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157 Cards in this Set

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What are the main elements of the CNS?
Cortex waar hypocampus in ligt, thalamus, hypothalamus en cerebeum. ( uitzoeken verder met Athlas)
Wat is ganglion?
Collection of neuronal cell bodies.
Wat is een cerebral ganglion?
Brain
Wat is Cerebrum(L)
Brain
How can the smooth muscle been stimulated?
It can be stimulated by via pre-, -ganglion, postganglionic neurons with Ach and noradrenaline release. Futhermore with sensory neurons.
How can the striated muscles been ted?( gestreepte spieren)
Bij acetylcholine via motor neuron and via sensory neuron.
What stimulates parasymphatetic NS and what does it?
It stimulates trophotropic functions which regulate: enhanced (verbeterde) digestion, enhanced elimination of body waste, slowing of heart rate, narrowing of pupil.
What stimulates symphatetic NS and what does it?
It stimulates ergotropic functions: inhibition of digestion, urinary and rectal outlets blocked, increased heart rate, dilation of pupil.
Waaruit bestaat CNS?
Spinal cord, hersens: forebrain, midbrain, hindbrain.
Waaruit bestaat perifere ZS?
Somatische en autonomische ZS. Beide bestaan uit sensory and motor. Autonomische sensory systeem bestaat uit sympatische en parasympatische systemen.
Beschrijf neuroendocrine systeem.
*no synapses with neurons, thus synapses with Chromaffin cells (postganglionische neuronen)
*These cells releasing signals to the blood.
How does the Chromaffin cells also called?
postganglionic cells or neuroendocrine transducer cells.
How can spinal cord stimulate the peripheral target?
Via motor neuron from SC to adrenal medula which releases hormons which effects peripheral target with nor/andrenaline.

Via preganglion from SC >> ganglion, postganglion to the peripheral target. with noradrenaline or adrenaline.
What is sensory coding?
Signals from enviroment are translated to receptor cells.(analog)
What is sensory transduction?
Changing receptor potential in action potential. ( frequency changing = digital). It induces the release of neurotransmitter in the brain via sensory neuron that comes from receptor.
Which imputs exist?
Somatic input:(touch,pain,thermo receptors), visual, auditory en olfactory inputs, gustatory input(taste input)
How the inputs are processed?
1)olfactory input direct to olfactory cortex

2) somatic input to thalamus and than to primary somatic cortex.

3)auditory input to thalamus and than to primary auditory cortex.

4) visual input to thalamus and then to primary visual cortex.
Which cells are GPCRs and which are ions?
GPCR: rode/cone cells, olfactory cells,sweet/bitter receptors.

Ion channels: mechano receptors, salt/soar receptors.
How does their work olfactory signal transduction?
signal transduction directly through olfactory cell.
How does their work visual signal transduction?
neurotransmitter release from rode/cone cell to the bipolar cell and then generation of AP.
What are the differensec between touch and pain receptors??
They have different firing treshold. Its lower by touch receptor.
How is the signal form pain/touch receptors is transduced?
via dorsal root ganglion (schakelneuron) which goes to spinal cord, in spinal cord it releases neurotransmitters, the signal is transduced to brain with schwann cells.
What are for sort channels are pain and touch receptors?
TR: BNC1 channel: pumps Na inside the cell.

PR: Trp channel: pumps Na inside the cell.
What are the evidences for itch receptor?
Since there are suggestions that itch receptor goes through GPCR mechanism. KO GPCR mouse doesnot itch but feels pain.
What is the correlation between pain and ithc?
Pain receptors suppresses itch . Touch and pain are separated sensory systems. The sensory transduction proteins are very diverse and ancient.
How does the heat receptor works?
It is Na/Ca cotransporter.
Wat is stereotactic apparatus?
De electrode in hersens inbrengen op grond van joint between bones of the cranium and junction of sagital and coronal sutures.
What information is stored in thalamus?
fast responses(defence), fast signals,
Which output has limbic system?
Hard wired
What does toxoplasma gongii?
Het zorgt ervoor dat muzen geen angst voor katten hebben. Can only sexualy reproduce in the gut of cat.
Which domain in glomeruli is responsive for giving innate fear responses?
D domain, is responsible for learned fear.
What function has central amyglada?
defence program. It can recall them from cortex or from thalamus(fast).
Some parts of the amyglada is programable ( where the fear memories are located).
Which two destination of the input there are?
from primary somatic cortex and cerebellum ( motor infromation, inf. over concentration and ballance)
What are the two mechanisms of TRP channels working ?
As a sensor and as a downstream ( via IP3 second messendger)
What is TRP?
Transient receptor potential channel

