• Damian G Kelty-Stephen added an answer:
    What are the physiological mechanisms involved in cognitive impairment?

    What are the physiological mechanisms involved in cognitive impairment?

    Damian G Kelty-Stephen · Grinnell College

    The answer may depend, unfortunately for compact answers in science or here in RG, on what sort of impairment you are interested in.  Impairment following insult to neural tissue?  Or impairment over the longer-haul of development over the lifespan? The answer can be more surprising as you move from the double-dissociation options for the former to the more complex phenomena of the latter.

    It is often quite straightforward to implicate physiological mechanisms within the closely related neural circuitry, as Abhijit's helpful answer points out. However, there a lot of newer findings showing the effects of things we think of as farther "downstream" and more as "outputs." Curiously, simple experiential habits like physical exercise, diet can be among the best predictors of impairment over the lifespan. I share the following three that I've been looking at recently:

    The cropping-up of nonobvious causes now with more data, more diverse scientists, and more ways to measure cognitive performance seems symptomatic (to me and my friends, biased though we all may be) of cognitive phenomena requiring systems-y explanations like those increasingly pursued in biological sciences.

    Best wishes,


  • Steingrimur Stefansson added an answer:
    Why PT or INR is a better measure for evaluating the effect of vitamin K on coagulation process than PTT?

    As we know, vitamin K is essential for the formation of factors 2,7,9,10 in the coagulation cascade, which factor 7 participates in extrinsic pathway, factor 9 participates in the intrinsic pathway and factors 2 and 10 participate in the common pathway
    From the above information we can say that vitamin K is essential for both extrinsic and intrinsic pathways. But as we know, for evaluation of effect of vitamin K on coagulation process, we measure PT or INR.

    Steingrimur Stefansson · HeMemics Biotechnologies Inc

    I forgot to add that PTT also activates the intrinsic pathway starting with XII, and XI, which are not Vit. K dependent proteinases, so it can be less sensitive to Vit. K deficiency or warfarin.

  • Zhuo Shao added an answer:
    How to accurately determine Postnatal Day 6 (P6) of mice to evaluate angiogenesis at P6?

    I am working in the field of angiogenesis and I analyse physiological angiogenesis in mouse retina. I always have to analyse angiogenesis at P6 and therefore it is really important to know when the pups are born, so that one can accurately determine P6.  I usually check for the pups twice or thrice a day, but I see variability in my result and most probably it is due to not accurately determining the birth date of pups. Could anyone give me suggestions how can I accurately determine when the pups are born? Thanks ahead.

    Zhuo Shao · McGill University

    I agree with Florian and Agnieszka, even you know the exact age, there will still be variation on retinal angiogenesis. Weight gain plays a critical role in retinal vascular development. You can refer to the following paper on this:

    Postnatal weight gain modifies severity and functional outcome of oxygen-induced proliferative retinopathy.

    Stahl A, Chen J, Sapieha P, Seaward MR, Krah NM, Dennison RJ, Favazza T, Bucher F, Löfqvist C, Ong H, Hellström A, Chemtob S, Akula JD, Smith LE.

  • Nikola M Stojanovic added an answer:
    Can anyone help me to know the enzymes that affect renal function in rats treated with the extract flaxseed (physiological and histological)?

    I need to research have been published in this topic

    Nikola M Stojanovic · University of Niš

    If you are looking for enzymes that may be altered under the influence of your extracts you can always try assaying for enzymes that prevent oxidative damage: catalase, SOD, GSH peroxidase/reductaze etc. 

    Also non-enzyme products can be measured - carboxilated proteins, AOPP, GSH, TBARS...

