honors anatomy & physiology. in pns operates via reflex arcs includes: autonomic sensory...
TRANSCRIPT
THE AUTONOMIC NERVOUS SYSTEM
Honors Anatomy & Physiology
ANS
in PNS operates via reflex arcs includes:
autonomic sensory neurons integrating centers in CNS autonomic motor neurons
AUTONOMIC REFLEX ARC
AUTONOMIC MOTOR NEURONS
when somatic motor neurons sends impulse to a muscle the effect always excitatory…if they stop sending impulses that muscle atrophies
autonomic motor neurons regulate visceral activities by either increasing (exciting) or decreasing (inhibiting) ongoing activities in their effector tissues (cardiac or smooth muscle, glands)
COMPARISONS OF ANS & SOMATIC NS
AUTONOMIC SENSORY NEURONS
source of most input to ANS via sensory receptors called interoceptors
not consciously perceived most of time located in:
blood vessels visceral organs muscles in nervous system
AUTONOMIC RESPONSES
most cannot be altered to any great degree making some responses ideally suited for lie detector tests
AUTONOMIC MOTOR PATHWAYS
most consist of 3 motor neurons in series
1st neuron has cell body in CNS myelinated axon synapses in autonomic ganglion with 2nd motor neuron cell body: its unmyelinated axon effector
except
AUTONOMIC MOTOR PATHWAY
2 BRANCHES OF MOTOR PART OF ANS
SYMPATHETIC DIVISION PARASYMPATHETIC DIVISION
preganglionic axons from thoracolumbar nerves
ganglia far from visceral effector in: sympathetic chain or
collateral ganglia neurotransmitter used:
ACh in ganglia NE in effector organ
preganglionic axons from craniosacral nerves
ganglia near or w/in visceral effector organs
neurotransmitter used: ACh in ganglia ACh in effector organ
MOTOR PART OF ANS
most organs have dual innervation nerve impulses from 1 will increase
activity (excitation) & impulses from other decrease activity (inhibition)
SYMPATHETIC GANGLIA
2 groups:1. sympathetic trunk ganglia
1. lie in vertical row, either side of vertebrae
2. prevertebral ganglia1. lie anterior to vertebral column close
to large abdominal arteries
SYMPATHETIC DIVISION OF ANS
PARASYMPATHETIC GANGLIA
most close to or w/in effector organ
EFFECTS OF SYMPATHETIC & PARASYMPATHETIC DIVISIONS OF THE ANS
HOMEOSTATIC IMBALANCES OF THE ANS
Raynaud’s phenomenon: due to excessive sympathetic stimulation
of smooth muscles in arterioles of digits digits become ischemic (lack of blood)
after exposure to cold or with emotional stress
MEDICAL TERMINOLOGY
autonomic nerve neuropathy: often caused by long-standing diabetes, neuropathy affects 1 or more autonomic nerves, can interfere with reflexes
hyperhydrosis: profuse sweating due to intense stimulation of sweat glands
vagotomy: cutting vagus nerve; often done to decrease production of HCl in patients with severe ulcers