Autonomic Nervous System Dr. Donald Allen

Role of Autonomic Nervous System Homeostasis Internal Organs Vasculature

Autonomic Sensation Stretch/Pressure Pain Temperature Oxygen, pH

Mechanoreceptors Pressure Stretch

Chemoreceptors Carotid and aortic bodies Medulla Hypothalamus

Nociceptors Stretch Ischemia

Thermoreceptors Hypothalamus Skin

Afferent Pathways Dorsal roots Cranial Nerves (taste and viscera) VII IX X

Visceral Control Areas Medulla Pons

Visceral Modulatory Areas Hypothalamus Thalamus Limbic System

Efferent (Motor) Systems Neurons Neuron SomaticAutonomic

Preganglionic Neurotransmitter

Neurotransmitters of Postganglionic Neurons Parasympathetic nervous system Sympathetic Nervous system (most) Sympathetic Nervous system (some blood vessels and sweat glands)

Parasympathetic NS Some Sympathetic Fibers muscarine

Most Sympathetic Fibers

Adrenal Medulla

Sympathetic Nervous System Preganglionic Neuron T1-L2

Targets ONLY part of Autonomic NS that innervates the extremities

Functions of Sympathetic Nervous System Cholinergic Adrenergic

Increase HR and contractility Bronchodilation Slow down

Sympathetic to head and upper limbs Superior cervical ganglion Middle Cervical Ganglion Stellate ganglion

Sympathetic Cervical Ganglia

Regulation of body temperature by sympathetic nervous system Increased metabolic rate Decreased blood flow to skin Sweating Erection of hair (piloerection)

Parasympathetic Nervous System

Parasympathetic Nervous System in the Brainstem Cranial nerve III – Oculomotor nerve –Constrict pupil –Increases convexity of lens – near vision Cranial nerve VII – Facial nerve –Salivary glands Cranial nerve IX – Glossopharyngeal nerve –Salivary glands –Lacrimal glands

Cranial nerve X – Vagus nerve –75% of brainstem autonomic efferents –Heart –Lungs –Upper GI tract –Liver

Parasympathetic Nervous System in the Sacral Spinal Cord Bowel and Bladder Sexual organs

Unique functions Sympathetic –Effectors in limbs, face and body wall –Assist in elevation of upper eyelid (other part is skeletal muscle and somatic motor system) Parasympathetic –Increasing convexity of lens

Clinical Correlations Peripheral Nerve Spinal Cord Brainstem Cerebral region - hypothalamus

Peripheral Nerve Losses

Spinal Cord Bowel and bladder control problems BP regulation Body temperature

Brainstem Interfere with control of heart rate, blood pressure, respiration May affect cranial nerve nuclei

Cerebral Region - Hypothalamus Disrupts homeostasis (metabolic and behavioral dysfunctions) –Weight –Temperature regulation –Emotional displays