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Saladin A&P Chapter 15

Terms in this set (48)

a motor nervous system that controls glands, cardiac muscle, and smooth muscle
autonomic nervous system (ANS)
ANS is also called
visceral nervous system
the primary target organs of the ANS are..
viscera of the thoracic and abdominopelvic cavities and some structures of the body wall
ANS is responsible for the body's
visceral reflexes
unconscious, automatic, stereotyped responses to stimulation
visceral reflexes
autonomic activity involves a visceral reflex arc that includes..
• receptors
• integrating center
• effector
1. Rise in BP
2. Signal from baroreceptor to medulla via glossopharyngeal nerve
3. Signal from cardiac center to heart via vagus nerves
4. Reduced heart rate and BP

A negative feedback loop. Maintains blood pressure homeostasis.
baroreflex
adapts the body in many ways for physical activity
"fight or flight"
sympathetic division
calms and relaxes the body
"resting and digesting"
parasympathetic division
sympathetic division and parasympathetic division both are..
active simultaneously
background rate of activity
autonomic tone
autonomic output pathway where a motor neuron in the brainstem or spinal cord issues a myelinated axon that reaches all the way to a skeletal muscle.
somatic pathways
the signal must travel across two nerve fibers to get to the target organ, and it must cross a synapse where these two neurons meet in an autonomic ganglion
autonomic pathways
first fiber of autonomic pathways that is myelinated and leads from a soma in the brainstem or spinal cord to the automatic ganglion
preganglionic fiber
second fiber of autonomic pathways that is unmyelinated
postganglionic fiber
ANS do not end by synapsing with a specific target cell, but with a chain of..
varicosities
rest like hats on the superior poles of the kidneys
adrenal (suprarenal) glands
outer rind of adrenal glands that secretes steroid hormones
adrenal cortex
the inner core of adrenal glands that is essentially a sympathetic ganglion
adrenal medulla
the sympathetic nervous system and adrenal medulla are so closely related in development and function that they are referred to collectively as..
sympathoadrenal system
hormones of adrenal glands
catecholamines
the digestive tract has a nervous system of its own called
enteric nervous system
regulates the motility if the esophagus, stomach, and intestines and the secretion of digestive enzymes and acid
enteric nervous system
_______ division accelerates the heartbeat and the _______ division slows it down
• sympathetic
• parasympathetic
contracts the wall of the urinary bladder but relaxes the internal urethral sphincter
parasympathetic division
2 fundamental reasons why different autonomic neurons have contrasting effects
1. sympathetic and parasympathetic fibers secrete different neurotransmitters
2. target cells respond in different ways even to the same neurotransmitter depending on what type of receptors they have for it
autonomic nerve fibers secrete...
1. acetylcholine (ACh)
2. norepinephrine (NE)
receptor secreted by the preganglionic fibers in both divisions and the post ganglionic fibers of the parasympathetic divisions
acetylcholine (ACh)
any nerve fiber that secretes ACh
cholinergic fiber
any receptor that binds ACh
cholinergic receptor
two categories of cholinergic receptors
1. muscarinic receptors
2. nicotinic receptors
all cardiac muscles, smooth muscles, and gland cells that receive cholinergic innervations have a..

some excited, some inhibited by ACh
muscarinic receptors
receptor that occurs at all synapses in the autonomic ganglia,where the preganglionic fibers stimulate the postganglionic cells

always excited by Ach
nicotinic receptors
neurotransmitter that is secreted by nearly all sympathetic post ganglionic fibers
norepineohrine (NE)
fibers that secrete norepineohrine
adrenergic fibers
receptors for norepineohrine
adrenergic receptors
two principle categories of NE receptors
α-adrenergic receptors
β-adrenergic receptors
NE receptors that have excitatory effects
α-adrenergic receptors
NE receptors that are usually inhibitory
β-adrenergic receptors
viscera that recieve nerve fibers from both the sympathetic and parasympathetic divisions
dual innervation
effects that oppose each other
antagonistic effects
effects when two divisions act on different effectors to produce a unified overall effect
cooperative effects
the adrenal medulla, piloerector muscles, sweat glands, and many blood vessels receive only
sympathetic fibers
most significant example of a control without dual innervation
regulation of blood pressure
vessels in state of partial constriction
vasomotor tone (sympathetic tone)
can shift blood flow from one organ to another according to the changing needs of the body
sympathetic control of vasomotor tone
ANS is influenced by CNS through:
• cerebral cortex
• hypothalamus
• midbrain, pons, and medulla oblongata
• spinal cord
Enteric Nervous System
In wall of esophagus, stomach, intestines.
100 million neurons—more than the spinal cord!
Coordinates motility and secretion of digestive tract.
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