Intro to ANS Flashcards
Autonomic Nervous System uses how many neurons?
- Preganglionic and postganglionic.
What types of things does the ANS innervate?
Smooth and cardiac muscle, glands.
Enteric Branch of the ANS
Network of neurons in the gut, mostly independent of the CNS, extensive intrinsic activity that includes peristalsis.
Sympathetic Branch: Location of preganglionic cell bodies, which nerves carry preganglionic axons, where are the ganglia located?
Thoracic and lumbar levels of the spinal cord, carried by thoracolumbar spinal nerves, ganglia located in chain ganglia or in prevertebral ganglia.
Adrenal gland is the exception
Parasympathetic Branch: Location of preganglionic cell bodies, which nerves carry preganglionic axons, where are the ganglia located?
Medulla and sacral level of spinal cord, carried by cranial nerves and sacrospinal nerves, ganglia located near wall of innervated organ.
Do postganglionic nuclei of sympathetic branch need to be on the same level of chain ganglia?
No.
Can sympathetic preganglionic axons synapse on more than one postganglionic neuron?
Yes.
Dominant Tone
Usually the autonomic branch that makes the organ contract or move. For example, GI is parasympathetic (rest and digest).
One exception to Dominant Tone
The heart. The dominant tone is parasympathetic, even though it slows the heart.
Atrial Innervation
Parasympathetic and sympathetic
Ventricular Innervation
Just sympathetic
Adrenal Gland Innervation
Just sympathetic
Sweat Gland Innervation
Just sympathetic
What is special about the fibers that innervate the pancreatic ß cells?
They are only sympathetic fibers, but the preganglionic neuron travels all the way to the organ.
Which branch constricts the pupils?
Parasympathetic. Also increases near vision by rounding the eye.
Are the actions of the sympathetic and parasympathetic branches always opposing?
No. For example: salivary glands, both systems increase secretions, but different types.
Where do autonomic sensory neurons project to?
The NST in the medulla.
Baroreceptor Reflex
In carotid and aorta. Contain baroreceptors, when stretch decreases due to decreased BP, signal is relayed to medulla, which increases sympathetic activity, causing vasoconstriction and increased cardiac output, leading to increase in BP.
Two major neurotransmitters at ANS synapses
ACh, NE, sometimes DA
Which signal is released from adrenal medulla?
Epinephrine.
Which neurons release ACh?
All preganglionic neurons (P and S), all parasympatheic postganglionic neurons, some sympathetic postganglionics.
Which neurons release NE?
Most of the sympathetic postgangionic neurons.
Function of ß Adrenergic receptors
Coupled to Gs.
Sensitization
Increase in responsiveness due to under-stimulation. Can happen in seconds or hours.