transient = kortstondig
What can be done with electrode ??
Electro stimulation (give small currents)
Electro lesions ( give high currents)
Electrical recordings ( action potential)
Iontophoresis ( administer transmitters)
Microdialysis
What does cerebellum?
It's responsible for timing, pattern, position coordination.
Which color receptors are there?
Blue,Green,Red
How many taste receptors there are and how they work?
Sweet,bitter,sour,salt receptors. Sweet - sugar receptors, sour - H+ receptors, salt - Na receptors, bitter: many receptors, GPCRs.
Why we cant distinguish between different bitters?
We have 50 different GPCR receptors for bitter taste.
Name 3 different purposes of glutamate in humans?
Amino acid, neurotransmitter, flavour.
How T1R2 receptors in rodent differences from T1R2 in humans?
Rodents cant taste artificial sweetners (kunstmatige)
What is the rol of T1R2 and T1R3 receptors in gut?
When you have glucose in gut it acts on T1R2 and T1R3 receptors so it leads to release of glucagon like peptide ( GLP). GLP acts on receptors in gut and activates glucose transporters.
Tell what u know about umami receptors.
Umami receptor is responsible for savoury,pungent,meaty taste.

Umami signals through PLCbeta.
Umami acts on PLCbeta through G protein in gut. PLCbeta activates TRP channel which transport Na inside cell.
What do we know about activation of TRP with bitter receptors?
We dont know through which protein the bitter receptor acts, but we know that it leads to activation of PLCbeta as by umami and sweet receptors.
How the vector coding for color vision works?
The cone cells in eye are responsible for color vision. There are 3 different cone cells each expresses dofferent opsin protein. The opsin protein together with the compound retinal produces the visual pigments in the cone cells for absorption of light.Retinal is responsible for the light absorption but it is the nature of the protein to which it is attached that determines what wavelength is absorbed.
What is resulted in trichromatic vision in humans?
About 40 million years ago there was a chance duplication of one of the genes on the X chromasome in the linage leading to humans and Old World primates that ultimately resulted in trichromatic vison.
What was the advantage of long wave lenght vision for primates?
They could see red cherries...thus leading to a rapid acquirement (prisposoblenie) of trichromatic vision in old world monkeys.
How did it go so wrong with the study reported in Nature Neuroscience with umami receptors?
Neurotransmitter receptors such as glutamate receptors work in Nm concentration, however mGlu4t receptor works in uM concentrations.

mGlu4t reaces membrane only in tumor cells, because of overexpression of this protein.

Futhermore umami receptor acts via PLCbeta and not via adenil cyclase.
What is umami L-amino-acid sensor?
T1R1/T1R3 dimer.
What forms umami dimer to function as sweet receptor?
T1R2/T1R3
What compound in human responsible for artificial tastes?
T1R2 component of sweet receptor is responsible for artificial tasting.
How big are TR1 and TR2 families of receptors?
TR1 small, TR2 big up to 50 receptors.
What happens in Trpm5 KO mouse?
no sweet, no bitter , no unami signalling in KO mouse.
Which channel is involved in sour signalling and respiration system?
PKD2 channel is directly sensitive to H+ protons.

