Lecture 6 - Autonomic Nervous System Flashcards
ANS is predominantly an _____ system
efferent
the ANS transmits impulses from ____ to ____
transmits impulses from CNS to peripheral organ systems
three subdivisions of the ANS
Sympathetic, Parasympathetic, Enteric
Is ANS a two or one neuron transmission
ANS is always a 2 neuron system
is somatic nervous system a 1 neuron system or 2 neuron system
1 neuron system
describe the path of transmission of the ANS starting at the central nervous system to the effector organ
CNS –> preganglionic fiber –> preganglionic NT to the postganglionic fiber at the level of the autonomic ganglion –> postganglionic fiber –> postganglionic NT at varicosity –> effector organ
*****compare and contrast somatic nervous system and autonomic nervous system (important, said would be on test)
Somatic: one neuron connects directly to effector, connects only to muscle (skeletal), only excitatory effects, one transmitter
Autonomic: two neurons connect to effector, can be a muscle or a gland (smooth or cardiac muscle), can be released directly to blood stream (ex. adrenal medulla), Both inhibitory and excitatory effects (ex. heart rate)
is fight or flight a branch of sympathetic or parasympathetic
sympathetic
what are some of the effects of the sympathetic nervous system
pupil dilation, vasoconstriction (GI, skin, brain, periphery), goosebumps, sweating, vasodilation (in heart, skeletal muscle, lungs), increased HR and BP, bronchodilation
is “rest and digest” controlled by parasympathetic or sympathetic
Parasympathetic
does the somatic NS have ganglia
naur
2 kinds of ACh receptors
muscarinic and nicotinic
Describe muscarinic receptor action and targets
action: can be inhibitory and excitatory depending on receptor subtype (ex. M1-5)
Target tissue (ex. bronchoconstriction, decreased heart rate)
Describe nicotinic receptor action and targets
Action: excitatory, fast (ex. noticing a predator)
Target: post ganglionic (parasympathetic + sympathetic)
Name the norepinephrine receptors and wether they are excitatory or inhibitory
R-alpha: excitatory (except for gut)
R-beta 1: Excitatory/ inhibitory
R beta 2: inhibitory
where are ANS norepinephrine receptors located
all ANS norepinephrine receptors are located on target tissues (target effectors)
Describe the key structure for controlling autonomic function
hypothalamus: key for thermoregulation, BP, heart rate, and multiple other functions
is control of the ANS accomplished by one centres or multiple centres in the brain
complex, accomplished by multiple centers
Describe the relationship between the enteric NS, parasympathetic and sympathetic nervous systems
enteric nervous system generally functions independently of sympathetic and parasympathetic nervous system but can be influenced by them
Name some neurotransmitters contained in the enteric nervous system
serotonin (5-HT),
Functions of the enteric system
Motility (peristalsis), Secretions (digestive enzymes), fluid regulation, GI blood flow
name the layers of the enteric system starting at the lumen, working outwards
lumen
mucosal
submucosal
submucosal plexus
circular muscle
Mysenteric plexus
longitudinal muscle
serosa
describe the serosa
double membrane lining closed cavities
what is longitudinal muscle
smooth muscle
Describe the myenteric plexus
neural controls motility and peristalsis
Contains neurons responsible for regulating enzyme output of adjacent organs
(extensive innervation)
what is circular muscle
smooth muscle
describe the submucosal plexus
neural control for ion and water transport
contains sensory cells that communicate with the mesenteric plexus and motor fibers stimulate secretions of fluid into lumen
describe the lumen
no nerves enter this area, where digestion occurs
describe the mesentary
attaches bowel to body wall and contains major arteries, veins, lymphatics and external nerves
Describe the parasympathetic nervous system control of the enteric nervous system
PNS is generally stimulatory
- increases secretions, motility and blood flow (rest and digest)
Describe the sympathetic nervous system control of the enteric nervous system
