501 Pharma - The Autonomic Nervous System (Lec 5)

CNS + PNS

TWO anatomical divisions

CNS

brain + spinal cord; main processing & integration center

PNS

nerves connecting CNS to peripheral tissues

afferent + efferent division

PNS divided into

afferent

sensory; info from peripheral to CNS + reflex pathways

efferent

motor; info from CNS to peripheral tissues + responses of target organs & tissues

somatic and ANS

efferent portion of the PNS is further divided into two major functional subdivisions

somatic

voluntary control of body movement (skeletal muscle)

ANS

involuntary regulation of vital body functions (smooth + cardiac muscle, blood vessels, glands)

somatic motor nerve

carries motor signals from the CNS to skeletal muscles

neuron

One man band; uses this instead of ganglion in somatic functional division within PNS

ACh

neurotransmitter of somatic motor nerve

nicotinic receptors

receptors of somatic motor nerve

endocrine system

blood-borne hormones acting on target tissues

nervous system

rapid responses through electrical impulses transmitted along nerve fibers

Autonomic drugs

medications that mimic, enhance, or inhibit ANS functions

SNS+ PSNS

must be synchronous (25-30% of drugs act here); w/in ANS

SNS

Fight or flight; respond to unexpected stimuli

PSNS

Rest, recovery, and energy conservation; restore homeostasis

GI tract, pancreas, gallbladder

MAIN organs affected by ENTERIC nervous system

ENS

Functions independently of the CNS

SNS + PSNS

ENS is REGULATED + MODIFIED by

PREganglionic neuron

cell body in CNS

POSTganglionic neuron

cell body in autonomic ganglion

smooth + cardiac muscle & exocrine glands

NTs effector tissues

thoracolumbar spinal cord (T1-L2)

SNS orignates here

ACh to nicotinc receptors

PREganglionic neurons release _____ TO ________/ion channels then POST

NE to adrenergic receptors/GPCRs

POSTganglionic neurons release ______ to __________ then target/effector tissues

Epi in blood

Adrenal medulla release _______ in ___________ to amplify SNS

brainstem + sacral spinal cord: S2-S4

PSNS originates from

LONG and MYELINATED

PSNS PREganglionic neurons are HELLA

SHORT and UNMYELINATED

PSNS POSTganglionic neurons are HELLA

WIDESPREAD

Longer SNS POSTganglionic neuron is more

LOCALIZED

Shorter PSNS POSTganglionic neuron is more

diffusion

SNS = ______ because LONG POSTganglionic neuron may innervate more than one organ

discrete

PSNS = ________ because SHORT (NON-BRANCHED) POSTganglionic neurons are directed to specific organ

hypothalamus, medulla oblongata, spinal cord

Afferent signals go to

Endocrine

hormones; far-reaching

Paracrine

local mediators; nearby

Synaptic

nerve endings; nearby

Depolarization

Ca2+ channels open

ACh

major NTs of preganglionic SNS ganglia

NE

major NTs of postganglionic SNS ganglia

Epi

adrenal medula into blood

NE + Epi role

adrenergic singaling of hear and blood vessels

ACh role

GI motility + secretions; blocking muscarinic receptor activation can reduce excessive PSNS effects