  • J. Redmond added an answer:
    Why isn’t nutrition a bigger part of conventional medical school education?
    Diet is arguably the single most important preventive measure for healthy aging because it affects the functioning of every organ in the body and is a factor both in the development of disease and in recovery.
    J. Redmond · University of Cambridge

    Dear Hashem Adnan Kilani, I agree, you are absolutely correct. It would be impossible to fit a complete nutrition education into an already packed medical degree. It is important to identify the key concepts and allow doctors to have a better understanding / appreciation of the role that they can play, for example even in making informed and appropriate dietitian referral or ONS prescription. This could be done with well-planned and well-executed lectures and training days. Our 'Nutrition Education and Leadership for Improved Clinical Outcomes (NELICO)' has tried to address this - by recruiting interested junior doctors who are willing to partake ... they in turn become 'nutrition champions' in their own hospitals and help to spread the knowledge about nutrition on the job. 

  • Alaaeldin A. Hamza added an answer:
    After the infusion of glucose to a Wistar rat, how much time does it take for the pancreas to start secreting insulin?

    Please refer your answers to reliable reference(s).

  • Jordan Kolarov added an answer:
    Where can I find the protocols for mitochondrial depletion with ethidium bromide?

    Mitochondrial stress induction protocols.

    What about other protocols for oxidative stress induction by using H2O2? 

    Jordan Kolarov · Comenius University in Bratislava

    If you put in Google (rho zero cells), you will get a number of relevant publications on both mammalian and yeast cells answering your questions. Here is just one example -Methods Mol Biol. 2009;554:383-91. doi: 10.1007/978-1-59745-521-3_23.
    Establishment of human cell lines lacking mitochondrial DNA.
    Hashiguchi K1, Zhang-Akiyama QM.

  • Is there a direct correlation between a particular stimulus and an effector response?

    Is there the possibility to modulate a stimulus (by changing frequencies and duration) and set a direct relationship between that stimulus and a certain muscle AP? Telling it otherwise, applying the same stimulus (maintaining the same frequency and duration), again and again, on the same alpha neuron, I will have the same effector contraction (with plenty of time to relax between stimulus)? If the answer is yes, it is possible to build a matrix with different stimulus and correlated muscles AP's?

    Douglas Crispin Castellanos · Universidad Isla de la Juventud, Cuba.

    Si existe esa correlación directa porque el organismo está diseñado para dar respuestas efectoras a determinados estímulos que provienen del exterior o el interior del cuerpo humano; por ejemplo cuando un atleta ha recibido una sobrecarga de entrenamiento su organismo puede responder de diferentes formas en correlación al estímulo que llega al cerebro; una respuesta puede ser colapsar durante las practicas o las competencias, esa es la respuesta que busca el organismo para defenderse en esos momentos del estímulo que le llega, esa respuesta efectora es una respuesta protectora del organismo.
    También el organismo puede responder ante este estimulo variando la conducta psicológica de los atletas, como la apatía, trastornos en el sueño, entre otros. Esto dependerá en gran medida del tipo de predisposición competitiva que tenga el sujeto en cuestión y así será entonces su respuesta efectora ante este estimulo.

  • Thamir Ismail added an answer:
    Final concentration of 100% ethanol is 1% (50ul in 5ml) in cell culture dish, having 5ml cell suspension. Does it affect the cell line?

    I have cultured HCT-15 (Adherent), colon cancer cells in 35mm cell culture dish, having 5ml of RPMI-1640 media. I have to treat these with 10uM of a drug. The stock concentration of drug (C1) is 1mM, dissolved in 100% ethanol. So i have to add 50ul of the stock solution of drug to the cell culture dish, where according to C1V1=C2V2, it final concentration (C2) becomes 10uM. As the drug has been dissolved in ethanol, it means that i have added 50ul of ethanol to 5ml of cell culture media, where its final concentration becomes 1% (50ul per 5ml). The desirable effect of drug is induction of apoptosis. So I want to know whether besides the desirable effect of drug, this concentration of 100% ethanol has some influence on cell line or not? No doubt that any effect of ethanol is undesirable. If anyone help me in this regard, I will be grateful. Provision of reference will be highly appreciated. 

    Thamir Ismail · University of Liverpool

    I 100% agree with Tognolini.  Its better to try different concentrations of ethanol treatment as some of the cell lines are happy up to 2% ethanol.  But, to be on the safe side, 0.5% is safe to use.