The rol of PKD2 channels in RS was shown with dynamic imaging.
What does olfactory system does and how does it work?
It helps us to distinguishing between the individuals, determine their reproductive state, detect the predators. There are many many receptors each of them codes for different protein, so a dog can distinguish between different smells.
What are the orphan receptors?
a receptor with an unknown ligand.
2000-3000 orphan receptors, 700-800 olfactory receptors.
How do "one receptor type,one cell" realizes?
One of the genes coding for the receptor activates by chance, this receptor is expressed on the membrane and suppresses all other genes that code for receptors.
What is the vomeronasal organ responsible for?
The VNO is responsible for detecting pheromones, which are important for the social interaction between animals of the same species.
Why evolution of color vision coincides with growing complement of OR pseudogenes and deterioration of the sense of smell?
Perharbs visual cues became more inmportant in finding food.
Give a characteristic to the work of brains.
Activation of layers, parallel work of individual units,slow,making errors no freqeuntly but even an error has no significant influence on the whole process.
How many neurons are there in human brain?
100 billion
What is idea of plastic brain?
The synaptic strength between neurons is dynamic , they can change in the process known as synaptic plasticity.
What is the processing element and its function?
The representation of neuron in artificial neuronal network jargon.

The function of PE is to make a sum of strenght of each input (I). Multiplied by weight factor (connection strenght = synaptic srenght)
How does "back propagation" in ANN works?
Thus, after doing as well as possible the output layer it next starts adjusting W values of the processing elements in the hidden layer and finally moves on to the input layer.
It is performing these adjustments for the complete training set so that, when it is fully trained, it can give the correct output for each of inputs of the training set.
What for sort information can be processed with ANN?
signatures ( bank ) , figerprints, patterns in stock market. ANN for face recognition.
How does the face recognition region in human brain works?
The face-coding region in the human brain is a least five synaptic steps and five neuronal populations downstream form the retinal, and not 3 steps, as in the model.
Describe the recurrent networks?
In recurrent network the information besides projecting forward, goes also backward.

Recurrent networks can generate complex sequences of activation vectors all by themselves, even if its input layers fall silent.

They are thus ideal as pattern generators.
What similarities does the brain and ANN have?
They are both good at pattern recognition and both are error tolerant.
The simpsons??
See short movies and place an electrode in hyppocampus. Each time when u see short simpsons fragment, you get an activity of a particular neuron in hyppocampus.
What is the main conclusion of the expreriment with short film fragments of the simpsons?
De verbalisatie (iets formuleren) gaat trager dan de iets zich herinneren(recall).
What are the problems with seeing the destribution processing in brains?
fMRI: to low spatial resolution ( in millimeters), to low temporal resolution in (seconds).
Solution: to see a activity of neurons over the wide brain area.
What are the aims/conclusions of the experiment which was made to see distribution processing of brain?
aim: to prove that there is trace-reactivation
conclusion: there was trace reactivation.
how: the memory of the red dot and juice reward is played back after the event has occurred.
conclusion2: there is distribution processing in memory.
how: These two neurons are from very different parts of the cortex and yet they are linked in the construction of the memory of the red dot and juice. THE MEMORIES ARE DISTRIBUTED OVER WIDE AREA IN THE CORTEX.
What is the trace reactivation??
This is the theory that states that neurons recapitulate memory traces in the process of strengthening the memory for long term storage.
Can the same neuron be used to store different memories?
YES
What happens in brain stem and what is the correlation of in with hypothalamus?
In the brain stem are many pattern generators that control respiratory system, heart contractions. So there are neuronal networks involved. The hypothalamus can change the rate of the heart contraction etc. so it has influences on brain stem.
What pattern generator is found in the spinal cord of humans?
In the spinal cord one finds pattern generators for controlling the repetitive firing required for walking.

