Unit 3 - Autonomic Nervous System Flashcards
true or false: the autonomic nervous system carries out involuntary functions
true
what are the three key functions of the autonomic nervous system?
- maintenance of homeostasis
- activation of energy mechanisms (fight or flight)
- housekeeping functions (digestion)
what is the function of afferent neurons?
relay sensory information to the CNS
what is the function of efferent neurons?
relay motor commands from the CNS to target tissues
the efferent division of the autonomic nervous system is split into what two parts?
- somatic motor
- automatic motor
how many cranial nerves are there?
12
true or false: cranial nerves contain only efferent fibers
false. they have both afferent and efferent components
how many pairs of spinal nerves are there?
31
true or false: spinal nerves contain only afferent fibers
false. they have both afferent and efferent components
- single neuron
- single target
- single synapse
- always excitatory
these are characteristics of neurons from the:
somatic nervous system
- 2 neuron chain connected by a synapse
- multiple targets
- excitatory and inhibitory effects
these are characteristics of neurons from the:
autonomic nervous system
a cluster of neuron cell bodies outside the CNS
ganglion
in the parasympathetic nervous system, there is a ______ preganglionic fiber, and a ______ postganglionic fiber
long, short
in the sympathetic nervous system, there is a ______ preganglionic fiber, and a ______ postganglionic fiber?
short, long
the sympathetic nervous system is located in:
the thoracic and lumbar regions
a set of paired chains of interconnected ganglia that lie on either side of the vertebral coloumn
sympathetic trunk/chain
the sympathetic trunk is also known as the:
paravertebral ganglion
sympathetic ganglia located in front of the vertebral column, outside the symathetic chain, close to the viscera and arteries
collateral ganglion
in the sympathetic division of the ANS, a signal has three neural pathways it can travel through after passing through the ventral root. what are those three pathways?
1) synapse immediately with a postganglionic neuron in sympathetic ganglion
2) travel up or down the chain and synapse in ganglia at other levels
3) pass through chain without synapsing, continue to collateral ganglion as splanchnic nerve
two branches which connect a paravertebral ganglion to a spinal nerve
communicating rami
a branch of the sympathetic pathways by which a myelinated preganglionic fiber leaves the spinal nerve and enters a sympathetic ganglion
white rami
a branch of the sympathetic pathways by which unmyelinated postganglionic fibers leave the ganglion to re-enter the spinal nerve
grey rami
what effect does the sympathetic nervous system have on the eyes?
dilation of pupils; adjustment for far vision
what effect does the sympathetic nervous system have on the cardiovascular system?
increased heart rate and force of contraction
what effect does the sympathetic nervous system have on most of the arterioles and veins?
constriction
what effect does the sympathetic nervous system have on the skeletal muscle?
either constriction or dilation, depending on what neurotransmitter is released
what effect does the sympathetic nervous system have on the lungs?
dilation of bronchioles and inhibition of mucus secretion
what effect does the sympathetic nervous system have on the digestive tract?
decreased motility and inhibition of degestive secretions
what effect does the sympathetic nervous system have on the adrenal medulla?
stimulation of epinephrine and norepinephrine secretion
what effect does the sympathetic nervous system have on the sweat glands?
stimulation of secretion (most - thermoregulation)
what effect does the sympathetic nervous system have on the salivary glands?
stimulation of small volume of thick saliva which is rich in mucus
what effect does the sympathetic nervous system have on the bladder?
prevents voiding
what effect does the sympathetic nervous system have on the genitals?
males: emission
females: uterus contraction
the adrenal medulla is innervated by:
sympathetic preganglionic neurons
the adrenal medulla releases _____% epinephrine and _____% nerepinephrine
80, 20
true or false: epinephrine and norepinephrine are only neurotransmitters
false, they can be either neurotransmitters or hormones depending on how and where they are released
why are the effects of epinephrine and norepinephrine so long lasting?
