Autonomic Nervous System Flashcards
What’s the Basic Function of the Nervous System?
Voluntary motor function (skeletal muscle)
Sensory Input
Automatic Response
What does the Central Nervous System include
Brain and spinal cord
What does the brain stem house and what does it control?
Brain stems includes clusters of cells that control respiration, cardiac, vascular function, digestive functions
Reticular activating system runs through brain stem (alertness and attention)
sleep functions
What does the spinal cord consist of?
White matter: bundles of nerve fibers with similar function (some afferent and some efferent)
Gray Matter: butterfly shape surrounded by white matter and is neuron cell bodies and glial cells
Ventral/Dorsal/Lateral Horn functions:
Ventral horn: contains cell bodies of somatic efferent motor neurons supplying skeletal muscles
Dorsal Horn: cell bodies of interneurons/ afferent sensory neurons terminate
Lateral Horn: ANS nerve fibers supplying cardiac and smooth muscle, and endrocine glands originate in cell bodies here
What is included within the Peripheral Nervous System of CNS:
Cranial and Spinal Nerves
What do the Cranial Innervate? (Peripheral NS)
12 paired nerves that branch off brainstem
Mainly innervate head and neck regions with the exception of the vagus nerve (GI)
What do the spinal nerves innervate? (Peripheral NS)
Paired nerves branching off of spinal cord and innervating post cranial body (skin, muscle, organs…)
8 C, 12 T, 5 L, 5 S, 1 C
Spinal Nerves:
Sensory information comes into spinal cord through neurons in the dorsal root (houses sensory afferent)
Motor (efferent) neurons leave the spinal cord through ventral root (carrying signals to body)
Afferent Sensory Neurons sense what?
mechanoreceptors= positional sensation, touch, vibration
Nociceptors= pain
Thermoreceptors
What does the ANS Innervate and what do SNS and PNS do within the ANS system?
ANS: Efferent neurons that carry out specific function and target smooth/ cardiac muscles and glands
SNS: maintains metabolic homeostasis and increases overall activity in response to increased demand
PNS: Produces more targeted responses to facilitate digestion, repair and resting functions to allow body to maintain energy stores/recover
Where does Sympathetic Nervous System start?
Begins in the central portion of the spinal cord
Preganglionic neuron extends a shorter distance than the postganglionic
Where does Parasympathetic Nervous System start?
PNS begins in the brain stem or in the sacral region
Preganglionic neuron extends longer distance than the postganglionic neuron
All autonomic nerves leaving the spinal cord are what?
What is the neurotransmitter released?
Cholinergic
Acetylcholine: signals the first synapse outside the spinal cord for both SNS and PNS
What’s the difference between PNS and SNS neurons?
Postganglionic synapses of PNS is cholinergic
Postganglionic synapses of SNS is adrenergic
What Neurotransmitter is released at SNS motor neurons and as a hormone by the adrenal medulla?
Norepinephrine (catecholamines)
Primary neurotransmitters for postganglionic SNS (adrenergic) responses?
NE (also epinephrine and dopamine)
What destroys NE at the synaptic cleft?
Catecholamine-o-methyl transferase
Can reauptake
If reuptake, NE can be reused or destroyed by an enzyme called monoamine oxidase
What destroys NE at the synaptic cleft?
Catecholamine-o-methyl transferase
Can reauptake
If reuptake, NE can be reused or destroyed by an enzyme called monoamine oxidase
Alpha 1 Receptor Location and response:
EXCITATORY- Dilation of pupils
sympathetic target tissue (includes major arteries, arterioles of GI, arterioles of skin)
Alpha 2 Receptor Location/Response:
INHIBITORY-Inhibit release of norepinephrine (dilator)
Mainly on Digestive organs- Decreases smooth muscle contraction in GI tract
Beta 1 Receptors Location/Response:
Excitatory- Increase heart rate and force of contraction
SA/AV Nodes of heart, ventricular myocardium, kidneys
Beta 2 Receptors Location/Response:
INHIBITORY-arteriolar or bronchiolar dilation
Smooth muscles of arterioles or bronchioles
Primary neurotransmitter in Parasympathetic system and what metabolizes it?
Acetylcholine
Acetylcholinesterase (metabolizes)
Cell receptors that initiate parasympathetic responses are called?
cholinergic receptors (2 types muscarinic and nicotinic)
Where are (cholinergic) nicotinic receptors located and response?
Nicotinic:
-Primary location is in ganglionic synapse of both PNS and SNS
-Stimulation of smooth/skeletal muscle and gland secretions
Muscarinic:
-Located on PNS organs (smooth muscle/ cardiac muscle/gland)
-Stimulation of smooth muscle and gland secretions
-Decrease hear rate/contraction
What are SNS adrenergic receptors called:
a1, b1, a2, b2, b3
SNS and PNS action on the eye:
PNS: stimulation constricts the pupil and drain fluid chambers
SNS: increased fluid production and dilating pupils
B2 and M receptors on the lungs do what?
Beta 2 when stimulated by NE/adrenergic agonists bronchodilate and decrease airway secretions
M when stimulated by Ach/cholinergic agonist drugs will bronchoconstrict and increase secretion
Heart receptors and action:
B1 receptors stimulation from NE/ adrenergic agonists increase heart rate, contractility, AV Nodal conduction and cardiac output
Muscarinic receptors stimulation from Ach/cholinergic agonist decrease SA nodal firing and decrease AV node conduction decreases
Sympathomimetics:
drugs that mimic action of NE are adrenergic drugs (sympathomimetics)
Adrenergic agonists initiate similar response to catecholamines such as NE
Directed-Indirect (Stimulates release of NE)-mixed/acting (both)
Sympatholytic Drugs:
Drugs that block effects of catecholamines such as NE are adrenergic antagonists (prevent response)
Parasympathomimetics:
stimulate cholinergic receptors of PNS
Direct-Indirect Iinhibit enzyme that destroys Ach)
Parasympatholytics:
Drugs that block effects of Ach are cholinergic blockers or anti-chol.
Major responses:
-Decreased GI motility, decrease in saliva, dilation of pupils
