Chapter 15 Autonomic Nervous System PDF

Parasympathetic Innervation Only: The glossopharyngeal and Vagus parasympathetic nerves innervate glands of the upper tract; these include the salivary glands, esophageal glands, gastric glands, pancreas, and Brunner’s glands in the duodenum. Parasympathetic...

Parasympathetic Innervation Only: The glossopharyngeal and Vagus parasympathetic nerves innervate glands of the upper tract; these include the salivary glands, esophageal glands, gastric glands, pancreas, and Brunner’s glands in the duodenum. Parasympathetic activation of the muscarinic receptors causes ciliary muscle contraction. The effect of contraction is to decrease the diameter of the ring of ciliary muscle causing relaxation of the zonule fibers, the lens becomes more spherical, increasing its power to refract light for near vision. Bronchial smooth muscle: constiction Parasympathetic activation of the M3 muscarinic receptors causes ciliary muscle contraction, the effect of contraction is to decrease the diameter of the ring of ciliary muscle. The parasympathetic tone is dominant when a higher degree of accommodation of the lens is required, such as reading a book.  Autonomic N.S. Neurotransmitters and Receptors Trick to Remember Beta Heart and Lung Receptors Beta1 (One) Heart = There is 1 heart in the body Beta2 (Two) Lungs = There are 2 lungs in the body Alpha1 receptors are located on structures such as the vasculature, prostate, urethral sphincter, pylorus and will cause smooth muscle contraction. Alpha2 receptors are found on presynaptic nerve terminals and inhibit further release of norepinephrine. Beta1 receptors are on the heart and kidneys and lead to increased inotropy/chronotropy and renin release respectively. Beta2 receptors are located on lungs, bladder, uterus, GI tract, blood vessels and lead to smooth muscle relaxation.