Readings

• autonomic ganglion: connection of synapses between the pre- and post- ganglionic nerve fibers
• cholinergic (muscarinic) receptor: receptor located on internal organs and glands that responds to acetycholine
• nicotinic receptor: cholinergic receptor located on autonomic ganglia(Nn) and skeletal muscle (Nm)
• postganglionic nerve fiber: autonomic nerve fiber that travels from the autonomic ganglia to internal organs and glands
• The autonomic nervous system is also referred to as the visceral divison
• The somatic nervous system is controlled by the cerebral cortex while the autonomic nervous system is controlled by the medulla oblongata and the hypothalamus
• dual autonomic innervation: one division increases the activity of an organ while the other decreases it
• Parasympathetic division is known as the craniosacral division while the sympathetic is known as the thoracolumbar
• In the PSNS, ACH is released at both pre and post ganglionic nerve endings. In the SNS, ACH is released at the pre ganglionic nerve ending while NE is released at the post
• There are 2 types of cholinergic receptors: nicotinic and muscarinic
• Cholinergic receptor refers to the receptor binding of ACH while muscarinic and nicotinic differentiate different cholinergic sites
• Muscarinic receptors are located on the cell membranes of visceral organs and glands and are stimulated by ACH released from postganglionic nerve endings. Results will depend on which organ that ACH stimulates
• There are 2 types of nicotinic receptors: nicotinic-nerve(Nn) and nicotinic-muscle(Nm)
• Nn receptors are found in both parasympathetic and sympathetic ganglia and are stimulated by ACH released from preganglionic nerve endings to propagate those impulses across the autonomic ganglia so it reaches the postganglionic fibers of both autonomic divisions
• Nm receptors are located on the cell membranes of skeletal muscles and are stimulated by ACH from somatic nerve endings to contract skeletal muscles
• Nn receptors are autonomic while Nm receptors are somatic
• There are 4 adrenergic receptors: alpha 1, alpha 2, beta 1 and beta 2
• adrenergic neuronal blocker: drug that acts at the neuronal nerve endings to reduce release of NE
• alpha 1 adrenergic blocker: drug that blocks the alpha 1 effects of NE and EPI
• Alpha 2 adrenergic receptor: receptor on adrenergic nerve endings that reduces the the release of NE
• beta 1 adrenergic receptor: receptor located on the heart that increases chronotropy and ionotropy
• beta 2 adrenergic receptor: receptor located on smooth muscle that relaxes the smooth muscle when stimulated
• Sympathomimetics are drugs that produce the effects of the sympathetic nervous system by promoting stimulation of sympathetic nerves
• false transmitter is a substance formed in nerve endings that mimics and interferes with the actions of the normal transmitter
• nonselective beta adrenergic blocker: drug that blocks both beta 1 and 2 adrenergic receptors
• sympatholytic: refers to action of an adrenergic blocking drug or action that decreases sympathetic activity.
• NE is formed thru these series of steps: Tyrosine -> DOPA -> Dopamine -> NE
• Inside nerve endings, NE may be reused/destroyed by the enzyme monoamine oxidase (MAO)
• EPI can relax smooth muscles while NE does not
• EPI is only produced in the adrenal medulla while NE is not
• Alpha 1 receptors are found mostly on smooth muscles of arteries, veins and sphincters of the urinary and GI tract
• When stimulated by NE/EPI, alpha 1 receptors produce contraction in the GI//Urinary tract to divert blood flow to organs that are more involved in a sympathetic reaction.
• Alpha 2 receptors are located on adrenergic nerve endings; they're stimulated by NE/EPI to activate a negative feedback loop that regulates the release of additional NE. Drugs that affect this receptor are used in the treatment of hypertension
• Beta 1 receptors are found in the heart and smooth muscles and they increase the chronotropy and inotropy in the heart; stimulated by EPI/NE
• Beta 2 receptors are found in the smooth muscle of coronary, skeletal muscle blood vessels and bronchiolar smooth muscles
• Beta 2 receptors are stimulated by EPI to produce vasodilation and bronchodilation to increase blood flow and deliver more O2.
• Alpha receptors cause smooth muscle contraction at some sites while beta 2 causes smooth muscle relaxation at other sites
• NE does not stimulate beta 2 receptors
• nonselective beta adrenergic drugs stimulate beta 1 receptors (stimulates the heart) and stimulates beta 2 receptors (relax the smooth muscles)
• Selective beta 2 adrenergic drugs are primarily used as bronchodilators