  • Gunjan Pandey asked a question:
    "L-DOPA methyl ester" physiological role

    Dear Authors, 

    Could you please point me in the right direction to find out the natural occurrence and physiological role of L-DOPA methyl ester?

    Many thanks for your help.



  • Does someone know of a research supporting the teaching of breathing in through the nose and out through the mouth?

    We are putting together an online CBT intervention for children and adolescents with functional abdominal pain. Many in our team have been taught to breathe in through the nose, out through the mouth. I am wondering whether there is any empirical evidence supporting this teaching. Thanks in advance!

    Amandio Aristides Rihan Geraldes · Universidade Federal de Alagoas

    "Nasal breathing (as opposed to mouth breathing) increases circulation, blood oxygen and carbon dioxide levels, slows the breathing rate and improves overall lung volumes " Swift, Campbell, McKown 1988 Oronasal obstruction, lung volumes, and arterial oxygenation. Lancet 1, 73-75

    "The internal nose not only provides around 90% of he respiratory system air-conditioning requirement but also recovers around 33% of exhaled heat and moisture. Elad, Wolf, Keck 2008 Air-conditioning in the human nasal cavity. Respiratory Physioolgy and Neurobiology 163. 121-127

    "The nasal cycle, which is part of an overall body cycle, is controlled by the hypothalamus. Sympathetic dominance on one side causes nasal vasoconstriction of the ipsilateral turbinate, while parasympathetic dominance on the other causes nasal vasoconstriction of the contralateral turbinate. Increased airflow through the right nostrii is correlated to increased left brain activity and enhanced verbal performance, where as increased airflow through the left nostril is associated with increased right brain activity and enhanced spatial performance."
    Shannahoff-Kalsa, 1993 The ultradian rhythm of alternating cerebral hemispheric activity. International journal of Neuroscience 70, 285-298

    "During exercise, nasal breathing causes a reduction in FEO2, indicating that on expiration the percentage of oxygen extracted from the air by the lungs is increased and an increase in FECO2, indicating an increase in the percentage of expired air that is carbon dioxide". Morton, King, Papalia 1995 Comparison of maximal oxygen consumption with oral and nasal breathing. Australian Journal of Science and Medicine in Sport 27, 51-55

  • Atena Eslami added an answer:
    Does anyone know whether there is a site that had transparent pictures of salty glands in plants or not?
    I have been accumulating some papers for a seminar, but unfortunately I don't have enough pictures of that. Can anyone help me?
    Atena Eslami · Lorestan University

    Hi dear

    thanks for your answer but would you please send me the chapter which related to the salty glnds?

  • Adam R Kennedy added an answer:
    What will happen if someone to be in darkness for 10 years?

    Physiological changes

    Adam R Kennedy · Cytokinetics

    The answer to this question would require several assumptions.  Keeping someone in darkness for 10 years would require a rather sadistic psychology on the part of the captor and the likelihood of that being the only negative aspect of their incarceration is very low.  However, assuming that this person was being kept otherwise healthy, well fed, entertained (isolation would lead to severe psychological distress) and sheltered from heat or cold, the main effects would be on the pigmentation of their skin (skin color would lighten) and their ability to produce vitamin D which would lead to soft bones, possibly rickets.  The mammalian circadian rhythm is 26-27 hours long, so it would be possible to change the persons circadian rhythm if all other timed stimuli were removed or provided randomly.  Sleep patterns may be disrupted (outsize of the timing), with less sleep in sibling bouts (this happens in totally blind people).  

  • Miranda Yeoh added an answer:
    Have you tried meditation for stress removal, and what is its effect on your work, teaching and research?
    Meditation has physiological and psychological effects that include reduced respiration rate, decreased heart rate, changes in brain wave patterns, lowered stress, improved emotional well-being, blood pressure and working memory. So, have you tried meditation? What effects have you observed?
    Miranda Yeoh · Kolej Matrikulasi Selangor, MALAYSIA (Selangor Matriculation College)

    Very true, dear Kuldeep and friends: 'Meditation helps in restoring energy, thinks positively, increases concentration and relaxes both body and mind'.  Let me share too.

