24.3 Autonomic nervous system Flashcards
What are visceral change the ANS can alter rapidly and intensly?
- HR can double in 3-5 seconds
- double arterial pressure
- initiate sweating
What is the best way to describe the pathways of the ANS?
2 series of neurons. preganglionic and postganglionic neurons
Describe the features of a preganglionic neuron.
- CNS contains the cell bodies
- myelinated axons
- Ach is the neurotransmitter
Whate are unique features of the postganglionic neurons?
- cell bodies locate in peripheral ganglia
- non-myelinatd
3.parasympathetics=Ach
sympathetics= norepinephrine
Where are large numbers of mitochondria generally found in the ANS pathways to organs?
in terminal fibers with enlarged varicosities
Where do preganglionic neurons of the sympathetic system lie?
- T1-L2 intermediolateral horn
2 synapse in paravertebral chain
What fibers form 8% of fibers in teh average nerve?
postganglionic sympathetic fibers
What kind of fibers are postganglionic sympathetic fibers?
type C fibers (unmyelinated) that control blood vessel, sweat glands and piloerector muscles
What nerve fibers pass through the gray rami?
postganglionic sympathetic fibers
What are the 12 thoracic ganglia pairs normally referred to?
stellate ganglion. with first pair fused with inferior cervical ganglion
What are the components of the cervical ganglia?
- superior
- middle
- inferior
What nerves supply the preganglionic sympathetic supply to the thoracic viscera?
T1-T5
What nerves supply the postganglionic sympathetics to the thoracic viscera?
- superior, middle, inferior cervical ganglion
2. T1-T5 paravertebral ganglia
What is the function of the cardiopulmonary splanchnic nerves that travel all by themselves?
- dilate coronary artery
- increase heart rate
- bronchodilation
What comprise splanchnic nerves?
preganglionic fibers and visceral sensory fibers
What do splanchnic nerves supply?
abdominal viscera
Where do splanchnic nerves synapse?
prevertebral ganglia
What nerves form the greater splanchnic nerves?
- T5-T9
2. synapse in the celiac region
What nerves form the middle splanchnic nerves?
T10-T11, synapse in superior mesenteric ganglion
What nerves form the least splanchnic nerves?
T12, synapse in the aorticorenal ganglion
The adrenal medulla releases 80% epinephrine and 20% norepinephrine via the______________system.
sympathetic
Effects of circulating norepinephrine?
- blood vessel constriction
- increase HR
- inhibit GI
- dilate pupils
What are the secretory cells of teh adrenal medulla?
innervated by postganglionic neurons with rudimentary fibers that secrete epinephrine and norepinephrine
Which hormone is more effective in elevating arterial pressure?
norepinephrine
Which hormone increases cardiac output most effectively?
epinephrine
Which hormone affects metabolism most effectively by increasing rate 5-10 times?
epinephrine more effective than norepinephrine
Where is 75 % of all parasympathetic fibers contained?
1) vagus nerve CNX
Where are postganglionic parasympathetic fibers located?
in the wall of the organ and use Ach as NT
What 4 cranial nerves contain parasympathetics?
- III
- VII
- IX
- X
What are the funcitons of the oculomotor nerve?
1.supplies extrinsic eye muscles and levator palpebra superioris
What is the path of oculomotor nerve preganglionic parasympathetic nerve?
- edinger-westphal nucleus to ciliary ganglion
WHat is the path of oculomotor nerve postganglionic parasympathetics?
ciliary ganglion to sphincter pupillae muscle
What are the primary funcitons of the Facial Nerve?
- innervate muscles of facial expression
2. provide taste to the anterior 2/3 of tongue
What are the parasympathetic functions of the Facial Nerve?
- preganglionic: superior salivary and lacrimal nuclei to the submandibular/sublingual ganglia
- postganglionic: to lacrimal gland, submandibular/sublingual gland, mucous glands of mouth and nose
What are functions of the glossopharyneal nerve?
- general sensation and sensation from posterio 1/3 of tongue
What are the parasympathetic functions of the glossopharyngeal nerve?
