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143 Cards in this Set

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Where do preganglionic neurons of the sympathetic NS originate?
T1-T12; L1-L3 (or just T1-L3) (throacolumbar region)
Where do preganglionic neurons of the parasympathetic NS originate?
S2-S4 (craniosacral region) and in the nuclei of cranial nerves
Where do preganglionic fibers syjnapse in the adrenal gland?
in the chromaffin cells of the adrenal medulla
Notes on Chromaffin
Chromaffin cells of the adrenal medulla are innervated by the splanchnic nerve and secrete adrenaline, noradrenaline, and enkephalin into the bloodstream. As such, they play an important role in the fight-or-flight response. They are also referred to as granules and this is where the enzyme dopamine-hydroxylase catalyzes the conversion of dopamine to norepinephrine.
What do chromaffin cells do?
secrete epinephrine (80%) and norepinephrine (20%) into the circulation
What is pheochromocytoma?
tumor of the medullary gland --> over secretion of catecholamines --> increased VMA levels (VMA is found in vanilla ice cream)
what is the NT of adrenergic neurons?
NorEpi
What is the NT of cholinergic neurons?
ACh
What are some types of nonadrenergic and noncholinergic neurons, and what do they secrete?
some postganglionic parasympathetic neurons of the GI tract
- secrete substance P, vasoactive intestinal peptide (VIP), or NO
Give the chart for NT in ganglion for sympathetic and parasympathetic neurons and the same thing for the effector organs
ACh for symp and para in ganglion
NorEpi for symp and ACh for para in effetor organs
(one exception: Sweat glands (Sympathetic effector organ) uses ACh
What is the receptor type at the effector organ for parasympathetic neurons?
Muscarinic
What is the receptor type at the effector organ for sympathetic neurons?
a1, a2, b1, b2
What is the receptor type at the effector organ for somatic (PNS) neurons?
nicotinic
Where do you find alpha 1 receptors?
- vascular smooth muscle of skin and splanchinc regions
- GI and bladder sphincters, and - radial muscle of iris
What are the effects of ligand binding to alpha 1 receptors?
excitation (contraction or constriction)
What is a Jacksonian Seizure?
Jacksonian seizures are initiated with abnormal electrical activity within the primary motor cortex. They are unique in that they travel through the primary motor cortex in succession, affecting the corresponding muscles, often beginning with the fingers. This is felt as a tingling sensation. It then affects the hand and moves on to more proximal areas. Symptoms often associated with a Jacksonian seizure are sudden head and eye movements, tingling, numbness, smacking of the lips, and sudden muscle contractions. Most of the time any one of these actions can be seen as normal movements, without being associated with the seizure occurring. They occur at no particular moment and last only briefly.
What is the function of white fat?
Most adipose tissue is white, the focus of this review. White adipose tissue serves three functions: heat insulation, mechanical cushion, and most importantly, a source of energy.
What is the function of brown fat?
Its primary purpose is to generate body heat. In contrast to white adipocytes (fat cells), which contain a single, large fat vacuole, brown adipocytes contain several smaller vacuoles and a much higher number of mitochondria. Brown fat also contains more capillaries since it has a greater need for oxygen than most tissues.
What are the three divisions of the autonomic nervous system?
1. sympathetic
2. parasympathetic
3. enteric
What are the two nervous system branches?
1. autonomic nervous system
2. somatic nervous system
Where are the preganglionic neurons of the sypathetic nervous system found?
T1-L3
Where are the preganglionic neurons of the parasympathetic NS found?
- nuclei of cranial nerves
- S2-S4
IS the Adrenal medulla a ganglion of the sympathetic or parasympathetic NS?
Sympathetic NS
Where do preganglionic fibers synapse to in the adrenal medulla?
Chormaffin cells
WHat do chromaffin cells secrete?
80% epi
20% norepi
Where are a1 receptors found?
-vascular smooth mucle of skin and splanchnic regions
- GI sphincters
- bladder sphincters
- radial muscle of iris
What do a1 receptors do?
produce excitation (contraction/constriction)
What do a1 receptors respond to?
equally sensitive to eoorepi and epi, but only norepi is released in high enough concentrations
What is the mechanism of action of a1 receptors?
Gq protein stimulates phospholiase C --> increased IP3 and intracellular Ca
Where are a2 receptors found?
- presynaptic nerver terminals
- platelets
- fat cells
- walls of the GI tract
What do a2 receptors do?
inhition (relaxation/dilation)
What is the mechanism of action of a2 receptors:
Gi protein inhibits adenylate cyclase and decreases levels of cAMP
Where are B1 receptors found?
- SA node
- AV node
- ventricular muscle of heart
What do B1 receptors do?
produce excitation
- increase HR
- increase conduction velocity
- increase contractility
What are B1 receptors sensisitive to?
-both norepi and epi and are more sensitive than a1 receptors
What is the mechanism of action of B1 receptors?
