CHAPTER 15 Flashcards
Autonomic means
-self governed
-independent of our will, carries actions involuntary
-regulates heart rate (cardiac muscle) temperature, smooth muscle
ANS can also be called
visceral motor system
Denervation hypersensitivity
exaggerated response of cardiac and smooth muscles if autonomic nerves were severed
visceral reflexes
automatic responses to stimulation involving visceral receptors/effectors
visceral reflex arch
Receptors: nerve endings detecting tissue damage etc
* Afferent neurons: lead to CNS
* Integrating center: interneurons in the CNS
* Efferent neurons: carry motor signals away from the CNS
* Effectors: carry out end response (muscles, glands)
PNS arch starts where, what is everything else
starts at vagus to effector
everything else is CNS
sympathetic division
-fight or flight
-widespread effect
-prepares body for physical activity
-ACh and NE
-trauma, anger, fear
-increase in heart rate, pupils dilate
parasympathetic
-rest and digest
-ACh only
-calms body and reduces energy
-effects more local
autonomic tone
normal background rate of activity that represents the balance of the two systems according to the body’s
needs
parasympathetic tone
Maintains smooth muscle tone in intestines
* Holds resting heart rate down to about 70 to 80 beats per minute
sympathetic tone
Keeps most blood vessels partially constricted and maintains blood
pressure
ANS has components in both
CNS and PNS
somatic pathway
-one motor neuron from brainstem to skel muscle
-no ganglia
-NT = ACh
autonomic pathway
-signal passes two motor neurons to reach target organ (first in brainstem or spinal cord and second at ganglion)
–have myelinated pre and unmyelinated postganglionic
-one pre gang can fan out to many
Syma vs Para divisons
-thoracolumbar
-craniosacral
Sympathetic nerve fibers are distributed to
every level of
the body
Adrenal cortex and Adrenal medulla
AC: outer layer
AM: inner layer, ganglion, Secretes hormones into bloodstream (adrenaline and noradrenaline)
Enteric nervous system
the nervous system of the digestive tract, regulates motility
Dual Innervation Antagonistic effects
oppose each other (most common)
-same effector cells Heart rate dec (parasympathetic) Heart rate inc (sympathetic)
-
Dual Innervation Cooperative effects
when two divisions act on different
effectors to produce a unified effect
-Parasympathetics increase salivary serous cell secretion
* Sympathetics increase salivary mucous cell secretion
Control Without Dual Innervation
Some effectors receive only sympathetic fibers
* Adrenal medulla, arrector muscles, sweat glands, and
many blood vessels
Control Without Dual Innervation: vastor motor tone
-firing frequency
Increase in firing frequency—vasoconstriction (being cold)
* Decrease in firing frequency—vasodilation
Central Control of Autonomic Function – ANS regulated by several levels of CNS
-cerebral cortex- anger fear
-hypothalamus- motor control
-mid, pons, med
-spinal cord reflex
