NEUR533 - Wk1 - chemical control Flashcards
What cells stimulate oxytocin and vasopressin?
Mangocellular cells in the hypothalamas
What 2 neurohormones come from the posterior pituitary gland?
Oxytocin
Vasopressin
What cells within the hypothalamus regulate anterior pituitary lobe homeostasis?
Parvocellular cells
What do preganglionic neurons release onto muscaniric and nicotinic receptors?
Achetylcholine
What does the periventricular zone connect to?
The brainstem
Spinal cord nuclei
Nucleus of solitary tract
What is the function of solitary nucleus?
Sensory internal organ info integration
Coordinates output to autonomic brain stem nuclei
Preganglionic neurotransmitters: ACh binds to nAChR evoking fast or slow EPSP?
Fast
Ganglionic Ach activates mAChR causing _____ EPSPs and IPSPs?
Slow
Where does the substantia nigra dopaminergic neurons send dopamine primarily?
To the striatum
Where does the ventral tegmental area neurons send dopamine primarily?
Frontal lobe
What do parvocellular neuroscretory cells of the hypothalamus secrete hypophysiotropc hormones into?
Specialized hypothalamo-pituitary portal capillary beds (anterior pituitary)
How many seconds does CRH take to stimulate the anterior pituitary release of ACTH?
estimated 15 seconds
What is the primary transmitter of peripheral autonomic neurons?
acetylcholine ACh
What do pregnanglionic neurons of both sympathetic and parasympathetic divisions release?
ACh
When ACh binds to a nictonic receptor for EPSP is it fast or slow?
fast
muscanaric ACh receptors (mAChR) are what type of receptor?
a. Metabotropic (G-coupled)
muscanaric ACh receptors (mAChR) cause what affect?
Opening and closing of ion channels
What affect do postganglionic neurotransmitters have of the autonomic motor neurons?
Induces/triggers glandular secretion, sphincter control
What is the main neurotransmitter of the sympathetic postganglionic division?
norepinephrine (NE)
Whats the main neurotransmitter released by the postganglionic PNS?
ACh
What are the 4 neurotransmitters that regulate diffuse modulatory systems?
- Dopamine
- Serotonin
- Acetylcholine
- Norepinephrine
Why are the 4 neurotransmitters key for diffuse modulatory systematic mechanisms?
Metabotropic G-protein coupled receptors
What are key features of diffuse modulatory system neurons?
- Small, core set of neurons
- Cell bodies in brainstem (not cortical)
- Diffuse neurotransmitter release
- Widespread influence
Noradrenergic locus coeruleus USES WHAT NEUROTRANSMITTER?
Norepinephrine
What is the origin, target and activation of the noradrenergic locus coeruleus?
Origin: pons
Target: most of the CNS
Activated by: New, unexpected, nonpainful sensory stimuli
What is the Locus Coeruleus involved in?
- Attention
- Arousal
- Circaidian rythm
- Learning/memory
- Pain
- Mood
- Brain metabolism
Where are the serotonergic raphe nuclei located?
Pons and medulla
What system is the serotonergic raphe nuclei part of?
Ascending reitcular activating system
What is the serotonergic raphe nuclei involved in?
- Sleep/wake cycle
- Mood
- ## Most active during wakefulness
How many estimated synaptic connections can one Locus Coeruleus neuron make?
250,000 synpases
Where does the nigrostriatia dopamine system originate?
Substantia Nigra pars compacta (midbrain)
What are the key targes of the nigrostriatal dopamine system?
- Dorsal striatum (caudate/putamen)
What is the nigrostriatal dopamine system involved in?
- Movement
What is the origin of the mesolimbic dopamine system?
- Ventral tegmental area (midbrain)
What are the targets of the mesolimbic dopamine system?
- Ventral striatum (nucleus accumbens)
- Frontal cortex
What are the key involvements of the mesolimbic dopamine system
- Reward
- Reinforcement
- (food, water, sex, accomplishments)
- Addiction is associated with overstimulation of this system
What is the origin of the cholinergic basal forebrain system?
Basal forebrain
(Medial septal nuclei)
+ Basal nucleus of Meynert
What does the cholinergic basal forebrain system target?
- Cerebral cortex
- Hippocampus
What is the cholinergic basal forebrain ssystem involved in?
- Circadian
- Learning/memory
Where is the origin of the cholinergic brainstem system?
Ponomesencephalo-tegmental complex
What is the target of the pontomesencephalo-tegmental complex cholinergic system?
Dorsal thalamus
What is the pontomesencephalo-tegmental complex involved in?