Finally we have, within the spinal cord, neural networks that drive our protective reflexes…they ensure a fast coordinated motor response to painful situations (sharp object, burn etc).
Which models of cell communication exist?
Endocrine, neuroendocrine, chemical synapse, electrical synapse.
How does electrical synaps work?
Through 6 connexins, which form gap junction.
What is special about electrical synapses?
*found only in vertebrates (позвоничные)
*permeate to mm 1000 daltons: all ions, most second messendgers.
*involved in extremly fast responces ( protective responses)
*might be used to obtain synchronous firing of neurons
*glial cells are coupled through gap junctions.
How is peptide distinguished from protein?
peptide: 2-40 aas
protein: >40 aas
Which molecules can be hormones?
Peptides, proteins, midified amino acids.
What do u know about thyroxin?
*thyroxin is from thyroid gland
*its derived from two molecules of thyrosine
From what molecule all steroid hormones such as andro-,estrogens are derived?
cholesterol, which itself is steroid
What are the two important considerance of the hydrophobicity of the messadge molecules?
*cant cross the cell membrane thus induce the transmembrane signal transduction
* cant cross the BBB
What is cerebrospinal fluid CSF?
CSF is the liquid that can be found in the ventricles (hollow fluid filled cavities) and in the extracellular space of the brain.
How effective is the blood-brain barrier?
The BBB dont let the proteins to cross the membrane so the protein content of CSF is only 0.5%
What is the difference in hydrophobicity between morphine and heroine and its related to their structure?
Free hydroxil groups in heroine are acetylated >> more hydrophobic than morphine.
What function has morphine and heroine and what is the mechanism?
Heroine is an opiaat - it goes in brains through BBB. Morphine is analgesic - only for peripheral targets. Heroine must be first converted to morphine with acetylcholine sterase ( has low substraat specificity)
What does acetylcholineesterase?
It breaks acetylcholine in acetaat en choline.
What is the evidence for the effectiveness of BBB?
Small radiolabeled thyrotrophin. Only 2% found in CNS >>>> effective BBB.
How steroid hormones coordinate events in CNS and periphery?
Estrogen: induces oestrus in CNS,thickening in the lining of the uterus in the periphery.(preparing for pregnancy)
Give an example of peptide hormone which can be neuropeptide?
CCK released in the blood if there is food in there. CCK induces the release of digestive enzymes with pancreas. CCK - hydrophylic so it does not go across BBB if its released in brains. So these two systems: peptide hormone and neuropeptide cant influence eacht other.
Why use the same peptide for two different functions?
Having made such an investment (CCK in gut)during evolution, nature will use the investment whereever it can, rather than develop a new system.
Is there a relationship between the functions of central neuropeptides with their corresponding peripheral peptide hormone?
*like with CCK, its released when the gut is full to stop food intake.
*central neurons release peptides both centrally (i.e. as a neuropeptide) and into the blood for peripheral action (i.e. as a hormone) or a peptide hormone (thus of peripheral origin) is pumped over the BBB by a specific high-affinity uptake system to have central action.
By what tissues is the brain tissue surrounded?
bone, dura mater, arachnoid membrane, pia mater
How many ventricles there are in brains?
4. I, II Lateral ventricles
III third verntricle
IV fourth ventricle
what is the function of choroid plexus and where is it build of?
*It is of the primary entry point for glucose, ions and water into this closed system.
* The choroid plexus consists of blood vessels surrounded by an epithelial layer of cells possessing tight-junctions. Hydrofobic compunds cannot enter the brains because of tight junctions.The cells of the epithelial layer possess specific pumping mechanisms for pumping material required by the brain into the ventricles (e.g. glucose, ions and water).
With all this production of CSF, there must be an outlet to ultimately get rid of it. How does CSF leaves subarachoid space?
The exit point for the CSF is in the blood vessels of the arachnoid villi
The arachnoid villi act as one-way valves. ( so the blood can never enter the brain even if the pressure in blood is higher than in brain).
