Pharm Test 1 2
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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 - 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 - 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 - What is the role of neurotransmitters?
- to cause exciatatory or inhibitory potentials
- Where are excitatory and inhibitory NTS found?
- In both, PNS and CNS
- What is the hallmark of Alzheimer's Disease?
- Destruction of neurons that release ACH in the brain
- Area between presynaptic and post synaptic cell which contains acetylcholinesterase
- 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
- 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 - Types of Neurotransmitters
- 1) acetylcholine 2) amino acids 3) biogenic amines 4) neuropeptides 5) gases
- Excitatory Amino Acid NTS found in the brain
- Glutamate and Aspartate
- Inhibitory Amino Acid NTS
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1.GABA-primarily in the brain
2.Glycine-Primarily in the spinal cord - How does Valium work?
- It enhances the the action of GABA with further inhibition
- 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) - Implicated in maintaining arousal, dreaming and mood regulation
- NOREPINEPHRINE (NE) & EPINEPHRINE
- Where is Epi found?
- In the Brain and Spinal Cord
- Where is Norepi found?
- NE found in brain, spinal cord, GI tract, Sympathetic endings
- What are the actions of Dopamine
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Involved in emotional responses
Regulates gross automatic movements of skeletal muscles - What causes Parkinson's Disease?
- Degeneration of neurons producing dopamine causes Parkinson's Disease
- Where is Dopamine found?
- DA is found in the brain, retina, sympathetic ganglia
- Serotonin (5-HT) is involved in?
- Induces sleep, sensory perception, temperature regulation and control of mood
- Name a drug that inhibits serotonin reuptake
- Prozac, its an anti-depressant
- What is the action of Angiotensin II
- stimulates thirst
- Name some Neuropeptides
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May also act as hormones
Angiotensin II
Oxytocin
Antidiuretic hormone, Enkaphalins and endorphins
Atrial Natriuretic Peptide, Gastrin - What type of effects do Enkaphalins and endorphins have
- analgesic effects
- This type of NTS is released by endothelial cells lining blood vessels - Causes relaxation and vasodilation
- Nitric Oxide
- What are the effects of Nitric Oxide?
- Causes relaxation and vasodilation. Effect is to lower BP
- Name some factors that alter the impulses and synapses
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Alkalosis
Acidosis
Hypnotics
Caffeine
Drugs - 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 - 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 - How do HYPNOTICS, TRANQUILIZERS, ANESTHETICS affect the threshold?
- Increases the threshold for excitation
- How do CAFFEINE, BENZEDRINE, NICOTINE affect the threshold?
- Reduces threshold for excitation
- What is the Lambert-Eaton Myasthenic Syndrome?
- Autoimmune disorder production of antibodies to presynaptic Ca++ channels leading to decreased presynaptic release of ACH
- What is Myasthenia Gravis?
- Autoimmune disorder involving production of antibodies to nicotinic ACH receptors
- How does botulism work?
- It blocks presynaptic Ach release at neuromuscular junction, causing paralysis
- How do you get botulism?
- Ingestion of endotoxins from improperly cooked foods
- 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 - What do cholinergic receptors do?
- mediate the actions of acetylcholine (ACh)
- The types of cholinergic receptors
- nicotinic and muscarinic
- Site of muscarinic receptors
- at the postganglionic parasympathetic neuroeffector junction in smooth muscle, heart, and exocrine glands
- What are the effects of muscarinic receptors
- salivation, urination, defecation, pupillary constriction, vasodilation, cardiac slowing, depressed AV nodal conduction, and bronchoconstriction
- Name an antagonist of muscarinic receptors
- Atropine is antagonist at this receptor (m2)
- What is the action of nicotinic receptors
- mediate most of the actions of nicotine and some of those ACh
- Effects of nicotinic receptors
- release of catecholamines from the adrenal medulla, ganglionic transmission, and transmission of the somatic neuromuscular junction
- The two types of nicotinic receptors
- Nn and Nm
- Where are Nn receptors located?
- in Ganglia
- Where are Nm receptors located?
- in the neuromuscular junctions
- 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) - What does activation of the presynaptic alpha 2 receptors do?
- inhibits the release of NE
- 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 - Classical agonist of beta-receptors
- isoproterenol (Isuprel)
- Classical antagonist of beta receptors
- propranolol (Inderal)
- What do Beta 1 receptors do when activated
- Beta1 receptors, when activated, produce cardiac positive chrono- and inotropic responses and lipolysis
- Name a Selective antagonist of beta 1 receptors
- metoprolol (Lopressor®)
- Name a Selective beta 2 agonists, which are useful in the treatment of asthma
- terbutaline (Brethine)
- This drug is a selective alpha1 antagonist, and a non-selective antagonist of both beta1 and beta2 receptors
- labetalol (Normodyne)
- 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 - The effector molecule which catalyzes the conversion of ATP into the "second messenger" cyclic AMP (cAMP)
- Adenosine Cyclase
- Types of intracellular mediators
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Second Messengers
Protein kinases
G-Proteins