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
-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?
Which structures only receive innervation from the sympathetic system?
-arrector pili mm
-most blood vessels
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?
-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
-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?
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?
What are the effectors of the autonomic NS?
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