Intro to Autonomics -Pechnick Flashcards
Where do sympathetic nerves originate?
T1-L2
Where do parasympathetic nerves originate?
craniosacral
CN 3, 7, 9, 10, S2-4
What are the PNS and SNS differences in their length of pre- and post-ganglionic fibers? Where are their corresponding ganglia located? what is the degree of branching of their preganglionic axons?
PNS: long pre-ganglionic and short post-ganglionic nerves.
SNS: short pre-ganglionic, long post-ganglionic.
PNS: ganglia at or near the organ
SNS: ganglia paired paravertebral, prevertebral
degree of collateral branching of preganglionic axons is greater in SNS than in PNS (PNS=1 pre : 1 post)
What is the NT at all autonomic ganglia? Where else is this NT found?
ACh!!
it is also found in post-ganglionic parasympathetic
What NT is only found in the SNS?
Norepinephrine (NE)
found at MOST sympathetic nerve terminals
What are the subtypes of cholinergic receptors? and adrenergic receptors?
cholinergic: muscarinic and nicotinic
adrenergic: alpha (1, 2) and beta (1, 2, 3)
Where is ACh found in the SNS?
sweat glands!! (this is the only place ACh works in the postganglionic SNS)
important in cooling
What are the other NT’s (other than NE) that can be found in post-ganglionic SNS?
- ACh at sweat glands
- dopamine at the smooth mm of the renal vascular bed
Where do the synapses for SNS stimulation of the adrenal glands occur?
Preganglionic neurons synapse directly on the adrenal gland, release acetylcholine, and activate nicotinic receptors on the adrenal gland
Adrenal glands release epinephrine and norepinephrine (4:1) into the systemic circulation
What occurs with SNS activation of the eye?
Pupils dilate (mydriasis) by radial dilator muscle contraction (a1)
Ciliary muscle relaxes (alpha2) and the lens flattens for far vision
beta 2 receptors facilitate secretion of aqueous humor from ciliary epithelium
What occurs with PNS activation of the eye?
Pupils constrict (miosis) – circular muscle contracts (M)
Ciliary muscle contracts (M) and the lens rounds for close up vision (accommodation)
What do SNS fibers affect in the heart? What effect does this have on cardiac output?
What receptor subtypes are used?
Sympathetic Innervation
(Adrenergic)
1. SA Node
2. Atrial Wall
3. AV Node
4. Ventricular Conducting System
5. Ventricular Wall
increases both rate and force of contraction and conduction velocity
receptor beta 1 and beta 2
How does PNS innervation decrease cardiac output?
What receptors?
decrease heart rate and conduction velocity
muscarinic receptors
What are the effects of SNS innervation on blood vessels? PNS?
SNS: Vessels in skin, abdominal and renal areas contract (alpha 1)
Vessels in skeletal muscle relax (beta 2)
PNS: no direct innervation (except coronary vessels and erectile tissue)
What are the SNS effects on the lungs? PNS?
SNS:
- No innervation of bronchial smooth muscle but they do have beta receptors
- Epinephrine released from the adrenal gland relaxes smooth muscle and causes dilation (beta 2)
PNS:
- Bronchial smooth muscle is innervated
- Constriction occurs (M)
