autonomic nervous system (ANS) PowerPoint pr

autonomic nervous system (ANS) is the part of the nervous system that controls involuntary bodily functions, such as breathing, heart rate, and blood pressure. It has two main divisions: the sympathetic, which handles the "fight-or-flight" response to stress, and the parasympathetic, which manages "rest and digest" functions

1. Physiology of Autonomic Nervous S ystem

2. 2 Objectives At the end of this chapter the student will be able to: Define Nervous system. Explain the Autonomic nervous system. List the 2 divisions of the ANS. Enumerate functions of the ANS. Discuss autonomic reflex . 2

3. Autonomic nervous system 3 They are autonomic

4. 4 Comparison of peripheral NS 4 Comparison of peripheral NS T1–L3 C–S2-4 chromaffin cells The effects last 5 to 10 times as long

5. 5 Identify which is Parasympathetic? 5 75%

6. Properties of ANS Dual innervation: antagonism or synergism Exceptions to dual innervation: SwG , AdG , PEM, BV Antagonistic control is a hallmark of the autonomic division Exceptions to dual antagonistic innervation: sexual act and sweating of palms and soles The postganglionic sympathetic nerve fibers to the sweat glands ( except for a few adrenergic fibers to the palms and soles: NE ), piloerector muscles of the hairs, apocrine glands in the axillae, and to a very few blood vessels are cholinergic. Sympathetic tone and parasympathetic tone Sympathetic mass discharge 6

7. 7 Values of adrenal medulla to SNS functions Organs can be stimulated indirectly form the gland As safety factor/ Has substitution function.  If direct sympathetic stimulation blocked, organ still stimulated sufficiently. Sympathetic destruction may not stop organ stimulation What happen in Pheochromocytomas ? 7

8. Signaling pathways and mechanisms for autonomic receptors 8

9. Why do some cells respond to a chemical signal while other cells do not? 9

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11. 11 Autonomic Effects on Various Organs of the Body

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13. The Enteric Nervous System Can act independently AKA Intramural, little brain The magnitude & complexity of the ENS is immense - it contains as many neurons as the spinal cord . about 100 million 13 13 Myenteric plexus located between the longitudinal & circular layers of muscle in the tunica muscularis . exerts control over digestive tract motility . 2 types Submucosal plexus buried in the submucosa . sens the environment within the lumen, regulate gastrointestinal blood flow & control epithelial cell function ( secretion and absorption ).

14. Enteric Nervous System… 14 14

15. 15 ENS interaction with ANS

16. 16 Autonomic reflexes Reflex = fast & involuntary response to a stimulus. Reflex action = an action that is signalled to CNS and a reaction sent by the CNS. Reflex arc = a nerve pathway that is responsible for triggering a reflex action. Has 5-components: 1. Receptor - detects changes & generates action potential (AP). 2 . Afferent (sensory) pathway - Conducts AP to CNS. 16

17. 17 Autonomic reflexes…cont’d 3 . Integrating center - Brain & Spinal cord, interpretation of sensory input 4. Efferent (motor) pathway - Conducts AP to effectors. 5. Effector - Cardiac & smooth muscles and glands – Receive Feed back and respond accordingly. 17

18. 18 Autonomic reflexes…cont’d Representative autonomic reflexes are: Baroreceptor reflex Chemoreceptor reflex Defecation reflex Micturition reflex Sexual reflex 18

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