Swedish scientists Nils-Åke Hillarp
and Bengt Falck developed a histochemical method, called…..
formaldehyde-induced fluorescence, which caused mono- amines (NE, dopamine, and serotonin) to fluoresce when il- luminated with the appropriate wavelength of light.
The effect of locus coeruleus stimulation was lost when NE was depleted using inhibitors of tyrosine hydroxylase, or eradicated with 6-hydroxydopamine.
In many instances, the transmitter defines the system. For example, in the peripheral nervous system, we can use the words “noradrenergic” and “sympathetic” interchangeably.
In many instances, the transmitter defines the system. For example, in the peripheral nervous system, we can use the words “noradrenergic” and “sympathetic” interchangeably. The same thing goes for “raphe” and “serotonin” in the forebrain, and “substantia nigra” and “dopamine” in the basal ganglia.
Patterns of communication in the nervous system
Each side of the hypo- thalamus has three functional zones: lateral,_____, and periventricular
medial
Zones of the hypothalamus
Magnocellular neurosecretory cells of the hypothalamus.
The largest of the hy- pothalamic neurosecretory cells, magnocellular neurosecretory cells, extend axons down the stalk of the pituitary and into the__________ lobe
posterior
Magnocellular neurosecretory cells secrete_____________ and______________ directly into capillaries in the posterior lobe of the pituitary.
oxytocin
vasopressin
Communication between the kidneys and the brain
Under conditions of lowered blood volume or pressure, the kidney secretes renin into the bloodstream. Renin in the blood promotes the synthesis of the peptide angiotensin II, which excites the neurons in the___________ organ. The____________ neurons stimulate the hypothalamus, causing an increase in vasopressin (ADH) production and a feeling of thirst.
subfornical
subfornical
Unlike the posterior lobe, which really is a part of the brain, the anterior lobe of the pituitary is an actual________.
gland
the _______ _________ was traditionally described as the body’s “master gland.”
anterior pituitary
But what controls the anterior pituitary? The secretory____________. The___________ itself is the true master gland of the endocrine system.
hypothalamus
hypothalamus
The anterior lobe is under the control of neurons in the periventricular area called_____________ neurosecretory cells.
parvocellular
hypothalamic parvocellular neurosecretory cells do not extend axons all the way into the anterior lobe; instead, they communicate with their targets via the____________
bloodstream
parvocellular neurosecretory cells secrete what are called____________ hormones into a uniquely specialized capillary bed at the floor of the third ventricle.
hypophysiotropic
the bloodstream (Figure 15.6). These neurons secrete what are called hypophysiotropic hormones into a uniquely specialized capillary bed at the floor of the third ventricle. These tiny blood vessels run down the stalk of the pituitary and branch in the anterior lobe. This network of blood vessels is called the ____ _____ ______ portal circulation.
hypo- thalamo-pituitary
Hormones of the Anterior Pituitary
CRH travels the short distance to the anterior pituitary, where, within about____ seconds, it stimulates the release of corticotropin aka adrenocorticotropic hormone (ACTH).
15
The organization of the three neural outputs of the CNS
As we have said, the_____________ is the main regulator of the autonomic preganglionic neurons.
hypothalamus
The___________ nucleus integrates sensory information from the internal organs and coordinates output to the autonomic brain stem nuclei.
solitary
Preganglionic Neurotransmitters. The primary transmitter of the peripheral autonomic (PNS) neurons is ___________, the same transmitter used at skeletal neuromuscular junctions.
acetylcholine (ACh)
The preganglionic neurons of both sympathetic and parasympathetic divisions release______
ACh
The immediate effect is that the ACh binds to nicotinic ACh receptors (nAChR), which are ACh-gated channels, and evokes a_____ excitatory postsynaptic potential (EPSP) that usually triggers an action potential in the post-ganglionic cell.
fast
Ganglionic ACh also activates muscarinic ACh receptors (mAChR), which are metabotropic (G-protein-coupled) receptors that can cause both the opening and the closing of ion channels that lead to very____ EPSPs and IPSPs.
slow
some preganglionic terminals release a variety of small, neuroactive peptides such as _____ and vasoactive intestinal polypeptide (VIP)
neuro- peptide Y (NPY)
Postganglionic PNS neurons release ACh, but those of most parts of the SNS use ________.
norepinephrine (NE)
Parasympathetic ACh has a very_____ effect on its targets and acts entirely through________.
local
mAChRs
Drugs that promote the actions of norepinephrine or inhibit acetylcholine muscarinic actions are ____________; they cause effects that mimic activation of the sympathetic division of the ANS.
sympathomimetic
atropine, an_________ of mAChRs, produces signs of sympathetic activation, such as dilation of the pupils. This response occurs because the balance of ANS activity is shifted toward the sympathetic division when parasympathetic actions are blocked.
