Download No Slide Title

PNS: Autonomic nervous system
Autonomic NS regulates smooth muscle, cardiac
muscle, gland tissue and adipocytes
• Anatomy of efferent pathways
– Sympathetic vs parasympathetic vs somatic motor
– Location of neurons and synapses
– Neurotransmitters
• Specific autonomic neuron functions
• Neurotransmitter receptor mechanisms
* Autonomic efferent neurons: preganglionic and postganglionic
Neural Systems
Parasympathetic Division
•
•
•
•
“Rest and digest”, relaxed state
Does not typically activate as a whole
Decrease HR, increase digestive fxn
Preganglionic neurons originate in
midbrain, medulla, pons and 2-4 sacral
• Preganglionic fibers long, post short
Sympathetic Division
• Fight or flight (prepares for intense activity)
• Heart rate increases, bronchioles dilate,
plasma [glucose] increases
• Preganglionic neurons originate from spinal
cord from T1 to L2 spinal nerves
• Preganglionic short, post-long
• Can have mass action: distributed to heart,
blood vessels, skin, adrenal glands
http://medlib.med.utah.edu/kw/hyperbrain/anim/reflex.html
Neurotransmitters and Receptors
• ACh receptor = cholinergic receptors
– nicotinic
– muscarinic
• NE and E receptor = adrenergic
– 1 and 2 (alpha)
– 1 and 2 (beta)
Human Physiology, 6th ed., Fox, SI; WC Brown, Fig.9.9
Parasympathetic
• preganglionic ACh : nicotinic receptor
… is a Na+ / K+channel
• postganglionic ACh: muscarinic rec.
G-protein coupled receptor links to 2nd
messenger; several different kinds
Sympathetic
• preganglionic ACh : nicotinic receptor
…is a Na+ / K+channel
• postganglionic NE: adrenergic receptor,
alpha or beta, G-protein coupled
receptor links to 2nd messenger
(see Table 11.1)
Adrenergic receptors
Rec. Intrac. effect
Functional roles, locations
1
 IP3,DAG
contractile for smooth m.,
blood vessels
2
 cAMP
inhibitory, GI tract, pancreas
1
 cAMP
cardiac muscle, kidney
2
 cAMP
relaxes smooth m., GI tract,
blood vessels,bronchioles
Autonomic Motor NS
• Central control by limbic system,
hypothalamus, brainstem, spinal
cord.
• Adrenergic receptors.
• Example pathways with autonomic
motor efferents.
Influence of Brain on Autonomic Functions
Thoughts &
emotions
influence ANS
by hypothalamus.
ANS integrating center that
interacts with cerebrum, limbic
system, brainstem, and spinal
cord.
ANS reflex centers for controlling pupil
size, accomodation, tear production,
salivation, coughing, digestive activities,
heart, blood vessel diameter and
respiration.
ANS reflex control of defecation, urination,
genital erection and ejaculation.
Spinal cord