiological processes may be brought under voluntary control Visual imagery Diaphragmatic breathing (deep breathing to slow the stress response)

34. Instrumentation used to train the patient EMG (electromyography) & temperature trainer Tem. Training = hand warming through visual imagery Leads to to vasodilation in the blood vessels of the body EMG training = method of learning used to achieve deep muscle relaxation through feedback