Autonomic Nervous System Flashcards
function of autonomic nervous system
motor nervous system that controls glands, cardiac muscle, and smooth muscle
primary organs of the ANS
- Viscera of thoracic
- abdominal cavities
- Cutaneous blood vessels
- Sweat glands
- Arrector muscles
unconscious, automatic, stereotyped responses to stimulation involving visceral receptors and effectors .
visceral reflex
Give an example of visceral reflex using blood pressure regulation
High blood pressure detected by arterial stretch receptors (1), afferent neuron (2) carries signal to CNS, efferent (3) signals travel to the heart, then (4) heart slows reducing blood pressure
components of a visceral reflex arc
- Receptors: nerve endings that detect
stretch, tissue damage, blood
chemicals, body temperature, and other
internal stimuli - Afferent neurons: lead to CNS
-Integrating center: interneurons in the
CNS
- Efferent neurons: carry motor signals
away from the CNS - Effectors: carry out end response
- ANS considered the efferent pathway
What are the two divisions of the autonomic nervous system
Parasympathetic division
Sympathetic division
function of Parasympathetic division
Calms many body functions reducing energy expenditure and assists in bodily maintenance; Digestion and waste elimination
“resting and digesting”
function of Sympathetic division
Prepares body for physical activity: exercise, trauma, arousal, competition, anger, or fear; Increases heart rate, BP, airflow, blood glucose levels, etc.; reduces blood flow to the skin and digestive tract.
“fight or flight”
normal background rate of activity that represents the balance of the two systems according to the body’s needs
autonomic tone
Must cross a synapse where the two neurons meet in an autonomic ganglion
autonomic pathway
Where is the Preganglionic (presynaptic) neuron located
the first neuron has a neurosoma in the brainstem or spinal cord
Where is the Postganglionic (postsynaptic) neuron located
neuron whose axon extends the rest of the way to the target cell
length of Preganglionic fibers of sympathetic division
relatively short
length of Preganglionic fibers of parasympathetic division
relatively long
Neurotransmitters of Preganglionic fibers of sympathetic division
acetylcholine
Neurotransmitters of preganglionic fibers of parasympathetic division
acetylcholine
length of Postganglionic fibers of sympathetic division
long
length of Postganglionic fibers of parasympathetic division
short
Neurotransmitters of Postganglionic fibers of sympathetic division
normally: Epinephrine (NO)
sometimes: Norepinephrine (NE) or Acetylcholine (ACh)
Neurotransmitters of Postganglionic fibers of parasympathetic division
Acetylcholine (ACh)
receptors of postganglionic neuron
nicotinic receptor
explain the receptors of a parasympathetic fiber
pregang releases ACh which connects to Postgang’s nicotinic receptor which releases ACh and connects to the target cell’s muscarinic receptor
types of sympathetic fibers
sympathetic adrenergic fiber
sympathetic cholinergic fiber
explain the receptors of a sympathetic adrenergic fiber
pregang releases ACh which connects to Postgang’s nicotinic receptor which releases NE and connects to the target cell’s adrenergic receptor
explain the receptors of a sympathetic cholinergic fiber
pregang releases ACh which connects to Postgang’s nicotinic receptor which releases ACh and connects to the target cell’s muscarinic receptor
Nerve fibers leave the sympathetic chain by three routes
- Spinal nerve route
- Sympathetic nerve route
- Splanchnic nerves
postganglionic fibers exit a ganglion by way of the gray ramus
Return to the spinal nerve and travel the rest of the way to the target organ
Spinal nerve route
nerves leave by way of sympathetic nerves that extend to the heart, lungs, esophagus, and thoracic blood vessels.
Sympathetic nerve route
fibers that arise from spinal nerves T5 to T12 pass through the sympathetic ganglia without synapsing continue on as the splanchnic nerves.
Splanchnic nerves
Nerve fibers of the Parasympathetic division
CN III
CN VII
CN IX
CN X
Pelvic nerves
CN III
Occulomotor nerve (III)
* Narrows pupil and focuses lens
CN VII
Facial nerve (VII)
* Tear,nasal,andsalivaryglands
CN IX
Glossopharyngeal nerve (IX)
* Parotid salivary gland
CN X
Vagus nerve (X)
- Viscera as far as proximal half of colon
- Cardiac, pulmonary, and esophageal plexuses that give off anterior and posterior vagal trunks
Preganglionic fibers are small myelinated fibers that travel from spinal nerve to the ganglion by way of the
white communicating rami
Postganglionic fibers leave the ganglion by way of the
gray communicating rami
Collateral ganglia contribute to a network called
abdominal aortic plexus
three major collateral ganglia in this plexus
- Celiac,
- Superior mesenteric
- Inferior mesenteric
collective name for the celiac and superior mesenteric ganglia.
solar plexus
functions of the adrenal glands
produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress and other essential functions
Secretes steroid hormones
Adrenal cortex
Essentially a sympathetic ganglion consisting of modified postganglionic neurons (without fibers)
Adrenal Medulla
function of enteric nervous system
the nervous system of the digestive tract
hereditary defect causing absence of enteric nervous system
Hirschsprung disease
effects of Acetylcholine
is secreted by all preganglionic neurons in both divisions and by postganglionic parasympathetic neurons
can be excitatory or inhibitory Found in all cardiac muscle, smooth muscle, and gland cells
effects of Muscarinic receptors
Excitatory when ACh binding occurs. Found on all ANS postganglionic neurons, in the adrenal medulla, and at neuromuscular junctions of skeletal muscle.
effects of Nicotinic receptors
is secreted by nearly all sympathetic postganglionic neurons called adrenergic fibers
effects of Norepinephrine
Receptors for Norepinephrine
adrenergic receptors
Alpha-adrenergic receptors
Usually excitatory
Beta-adrenergic receptors
Usually inhibitory
most viscera receive nerve fibers from both parasympathetic and sympathetic divisions
dual innervation
oppose each other
Antagonistic effect
two divisions act on different effectors to produce a unified
overall effect
Cooperative effect
Parasympathetic exerts more influence on what organs?
digestive organs
Sympathetic has greater effect on what organs?
ventricular muscle of heart
Some effectors receive only sympathetic fibers and no parasympathetic fibers
control without dual innervation
has an influence: Powerful emotions such as anger, fear, anxiety influence the ANS because of the connections between our limbic system and the hypothalamus.
Cerebral cortex
major visceral motor control center. Contain the nuclei for primitive functions—hunger, thirst, sex.
Hypothalamus
Nuclei for cardiac and vasomotor control, salivation, swallowing, sweating, bladder control, and pupillary changes
Mid brain, pons, and medulla oblongata
Defecation and micturition reflexes are integrated in spinal cord. We control these functions because of our control over skeletal muscle sphincters; if the spinal cord is damaged, the smooth muscle of bowel and bladder is controlled by autonomic reflexes built into the spinal cord.
Spinal cord reflexes
effects of sympathomimetics and an example
enhance sympathetic activity. Stimulate receptors or increase norepinephrine release.
albuterol or nasal decongestant
effects of sympatholytics and an example
suppress sympathetic activity. Block receptors or inhibit norepinephrine release
beta-blockers
effects of parasympathomimetics and an example
enhance activity of the parasympathetic nervous system
sleeping pills
effects of parasympatholytics and an example
suppress activity of the parasympathetic nervous system.
Caffeine
effects of caffeine and an example
competes with adenosine (the presence of which causes sleepiness) by binding to its receptors
