| How is the anatomy of the ANS? | Efferent neurons consist of two neurons, preganglionic (cell body in CNS) relays in ganglia with postganglionic neuron (cell body in ganglion, non-myelinated ends on effector organ), it is divided into sympathetic and parasympathetic
Afferent neurons important in reflex regulation of this system (sensing carotid sinus pressure), and signals to efferent system to respond. |
| How are parasympathetic neurons? | Arise from cranium (cranial nerves III, VII, IX, X) and sacral region of spinal cord, synapse in near ganglia or effector organ.
Preganglionic fibers are long, postganglionic are short with ganglia close to organ or within organ innervated.
Releases Ach to Ach receptors |
| How are sympathetic neurons? | Preganglionic neurons come from thoracic and lumbar regions of spinal cord, synapse in 2 cord-like chains of ganglia parallel to each other in spinal cord.
Preganglionic are short, postganglionic are long, extend from ganglia to tissues they innervate
Release NE to adrenergic receptors. |
| How are sympathetic neurons of adrenal medulla? | Like other sympathetic ganglia, receive preganglionic fibers from sympathetic system, and adrenal medulla influences other organs by releasing epinephrine into the blood (and lesser amount NE) |
| What do preganglionic fibers release to postganglionic in synapse? | Ach to nicotinic receptors (in both sympathetic and parasympathetic) |
| What are functions of sympathetic and parasympathetic NS on organs? | Eye (Sym: contract iris radial muscle dilate, Para: contract sphincter constrict and ciliary muscles accomodates near vision)
Trachea and Bronchioles (Sym: Dilate, Para: Constricts and increase secretions)
Adrenal Medulla (Sym: release epi and NE)
Kidney (Sym: release renin - beta receptors increase, alpha decrease)
Ureters (Sym: relaxes detursor, contract trigone and sphincter, Para: opposite)
Genitalia (male [Sym: stimulate ejaculation, Para: stimulate erection)] Female (Sym: relax uterus)
Lacrimal glands (Para; stimulate)
Salivary gland (Sym: thick viscous secretion, Para: Watery)
Heart (Sym: increase HR and contraction, Para; opposite)
GI (Sym: decreased muscle motility and tone and contract sphincter, Para: opposite)
Vessels (dilation symp in skeletal muscles and constrict smooth) |
| What is the role of CNS in control of ANS function? | ANS is motor system, requires sensory input, feedback given by streams of afferent impulses from viscera traveling to integrating centers in CNS, these centers send out an efferent reflex via ANS.
Reflex arcs: afferent impulses given without consciousness, like fall of BP cause pressure-sensitive neurons to send impulses to cardiovascular center in brain, which leads to reflex increase sympathetic signals and decrease parasympathetic to compensate BP and tachycardia |
| What are neurotransmitters? | Epi, Ach, DA, Serotonin, Histamine, GABA involved in drugs.
Each bind to specific family of receptors, Ach and NE are most important in ANS. |
| What are second messengers in intracellular response? | The binding of NT to receptors activate enzymes in membrane to produce a response, second-messengers may be made and translate the extracellular signal into a response |
