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Flashcards in #11. Autonomic NS Deck (31):

What does the PNS divide into?

-the somatic nervous system
-autonomic nervous system
-enteric nervous system


Describe the somatic nervous system

-consciously controlled
-sensory receptors and motor neurons to skeletal muscles


Describe the enteric nervous system

-sensory from chemical changes in GI tract and stretching it
-motor to GI smooth muscle
-actual muscles that move food through the GI tract


Describe the autonomic nervous system

-sensory from visceral organs
-motor to smooth muscles, cardiac muscles and glands


What does the ANS divide into?

sympathetic and parasympathetic


describe the sympathetic nervous system

"fight or flight"
--increased alertness and metabolic activities in order to prepare the body for an emergency situation


Describe the parasympathetic nervous system

"rest and digest"
-activites conserve and restore body energy
-most output is to smooth mm and glands of GI tract and respiratory tract
-dilating vessels to GI tract which speeds processes.


Explain autonomic tone

typically the two divisions of the ANS work in opposition to one another. Despite this fact most organs receive innervation from both. autonomic tone is the balance between the sympathetic and parasympathetic activity in one structure


What regulates autonomic tone?

the hypothalamus


Which structures only receive innervation from the sympathetic system?

-sweat glands
-arrector pili mm
-most blood vessels
-adrenal medullae


How do the organs that do not receive parasympathetic innervation still have a range in responses?

by increasing or decreasing the sympathetic tone. an increase in sympathetic tone has one effect while a decrease in symp tone would do the opposite


What happens in a sympathetic response?

-pupils dilate
-HR, force of heart contraction and BP increase
-airways dilate (faster mvmt of air in and out of lungs)
-BV to skeletal mm dilates
-BV to cardiac mm dilates
-BV to GI tract constrict
-BV to kidneys constrict
-BV to liver dilate (for glycogenolysis)
-BV to adipose tissue dilate (for lypolysis)


What happens in a parasympathetic response?

-decreased HR, diameter of airways (aka. bronchoconstriction), and pupil diameter


Where does the somatic NS get its sensory input?

-from receptors for somatic senses (tactile, thermal, pain, proprioceptive sensations) and from receptors for special senses (sight, hearing, taste, smell, equilibrium)
-these are consciously perceived


Where does the autonomic NS get its sensory input?

-from interoreceptors (sensory receptors located in BVs, visceral organs, mm and nn that monitor conditions in the internal environment)
-not usually consciously perceived


Where does control of motor output for the somatic NS come from?

-primary motor area of cerebral cortex
(with contributions from basal nuclei, cerebellum, brainstem and SC)


Where does control of motor output for the autonomic NS come from?

-involuntary control from the hypothalamus


Describe the motor neuron pathway for the somatic NS

-one neuron pathway
-somatic motor neuron goes from CNS to skeletal muscle
-type A fiber


Describe the motor neuron pathway for the autonomic NS

-two types:
-one is a two neuron pathway with an aunomic ganglion and the first neuron is a type B fiber and the second is a type C fiber.
- the other is only to chromaffin cells in the adrenal medulla which then release hormones that affect BV diameter. this is a one neuron pathway and is a type B fiber.


What neurotransmitter is involved in the somatic NS?

only ACh


What neurotransmitters are involved in the autonomic NS?

ACh and norepinephrine


What hormones are involved in the autonomic NS?

norephinephrine and epinephrine


What are the effectors of the somatic NS?

skeletal mm


What are the effectors of the autonomic NS?

-smooth mm
-cardiac mm


What is the response from the somatic NS?

contraction of skeletal mm


What are the responses from the autonomic NS?

-contraction or relaxation of smooth mm
-increase or decrease in rate and force of contraction of cardiac muscle
-increase or decrease in secretions by glands


What are the main parts of the autonomic motor pathway?

1. preganglionic neuron
2. postganglionic neuron
3. autonomic ganglia


Describe the preganglionic neuron

-first neuron in the pathway
-cell body is in the CNS
-axon is a type B fiber
-usually goes to autonomic ganglion and synapses with postganglionic neuron


What is the thorocolumbar division/sympathetic division?

-in the sympathetic division, preganglionic neurons have their cell bodies in the lateral horns of gray matter in T1 to L2 (sometimes L3)


What is the craniosacral division/parasympathetic division?

-in the parasympathetic division, cell bodies of preganglionic neurons are in the nuclei of 4 cranial nerves (X, XI, VII, III) and in the lateral gray matter of S2 to S4


Describe the postganglionic neuron

-the second neuron in an autonomic motor pathway
-in the PNS
-cell body is in an autonomic ganglion
-type C fiber
-terminates in a visceral effector