Gs protein stimulates adenylate cyclase and increases cAMP
Where are B2 receptors found?
- vascular smooth muscle of skeletal muscle, bronchial smooth muscle, and walls of GI tract and bladder
What do B2 receptors do?
relaxation (dilation/relaxation)
What do B2 receptors respond to?
more sensitive to epi than to norepi
more sensitive to epi than a1 receptors
What is the mechanism of action of B2 receptors?
Gs protein stimulates adenylate cyclase and increases cAMP
Where are nicotinic receptors found?
- autonomic ganglion
- neuromuscular junction
- adrenal medulla
What are nicotinic receptors activate by?
- Ach
- nicotine
What are the actions of nicotonic receptors?
- activation
- binds to alpha subunit and allows passage of Na and K
What are nicotinic receptors blocked by?
- ganglionic blockers (hexamethonium)
What is hexamethonium?
Hexamethonium is an nAch receptor antagonist which acts in autonomic ganglia by preventing the acetylcholine molecules from binding to the site of the cholinergic receptor. It has no effect on the muscarinic acetylcholine receptors, or mAChRs.
Where does hexamethonium act?
at the autonomic ganglia, but not at the neuromuscular junction
Name the types of muscarinic receptors and where they're found
M2: heart
M3: smooth muscle and glands
How do muscarinic receptors act in the heart?
are inhibitory:
decreased HR
decreased condiction velocity in AV node
How do muscarinic receptors act at the smooth muscle and glands?
excitatory:
- increased GI motility
- increased secretion
What activates muscarinic receptors?
ACh and muscarine
What blocks muscarinic receptors?
atropine
How do muscarinic receptors act on the Heart?
AT the SA node, Gi protein inhibits adenylate cyclase, whcih leads to opening of the K+ channels. This slows the rate of spontaneous Phase 4 depolarization and decreases heart rate
How do muscarinic receptors act on the smooth muscles and glands?
Gq protein stimulates phospholipase C increases IP3 and intracellular Ca2+
Name the autonomic centers in the medulla
1. vasomotor center
2. respiratory center
3. swallowing, coughing, and vomiting centers
Name the autonomic centers in the pons
pneumotaxic center
Name the autonomic centers in the midbrain
micturation center (urination)
name the autonomic centers in the hypothalamus
- temperature regulation center
- thirst and food intake regulatory centers
Name the 5 mechanoreceptors
1. Pacinian corpuscles
2. joint receptors
3. stretch receptors in muscle
4. hair cells in auditory and vestibular systems
5. baroreceptors in carotid sinus
Name the 4 chemoreceptors
1. olfactory receptors
2. taste receptors
3. osmoreceptors
4. carotid body O2 receptors
Give an example of a slowly adapting, or tonic receptors
muscle spindle.
- responds repetitively to a prolonged stimulus
Give an example of a rapidly adapting or phasic receptor
Pacinian corpuscle
- detects the onset and offset of a stimulus
Where are cell bodies of the primary afferent neurons found?
- dorsal root
- spinal cord ganglion
What does the dorsal column sense?
- fine touch
- pressure
- two-point discrimination
- vibration
- proprioception
What types of fibers make up the dorsal column system?
group II fibers
Describe the course of the dorsal column
cell bodies are in dorsal root.
- axions ascend ipsilaterally to the nucleus gracilis and nucleus cuneatus of the medulla
- cross at the medulla
- synapse at the VPL
What does the anterolateral system sense?
- temperature
- pain
- light touch
What types of fibers make up the anterolateral system?
- group III and IV fibers
- enter the spinal cord and termiante in the dorsal horn
Describe the course of the anterolateral system.
second order neurons cross the midline at the anterolateral quadrant of the spinal cord
- ascend to the contralateral VPL
What happens whn you have destruction of the thalamic nuclei?
loss of sensation from the contralateral side of the body
Which are the main somatosensory areas of the cortex?
SI and SII
Pacinian corpuscle: description
onion like structions in the subcutaneous kins (surroundeing unmyelinated nerve endings)
pacinian corpuscles: sensation carried
vibration, tapping
pacinian corpuscles: adaptation
rapid
meissner's corpuscle: description
found in non-hairy skin
meissner's corpuscle: sensation carried
velocity
meissner's corpuscles: adaptation
rapid
Ruffini's corpuscle: description
enclapsulated
ruffini's corpuscle: sensation carried
pressure
ruffini's corpuscle: adaptation
slowly adapting
merkel's disk: description
transducer is on epithelial cells
merkel's disk: sensation carried
location
merkel's disk: adaptation
slow
what is the NT for nociception?
substance P
How do you inhibit substance P release?
opiods
how is fast pain transmitted?
by group II fibers
how is slow pain transmitted?
by C fibers
- throbbing, aching
- poorly localized
how is refractive power of a lens measured?
in diopters
- the reciprocoal of the focal distance
emmetropia
normal
- light focuses on retina
hypetropia
farsighted
- light focuses behind retina
- corrected by convex lens
myopia
nearsighted
- light focuses in front of the retina
- corrected by biconcave lens
astigmatism
curvature of lens is not uniform.
