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60 Cards in this Set
- Front
- Back
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What takes place during depolarization in regards to an action potential
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-Excitable cells triggered
-Na in, K out -Fast Na channel open first -slow K channels open later |
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Repolarization
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-slow Na channels close
-slow K channels cont to open -conductance of K peaks @ mid-repolarization |
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After-depolarization
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-Occurs after spike potential and after repol is approx 70% complete
-rate of repol is decreased -conductance of K and Na decreases |
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Hyperpolarization
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-Occurs at end of AP
-membrane potential becomes more negative than resting pot. -conductance of Na returns to resting level -conductance of K remains elevated above resting level |
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What is the role of neurotransmitters?
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to cause exciatatory or inhibitory potentials
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Where are excitatory and inhibitory NTS found?
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In both, PNS and CNS
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What is the hallmark of Alzheimer's Disease?
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Destruction of neurons that release ACH in the brain
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Area between presynaptic and post synaptic cell which contains acetylcholinesterase
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Synaptic cleft
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This period of the Action Potential constitutes:
1. Resting membrane potential 2. Ends when threshold is reached and action potential begins 3. Determined by extracellular K Concentration |
The latent period
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Actions of ACH at the neuromuscular junction and at the heart
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Excitatory at neuromuscular junction- Acts to open chemically gated ion channels
Inhibitory in parasympathetic fibers of Vagus nerve (cranial nerve X) - Innervates the heart - Slows the heart rate down |
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Types of Neurotransmitters
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1) acetylcholine 2) amino acids 3) biogenic amines 4) neuropeptides 5) gases
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Excitatory Amino Acid NTS found in the brain
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Glutamate and Aspartate
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Inhibitory Amino Acid NTS
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1.GABA-primarily in the brain
2.Glycine-Primarily in the spinal cord |
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How does Valium work?
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It enhances the the action of GABA with further inhibition
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Types of Biogenic Amines, also called catecholamines and are actively transported back into the synaptic bulb after release
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NOREPINEPHRINE (NE) EPINEPHRINE
DOPAMINE (DA) SEROTONIN (5-HT) |
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Implicated in maintaining arousal, dreaming and mood regulation
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NOREPINEPHRINE (NE) & EPINEPHRINE
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Where is Epi found?
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In the Brain and Spinal Cord
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Where is Norepi found?
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NE found in brain, spinal cord, GI tract, Sympathetic endings
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What are the actions of Dopamine
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Involved in emotional responses
Regulates gross automatic movements of skeletal muscles |
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What causes Parkinson's Disease?
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Degeneration of neurons producing dopamine causes Parkinson's Disease
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Where is Dopamine found?
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DA is found in the brain, retina, sympathetic ganglia
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Serotonin (5-HT) is involved in?
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Induces sleep, sensory perception, temperature regulation and control of mood
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Name a drug that inhibits serotonin reuptake
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Prozac, its an anti-depressant
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What is the action of Angiotensin II
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stimulates thirst
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Name some Neuropeptides
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May also act as hormones
Angiotensin II Oxytocin Antidiuretic hormone, Enkaphalins and endorphins Atrial Natriuretic Peptide, Gastrin |
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What type of effects do Enkaphalins and endorphins have
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analgesic effects
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This type of NTS is released by endothelial cells lining blood vessels - Causes relaxation and vasodilation
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Nitric Oxide
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What are the effects of Nitric Oxide?
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Causes relaxation and vasodilation. Effect is to lower BP
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Name some factors that alter the impulses and synapses
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Alkalosis
Acidosis Hypnotics Caffeine Drugs |
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What does alkalosis do to a neuron?
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It increases the excitability of neuron
Impulses arise inappropriately - Light headedness, numbness, tingling, nervousness, muscle spasms |
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What is acidosis and what does it do?
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Decrease in pH below 7.3
Progressive depression of neuron activity Produces apathy and muscle weakness |
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How do HYPNOTICS, TRANQUILIZERS, ANESTHETICS affect the threshold?
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Increases the threshold for excitation
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How do CAFFEINE, BENZEDRINE, NICOTINE affect the threshold?
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Reduces threshold for excitation
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What is the Lambert-Eaton Myasthenic Syndrome?
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Autoimmune disorder production of antibodies to presynaptic Ca++ channels leading to decreased presynaptic release of ACH
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What is Myasthenia Gravis?
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Autoimmune disorder involving production of antibodies to nicotinic ACH receptors
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How does botulism work?
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It blocks presynaptic Ach release at neuromuscular junction, causing paralysis
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How do you get botulism?
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Ingestion of endotoxins from improperly cooked foods
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What is Tetanus?
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causes spasmodic muscle contraction and you get it by
skin exposure to exotoxins which block presynaptic release of Ach |
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What do cholinergic receptors do?
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mediate the actions of acetylcholine (ACh)
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The types of cholinergic receptors
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nicotinic and muscarinic
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Site of muscarinic receptors
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at the postganglionic parasympathetic neuroeffector junction in smooth muscle, heart, and exocrine glands
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What are the effects of muscarinic receptors
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salivation, urination, defecation, pupillary constriction, vasodilation, cardiac slowing, depressed AV nodal conduction, and bronchoconstriction
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Name an antagonist of muscarinic receptors
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Atropine is antagonist at this receptor (m2)
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What is the action of nicotinic receptors
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mediate most of the actions of nicotine and some of those ACh
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Effects of nicotinic receptors
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release of catecholamines from the adrenal medulla, ganglionic transmission, and transmission of the somatic neuromuscular junction
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The two types of nicotinic receptors
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Nn and Nm
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Where are Nn receptors located?
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in Ganglia
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Where are Nm receptors located?
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in the neuromuscular junctions
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The two major types of Adrenergic receptors
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Alpha 1 receptors are sensitive to blockade by prazosin (Minipress®) postsynaptic
Alpha 2 receptors are sensitive to blockade by yohimbine. Alpha2 (presynaptically on sympathetic postganglionic nerve terminal) |
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What does activation of the presynaptic alpha 2 receptors do?
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inhibits the release of NE
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What do Beta receptors do when activated?
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generally produce "inhibitory" responses of smooth muscle in which they are located.
Bronchodilation and vasodilation |
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Classical agonist of beta-receptors
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isoproterenol (Isuprel)
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Classical antagonist of beta receptors
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propranolol (Inderal)
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What do Beta 1 receptors do when activated
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Beta1 receptors, when activated, produce cardiac positive chrono- and inotropic responses and lipolysis
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Name a Selective antagonist of beta 1 receptors
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metoprolol (Lopressor®)
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Name a Selective beta 2 agonists, which are useful in the treatment of asthma
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terbutaline (Brethine)
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This drug is a selective alpha1 antagonist, and a non-selective antagonist of both beta1 and beta2 receptors
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labetalol (Normodyne)
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What are some of the causes for receptor malfunction?
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Receptors response to drugs and Diseases such as:
Diabetes Guillan-Barre Myasthenia gravis |
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The effector molecule which catalyzes the conversion of ATP into the "second messenger" cyclic AMP (cAMP)
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Adenosine Cyclase
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Types of intracellular mediators
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Second Messengers
Protein kinases G-Proteins |
