Neurotransmitters Pt. 2 Flashcards
What are agonists?
Substances that bind and activate a receptor.
What are antagonists?
Substances that bind and block a receptor.
What is phenylephrine?
A cold/sinus medication.
What receptor does phenylephrine bind to and what is its mode of action?
An adrenergic alpha-1 receptor agonist.
What is the function of phenylephrine?
Constricts blood vessels in the nasal mucosa, decreasing mucus production.
What is atropine?
A muscarine receptor antagonist.
What is the function of atropine?
- Dilates the pupils.
- Reduces glandular secretions.
- Relaxes smooth muscles in the GIT.
What is atropine an antidote for?
Chemical warfare agents.
What is propranolol?
Nonselective beta blocker.
What is the function of propranolol?
- Decreased HR.
- Decreased force of contraction
- Decreased blood pressure.
*Used to treat hypertension.
What are the undesired effects of propranolol?
- Hypoglycemia.
- Mild bronchoconstriction.
What is autonomic tone?
The balance between the parasympathetic and sympathetic divisions of the ANS, which most organs receive input from.
What gland regulates autonomic tone?
The hypothalamus through the upregulation of one ANS division while simultaneously downregulating the other ANS division.
What 6 structures are innervated by the sympathetic division only?
- Adrenal medulla.
- Erector pili muscle.
- Kidneys.
- Most blood vessels.
- Spleen.
- Sweat glands.
How are tissues only innervated by the sympathetic division only regulated?
By increases and decreases in sympathetic tone.
What does the sympathetic division upregulate in response to?
- Stress, real or perceived.
- Fear.
- Rage.
What happens when the sympathetic division is activated?
- ATP synthesis is increased through glycogenolysis and lipolysis.
- Pupils dilate.
- Blood pressure increases.
- Airways dilate.
- Most visceral blood vessels constrict.
- Muscular blood vessels dilate.
What does the parasympathetic division upregulate in response to?
When the body is at rest and conserving energy.
What happens when the parasympathetic division is activated?
- Salivation.
- Lacrimation.
- Urination.
- Defecation.
- Digestion.
*Digestive glands and GIT smooth muscle is active.
What is gamma-aminobutyric acid?
An inhibitory CNS neurotransmitter.
What 4 portions of the CNS release GABA?
- Basal ganglia.
- Cerebellum.
- Cortex.
- Spinal cord.
What does GABA cause?
- IPSP through opening Cl- channels.
- Muscle relaxer.
What portion of brain synapses have GABA receptors?
1/3.
What 2 drugs utilize the action of GABA?
- Benzodiazopine (enhances it).
- Diazepam/valium.
Where do the neurons that secrete dopamine originate?
The substantia nigra.
Where do the neurons from the substantia nigra terminate?
The basal ganglia.
Is dopamine an inhibitory or a stimulatory neurotransmitter?
Inhibitory.
What does dopamine cause when it binds to D1 receptors?
Stimulate(stm) adenylate cyclase.
What does dopamine cause when it binds to D2 receptors?
Inhibits(inh) adenylate cyclase.
What are the functions of dopamine?
- Addictive behavior.
- Emotional responses.
- Pleasurable experiences.
- Regulate skeletal muscle tone.
How does does fescue toxicity occur in mares?
They consume fescue grass that contains the alkaloid ergovaline, which mimics dopamine and binds to D2 receptors.
What effect does ergovaline have in the body that is important in pregnant mares?
It suppresses prolactin production, which is essential for milk production and signaling of the final stage of pregnancy.
What is the treatment for fescue toxicity?
Domperidone.
What is Domperidone?
A paste that acts as a D2 receptor antagonist to relieve the prolactin-depressing effects of alkaloids.
What is the cause of Parkinson’s Disease?
The destruction of dopamine-secreting nerves causing an imbalance in Ach and DA.
What are the signs of Parkinson’s Disease?
- Akinesia.
- Hypokinesia (Difficulty initiating movement).
- Involuntary tremors.
- Muscle rigidity.
What age group does Parkinson’s Disease normally appear in?
Age 60+.
What leads to the destruction of nerve fibers that eventually causes Parkinson’s Disease?
Suspected to be environmental chemicals, but genetics may also play a role.
How is Parkinson’s Disease treated through increasing DA levels?
- L-Dopa.
- Deprenyl (MAO inhibitor).
How is Parkinson’s Disease treated through decreasing ACh levels?
Benzotropine (Blocks ACh effects).
How is nitric oxide different than other small molecule neurotransmitters?
It is made as needed, not preformed and stored in vesicles.
What does nitric oxide alter when it binds to the post-synaptic neuron/effector tissue?
The intracellular metabolism.
Where is nitric oxide released from outside of the nervous system?
Endothelial cells in the blood.
What is the function of nitric oxide?
- Long-term behavior.
- Long-term memory.
- Smooth muscle relaxation.
- Vasodilation.
What pharmaceutical makes use of nitric oxide?
Sildenafil/Viagra.
What are endorphins and enkephalins classified as?
Neuropeptides, specifically opioid peptides.
What are the functions of endorphins and enkephalins?
- Euphoria.
- Learning.
- Memory.
- Potent analgesic.
*Associated with the runner’s high.
