The document summarizes the key aspects of the autonomic nervous system (ANS). It describes how the ANS is divided into the sympathetic and parasympathetic divisions which work antagonistically to innervate organs like the heart. The sympathetic division prepares the body for fight or flight while the parasympathetic division promotes rest and digestion. The ANS acts involuntarily to maintain homeostasis through dual innervation of target organs and tissues.

1. The Autonomic Nervous System

7. Features of ANS Input (sensing): Sensory nerve endings testing the outside (eg via skin, gut wall) Sensing within body (eg chemo- and baro-receptors, temperature etc) Input from eye etc. Evaluation (set limits): Centres in brain (eg respiratory, cardiac centres etc) Reflexes Exchange of information Output (motor): Sympathetic Parasympathetic Enteric

8. General outline Testing (sensing) CNS Evaluation (set points) Motor ANS Somatic NS visceral & vascular effectors 3. 1. 2. (efferent, adjusting) A. B. 4. adrenal Skeletal muscle

9. Sensory neurons 1.

10. Sensory nerves in ANS Spinothalamic tract Dorsal root ganglion Sympathetic chain ganglia From body wall T1-L3 From the viscera To viscera Dorsal Ventral From the brain

12. DRG Sympathetic chain ganglion Dorsal Ventral

13. ANS in the brain 2.

17. Higher centres involved in ANS 2. Limbic (satiety, aggression, flight and other survival behaviours) 3. Thalamus (receives and distributes information) 1. Cortex (thought of, sight of etc).

25. Sympathetic Paths

29. 4. Autonomic ganglia

42. Autonomic Nervous System Actions Structure Sympathetic Stimulation Parasympathetic Stimulation iris of the eye pupil dilation pupil constriction salivary glands reduce salivation increase salivation oral/nasal mucosa reduce mucus production increase mucus prod. heart increase rate and force of contraction decrease rate and force of contraction lung relax bronchial smooth muscle constrict bronchial smooth muscle

43. Autonomic Nervous System Actions Structure Sympathetic Stimulation Parasympathetic Stimulation stomach reduce peristalsis; decrease gastric secretions increase peristalsis; increase gastric secretions small intestine reduce peristalsis; decrease intestinal secretions increase peristalsis; increase intestinal secretions large intestine reduce peristalsis; decrease intestinal secretions increase peristalsis; increase intestinal secretions liver increase conversion of glycogen to glucose; release glucose into bloodstream n/a

44. Autonomic Nervous System Actions Structure Sympathetic Stimulation Parasympathetic Stimulation kidney decrease urinary output increase urinary output urinary bladder wall relaxed; sphincter closed wall contracted; sphincter relaxed adrenal medulla secrete epinephrine and norepinephrine n/a sweat glands increase sweat secretion n/a blood vessels Constricts most blood vessels and increases BP(  1 ,  2 ).Dilation by  2 Little effect

45. Sympathetic vs. Parasympathetic Structural Differences : Point of CNS Origin T1  L2 (thoracolumbar) Brainstem, S2  S4 (craniosacral) Site of Peripheral Ganglia Paravertebral – in sympathetic chain On or near target tissue Length of preganglionic fiber Short Long Length of postganglionic fiber Long Short

46. Sympathetic vs. Parasympathetic Receptor/NT Differences: Symp . Parasymp . NT at Target Synapse Norepinephrine (adrenergic neurons) Acetylcholine (cholinergic neurons) Type of NT Receptors at Target Synapse Alpha and Beta (  and  ) Muscarinic NT at Ganglion Acetylcholine Acetylcholine Receptor at Ganglion Nicotinic Nicotinic