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Neuroscience > Lecture #13 > Flashcards

Lecture #13 Flashcards

1
Q

describe the distribution of the sympathetic division:

A
  • preganglionic motor neurons in the spinal cord
  • preganglionic motor neurons in the intermediolateral region (send a relatively short axon that can exit the spinal cord using the same roots of voluntary motor neurons)
  • preganglionic neurons (paravertebral ganglia + pre vertebral ganglia)
  • celiac ganglion + two superior and inferior mesenteric ganglia
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2
Q

describe the organization of the parasympathetic system:

A

-preganglionic neurons are usually located in the anterior part of the spinal cord, in a region in the medulla and sacral region - closely in contact with the organs they innervate

  • post ganglionic motor neurons that send the short axon controlling the organ
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3
Q

what are the symptoms of Horners syndrome?

A

affects the sympathetic branch → decrease in diameter of the pupil, drooping of eyelids, sinking of the eyeball (enopthalmos)

sometimes symptoms involving the skin such as increased temperature, sweating, and flushing

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4
Q

what is a stellate ganglion?

A

when the axon enters the ganglion it turns 90 degrees toward the region that are more cranial and migrate up to innervate specific ganglionic motor neurons that are upstream in the T1 level

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5
Q

what occurs in Horner’s syndrome?

A

some of the ganglia from the superior cervival ganglion star to innervate the pupillary dilator muscle and therefore it is not possible to modulate the proper dilation of the pupillary muscle → causes miosis in the eyeball

often results from severe lesions in the cervical ganglia

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6
Q

which neurons release acetylcholine?

A

virtually all preganglionic motor neurons, all parasympathetic postganglionic neurons, and some sympathetic postganglionic neurons

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7
Q

what neurotransmitter do the postganglionic neurons in the sympathetic division release?

A

norepinephrine

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8
Q

what is often co-released with neurotransmitters?

A

biogenic amines at the same time in the synapses

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9
Q

how are neurotransmitters typically organized?

A

in vesicles - some are docked and ready to release the neurotransmitter in the cleft depending on the functionality of the specific neuron

typically a uniform population so the vesicles can only contain one specific neurotransmitter

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10
Q

how are neurotransmitters typically organized?

A

in vesicles - some are docked and ready to release the neurotransmitter in the cleft depending on the functionality of the specific neuron

typically a uniform population so the vesicles can only contain one specific neurotransmitter

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11
Q

how are neurotransmitters typically organized?

A

in vesicles - some are docked and ready to release the neurotransmitter in the cleft depending on the functionality of the specific neuron

typically a uniform population so the vesicles can only contain one specific neurotransmitter

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12
Q

why can a classical sympathetic post-ganglionic neuron express at the same time both nicotinic and muscarinic receptors?

A

the activation of the nicotinic receptor causes depolarization of the membrane and short depolarization, while the muscarinic activation (G-coupled protein receptor) can cause long-term transmission

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13
Q

why can a classical sympathetic post-ganglionic neuron express at the same time both nicotinic and muscarinic receptors?

A

the activation of the nicotinic receptor causes depolarization of the membrane and short depolarization, while the muscarinic activation (G-coupled protein receptor) can cause long-term transmission

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14
Q

how do the classical post-ganglionic sympathetic motor neurons that release norepinephine work?

A

the norepinephrine starts to activate ⍺1-adrenergic receptors that cause vasoconstriction

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15
Q

what is a beta blocker?

A

a small molecule that is able to regulate adrenergic receptors used to treat hypertension (Propranolol)

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16
Q

post-ganglionic motor neurons can release acetylcholine that interacts with what peptide?

A

the G-coupled muscarinic receptor and the vasoactive intestinal peptide (VIP)

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17
Q

in what situation do the post-ganglionic motor neurons release acetylcholine that interacts with VIP?

A

in the salivary glands it is important to regulate secretion

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18
Q

what is the primary action of muscarinic receptors in the autonomic ganglia?

A

to close the potassium channel → allows the neurons to become more sensitive to fire (because by blocking the K it means the mp starts to drift from the negative value to the values more positive and closer to the critical threshold making the neuron more excitable)

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19
Q

give an example of how an inotropic transmission works:

A

in the case of G-coupled protein receptors, we have a classical alpha-adrenergic receptor stimulated by norepinephrine, it involves the activation of the G protein cascade

there is also the activation of adenylate cyclase and therefore the production of cyclic AMP which is the second messenger

then there is the phosphorylation of the K channel and they start to become activated and increase the threshold o the sensitivity of the cell to firing

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20
Q

what is one of the most important functions of the autonomic system?

A

regulation of the cardiovascular system

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21
Q

what two things does the autonomic system monitor in the cardiovascular system?

A

barosensory: blood pressure

chemosensory: the percentage of oxygen and CO2 present in the blood

22
Q

where are baroreceptors usually located?

A

in the heart and are in close contact with the major blood vessels

23
Q

where are the chemoreceptors usually located?

A

carotid bodies: a small bunch of cells usually located at the bifurcation of the common carotid artery

24
Q

how do the chemoreceptors send information about oxygenation to the brain?

A

the information starts at these receptors and is sent to the visceral system regulating the heartbeat, and the vasoconstriction or vasodilation of arteries through the sympathetic and parasympathetic divisions

25
Q

which part of the brain is the cardiovascular information sent through the visceral sensory pathway?

A

pons

26
Q

what is the solitary nucleus?

A

a very long nucleus composed of thousands of neurons that is the final target of the sensory information coming from the heart

27
Q

where does the signal go from the solitary nucleus?