  • Irina Pechonkina added an answer:
    Why do we prefer things that are harmful for our bodies including sugars, carbohydrates and avoid things with beneficial effects like exercise?
    Harmful effects are associated with sweet taste, beneficial effects have no preferred taste.
    What do you think about?
    Irina Pechonkina · Math and Physical Lyceum

    An interesting article by American Psychological Association "Emotional distress regulation takes precedence over impulse control. If you feel bad, do it"

  • Hossein Hassanpoor added an answer:
    What are the mechanisms for secretion of different gliotransmitters such as glutamate, GABA, and ATP by astrocytes?
    Receptors for all major neurotransmitters seem to be present on the astrocytic plasma membrane (Volterra and Meldolesi,2005), and activation of these receptors (because of neural activities) leads to an intracellular Ca2+ increase and subsequent release of gliotransmitters from glial cells (Perea et al., 2009).
    The problem is, how can the astrocyte understand which of the gliotransmitters should be released in different states, according different neural activities?
    Hossein Hassanpoor · Amirkabir University of Technology

    Dear professor Verkhratsky

    Many thanks for your valuable suggestions

  • Timothy O'Leary added an answer:
    Have you used Gephi to visualize networks of pairwise correlations?
    I have a dataset where I am interested in all of the pairwise correlations between 12 different variables (12 nodes, 66 edges). I've been playing around with Gephi and I like how easy it is to use, but has anyone here actually published a paper using it? What are the standards for network parameters? I'm pretty inexperienced with working with networks (I'm primarily a physiological ecologist).
    Timothy O'Leary · Brandeis University

    I have not used Gephi, but for 12 x 12, an exhaustive pairwise scatterplot is a perfectly adequate way to visualise pairwise correlations. The matlab command 'plotmatrix' does this in one go. A similar function probably exists in Octave (free). See figures 3 & 4 in the attached publication.

  • Mudhir Sabir Shekha added an answer:
    Why does the SA node spontaneously fire at regular intervals?

    The SA node can be considered to be "self-firing". It repetitively goes through a depolarizing discharge and then repolarizes to fire again.Why does the SA node spontaneously fire at regular intervals? 

    Mudhir Sabir Shekha · Salahaddin University - Hawler

    Sinoatrial node  do not have a stable resting membrane potential. This membrane potential starts at about -60 mV and drifts upward, showing a gradual depolarization called WHAT? This results from a slow inflow of Na+ without a compensating outflow of K+.

  • Giancarlo Lopez-Martinez added an answer:
    Does anyone have information on up and down regulation of a gene?

    Hi All,

    I have a question regarding the interpretation of "up" and "down" regulated genes. I was wondering if biologically, when comparing two different stressors, having a high percentage of up regulated genes in one of the 2 means something specific. The question is if, independently from the physiological role of the up/down regulated genes, an enhanced up regulation of genes suggests a specific physiological "adjustment" that the organism is activating in response to the stressor. Did anyone have some references about this topic?



    Giancarlo Lopez-Martinez · New Mexico State University

    In a well-controlled experiment where you account for the most common possible variables (age, development, sex, sexual maturity, reproduction status, etc), a strong upregulation is definitely related to a physiological adjustment. The organism is responding to its environment and regardless of where on the pathway these gene products are located, they are responding to your treatment.

    Now, we know a fair amount about stress responses but there is still a lot we do not know. Thus, while it is not surprising to get a massive upregulation (both in numbers of gene products and intensity), it is the interpretation of that data that will be most telling. While the intensity of an upregulation might be symptomatic of the harshness of the stressor, it does not necessarily lead to that much protein, or activated gene product. So one must use caution if interpreting intensity over what was actually expressed.

