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ObjectivesObjectives
zz KnowKnow ANSANS divisionsdivisions andand organizationorganization
zz FunctionalFunctional unitsunits
zzzz PrincipalPrincipal neurotransmittersPrincipalPrincipal neurotransmittersneurotransmittersneurotransmitters
zz ReceptorReceptor typestypes
zz IdentifyIdentify sensorysensory inputinput toto ANSANS
zz ExplainExplain howhow itit integratesintegrates functionfunction (BP)(BP)
zz ListListListList mainmainmainmain physiologicalphysiologicalphysiologicalphysiological responsesresponsesresponsesresponses under underunderunder ANS ANSANSANS
controlcontrol
zz DistinguishDistinguish SNSSNS fromfrom PSNSPSNS mediatedmediated responsesresponses
zz UnderstandUnderstand thethe consequencesconsequences of ANSof ANS
dysregulationdysregulation
Autonomic vs. Somatic Nervous
System
- AUTONOMIC Effectors: cardiac & smooth muscle, viscera & glands Efferent: 2 ‐neuron chain Neurotransmitter (NT) effects Stimulatory or inhibitory dependent on NT & receptor type
SOMATIC
Effectors: skeletal muscles EfferentEfferent:: HeavilyHeavily myelinatedmyelinated axonsaxons fromfrom CNSCNS toto musclemuscle Neurotransmitter Effects: Acetylcholine excitatory effect in nicotinic (N 1 ) receptors
z Autonomic Nervous System
z Efferent motor neurons: innervate viscera & involuntary
muscle
z Afferent sensory neurons respond to:
z Stretch (heart, arteries) zz Glucose PCOGlucose, PCO 2 , POPO 2 (blood)(blood) z Osmolarity & pH (blood & intestinal content) z Temperature (skin & internal organs)
SNS & PSNS
Functional unit
2 neuron pathway
Neurotransmitters
z Principal: Acetylcholine & norepinephrine
z NN on traditionalt diti l
z ATP
z Colocalized with NE in SNS
z Purinoceptors (i.e., smooth muscle cells)
z Nitric oxide
z Pre & postganglionic neurons SNS & PSNSPre & postganglionic neurons SNS & PSNS
Enteric nervous system
z 2 networks of neurons
z Myentericy z Motility z Submucous z Secretions
z 3 types of neurons
z Motor zz SensorySensory z mechanical, thermal, osmotic & chemical z Interneurons
z Part of the PNS
Enteric nervous system
z Operates largely independently of the CNS
z Coordinates gastrointestinal function
z Monitors the state of lumen and gut wall
z Responds appropriately
z Activating intrinsic reflexes
z Mixing and propulsive & peristaltic movements
z Change blood flow & secretions of water & electrolytes
z Neurons & glia organized
into ganglia
Enteric nervous system
into ganglia
z Neurotransmitters:
z Acetylcholine z ↑ motility z ↑ intestinal secretions z ↑ enteric hormone release z NN orepinephrinei h i z ↓ acetylcholine effects z Others: VIP, opioids, 5-HT, Substance P, NO, etc.
SNS/PSNS
z Dual/antagonistic: GI, CV
z Exclusive SNS
zz Adrenal medullaAdrenal medulla z Sweat glands z Erector pili muscles z Kidneys: RAS →↑ MABP z Most blood vessels
z Exclusive PSNS
z Erectile tissues
SNS/PSNS: Dual/antagonistic
modulation of CV function.
z Carotid sinus & aortic arch pressure
zz Afferent signals integrated in brainstemAfferent signals integrated in brainstem
z ↑ Pressure
z ↓ SNS activity & ↓ BP z ↑ PSNS activity & ↓ HR
z ↓ Pressure
z ↑ SNS activity &y ↑ HR & BP
SNS & PSNS: Dual/antagonistic
modulation of GI function
z PSNS favors digestive processes
z Increased gut motility, acid & enzyme secretions
z Relaxation of sphincters
z SNS inhibits digestive processes
z Contraction of sphincters
z Pyloric, ileo-cecal & internal analy ,
z Inhibition of motor neurons throughout the gut
SNS: Exclusive modulation of
thermoregulation
z ↑ Environmental temperature z ↓ Environmental temperature z Skin vasoconstriction z Blood retained in vital organs z Shivering z Piloerection
z Sweat gland activation z Skin vasodilation z Warm blood to surface
Autonomic nervous system
z ANS divisions and organization
z Functional units
z Principal neurotransmitters
z Receptor types
z Sensory input to ANS & role in control of BP
z Main physiological responses under SNS &
PSNSPSNS control l
z Coordinated/antagonistic/exclusive
z ANS dysfunction?
z Examples? Manifestations?