A

there’s a specific motor neuron sending short axons to the parasympathetic motor neuron located in the nucleus ambiguous which I snot far from the nucleus solitario and the autonomic division of nerve 10

28
Q

what occurs if there is an increase in blood pressure?

A

you start to stimulate the activity of the parasympathetic prep-ganglionic neurons in the nucleus ambiguous and nerve 10, while at the same time releasing acetylcholine causing a vasodilation and reduction of pressure

29
Q

what occurs if you have a drop in blood pressure?

A

you must increase the heartbeat and activation of the smooth muscle → a small neuron sends information to the thoracic pre-ganglionic motor neurons of the sympathetic division in the paravertebral ganglia

then there is a second motor neuron that can extend a relatively long axon innervating the smooth muscle causing an increase in the artery pressure

30
Q

what occurs if there is a fall in blood pressure due to blood loss?

A

parasympathetic system is rapidly inhibited, (because it induces the relaxation) and at the same time you have the activation of the sympathetic post-ganglionic terminal increasing the heartbeat and therefore cardiac contractility

because the sympathetic system also causes vasoconstriction, there is an increase of blood pressure and the norepinephrine released from the terminals of the synaptic ganglia can also act on the smooth muscle of the arterioles increasing the tone and therefore the pressure

31
Q

what system adjusts the blood pressure when we change positions?

A

sympathetic division → orthostatic hypotension regulation

32
Q

how does the orthostatic hypotension regulation system work?

A

sympathetic innervation of the heart arises from pre-ganglionic neurons in the mediolateral spinal cord start to release acetylocholine activating thoracic post-ganglionic neurons that innervate the heart

they release norepinephrine increasing the heart rate and at the same time releasing norepinephrine in the arteries inducing vasoconstriction = increasing blood pressure

32
Q

how does the orthostatic hypotension regulation system work?

A

sympathetic innervation of the heart arises from pre-ganglionic neurons in the mediolateral spinal cord start to release acetylocholine activating thoracic post-ganglionic neurons that innervate the heart

they release norepinephrine increasing the heart rate and at the same time releasing norepinephrine in the arteries inducing vasoconstriction = increasing blood pressure

32
Q

how does the orthostatic hypotension regulation system work?

A

sympathetic innervation of the heart arises from pre-ganglionic neurons in the mediolateral spinal cord start to release acetylocholine activating thoracic post-ganglionic neurons that innervate the heart

they release norepinephrine increasing the heart rate and at the same time releasing norepinephrine in the arteries inducing vasoconstriction = increasing blood pressure

33
Q

what is the term for bladder voiding?

A

micturition

34
Q

describe how the sympathetic division allows us to control the bladder:

A

innervates the smooth muscle → the thoracic segment pre-ganglionic neurons send axons to classical pre-vertebral ganglia

from the pre-vertebral ganglia we have the second motoneurons sending axons back towards the smooth muscles of the bladder and the sphincter

35
Q

what is the neurotransmitter released and the receptor triggered in bladder voiding?

A

sympathetic system = norepinephrine

β2-adrenergic receptor, and then the ⍺1-adrenergic receptor in the sphincter itself

36
Q

what two muscles must be relaxed for bladder voiding?

A

the internal and external sphincter

37
Q

what happens when we have too much volume in the bladder?

A

blockage of the sympathetic system and activation of the parasympathetic system → activation of the pre-ganglionic motoneurons followed by the release of norepinephrine causing smooth muscle relaxation because it interacts with β2-adrenergic receptor

activation of somatic neurons as well in the sacral branch to open the external sphincter

38
Q

when we must void the bladder what does the sensing system interact with in the pons?

A

Barrington’s nucleus

39
Q

what do the neurons that contribute to ocular function belong to?

A

Edinger-Westphal nucleus → send a very long axon reaching the ganglion, and from this the axons run in the pupil leading to the activation of the parasympathetic branch causing pupillary constriction

40
Q

why is motor innervation in sexual functions complex?

A

it is regulated by a cognitive / emotional / contextual clues occurring in the limbic forebrain

41
Q

in what route does information travel where there is penile sensation?

A

information runs through the classical dorsal route ganglia and enters the dorsal spinal cord having first contact with the motoneurons in the sacral spinal cord

information runs to the cerebral cortex and the limbic system

41
Q

in what route does information travel where there is penile sensation?

A

information runs through the classical dorsal route ganglia and enters the dorsal spinal cord having first contact with the motoneurons in the sacral spinal cord

information runs to the cerebral cortex and the limbic system

42
Q

the main signal activating penile erection comes from which division?

A

sympathetic cell division - not different from the one involved in bladder voiding

43
Q

the neurotransmitter released by the parasympathetic division is acetylcholine - what is the one exception?

A

penis → neurotransmitter released is nitric oxide (second neurotransmitter)

44
Q

what occurs when nitric oxide is released?

A

vasodilation of the smooth muscles (corpus cavernosum) causing an increase in total blood flow

at the same time we have sensory inputs that enter the spinal cord and interact with a complex array of cortical and subcortical nuclei

45
Q

what happens around the time or orgasm?

A

the activation of the sympathetic branch that can induce the constriction of the prostate gland that is fundamental for ejaculation

at the same time it induces the constriction of the smooth muscles in the pelvic floor that are fundamental for the release of sperm

46
Q

what does an overstimulation of the sympathetic branch cause in times of stress?

A

vasoconstriction of the corpus cavernosim and inhibits erection

47
Q

describe the voluntary portion of motoneuron control that is similar to bladder voiding:

A

fundamental for the pumping of the anterior sphincters and for ejaculation

regulation of both the sympathetic and parasympathetic branches as well as the voluntary system

Neuroscience (19 decks)

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