  • Arjyabrata Sarker added an answer:
    How can a malignant melanoma be induced in sprague dowley?
    I have to induce malignant melanoma in sprague dowley rats. Prior to that, I need to suppress its immune system and, if possible, irreversibly weaken the immune system so that the rat's immune system can not respond to inoculated malignant melanoma cells, and malignant melanoma can develop.
    Any comments would be appreciated, Thanks
    Arjyabrata Sarker · Jahangirnagar University

    There is also a chance to decrease the immune response by initiating major injury for prolonged period before 3/4 weeks of insertion.

  • Does anyone know the whereabouts of a photo of Albert Frank Stanley Kent's (1863-1958)?

    I would like to attach to my presentation a photo of the important British physiologist Kent but I can't find it anywhere. Could anybody help me?

    Pandi-Perumal Seithikurippu Ratnas · Somnogen Canada Inc

    Hi there Eva, greetings from New York! He was a professor at the Department of Physiology, University College, Bristol (now, the University of Bristol):

    Please write to the chair of the department of physiology or the medical librarian to get a picture of Dr. Kent. I am sure they will have it somewhere in their archives!

    please also refer:

    Although you could locate his picture in the 'google images', the resolution might not be good for reproduction in your thesis!

    By the way, it is not rocket science to get someone's picture these days! ;)

    Just need to know where to ask! 

    If you don't get through source A, try source B:

    If I were in your situation, I would write both sources simultaneously. At least someone would respond positively! Just explain why you need it! Tell them that you will acknowledge their help! They will be happy to do it for you! (i.e. scan and email it to you!

    good luck!. 

  • Berhanu Abraha Tsegay added an answer:
    Physiology of Plant diseases

    I need urgent. If anybody has literature on Physiology of Plant Diseases, let me know. thanks in advance.

    Berhanu Abraha Tsegay · Bahir Dar University

    you can refer plant pathology books or search the literature on internet.

  • Hussin Jose Hejase added an answer:
    What is the purpose of sleep?
    The purpose of sleep has been studied for centuries, yet it is remains not very well understood and is the subject of ongoing research. What is intriguing is the fact that most people spend one third of their lives asleep - that amounts to 30 years for someone who lives 90 years!

    As an exercise, the question "speculate the reason for sleep" was recently asked to Biomedical Engineering junior undergraduate students at the end of a Quantitative Physiology course that has dealt with neuroscience to a great extent. The students were given 30 minutes to turn in their answers, and surprisingly, they were quite interesting, particularly that the students had no access to any reference whatsoever. Here are a few of the answers:

    "It is the mechanism where the human body relaxes and consumes the least possible amount of energy to recharge body resources so as to maintain a perfect homeostatic environment." W.S.

    "Sleep is a process of resting all the body's aspects involving the five senses: sight, hearing, olfaction, taste, and touch... Hence, the body becomes insensitive to external stimuli." R.Y.

    "Sleeping is a practice that living beings do to rest their bodies after functioning for around 16 hours. It helps the body parts relax to gain the energy lost during the said time to be ready to function again in the next day. Sufficient amount of sleep ensures a good performance of the body and gives the person a healthy look." D.H.

    "Physiologically speaking, sleep is the inhibition of sensory receptors and the full relaxation of nearly all skeletal muscles... After sleep, the person wakes up relaxed and energetic, and better off physically and mentally... If you think of the body as a battery, sleep is the charging of the human body, and tiredness triggers certain hormones that signals the person to sleep. Thus, sleep is a necessary mechanism for human beings the same way that eating and drinking are." A.I.
    Hussin Jose Hejase · American University of Science and Technology Lebanon

    Thank you Raymond for sharing.

    Very interesting comments ongoing and many tied the issue to the Bible. I guess the holy Cor'an compares sleeping to a form of death, but with a return on and on...

  • Neil Bryan Miras asked a question:
    Physiology research

    Suggestions of any research proposals related to physiology..

