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Bio 201 test 4
bio 201 test 4, ASU
40
Biology
Undergraduate 2
05/03/2010

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Term
ANS Controls ...
Definition
glands
cardiac muscle
smooth muscle
regulates unconcious process that maintains homeostasis
– BP, body temperature, respiratory airflow
– Receptors detect internal stimuli -- stretch, etc
Term
biofeedback
Definition
concious control of ANS
Term
Visceral Reflexes
Definition
Unconscious, automatic responses to stimulation of
glands, cardiac or smooth muscle
Term
Receptors (ANS)
Definition
detect internal stimuli -- stretch, blood chemicals, etc.
Term
Afferent neurons
Definition
transmit sensory signals to interneurons in the CNS
Term
Efferent neurons
Definition
carry motor signals to effectors
– ANS is the efferent neurons of these reflex arcs
Term
Effectors
Definition
glands, smooth or cardiac muscle
– ANS modifies effector activity, rather than causing it
Term
ANS is made up of the efferent neurons of
reflex arcs
Definition
presynaptic neuron cell body located in CNS
– brain or spinal cord
• postsynaptic neuron cell body in peripheral ganglion
Term
Divisions of ANS
Definition
1. Sympathetic division (thorocolumbar division)
– “fight or flight”
– prepares body for physical activity
• increases heart rate, BP, airflow, blood glucose levels, etc
2. Parasympathetic division (craniosacral division)
– “rest & digest”
– calms many body functions and assists in bodily maintenance
– digestion and waste elimination
• Neither has universally excitatory or calming effects
Term
Autonomic Tone
Definition
• The normal rate of activity that represents the
balance of the two systems
• This balance shifts depending on the needs of
the body
Term
Anatomy of Sympathetic NS
Definition
• Origin of presynaptic neurons
– lateral horns of gray matter of thoracic to lumbar cord
– fibers exit via spinal nerves T1-L2 leading to….
• Sympathetic chain ganglia (paravertebral
ganglia)
– On average 3 cervical, 11 thoracic, 4 lumbar, 4 sacral
and 1 coccygeal ganglia
– 2 branches called white and gray communicating
rami suspend ganglia from spinal nerve
Term
Pathways of preganglionic fibers
Definition
Small myelinated preganglionic fibers travel
from the spinal nerve to the white
communicating ramus, then enter ganglia
– Some synapse immediately with a postganglionic fiber
– Some travel to higher or lower ganglia & synapse
– Some pass through chain without synapsing to reach
collateral ganglia via splanchnic nerves
• Unmyelinated postganglionic fibers leave
ganglia via gray communicating ramus
Term
Neuronal convergence
Definition
– each postganglionic cell may receive signals from
multiple preganglionic cells
Term
Neuronal divergence predominates
Definition
each preganglionic cell branches and synapses on
multiple postganglionic cells
– There are ~ 17 postganglionic neurons for every
preganglionic neuron in the SNS
– produces widespread effects on multiple organs
Term
Sympathetic Innervation
Definition
Signals to effectors leave the sympathetic chain by 3 routes
- spinal nerve route
- sympathetic nerve route
splanchnic nerve route
Term
Spinal nerve route
Definition
– Effectors in body wall are innervated by sympathetic fibers that
travel through spinal nerves
– Sweat glands, piloerector muscles, blood vessels of skin & skeletal
muscles
Term
Sympathetic nerve route
Definition
Effectors in head and thoracic cavity are innervated by fibers in
specific sympathetic nerves
– Sweat, salivary, nasal glands; blood vessels, heart, iris
Term
Splanchnic (visceral) nerve route
Definition
– Effectors in abdominal cavity are innervated by sympathetic fibers
in splanchnic nerves that lead to 3 major collateral ganglia
• celiac, superior and inferior mesenteric ganglion
Term
Adrenal Glands
Definition
Paired glands (1 left, 1 right)
• Sit on superior pole of each kidney
• Cortex (outer layer)
– secretes steroid hormones (androgens, cortisol, etc)
• Medulla
– modified sympathetic ganglion that secretes
neurotransmitters (in the form of hormones) into blood
rather than onto other neurons
• catecholamines - 85% epinephrine (aka adrenaline), 15%
norepinephrine
– complementary involvement in mass activation that
occurs during fight or flight reaction
Term
Paired glands (1 left, 1 right)
• Sit on superior pole of each kidney
• Cortex (outer layer)
– secretes steroid hormones (androgens, cortisol, etc)
• Medulla
– modified sympathetic ganglion that secretes
neurotransmitters (in the form of hormones) into blood
rather than onto other neurons
• catecholamines - 85% epinephrine (aka adrenaline), 15%
norepinephrine
– complementary involvement in mass activation that
occurs during fight or flight reaction
Definition
Origin of preganglionic fibers
– pons and medulla oblongata (cranial nerve nuclei)
– spinal cord segments S2-S4
• Pathways of preganglionic fibers
– cranial nerves III, VII, IX and X
• cardiac, pulmonary, esophageal, abdominal aortic plexus
– arising from sacral spinal cord
• pelvic splanchnic nerves & inferior hypogastric plexus
– enervate the pelvic and genital organs, regulating the emptying of the
urinary bladder and the rectum as well as sexual functions like
erection and orgasm
• Terminal ganglia in target organs due to normally
short postganglionic fibers
Term
Oculomotor nerve (III)
Definition
– narrows pupil
– focuses lens
Term
• Facial nerve (VII)
Definition
– tear, nasal and salivary
glands
Term
Glossopharyngeal (IX)
Definition
– parotid salivary gland
Term
• Vagus nerve (X)
Definition
– All major viscera as far as
proximal half of colon
– Cardiac, pulmonary, and
esophageal plexus
Term
Enteric Nervous System
Definition
• Nervous system of the digestive system
• Composed of 100 million neurons found in the
walls of the digestive tract
– no components in CNS!
