ANS Flashcards
ANS Function
1) Regulate heart
2) Regulate secretory glands (salivary, gastric, sweat, bronchial)
3) Regulate the smooth muscles (bronchi, blood vessels, urogenital system, and gastrointestinal tract)
PRNS
“Rest and digest”
1) Slows heart rate
2) Increasing the gastric secretions
3) Empty bowel
4) Empty bladder
5) Focus eye for near vision
6) Constricting the pupil
7) Contracting bronchial smooth muscle
PRNS drugs targets
Digestion
Excretion
Control of vision
Conservation of Energy
SNS
1) Regulation of CV system
2) Regulation of body temp
3) Implementing “Fight or Flight”
SNS drug targets
Heart and blood vessels
Lungs
Dual innervation opposed
Both the PRNS and SNS innervate an area with opposing effects (heart rate)
Dual innervation complementary
Both the PRNS and SNS innervate an area with complementary effects (erection and ejaculation)
Only one division
Only innervation by one system (blood vessel by the SNS)
Baroreceptors
- Found in carotid sinus and aortic arch
- Sense bp and inform the brain, which will tell the SNS or PRNS to increase or decrease heart rate
Autonomic Tone
- Basal control by ANS
- There is always input to the ANS
- Most organs are regulated by PRNS
- Vascular system regulated by SNS
Location
- SNS from thoracic and lumbar regions of spine
- PRNS from lower lumbar/sacral and cervical spine
Cholinergic receptors
- Muscarinic
- NicotinicN on post ganglionic cells (N for nerves)
- NicotinicM at neuromuscular junctions (M for muscles)
Adrenergic receptors
- A1
- A2
- B1
- B2
- Dopamine
Muscarinic agonists
- AKA cholinergic drugs
- Bethanechol (urecholine)
- Binds reversibly to muscarinic receptors
- Clinical uses: For patients with urinary retention
- Side effects related to the low specificity (bradycardic, salvation, diarrhea, abdominal cramps, sweating, bronchoconstriction)
- Contraindicated (CI) for patients with BI and/or with bowel obstruction, patients with hyperthyroidism-cardiac dysrhythmia, patients with asthma
Muscarinic antagonists
- AKA anticholinergic
- Atropine
- Competitive blockage at muscarinic receptors (prevents activation by endogenous ACh
- Clinical uses: Pre-anesthesia to decrease secretions; prevent bradycardia; ophthalmic procedures; bradycardia; intestinal hypermotility; muscarinic agonist poisoning
- Side effects: Blurred vision and photophobia; increased intraocular pressure; urinary retention; constipation; tachycardia; anhydrosis (inability to sweat)