  • Oscar Sierra added an answer:
    How important is the dominant or non dominant leg for protein expression in muscle biopsy, in sedentary or active subjects?

    Looking to know how important it is to identify the dominant or non dominant leg in muscle biopsy and protein expression. Will appreciate very much your help and guide. Best Wishes.

    Oscar Sierra · Washington University in St. Louis

    This is tough problem because to answer it one has to have the ability to do multiple sampling, i.e, take tissue from different muscles at distal or proximal levels for the limb considered dominant and its contralateral one. Alternatively, a non-invasive technique would need to be applied. In tennis players, selected areas of the ulna or radius in the dominant arm might have up to twice the Bone Mineral Content (BMC). This question could be answered thanks to DEXA or other non-invasive radiographic techniques. But for muscle protein is more challenging. - I think this is an interesting question that could be first approached in an animal model assuming limb dominance is found in experimental animals and such dominance is not mainly related to CNS neurological skill but rather and as in tennis players, to the structure or mass of the limb. Thus, multiple tissue sampling could be done as it is the gold standard technique and it could be compared to imaging and non-invasive techniques. 

  • Jai Ghosh added an answer:
    Can anyone help me to get mitochondrial isolation from tissue in wistar albino rats?

    I want to isolate mitochondia from liver tissue in wistar albino rats.

    Jai Ghosh · Shivaji University, Kolhapur

    There are thousands of papers on mitochondrial isolation from liver of many mammals. Actually it does not matter whether it is albino rats of mice or rabbits etc.

  • Hossein Hassanpoor added an answer:
    What is the physiological or anatomical difference between place cells and grid cells in the hippocampus?

    In the medial temporal lobe,there are specific types of neural cells such as place cells, head-direction cells, grid cells, and boundary vector cells which involved in cognitive map and spatial memory. Hippocampal “place cells” encode the rat’s location within an open environment independently of its orientation and fire in the specific position. The complementary encoding of the orientation, independently of location, is done by “head-direction cells” .I think all of them are pyramidal neurons. So Is there any physiological or anatomical difference between these kinds of cell?

    Hossein Hassanpoor · Amirkabir University of Technology

    Dr. Burgess said:

    "The differences between grid cells and place cells may well be due to their inputs, although some of the stellate cells in layer II of medial entorhinal cortex are probably grid cells, and they have some differences to pyramidal cells."

  • Olga Krizanova added an answer:
    What would be a good option to specifically block the IP3R2 activity?

    We are interested in blocking the calcium efflux from the ER in hepatocytes, and turns out that they express mainly the type 2 of the IP3R. 2 APB may not work because it has more affinity for the types 1 and 3. What would be a good option to block the IP3R2 in these cell?  

    Olga Krizanova · Slovak Academy of Sciences

    We are using siRNA from Dharmacon, efficiency for the IP3R2 is about 70%. Xestospongin C is also an option, although it is not a type specific and moreover, not 100% specific for the IP3 receptors.

  • Hossein Hassanpoor added an answer:
    Is there any specifically exclusive to the hippocampal astrocytes property?
    The Hippocampal astrocytes may have specific property, which other astrocytes in other brain regions do not have it.
    Hossein Hassanpoor · Amirkabir University of Technology

    Dear professor Verkhratsky
    your suggestions are completely right. All cells are important.
    But I think astrocytes have tools for managing the neural system that other cells haven't it. Ca signaling ( local, global and spotty) and secretion of variety substances with different effects on function and performance of other cell (eg neuron) activities, are these tools. This is just a scientific sense.

  • Daniel Guillaume added an answer:
    Can feces can have traces of hormones, which can give clues about oestrus?
    At least in the case of higher mammals
    Daniel Guillaume · French National Institute for Agricultural Research

    All the steroids can be assayed in the dungs. See on pub med publications on rhinoceroses from a German research team. Of course the assay needs an extraction before immuno-assay. This extraction is difficult and induced a high variability. The immune assays are ELISA or RIA with tritium.

About Physiology

Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system.

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