• Has its own reflex arcs
• Regulates motility and secretion of digestive
enzymes and acid in concert with the ANS
Term
Neurotransmitters & Receptors
Definition
cholinergic fibers secrete ACh while adrenergic fibers
secrete NE (nor-epinephrine)
– only postganglionic sympathetic fibers are adrenergic
Term
Cholinergic Receptors
Definition
Acetylcholine binds to 2 classes of receptors
Nicotonic receptors
muscarnic receptors
Term
nicotonic receptors
Definition
• occur on all ANS postganglionic neurons, adrenal
medulla, on skeletal muscle
• excitatory when ACh binding occurs
Term
muscarnic receptors
Definition
• occur on all glands, smooth muscle & cardiac
muscle that receives cholinergic innervation
• either excitatory or inhibitory when ACh binding
occurs
Term
Adrenergic Receptors
Definition
2 categories of NE receptors
– alpha adrenergic receptors
• NE binding is excitatory
– beta adrenergic receptors
• NE binding is inhibitory
• Exceptions to normal results (EPSP or IPSP)
– existence of subclasses of each receptor type
• alpha 1 and 2; beta 1 and 2
• Function by means of 2nd messengers
– beta receptors activate cyclic AMP
– Alphas2 receptors suppress it
– Alpha1 receptors use calcium
Term
Dual Innervation
Definition
– antagonistic effects oppose each other
• exerted through dual innervation of same effector cells
– heart slowed down or speeded up
• exerted because each division innervates different cells
– pupillary dilator muscle & constrictor pupillae change pupil size
– Cooperative effects seen when 2 divisions act on
different effectors to produce a unified effect (salivation)
• parasympathetic NS increases salivary serous cell secretion
• sympathetic NS increases salivary mucous cell secretion
• Both divisions do not innervate an organ equally
Term
Control Without Dual Innervation
Definition
Adrenal medulla, arrector pili muscles, sweat
glands & many blood vessels receive only
sympathetic fibers
• Sympathetic tone is a baseline firing frequency
• provides partial constriction called vasomotor tone
– increase in firing frequency = vasoconstriction
decrease in firing frequency = vasodilation
• Vasomotor tone can shift blood flow from one
organ to another according to changing needs
– sympathetic stimulation increases blood to skeletal &
cardiac muscles -- reduced blood to skin
Term
Sympathetic and Vasomotor Tone
Definition
Sympathetic division
prioritizes blood vessels
to skeletal muscles and
heart in times of
emergency, stress, or
exercise
Blood vessels to skin
vasoconstrict to
minimize bleeding if
injury occurs during
stress or exercise
Term
Central Control of Autonomic
Function
Definition
ANS is regulated by several levels of the CNS
– Cerebral cortex
• influenced by our emotions
– Hypothalamus
• fight or flight responses originate here
– Reticular formation
• can respond directly to sensory input from cardiac,
vasomotor, & GI tract
– Spinal cord
• defecation & micturition reflexes are integrated in the
spinal cord
Term
Sympathomimetics
Definition
enhance sympathetic activity
– stimulate receptors or norepinephrine release
Term
Sympatholytics
Definition
suppress sympathetic activity
– inhibit norepinephrine release or block receptors
Term
Parasympathomimetics
Definition
enhance activity while
Parasympatholytics suppress activity
Term
Management of clinical depression
Definition
Prozac blocks reuptake of serotonin to prolong its moodelevating
effect
– MAO inhibitors interfere with breakdown of monoamine
neurotransmitters
• Caffeine competes with adenosine (inhibitory causing
sleepiness) by binding to its receptors
Term
A fractured spine, and subsequent severing of the spinal cord at C2 results in duadriplegia.
How is it that the patient's vital organs continue to function?
Definition
Vagus nerve
Term
Ephedrine and pseudoephedrine are the main ingredients in some very popular cold
remedies. Ephedrine and pseudoephedrine act to:
Definition
mimic the sympathetic division
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