If the pressure of the CSF is higher than the blood pressure (the usual situation) then CSF is given off to the blood.
What is CSF?
Cerebrospinal fluid.
What are the functions of cerebrospinal fluid?
*provides nutrients to brain
*let the brain float in CSF
*provides cushion to brains
How does the brain obtain glucose?
From the CFS and from the blood vessels in the brain.
What is hydroencephalitis?
If the flow of CSF to the outside of the brain is hampered in any way then pressure builds up and the ventricles swell, a condition known as hydroecephalitis This condition result in severe brain damage (called “water on the brain”). In adult is resulted in mentale verslechtering.
How the areas where is the breakdown of BBB are termed?
circumventricular organs
Which 3 possibilities there are to get stuff in brain?
*BBB disruption with hypertonic glucose solution
*lipidization of a molecule
*via transporters
Descripe BBB disruption by the hypertonic glucose solution?
Here a hypertonic glucose solution is injected into arteries in the neck.
The hypertonic blood pulls water out of the epithelial cells and the cell shrinkage disrupts the tight junctions.
9
In practice the BBB can be opened up in this way for 20 to 30 minutes.
The procedure is very risky because it leaves the brain vulnerable to infections and damage from toxins in the blood.
Even normal blood proteins such as albumin can have adverse effects in the brain.
Thus the procedure is used only in cases where it is absolutely necessary, for example for chemotherapy in the case of brain tumors.
What are the limitations of the lipidization method?
*the complex may become to big to diffuse via BBB
*the hydrophobic attachment may interfere with the workings of the drug.
How does the introduction of a compound in brain through transoporter works?
*You attach the molecule you want to get across the BBB to an antibody to transferrin.
*example: introduction of mRNA into the brain.
What is reinstatement?
the drug activates dormant neural circuits which lead to a overwhelming desire for the drug
How do the neuropeptides synthesized?
* they are synthesized from pro-hormones
* secrutory granules contain pro-hormone and enzymes to break these to make neuropeptides
*the bud vesicles transported down the axon of the neuron. Its active process and requires ATP.
* when the granule reaches the cell membrane the neuropeptides are ready.
Where the processing enzymes produced?
On the ribosomes that are found free in the cytoplasma of the neuron.
How do newly synthesized processing enzymes enzymes find their way to the terminal?
The newly synthesized enzymes find their way to the terminal by a process called axonal flow (reflecting the fact that there is a natural “flow” of cytoplasm from the cell body to the terminal). In the terminal the enzymes catalyze the production of neurotransmitter which are then actively pumped into secretory vesicles.
What can occur when the secretory vesicles are released by the synapse?
*they can bind on the postsynaptic receptor
*they might be broken down
*they may be taken up by high affinity pumps on the presynaptic membrane so it can be reused as a neurotransmitter.
Which three neuropeptides there are for neurotransmitters?
1.Processing enzyme: breken pro-hormone in stukjes ( neurotransmitters) in vesicles bij lage pH(5.5)
2. Byosynthetic enzyme
3. Breakdown enzyme
How does pro-hormone gets into ER?
The mRNA for pro-hormone possesses a hydrophobic N-terminal sequence - signal sequence. So it is recognized by SRP and the translation stops till it can be resumed on the ER membrane. The pro-hormone is simultaneously synthesized on the ER membrane and pushed into ER lumen via transolocon.
What are the two pathways in secretory releasing and where do the found?
1. Regulatory pathway. Release of neurotransmitters induced by second messengers. Only in neurons and endocrine cells.
2.The constitutive pathway is found in every cell, slowly delivering structural proteins to the extracellular compartment.
There are sequences for newly synthesized proteins which can be sorted to regulatory or constitutive pathway, how are the proteins called that involved here?
sortases
What are the sequences of cleavage of a precursor protein by peptidases?
* two or more basic amino acids in a row (lysine,arginine)
What are the most important peptidases involved in processing of precursor proteins for neuropeptides and peptide hormones?
PC1, PC2
How PC1 and PC2 cleave the protein?
*PC1 and PC2 cleave at the C-terminal side of the peptide bond of basic amino acids.
