Flashcards in ANS Ch 16 Deck (45):
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ANS
System of motor neurons that innervates smooth and cardiac muscles and glands. Also called involuntary or visceral motor system.
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Two neuron chain
ANS uses two neurons to reach the effector unlike the CNS that uses only one
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Preganglionic neuron
First neuron whose body lies lies within the brain or spinal cord, it synapses with the second motor neuron.
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Post ganglioninc neuron
Second motor neuron whose cell body is within the autonomic ganglion outside the CNS.
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2 autonomic neurotransmitters
Acetylcholine
Epi and Nor Epi
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Autonomic postganglionic fibers release?
Epi and Nor Epi
Secreted by most sympathetic fibers
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Parasympathetic fibers release
ACh
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Dual Innervation
Two divisions of the ANS--sympathetic and parasympathetic--balance each other out
Some organs only receive sympathetic stimulation but vital organs have both.
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Parasympathetic
Rest and digest:
Craniosacral: originate in brain and sacrum
Long preganglion short post ganglion fibers
Ganglion are close to organ served
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Sympathetic
Fight or flight:
Thoracolumbar: originate in thoracic and lumbar
Short preganglion and long post ganglion fibers
Ganglion are close to spinal cord
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Cranial Part
Oculomotor (III)
Facial (VII)
Glossopharyngeal (IX)
Vagus (X)
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Oculomotor nerve
Innervated the smooth muscles of the eye that causes the pupil to constrict and lens to bulge. Synapse in the ciliary ganglia
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Facial nerves
Activate nasal glands and lacrimal glands: pterygopalatine ganglia
Stimulate sublingual salivary glands: submandibular ganglia
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Glossopharyngeal nerves
Synapse in the otic ganglia. Activate parotid salivary glands anterior to the ears
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Vagus Nerve
Account for 75% or preganglionic parasympathetic fibers and innervate virtually every thoracic and abdominal oregan
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Sacral Part
Serves pelvic organs and distal half of the intestines. S1-S4 forn the pelvic splanchnic nerves.
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Sympathetic Division
Arise from T1 - L2,
Thoracolumbar division
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3 locations of sympathetic ganglionic neurons
Sympathetic chain ganglia (paravertebral)
Collateral ganglia (prevertebral)
Adrenal medulla (release neurotransmitters into the blood stream)
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Cholinergic fibers
Fibers that release ACh, effects are always excititory
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Adernergic fibers
Fibers that release NE,
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Cholinergic receptors
ACh binding receptors
Nicotinic
Muscarinic
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Nicotinic Receptors
Ach receptor
Affects are always stimulatory
Found on all postganglionid neurons both sympathetic and parasymathetic
Neuromuscular junctions
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Muscarinic Receptors
Ach receptor
Either inhibitory or stimulatory
Cardiac=slows
Smoth muscle=increases
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Adenergic receptors
NE Binding Receptors
Alpha
Beta
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NE and Epinephrine
Can be either excitatory or inhibitory
depending on target organ
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Sympathetic or vosomotor tone
Partial continual blood vessal constriction, dilate slightly and constrict slightly to maintain BP
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Parasympetheitc tone
Slows heart rate and dictates normal activity in the digestive and urinary tracts
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Uniquely sympathetic functions
Thermoregulatory responce to heat
Release of Renin from Kidneys
Metobolic rate regulation
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Localized affects
Parasympatheitc only has localized affects
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Localized and Diffuse affects
Parasympathetic is both
NE is not hydrolysed as fast as ACh
NE and Epinephrine are released into the boold streem by the Adrenal glands and have a longer lasting effect.
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Brain stem and spinal cord controls
Most direct influence over ANS
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Hypothalammus
"Boss"
Acting through the ANS it coordinated heart activity, BP, body temp, water ballance and endocrine activity. When there is an emotional sterss signal from limbic system the hypothalamas activates the ANS
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Bio Feedback
Becoming aware of physiological conditions with the goal of continual influence
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Visceral relexes
Have two neurons in motor componant
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Alpha
a 1 are the most common: stimulate G protein activation and cause a realease of intracellular calcium from ER
a2 results with lowering cyclic - AMP in the cytoplasm
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Beta
Effects skeletal muscles, heart, lungs, and liver.
G protein activation increases the cyclic- AMP in the cytoplasm
B1: increases metabolic activity
B2: causes inhibition respiratory passageways dilate
B3: lipolysis
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3 collateral ganglia
ciliac
superior mesenteric
inferior mesenteric
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Sympathetic Division Summary
2 sets of chain ganglia- on each side of spinal cord
3 collateral ganglia- one anterior and two to the adrenal medulla
Preganglionic fibers are short
Post ganglionic fibers are longer
All preganglionic neurons release Ach
Most post ganglionic neurons release NE but a few release Ach or NO.
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Two types of parasympathetic ganglia
Terminal: located near the target tissue
Intramural: embedded in the target tissue
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4 cranial ganglia of the parasympathetic
Pterygopalatine
Ciliary
Submandibulr
Otic
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Summary of the Parasympathetic Division
Visceral motor nuclei associated with cranial nerves III, VII, IX and X and sacral segments S1-S4
Ganglia are located proximal or in the target organ
All parasympathetic neurons are cholinergic
Contain either Nicotinic receptors or Muscarinic receptors (excitement of inhibition)
Stimulation is breif and restricted to specific organs
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6 autonomic plexus'
cardiac
pulmonary
esophageal
ciliac
inferior mesenteric
hypogastric
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Autonomic tone
Background level of activity in which both sympathetic and parasympathetic divisions innervate. This provides a grater range of control options because of the opposing effects of the two systems. Small amounts of Ach and NE are released contimuously.
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Visceral reflex arc
Consists of a receptor, a sensory neuron, a processing center (one or more interneurons) and two visceral motor neurons.
Long reflex: the processing step involves an interneuron within the CNS
Short reflex: Bypass the CNS - synapse in autonomic ganglia outside the spinal cord
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