Chapter 15: Visceral Reflexes Flashcards
autonomic nervous system
a motor nervous system that controls viscera organs
autonomic nervous system carries out actions _____
involuntarily
Visceral reflexes make it all the way to the _______
brainstem
parasympathetic division
rest & digest
digestion and waste elimination
autonomic tone
normal background rate of activity that represents the balance between parasympathetic and sympathetic systems as the body changes
parasympathetic tone
maintains smooth muscle tone in intestines
sympathetic tone
maintains blood pressure and keeps blood vessels constricted
ANS has components in the ___ and the ___such as what?
central and peripheral
nucleus of hypothalamus
motor neurons in spinal cord and peripheral ganglia
somatic vs. visceral motor pathway
somatic: myelinated axon reaches all the way to the skeletal muscle
visceral: must travel across two neurons to get to the target organ
What are the 2 signals in autonomic output pathways?
presynaptic neuron cell body in CNS
postsynaptic neuron cell body in peripheral ganglion (reaches target organ cell & takes longer)
Why does the postsynaptic neuron signal take longer?
because the cell loses its myelination
sympathetic division is also called the _____
thoracolumbar division (thoracic and lumbar regions)
sympathetic division has ____ preganglionic fibers which are found in the ___ ____and ____ postganglionic fibers
short;lateral horn; long
chain of ganglia
paravertebral ganglion
sympathetic division preganglionic fibers are _____ and _____ while the postganglionic fibers are ____ .
short myelinated
unmyelinated
what are 3 outcomes of the preganglion of sympathetic chain
- end in ganglia
- travel up and down the chain
- pass through the chain without synapsing
how can nerve fibers leave the sympathetic chain? (3)
- spinal nerves
- sympathetic nerves
- splanchnic nerves
spinal nerve route
making it through without synapse
exit ganglion by way of gray ramus and return to spinal nerve and travel the rest of the way to the target organ
splanchic nerve route
T5 to T12 pass through the ganglia without synapsing
What are the 3 major collateral ganglia in the abdominal aortic plexus?
- celiac
- superior mesenteric
- inferior mesenteric
adrenal glands
on top of the kidneys
parasympathetic division is called the _____
craniosacral division (brain to sacral region)
parasympathetic division has ____ preganglionic fibers which are found in the ___ ____and ____ postganglionic fibers
long; cranial nerves (3,7,9,10); short
___ ____ is less in the parasympathetic division than in the sympathetic division
neural divergence (wide spread effects)
enteric nervous system (3)
GUT
- nervous system of the digestive tract
- does not arise from the brainstem or spinal cord (no components in CNS)
- has own reflex arcs
megacolon
massive dilation of bowel accompanied by abdominal distension & chronic constipation (WE NEED FIBER)
hirschsprung disesase
hereditary defect causing absence of the enteric system that will not allow passage of feces
All autonomic fibers secrete either ____ or ____
ACh or NE
____ is secreted by all pregang neurons in both divisions and all postgang ____ divisions
ACh; parasympathetic
What are 2 types of cholinergic receptors?
muscarinic receptors (all cardiac muscles, smooth muscles,and gland cells) nicotonic receptors (all post gang neurons of ANS)
___ is secreted by nearly all ______ postgang neurons
NE; sympathetic
alpha adrenergic receptors
usually excitatory
beta adrenergic receptors
usually inhibitory
Which effects tend to last longer than the other?para or sym? why?
sympathetic; because Ach released by parasympathetics is broken down quickly in synapse
dual innervation
most viscera receive nerve fibers from both para and sympathetic divisions but don’t innervate an organ equally
dual innervation has ___ effects that oppose each other and ____ effects that produce a unified overall effect
antagonistic and cooperative
An example of a cooperative effect is?
saliva
What effector only receive sympathetic fibers
adrenal medulla
metics:____ while lytics:_____ sympathetic activity
enhance; suppress
in ANS the cerebral cortex
has an influence: anger, fear, anxiety
in ANS the hypothalamus
nuclei for primitive functions such as hunger, thirst, sex
in ANS midbrain, pons, and medulla oblongata
salivation, swallowing, bladder control
vasomotor tone
a baseline firing frequency of sympathetics that keeps vessels in state of partial constriction
increase firing frequency
vasoconstriction
decrease firing frequency
vasodilation