*one of the newly formed peptides still possess a lysine or arginine at its C terminal
*This is cleaved off by a carboxypeptidase (peptidase with a specificity for the C-terminal peptide bond).
How do PC1 and PC2 work when the basic amino acid is preceded with an amino acid glycine?
*during the cleavage process an enzyme called PAM consumes the glycine in a reaction that gives rise to a C-terminal amidation of the peptide
Why many neuropeptides and peptide hormones are C-terminally amidated?
*for the bioactivity of the peptide
*it gives the peptide a longer half-life after it has been release to the extracellular compartment, possibly because it is less susceptible to the proteolytic activity of carboxypeptidases that can be found in this compartment.
What is the post translational modification of the neuropeptides found on the N-terminus?
*N-terminal acetylation on the free amino N-terminal
*The acetyl group on acetyl-coenzyme A is transferred by the enzyme NAT to the free -NH3 group.
Acetylation can effect both the biological activity and the biological half-life of the peptides involved this type of modification.
What enzyme cleaves basic amino acids?
trypsin
The precursor protein proopimelanocortin (POMC) when its cleaved give different products. Which products there are?
*cleavage of one of the dibasic sites near the C-terminal of the precursor protein gives rise to the peptide beta-endorphin
*Towards the middle of POMC is the peptide alpha-melanocyte stimulating hormone (alpha-MSH)
*also about in the middle of POMC (with the alpha-MSH sequence at its N-terminal) is the peptide adrenocorticotropic hormone, ACTH.
What does beta-endorphin?
Peptide that acts on opiate receptors
What happens with alpha MSH after cleavage of it from POMC?
Alpha-MSH is N-terminally acetylated and C-terminally amidated.It stimulates pigmentation.
What does ACTH?
As the name indicates, this peptide stimulates the adrenal cortex.
It stimulates the synthesis and release of a steroid hormone called glucocorticoid that enhances the bodies use of glucose.
Where is the precursor protein proopimelanocortin found primarily?
The melanotrope cell and corticotrope cells of the pituitary gland and the neurons in brain.
How is the precursor protein proopimelanocortion processed in corticotrope cells?
*PC1 expressed in that cells cleaves POMC in 16K fragments.
*ACTH
*B-LPH ( unknown function )
How does POMC processed in melanotropes?
*the melanotropes express PC1, PC2, PAM and NAT
*PC2 breaks ACTH down to alpha-MSH and the same enzyme cleaves beta-endorphin out of beta-LPH.
*PAM catalyzes the C-terminal amidation of alpha-MSH and NAT catalyzes the N-terminal acetylation of both the alpha-MSH and beta-endorphin.
* beta-endorphin is not biologically active here only alpha-MSH
How does POMC processed in neurons?
*In general neurons express the same enzyme profile as the melanotropes with the exception of NAT.
*expression of the smaller versions of beta-edorphin.
*neurons in brains make endogenous opiate from POMC
In summary there are three tissue spicifiek procession of POMC, which signals can generate there different tissues?
-neurons - opiate
-melanotropic cell - melanotrope signal
-corticotropic cells - corticotroop signal
How does the pulse chase method work?
*as short pulse as possible ( radiolabeled aas)
*give chase at different time
* measure the products with chromatogram
How does radioactive peptides traced in cell within pulse-chase method?
Autoradiography with an electron microscope.
Which regios of POMC are conserverd through different species?
N terminal - dibasic amino acids
What does gamma MSH?
promotes the cell division and growth of the cells producing the glucocorticoids.
How were the endogenous opiates discrovered that they exist?
* morphine binds on opiaat receptor
*there must be molecules in the body that binds om opiaat receptor.
*radioimmunoassay: watch which molecules goes in competition with plant opiaat - morphine.
Which opiates there are ?
beto-endorphin, enkephalin, dynorphin ( from dynamate - strongest opiaat )
How is enkephalin made ?
Multiply copyes of enkephalin are produces from large precursor molecule. (proenkephalin)
2 forms of enkephalin are produced: leu-,met-enkephalin
How is dynorphin processed?
Prodynorphin has two opiate active peptides within its structure, dynorphin itself, which is a 17 amino acid peptide, and a peptide that has been called alpha-neo-endorphin.
