Flashcards in The Autonomic Nervous System Deck (64):
What are the 2 major components of the nervous system?
How do nerves transmit info to the effector cells?
What are the two ways nervous system is classified?
By physical location
How is the nervous system divided by physical location?
Central = brain and spinal cord
Peripheral = everything else
How is the nervous system divided by function?
Autonomic Nervous System
Somatic Nervous System
What does the Autonomic Nervous System do?
involves actions not under conscious control
controls visceral functions --> cardiac output, blood flow to vital organs, digestion
What does the Somatic Nervous System do?
Involves conscious functions
Movement, respiration, posture
How is the autonomic nervous system broken up?
Sympathetic = thoracolumbar
Parasympathetic = craniosacral
How does the autonomic nervous system exit the brain?
through preganglionic efferent nerve fibers
Where do the parasympathetic fibers exit the central nervous system?
exit through the cranial nerves and 3rd and 4th lumbar spinal nerves
Where do sympathetic fibers exit the central nervous system?
sympathetic fibers exit through thoracic and lumbar spinal nerves
Describe Efferent Nerves
Where do the preganglionic neurons originate and where do they go?
originate in the CNS and connect to ganglia in peripheral nervous system
What do postganglionic neurons do?
terminate on effector organs
What do the ganglia do?
act as relay stations to pass messages on to postganglionic nerves
What do afferent neurons do?
They regulate the autonomic nervous system by sensing actions and providing feedback to the CNS
bring info from effector organ to CNS
What are the neurotransmitters of the autonomic nervous system?
Which types of nerves release acetylcholine (ACh)?
cholinergic nerve fibers
ALL preganglionic efferent autonomic (sympathetic and parasympathetic) fibers
Somatic nerve fibers to skeletal muscles
Which types of nerves release norepinephrine?
adrenergic nerve fibers
MOST postganglionic sympathetic nerve fibers
What is the precursor molecule and enzyme that make ACh?
acetyl - CoA
Where is ACh synthesized in the nerve?
How is it stored in the nerve?
stored as packages of quanta in vesicles at the axon terminal
What stimulates the release of ACh?
What happens when ACh is released into the synaptic cleft?
binds to ACh - receptors
How is ACh action terminated?
Acetylcholinesterase (AChE) breaks down ACh --> choline and acetate
What happens if ACh isn't broken down?
continues to interact w/ receptors until it is broken down
Where are adrenergic nerve fibers found?
postganglionic neurons of the sympathetic nervous system
What do adrenergic nerve fibers do?
make adjustments in response to stressful situations
fight or flight
What are some of the actions of adrenergic nerve fibers?
increase HR and BP
mobilize energy stores
increase blood flow to skeletal muscles
divert blood flow from skin and internal organs
dilate pupils and bronchioles
Name the 3 ways norepinepherine is terminated?
metabolized by catalytic enzymes --> monoamine oxidase (MAO)
diffusion away from receptor site (then metabolized)
reuptake into terminal by norepinephrine transporter (NET) or other cells
What are receptors?
proteins that bind to endogenous molecules and then pass "message" to signaling proteins
What do agonists do?
mimic endogenous molecules that bind to receptors and produce signal
What do antagonists do?
they block signal
What are the two types of cholinergic receptors?
What are the 4 major adrenergic receptors?
alpha1 and alpha2 adrenoceptors
beta1 and beta2 adrenoceptors
Which system is the major target of the autonomic nervous system?
What are the CV effects of the parasympathetic nervous system?
decrease heart rate
What are the CV effects of the sympathetic nervous system?
alters periperal vascular resistance to manage BP
contraction force to manage cardiac output
renin production to manage renal blood flow
What is the point of the autonomic function?
prevent system from overstimulation
maintain effector organ functions w/ in a narrow window of tolerance
How is autonomic function controlled?
other integrated systems
How is autonomic function regulated presynaptically?
alpha2 receptors present on some nerve terminals
bind norepinephrine released from some nerves and decrease amount of norepinephrine from same neuron
Beta receptors will facilitate release of more norepinephrine
How is autonomic function regulated postsynaptically?
up or down regulate receptors
action of one receptor is affected by action of other receptors
Why does the body up or down regulate receptors?
in response to high or low activation from neurotransmitters
What are effector organs?
multiple receptor sites throughout the body
sensitive to adrenergic or cholinergic action
Are the actions of norepinephrine and acetylcholine opposing or synergistic?
Name the effects of the autonomic nervous system on the iris radial muscle
Sympathetic: contracts (pupilary dilation) --> alpha1 receptors
Name the effects of the autonomic nervous system on the iris circular muscle
Parasympathetic: Contracts (controls light entry and accommodation --> M3
Name the effects of the autonomic nervous system on the ciliary muscle
Sympathetic: Relaxes (allows for better focus on distance) --> Beta
Parasympathetic: Contrats (allows focus of near objects) --> M3
Name the effects of the autonomic nervous system on the sinoatrial node
Sympathetic: accelerates (increase HR - chronotropic) --> Beta1 and Beta2
Parasympathetic: decelerates (decrease HR) --> M2
Name the effects of the autonomic nervous system on the ectopic pacemakers
Sympathetic: acclerates (increases HR) --> Beta1 and Beta2
Name the effects of the autonomic nervous system on the Contractility
Sympathetic: increases (inotropic) --> Beta1 and Beta2
Parasympathetic: decreases --> M2
Name the effects of the autonomic nervous system on the blood vessels
Contract (vasocontriction; increase BP) --> alpha
Relaxes (vasodilation; decrease BP) --> Beta2
Name the effects of the autonomic nervous system on the Bronchiolar smooth muscle
Sympathetic: relaxes (open airways-bronchiodilation) --> Beta2
Parasympathetic: contracts (restricts airways -bronchoconstriction) --> M3
Name the effects of the autonomic nervous system on the smooth muscle walls of the GI
Sympathetic: relax (slows activity) --> alpha2 and beta2
parasympathetic: contract (increase activity) --> M3
Name the effects of the autonomic nervous system on the GI sphincters
Sympathetic: contract (blocks passage) --> alpha1
Parasympathetic: relax (opens passage) --> M3
Name the effects of the autonomic nervous system on GI secretion
Parasympathetic: increases --> M3
Name the effects of the autonomic nervous system on the bladder wall
Sympathetic: relaxes (prevents urinatin) --> Beta2
Parasympathetic: contracts (facilitates urination) --> M3
Name the effects of the autonomic nervous system on the genitourinary sphincter
Sympathetic: contracts (blocks urination) --> alpha1
Parasympathetic: relaxes (facilitates urination) --> M3
Name the effects of the autonomic nervous system on the uterus
Relaxes --> Beta2
Contracts --> alpha
Name the effects of the autonomic nervous system on the penis
Sympathetic: ejaculation --> alpha
Parasympethic: erection --> M3
Name the effects of the autonomic nervous system on the Liver
gluconeogenesis --> Beta2, alpha
glucogenolysis --> Beta2, alpha
Name the effects of the autonomic nervous system on fat cells
Sympathetic: Lipolysis --> Beta3
Name the effects of the autonomic nervous system on the Kidney
Sympathetic: Renin release --> Beta1