- preganglionic: from inferior salivary nucleus to otic ganglion
- postganglionic: to parotid gland
What are the functions of teh vagus nerve?
- motor supply to 4th and 5th pharyngeal arches. swallowing and speaking as well.
What is the major parasympathetic supply to thoracic and abdominal organs?
vagus nerve
WHat is the pathways of the parasympathetics for the vagus nerve?
- pre: from dorsal motor nucleus
2. post: myenteric plexus of wall of gut tube to left colic flexure
What is teh course of teh vagus nerve through the body?
- parallels and innervates esophagus
- posterior to root of lung on each side
- follows esophagus through esophageal hiatus
- is now gastric nerve
- supplies viscera in thoracic cavity
What are the branches of the vagus nerve?
- cardiac=> cardiac plexus
- pulmonary=> pulmonary plexus
- esophageal=> esophageal plexus
Which nerve wraps around teh arch of the aorta to the left of the ligamentum arteriosum?
left recurrent laryngeal nerve form the left vagus branch
Which nerve arise in the neck and not the thorax? Vagus nerve branch
- right recurrent laryngeal nerve from the right vagus nerve
What enzyme helps form acetylcholine?
choline acetyl-transferase
What enzyme helps degrade acetylcholine?
acetylcholinesterase
What is the process to form norepinephrine?
- hydroxylate tyrosine to dopa
- decarboxylate dopa to dopamine
- transport dopamine to vesicles
- hydroxylate dopamine to norepinephrine
- 80% of norepinephrine is methylated to form epinephrine
How can norepinephrine be removed?
- monamine oxidase
- catechol-O-methly transferase
- reuptake
- diffusion
Where are muscarinic acetylcholine receptors found?
- on all effector cells stimulated by postganglionic cholinergic neurons
Where are nicotinic acetylcholine receptors found?
- autonomic ganglia at synapse between pre-/postganglionic neurons
- on neuromuscular junction in skeletal muscles
Stimulation of beta 1 adrenergic receptors cause what response?
- cardioacceleration
- increase myocardial strength
- lipolysis
Stimulation of beta 2 adrenergic receptos cause what response?
- vasodilation, intestinal/uterine relax
- bronchodilation, calorigenesis
- glycogenolysis
What does stimulation of beta 3 adrenergic receptors cause?
- thermogenesis
What are the sympathomimetic drugs?
- norepi/epinephrine
- methoxamine
- phenylephrine
- isoproterenol
- albuterol
Which drugs cause release of norepinephrine?
- ephedrine
- tyramine
- amphetamine
What does reserpine do?
- block adrenergic activity
2. block norepinephrine synthesis/storage
What does guanethidine do?
- block adrenergic activity
2. prevent release of norepinephrine
What does phenoxybenzamine/phentolamine do?
- block adrenergic activity
2. blocks sympathetic alpha receptors
What does propranolol do?
- blocks adrenergic activity
2. blocks sympathetic beta 1 and beta 2 receptors
What does metoprolol do?
- blocks adrenergic activity
2. blocks sympathetic beta 1 receptors
What does hexamethonium do?
- blocks adrenergic activity
2. stops transmission through autonomic ganglia
What are parasympathomimetic drugs and what effect do they have?
- pilocarpine and methacoline
2. act on muscarinic receptors and are not readily removd by acetylcholinesterases
What drugs inhibit the activity of acetylcholinesterase?
- neostigmine
- pyridostigmine
- ambenonium
What drugs block the cholinergic activity?
- atropine
- homatropine
- scopolamine
Which system is responsible for causing pupil dilation?
- sympathetic
Which system controls pupil constriction and lens focusing?
- parasympathetic
Glands controlled by the sympathetic system elicits what responses?
- secretion of large amount of sweat. via cholinergic fibers.
- technically are parasympathetic fibers distributed via sympathetics
Glands controlled by the parasympathetic system are able to elicit what kind of response?
- stimulate lacrimal, nasal, salivary, GI glands of upper tract
* lower GI glands stimulated via enteric system
