PL8 ANS 2 Flashcards
(15 cards)
What are the primary functions of the Autonomic Nervous System (ANS)?
Sympathetic Nervous System (SNS): Active during emergencies (“fight or flight”).
Parasympathetic Nervous System (PNS): Active during rest (“rest and digest”).
What is the ‘Fight or Flight’ response of the SNS?
This reaction involves a mass sympathetic discharge that increases the body’s ability for vigorous activity by:
1. Increasing arterial pressure.
2. Redirecting blood flow to active muscles.
3. Boosting cellular metabolism.
4. Elevating blood glucose levels for energy.
What is the ‘Rest and Digest’ function of the PNS?
The PNS:
• Increases blood flow to the stomach and intestines for digestion.
• Decreases heart rate.
• Stimulates salivation and energy storage.
What distinguishes the sympathetic and parasympathetic nervous systems structurally and functionally?
Sympathetic Nervous System:
• Ganglia close to the CNS.
• Short preganglionic fibers and long postganglionic fibers.
• Widespread action and catabolic activity (energy expenditure).
• Parasympathetic Nervous System:
• Ganglia close to target organs.
• Long preganglionic fibers and short postganglionic fibers.
• Localized action and anabolic activity (energy storage).
What are the roles of the hypothalamus and brainstem in ANS control?
The hypothalamus and brainstem regulate autonomic functions like heart rate, arterial pressure, and respiratory rate. This regulation ensures homeostasis and integrates behavioral responses.
What is homeostasis, and how does the ANS maintain it?
Homeostasis refers to maintaining a stable internal environment. The ANS, along with the endocrine system, regulates:
• Blood pressure.
• Body temperature.
• Electrolyte and water balance.
• Glucose levels.
What are the two plexuses in the Enteric Nervous System (ENS)?
The ENS, located in the digestive tract, includes:
1. Myenteric (Auerbach’s) Plexus: Regulates gut motility.
2. Submucosal (Meissner’s) Plexus: Controls gastrointestinal blood flow and secretion.
What are adrenergic agonists and their actions?
Adrenergic agonists mimic the effects of norepinephrine and epinephrine:
• Examples:
• Phenylephrine (alpha receptors).
• Isoproterenol (beta receptors).
• Albuterol (beta-2 receptors).
What are adrenergic antagonists and their mechanisms?
Adrenergic antagonists block adrenergic activity:
1. Reserpine: Prevents NE/E synthesis and storage.
2. Guanethidine: Prevents NE/E release.
3. Beta Blockers: e.g., Propranolol (beta-2) and Metoprolol (beta-1).
What are cholinergic agonists and antagonists?
• Agonists:
• Examples: Pilocarpine (muscarinic receptor), Methacholine.
• Enhance cholinergic activity, e.g., with anticholinesterase drugs like Neostigmine.
• Antagonists:
• Atropine and Scopolamine block muscarinic receptors.
What are ganglionic agonists and antagonists
Agonists: Stimulate postganglionic neurons (e.g., Nicotine, Pilocarpine).
Antagonists: Block ganglionic activity (e.g., Hexamethonium).
What are the causes and manifestations of autonomic dysfunction?
• Causes: Drugs, neurodegenerative diseases, trauma, or inflammation.
• Manifestations:
• Complete dysfunction: Orthostatic hypotension, erectile dysfunction.
• Hyperactivity: Neurogenic hypertension, cardiac arrhythmias.
What is Horner’s syndrome, and what are its symptoms?
Caused by the interruption of sympathetic innervation to the face.
• Symptoms include:
• Ptosis (drooping eyelid).
• Miosis (constricted pupil).
• Anhidrosis (reduced sweating).
What is Raynaud phenomenon, and what triggers it?
condition triggered by stress or cold, affecting fingers, toes, and other extremities.
• Symptoms include:
1. Pallor (paleness).
2. Cyanosis (blue discoloration).
3. Rubor (redness) as blood flow recovers.
What are the clinical features of Myasthenia Gravis?
Characteristics:
• Progressive muscle fatigue and weakness.
•
Cause:
• Antibodies destroy nicotinic acetylcholine receptors.
Treatment:
• Acetylcholinesterase inhibitors (e.g., Neostigmine), glucocorticoids, thymectomy.