Which opiate receptors exist for opiate peptides and which affinity opiate peptides have to their receptors?
*Enkephalin has a high affinity for the delta receptor
*dynorphin had high affinity for the kappa receptor
*beta-endorphin shows only moderate affinity for the three opiate receptors
*endomorphine - high affinity to mu receptor.
What type receptors are opiate receptors?
G-proteins.
What is TRH?
TRH is the smallest of the neuropeptides, a tripeptide.
It is released by neurons in the hypothalamus and regulates the secretion of a hormone in the pituitary gland, thyrotropin (also called thyroid-stimulaitng hormone, TSH).
TSH stimulates the thyroid grand to release the hormone thyroxin (Tx). What regulates this hormoon?
Thyroxin uncouples oxidative phosphorylation in the mitochondria of striated muscles and there is heat production, seen as an increase in the so-called basal metabolic rate.
The TRH >TSH>Tx chain is involved in theromorergulation in warm-blooded animals
proTRH is another example of the principle “small peptide, multiple copies How many copyes of TRH there are?
There are 7 copies of TRH in the precursor protein, each bracketed with dibasic amino acids, one with the gly-dibasic structure indicating a C-terminal amidation.
Not surprising, TRH is indeed a C-terminally amidated peptide.
What do u know about pro-gonadrotropin releasing hormone?
* a peptide that regulates the release of gonadotropins.
*its hormone that stimulates gonads from pituary gland. Which in turn release steroid hormones.
Which hormones contains pro-GnRH(gonadotrope releasing hormone).
The pro-GnRH contains GnRH but also a highly conserved peptide on the C-terminal called GAP.
What does highly conserved peptide GAP?
*It has been reported that GAP inhibits the release of another pituitary hormone, prolactin.
What do u know about pro-calcitonin?
*Calcitonin is a peptide hormone produced in the thyroidal C-cells
*The peptide stimulates the uptake of calcium from the blood into the bone
*The calcitonin gene codes for two different bioactive peptides with the peptide being expressed depending upon tissue-specific alternative splicing of the primary transcript of the m-RNA.
*In thyroid C-cells exons A,B,C,D, and E are put into the mature mRNA.
Calcitonin is coded for in exon E and thus it is produced by the C-cells.
*In some neurons in the CNS exon F instead of exon E finds its way into the mature mRNA.
In this case CGRP is expressed and released as a neuropeptide.
Thus, one gene, alternative splicing and two different gene products
By which splicing mechanism is calcitonin expressed in C-cells and in neurons?
*Calcitonin is coded in exon E and thus it is produced by the C-cells.
*In some neurons in the CNS exon F instead of exon E finds its way into the mature mRNA. In this case CGRP is expressed en released as a neuropeptide.
Which another hormoon togather with calcitonin regulates extracellular [Ca2+]?
*parathyroid hormoon stimulates calcium release form bones.
*Both the C-cells and the parathyroid cells contain a membrane bound Ca2+ sensor, a G protein coupled receptor with Ca2+ as its endogenous ligand.
*Activation of the receptor stimulates calcitonin release and inhibits PTH release.
Is there CNS involved in calcium homeostasis?
There is no involvement of the CNS in Ca2+ homeostasis…the problem is simple (holding blood Ca2+ level at a set point) and the solution is simple (endocrine cells directly sensitive to Ca2+).
Describe glucose homeostasis.
*Both the pancreatic beta cell and the alpha cell are sensitive to blood glucose levels.
*High glucose levels stimulate release of insulin and low glucose levels stimulate release of glucagon
*no CNS is involved.
What does a circumventricular organ?
Circumventricular organs (CVO) are so named because they are positioned at distinct sites around the margin of the ventricular system of the brain.

They are among the few sites in the brain which have an incomplete blood–brain barrier. As a result, neurons located in circumventricular organs can directly sense the concentrations of various compounds, particularly peptide hormones, in the bloodstream, without the need for specialized transport systems which move those compounds across the blood–brain barrier.
what do the circumventricular organs?
they secrete or are site of action for different hormones.
What is Bregma?
The bregma is the anatomical point on the skull at which the coronal suture is intersected perpendicularly by the sagittal suture.