Biol 2420 Week 5
Biol 2420 Week 5 BIOl 2420
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This 3 page Class Notes was uploaded by Aurora Moberly on Saturday February 6, 2016. The Class Notes belongs to BIOl 2420 at Southern Utah University taught by Dr. Paul Pillitteri in Winter 2016. Since its upload, it has received 50 views. For similar materials see Human Physiology in Biology at Southern Utah University.
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Date Created: 02/06/16
Human Physiology Notes Week 5 - Autonomic Nervous System: Neurons that innervate your internal organs - Involuntary branch of PNS - Innervates cardiac muscle, smooth muscle, most glands - Two subdivisions: Sympathetic Division and Parasympathetic Division - Sympathetic Division NS: Dominated in emergency or stressful situations (fight or flight) - Promotes responses that prepare the body for strenuous physical activity - Parasympathetic Division NS: Dominates in quiet, relaxed (rest and digest) situations - Promotes body-maintenance activities such as digestion - Most visceral organs innervated by both sympathetic and parasympathetic fibers - In general these divisions produce opposite effects in a particular organ - Dual innervation of organs by both branches of ANS allows for precise control - Autonomic Nerve Pathways: Extend from CNS to the tissue that they are going to innervate - Two neuron chain: - Preganglionic Fiber: Cell body in CNS, synapses with cell body of the second neuron - Postganglionic Fiber: Innervated effector tissue - Sympathetic NS: - Preganglionic Fibers: Originate in the thoracic and lumbar regions of the spinal cord - Most are short - Release acetylcholine - Postganglionic Fibers: Extend out into the tissue - Most are long - Release norepinephrine (used to communicate with the muscles in the sympathetic nervous system) - Parasympathic NS: - Preganglionic Fibers: Originate in cranial and sacral areas of CNS - Most are long - Release acetylcholine - Postganglionic Fibers: - Very short - Imbedded in the tissues - Release acetylcholine - Receptor Proteins: Receptors will determine what affect the neurotransmitter will have - Postganglionic cell bodies must have nicotinic receptors to bind with the acetylcholine - Tissues innervated by ANS have one or more of several different receptor types - Cholinergic Receptors: Bind acetylcholine (ach) - Nicotinic Receptors: Found on all postganglionic cell bodies, bind to ach and cause depolarization (always excitatory) - Muscarinic Receptors: Found on parasympathetic target tissues, bind to ach and generate particular parasympathetic response for that tissue (excitatory or inhibitory) - Adrenergic Receptors: Bind norepinephrine (norepi) and epinephrine (epi), Metabotropic - Alpha 1: Most common, on most sympathetic target tissues (smooth muscle, glands), Bind norepi/epi, excitatory response - Alpha 2: Stomach, intestine, Bind norepi/epi, inhibitory response - Beta 1: Primarily in heart, Bind norepi/epi, excitatory response - Beta 2: Most other tissues, same places as alpha 1, inhibitory response, smooth muscle lining your airways in lungs - Adrenal Medulla: Modified ganglion of the sympathetic nervous system - Does not give rise to post ganglionic fibers - Not neurons, have nicotinic receptors - Endocrine cells that secrete hormones into the blood, norepinephrine and epinephrine - Innervated by preganglionic fibers - Epinephrine is ONLY a hormone - Hormones in the blood take time to work but has a much longer response that effects every tissue in the body - Sympathetic has this system the parasympathetic does not - Exceptions to Duel Innervation - Blood vessels (smooth muscle that controls diameter of blood vessels - Excitation of muscles causes contraction which make it more narrow (vasoconstriction) - Sweat Glands: - Salivary glands get duel innervation but it’s not opposite - Sympathetic innervation causes a secretion of high volume watery saliva - Parasympathetic innervations causes a secretion of low volume thick saliva - Iris: - Smooth muscle: Causes pupil constriction; Circularly arranged smooth muscle makes the pupil smaller or bigger innervated by PNS - Radial smooth muscle innervated by SNS; causes pupil dilation - Heart generates its own beat, SA node controls heart rate -SNS, PSN both innervate SA node - SNS increases heart rate; PSN decreases heart rate - SNS innervates cardiac muscle - Contractility: How hard the heart is contracting, the harder the contraction the more blood it is pushing - Drug Mechanisms - Agonist: Increase whatever that synapse usually does - Increases neurotransmitter release - Inhibit neurotransmitter re-uptake - Inhibit neurotransmitter breakdown - Mimics the neurotransmitter (NT) - Antagonists: Works against whatever that neurotransmitter does - Inhibits NT release - Blocks receptors - Drugs affecting ANS via receptors: - Alpha 1 Antagonists: Prevents alpha one from being stimulated - Treats blood pressure - Beta 1 Agonists: Increases heart rate and contractility - Beta 1 Antagonists: Prevent the sympathetic nervous system from stimulating the heart - Beta blockers, blood pressure treatment, heart attack patients - Beta 2 Agonists: Smooth muscles lining your airways or lungs, allows airways to dilate - Treats asthma - Amphetamines: Promotes release of NE (increases alertness) - Cocaine: Blocks re-uptake of NE - Albuterol: B-2 receptor agonist, inhibits smooth muscle in airways opening them up - Propranolol: Beta blocker, decreases contractility without effecting heart rate as much - Atropine: Blocks muscarinic receptors: Used in surgery to block parasympathetic to the heart - Drugs affecting the neuromuscular junction: - Nicotine: binds to receptors, not broken down by AchE (enzyme that breaks down Ach), addictive because it helps the brain release dopamine - Neostigmine: Inactivates AchE, Organophosphates: found in pesticides, inactivate AchE too - Black Widow Venom: Release of ach from motor neurons, muscle contracts until it can’t anymore and dies - Curare: Blocks Ach receptors - Botulinum toxin: Comes from the bacteria clostridium botulinum - Prevents Ach release from motor neurons - Botox - Myasthenia Gravis (autoimmune disease): Immune system attacks Ach receptors, loose function of muscles. Neostigmine can help with this disease
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