- corrected by cylindric lens
presbyopia
loss of accommodation power of lens
- comes with aging
What do pigment epithelial cells do?
- absorb stray light and prevent light scatter
- convert 11-cis retinal to all-trans retinal
what do bipolar cells synapse to?
receptor cells synapse to one bipolar cell, which then synapses to single ganglion cell
What is the ratio of cones to bipolar cells in the fovea?
1:1
What other cell types form local circuits with bipolar cells?
horizontal and amacrine cells
what cells are the output of the retina?
ganglion cells
- they form the optic nerve!
where do axons of the gaglion celsl go?
form the optic nerve and optic tract. end in the lateral geniculate body of the thalamus
What is rhodopsin composed of?
1. opsin (G-protein coupled receptor)
2. retinal (aldehyde of vit A)
what is photoisomerization?
UV converting 11-cis retinal to all-trans retinaa
what is one of the metabolites formed from photoisomerization?
metarhodopsin II
what happens during vit A deficiency?
night blindness
what does metarhodopsin II activate?
transducin (a G-protein)
what does transducin activate?
phosophodiesterase
what does the phosphodiesterase do during the phototransduction cascade?
converts cGMP to 5'-GMP and cGMP levels decrease
what happens with decreased cGMP levels during the phototransduction cascade?
- closure of Na channels -> hyperpolarization
What do simple cells respond to?
bars of light
pay attention to origentation and position
what do complex cells respond to?
moving bars or edges of light with the correct orientation
What do hypercomplex cells respond to?
lines with a particular length
- curves and angles
What is frequency measured in?
Hz
What is sound intensity measured in?
decibels
dB = 20log P/P_o

P = sound pressure being measured
P_o= reference pressure measured at the threshold frequency
what do you find in the middle ear?
- tympanic membrane
- auditory ossicles (M,I,S)
What do you find in the inner ear?
- semicircular canals
- cochlea
- vestibule
consists of bony and membraneous labyrinth
what are the three types of scala, and what types of fluid fill them?
scala vestibuli
scala media
scala tympani

Na - perilymph
K - endolymph
Na- perilymph
Where do you find the organ of corti?
basilar membrane
What types of cells are found in the organ of corti?
inner and outer hair cells. the cells have cilia that are embedded in the tectorial membrane
describe inner hair cells
- arranged in a single row
- few in number
describe outer hair cells
- arranged in parallel rows
- many in number
what do you find in the spiral ganglion?
cell bodies of the CN VIII
what happens when the cilia bend on the hair cells?
K+ conductance changes. depolarization in one direction and hyperpolarization in the other direction
what results from the oscillating potential cuased by the bending of cilia?
cochlear microphonic potential
which part of the basilar membrane detects high frequency sounds?
base of basilar membrane
which part of the basilar membrane detects low frequency sounds?
apex of the basilar membrane
Describe the vestibular organ
- 3 semicircular canals
- utricle
- saccule
what detects angular acceleration or rotation?
semicircular canals
what detects linear acceleration?
utricle and saccule
what structure contains the embedded ciliar of the receptor hair cells of the vestibular organ?
cupula
what is the single long cilium called?
kinocilium
what are the smaller cilia on hair cells called?
stereocilia
in which direction does nystagmus occur?
same direction as head movement
in which direction does postrotatory nystagmus occur?
in the opposite direction of the head rotation
what types of fibers make up the CN I nerve?
unmyelinated C fibers
- among the smallest and slowest of the nervous system
what else innervates the olfactory epithelium other than CN I
- CN V
- detects noxious and painful stimuli (e.g. ammonia)
hyposmia
- reduced sense of smell
anosmia
- no sense of smell
which are the second order neurons of the olfactory pathway?
Mitral cells
what is the output of the mitral cells?
olfactory tract --> piriform cortex
describe the signal transduction of olfaction
odorant molecules bind to olfacotry receptor proteins on the cilia of the olfactory reeceptor cells
- G_olf is activate --> activates adenylate cyclase
- increase in intracellular cAMP opens Na channes --> depolarizing receptor potietial
where are taste receptor cells found?
on taste buds that are found on papillae
describe the anterior 2/3 of the tongue
- fungiform papillae
- salty and sweet
- innervated by CN VII (chorda tympani)
describe the posterior 1/3 of the tongue
- circumvallate and foliate papillae
- sour and bitter
- CN IX (glossopharyngeal)
what is the back of the throat innervated by?
CN X
describe the taste pathway
CN VII, IX, and X enter the medulla
- ascend the solitary tract
- synapse at the solitary nucleus
- project to the VPM and then to the taste cortex