Flashcards in ANS Physiology (complete) Deck (13)
What are the general characteristics of the ANS?
- Diffuse projections (not specific)
- Slow action
- Innervates SM, cardiac muscle, and gland cells
- Disynaptic (always 2 synapses)
What are the 3 subdivisions of the ANS?
1) Sympathetic (fight/flight)
2) Parasympathetic (rest/digest)
3) Enteric -- semi-autonomous control of digestion
Describe the general anatomy of the sympathetic ANS
- Preganglionic neurons originate in thoracic and lumbar spinal cord
- Ganglia located near spinal cord
- 1:10 ratio of pre- to post-ganglionic neurons
Describe the general anatomy of the parasympathetic ANS
- Preganglionic neurons originate in brainstem and sacral spinal cord
- Ganglia located near target organs
- 1:3 ratio of pre- to post-ganglionic neurons
What is the neurotransmitter used in preganglionic neurons in the ANS?
What are the neurotransmitters used in post-ganglionic neurons of the sympathetic ANS?
- Norepinephrine (NE)
What is the neurotransmitter used in post-ganglionic neurons of the parasympathetic ANS?
What are the receptors of ACh?
- Nicotinic (depolarizes cell, symp)
- Muscarinic (relaxes cell, parasymp)
What are the receptors of NE?
Describe the adrenal medulla as a sympathetic ganglion
- innervated by pregang symp neurons
- releases NE and epinephrine to bloodstream => sympathomimetic effects
Describe the ways ANS regulates HR and force of contraction
- ^ NE => ^ BP
- ^ HR and contractile force
- ^ ACh => Decreased BP
- Decreased HR and contractile force
Describe how the baroreceptor reflex affects ANS output
- Low BP => ^ in sympathetic output
- High BP => ^ in parasympathetic output