antagonist
On the other hand, drugs that________ the muscarinic actions of ACh or inhibit the actions of NE are parasympathomimetic; they cause effects that mimic the activation of the______________ division of the ANS.
promote
parasympathetic
Anatomy and Functions of the Diffuse Modulatory Systems
The synapses made by many of these Diffuse Modulatory Systems release transmitter molecules into the ___________ _____, so they can diffuse to many neurons rather than be confined to the vicinity of the synaptic cleft.
extracellular fluid
the brain has 10–100 times more)__________ ACh receptors than ionotropic nicotinic ACh receptors.
metabotropic
The locus coeruleus makes some of the most diffuse connections in the brain, considering that just one of its neurons can make more than ___________synapses, and it can have one axon branch in the cerebral cortex and another in the cerebellar cortex!
250,000
The noradrenergic diffuse modulatory system arising from the locus coeruleus.
locus coeruleus neurons projects axons that innervate vast areas of the CNS, including the …
spinal cord, cerebellum, thalamus, and cerebral cortex.
Locus coeruleus NE cells seem to be involved in the regulation of attention, arousal, and sleep–wake cycles as well as learning and memory, anxiety and pain, mood, and brain metabolism.
Think of everything that NE does
locus coe- ruleus neurons are most strongly activated by____,________, nonpain- ful sensory stimuli in the animal’s environment.
new
unexpected
Each_____ nucleus projects to different regions of the CNS. Those more caudal, in the medulla, innervate the spinal cord, where they modulate pain-related sensory signals.
Those more_______, in the pons and midbrain, innervate most of the brain in much the same diffuse way as do the locus coeruleus neurons.
raphe
rostral
The _____ ______ and the _____ ______ are part of a venerable concept called the ascending reticular activating system, which implicates the reticular “core” of the brain stem in processes that arouse and awaken the forebrain.
locus coeruleus
raphe nuclei
Raphe neurons seem to be intimately involved in the control of ________cycles, as well as the different stages of sleep.
sleep–wake
Serotonergic raphe neurons are the most quiet during______
sleep
Studies conducted in the 1960s by ____________ of the University of Gothenburg in Sweden proved that dopamine was indeed a crucial CNS neurotrans- mitter. This discovery was honoured with the 2000 Nobel Prize in Medicine.
Arvid Carlsson
The serotonergic diffuse modulatory systems arising from the raphe nuclei.
In what part of the brainstem is the substantia nigra located?
midbrain
the substantia nigra cells project axons to the____________ which includes_______ and _______, where they facilitate the initiation of voluntary movements.
striatum
(the caudate nucleus and the putamen)
The midbrain is also the origin of the other dopaminergic modula- tory system, a group of cells that lie very close to the substantia nigra, in the ________ _______ _______.
ventral tegmental area
Axons from the VTA innervate circumscribed region of the telencephalon that includes the ______ cortex and ______ ______
frontal
limbic system
This dopaminergic projection from the midbrain is some- times called the_______________ dopamine system.
mesocorticolimbic
A number of different functions have been ascribed to mesocorticolimbic projections. For example, evidence indicates that it is involved in a _________ system that somehow assigns value to, or reinforces, certain behaviors that are adaptive.
“reward”
The substantia nigra projects to the ______ and _______ _____
Striatum (putamen and caudate nucleus)
Limbic areas
The dopaminergic VTA projects to the _______
Frontal cortex
there are two major diffuse modula- tory cholinergic systems in the brain, one of which is called the ______ ______ complex and the _______________ _________ complex.
basal forebrain
pontomesencephalo- tegmental
The basal forebrain complex is a “complex” because the cholinergic neurons lie scattered among several related nuclei at the core of the telencephalon, medial and ventral to the basal ganglia. The best known of these are the _____ ______ nuclei, which provide the cholinergic innervation of the hippocampus, and the _______ _______ ___ _______, which provides most of the cholinergic innervation of the neocortex.
medial septal
basal nucleus of Meynert
The medial septal cholinergic nuclei innovate the __________
Hippocampus
the _______ _______ ___ _______, which provides most of the cholinergic innervation of the neocortex.
basal nucleus of Meynert
the pontomesencephalo- tegmental complex are ACh-utilizing cells in the pons and midbrain___________.
tegmentum
the pontomesencephalo- tegmental complex system acts mainly on the ______ ______, where, to- gether with the noradrenergic and serotonergic systems, it regulates the excitability of the sensory relay nuclei.
dorsal thalamus
Stimulant drug action on the catecholamine axon terminal.
amphetamine blocks NE and DA reuptake and _____________________
stimulates the release of DA
cocaine targets DA reuptake more___________
selectively
