Unit 4_Autonomic Nervous System Flashcards
What nervous system presents as the following:
- Maintains homeostasis
- Vegetative (digestive) & visceral (organs) functions
- Generally, an involuntary system
Minimal voluntary control
Autonomic Nervous System (ANS)
What are the following associated with?
General sensations: Pain, temp, touch
Special senses: vision, auditory, vestibular, etc.
Visceral afferents: through nucleus of solitary tract (CNs IX &X)
Sensory Afferents Stimulate Reactions to the ANS
What do the following make up:
Efferents (the True ANS system)
Two functional systems
1. Sympathetic (SNS)
2. Parasympathetic (PNS)
Innervate smooth muscle, the heart, glands, and organs
*NO direct innervation of skeletal muscle
ANS
What kind of neurons sit within the brainstem and spinal cord inside the cns?
preganglionic
What kind of neurons include cells situated in ganglion outside cns?
postganglionic
What neuron includes:
Sympathetic: T1-L2 or L3 (Lateral Horn)
Parasympathetic: CN nuclei 3,7,9,10 (autonomic nuclei) and sacral spinal cord S2-S4 (lateral horn)
Preganglionic Neurons
What neuron includes:
Sympathetic:
A. Sympathetic trunks
B. three specialized prevertebral areas past the trunk:
1. celiac ganglion
2. superior mesenteric ganglion
3. inferior mesenteric ganglion
Axons go to the organs
Parasympathetic: various ganglions are located very near the target organ; very far from the spinal cord and brainstem
Postganglionic Neurons
What kind of neurotransmitters include the following:
Preganglionic cells release ACH onto postganglionic cell
Postganglionic cells release epinephrine and norepinephrine except on sweat glands where they release ACH
There also co-transmitters
Sympathetic
What kind of neurotransmitters includes the following:
Both pre & postganglionic cells use ACH
There can also be co-transmitters
Parasympathetic
What ANS includes the following:
- AKA thoracolumbar division
- preganglionic neurons located in T1-L3 (Lateral Horn)
- axons exit spinal cord through ventral root
- can do one of 2 things:
1. enter synaptic chain on either side of the cord
*synapses on postganglionic neuron in chain and release ACH
*axon of postganglionic cell travels in peripheral nerves to target organs where it synapses and releases norepinephrine (except sweat glands where they release ACH)
2. go directly to neurons in prevertebral ganglion
*synapse on postganglionic neuron in ganglion and release ACH
*axons from postganglionic neurons go direct to target organ and release norepinephrine
The target tissue or target organ receives norepinephrine from the postganglionic cell (except sweat glands). The receptors on the target organ are divided into 2 classes:
1. alpha adrenergic receptors - when these receive norepinephrine they excite the target tissue except in the GI system where they inhibit the target tissue.
2. beta adrenergic receptors - when these receive norepinephrine they inhibit the target tissue except in the heart where it excites the heart
Sympathetic
What organ has sympathetic innervation only and includes the following:
- There is only one efferent neuron
- When stimulated, this organ releases epinephrine
- This serves as a mechanism to release hormones quickly into the blood; “FIGHT OR FLIGHT”
adrenal medulla
What do the following organs have in common?
- Adrenal medulla
- sweat glands
- piloerector muscles
- peripheral blood vessels (in skin)
sympathetic innervation only
What do most organs contain?
both sympathetic and parasympathetic innervation
What kind of ANS innervation includes the following:
- follows 2 neuron pathway rules
- preganglionic neuron sits in thoracic cord axons, leave the spinal cord, and travel to postganglionic neurons either in the stellate or superior cervical ganglion
- Axons from these cells ascend and go to blood vessels and glands of the face through cranial nerves
- Goes to the eye to dilate the pupil through CN V (ophthalmic division)
- This is controlled via descending axons from the hypothalamus
Sympathetic innervation of face and head
What ANS is involved in catabolic responses (energy expediting)?
Sympathetic