it takes a while for them to be recycled back to the liver
the parasympathetic nervous system is located in the:
brain stem (cranium) and sacral regions
what nerve carries 75% of parasympathetic innervation?
vagus nerve (AKA the tenth cranial nerve)
a parasympathetic ganglion situated on or close to an innervated organ, the site where preganglionic nerve fibers terminate
terminal ganglion
what effect does the parasympathetic nervous system have on the eyes?
constriction of pupil; adjustment for near vision
what effect does the parasympathetic nervous system have on the cardiovascular system?
decrease heart rate and force of contraction to atria only
what effect does the parasympathetic nervous system have on the blood vessels?
almost no innervation (except to the genitals)
what effect does the parasympathetic nervous system have on the lungs?
constriction of bronchioles, stimulation of mucus secretion
what effect does the parasympathetic nervous system have on the digestive tract?
increased motility, stimulation of digestive secretion
what effect does the parasympathetic nervous system have on the adrenal medulla?
none
what effect does the parasympathetic nervous system have on the sweat glands?
none
what effect does the parasympathetic nervous system have on the salivary glands?
stimulation of a large volume of watery, enzyme rich saliva
what effect does the parasympathetic nervous system have on the bladder
voids the bladder
what effect does the parasympathetic nervous system have on the genitals?
males: erection
the background level of activity maintained by both sympathetic and parasympathetic divisions
autonomic tone
balance between sympathetic tone and parasympathetic tone shifts in accordance with:
the body’s needs
the sympathetic nervous system dominates during the _________ response, and the parasympathetic nervous system dominates during the _________ response
fight or flight, rest and digest
what is dual innervation?
the idea that most body organs receive both sympathetic and parasympathetic innervation
what are the exceptions to dual innervation?
adrenal medulla, most blood vessels, and sweat glands. they receive only sympathetic stimulation
what is an antagonistic effect?
when there are opposing effects in the autonomic nervous system.
what is a cooperative effect?
when the sympathetic and parasympathetic nervous system work together
chains of swellings along the branches of a postganglionic fiber; contain synaptic vesicles which release neurotramsmitters
varicosity
- found at all autonomic ganglia
- parasympathetic postganglionic endings
- a few sympathetic postganglionic endings
these area characteristics of the neurotransmitter:
acetylcholine (ACh)
- mostly sympathetic postganglionic endings
- released from the adrenal medulla
- can also be a hormone
these are characteristics of the neurotransmitter:
norepinephrine/epinephrine
what are the two main types of cholinergic receptors?
nicotinic and muscarinic
- found on the postsynaptic cell bodies in all autonomic ganglia
- ionotropic
nicotinic receptors (Nn)
what does it mean to be ionotropic?
receptors are also ligand-gated ion channels
- found on effector cell membranes (smooth muscle, cardiac musle, glands),
- blocked by atropine
- metabotropic
muscarinic receptors
what does it mean to be metabotropic?
binding of NE/E or ACh causes excitation or inhibition of target through G-protein coupled mechanism
- bind NE/E
- found on effector cell membranes (smooth muscle, cardiac muscle, glands)
- blocked by propanolol
- metabotropic
adrenergenic receptors
the binding of ACh to _______ receptors and NE/E to _______ receptors produces response through G-protein coupled mechanism
muscarinic, adrenergic
numerous presynaptic neurons form synapses with a single postsynaptic neuron
convergence
a small number of presynaptic neurons form synapses with a large number of postsynaptic neurons
divergence
the sympathetic nervous system exhibits a higher degree of _____ than the parasympathetic system
divergence
what are the three main integrating centers for the autonomic nervous system?
the spinal chord, medulla oblongata, and hypothalamus
integrates autonomic reflexes for things like urination and defacation (where the brain can be trained to influence these reflexes)
spinal chord
contains major ANS reflex centers for cardiovascular, respiratory, and digestive activity
medulla oblongata (brainstem)
integration and command center for autonomic functions; temperature regulation
hypothalamus