SNS is inhibitory to the ENS, reduces secretions and decreases blood flow and motility
compare and contrast the locations of preganglionic neurons of sympathetic vs parasympathetic pathways
Sympathetic:
- confined to thoracolumbar regions/ thoracolumbar in nature
parasympathetic:
- largely sacral and brainstem (craniosacral)
Describe the axon length of sympathetic autonomic neurons vs parasympathetic autonomic neurons
sympathetic: preganglionic neurons are very short in the 2 neuron system (neuron to effector is longer)
parasympathetic: 1st order neuron has long range axons with short neurons synapsing onto effector organs
what are the 3 exceptions of the sympathetic autonomic pathways where the pre-ganglionic fibers are longer than usual
coeliac ganglion, superior mesenteric ganglion, inferior mesenteric ganglion
describe what NTs are release from 1st order and 2nd order neurons in the parasympathetic nervous system, what receptors they act on, and the actions at target sites
1st order neurons –> Ach at nicotinic receptors on 2nd order neurons –> 2nd order neurons release Ach –> muscarinic receptors on effectors –> increase exocrine secretions, increase GI smooth muscle contractions, decrease heart rate, constricts pupil
describe what NTs are release by pre and post ganglionic fibers of the sympathetic nervous system, what receptors they act on, and the action at target sites
Preganglionic fibers –> Ach onto nicotinic receptors of postganglionic fibers –> Norepinepherine onto alpha and beta receptors
increases splenic contractions, increase force of cardiac muscle contractions, decrease contraction of GI smooth muscle, constricts peripheral blood vessels, dilates bronchial airways, dilates pupil
describe sympathetic innervation of the adrenal medulla, what is released and the downstream effects
neuron –> Ach to nicotinic receptors on adrenal medulla –> adrenal medulla releases epinephrine and norepinepherine into the blood (note: these are now considered hormones) –> alpha and beta receptors –> fight or flight actions
(increases splenic contractions, increase force of cardiac muscle contractions, decrease contraction of GI smooth muscle, constricts peripheral blood vessels, dilates bronchial airways, dilates pupil)
Which norepinephrine receptor receives signals exclusively from blood (hormones)
Beta 2 receptors
Radial muscle - iris NE receptor and response
Alpha 1 receptor, contraction (dilates pupils)
Cilliary muscle cholinergic response
contraction for near vision (lens)
Cilliary muscle NE receptor and response
Beta 2 receptor, relaxation for far vision
Sinoatrial node Cholinergic impulse
decrease in heart rate
sinoatrial node NE receptor and response
Beta 1 receptor, increase in heart rate
Atria Cholinergic response
decrease contractility
Atria NE receptor and response
beta 1, increase contractility and conduction velocity
AV node cholinergic response
AV block
AV node NE receptor and NE response
B1, increase in conduction velocity
Ventricles NE receptor and response
B1, increase contractility and conduction velocity
Coronary, skel. muscle, pulmonary, renal arterioles cholinergic impulse
dilation (sometimes skel. muscle)
Coronary, skel. muscle, pulmonary, renal arterioles NE receptor and response
Alpha –> constriction
Beta 2 –> dilation
skin, mucosal, salivary gland NE receptors and response
alpha –> constriction
Systemic veins NE receptor and response
alpha –> constriction
beta 2 –> dilation
bronchial muscle of lungs cholinergic impulse
contraction
Bronchial muscle NE receptor and response
Beta 2 –> relaxation
Bronchial gland of lung NE receptors and responses
alpha 1 –> decrease in secretion
Beta 2 –> increase in secretion
pilomotor muscles of skin NE receptor and response
alpha 1 –> contraction
Salivary gland cholinergic response
profuse watery secretion
salivary gland NE receptor and response
alpha –> scant, viscous secretion
review slide 22, 15,14, 11,10,9
srsly >:(
what are some of the effects of the parasympathetic nervous system
Vasodilation in periphery, urination and defecation, resting HR and BP, sexual arousal, salivation, contraction of pupil and lens, bronchoconstriction, digestion (enzymes and peristalsis)
