The area of physiology dealing with the production and effects of hormones.

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estradiol hormone role

Increasing estradiol (E2) hormone from ovarian follicles prior to ovulation has been hypothesized to play a critical role for induction of pheromones. These pheromones render females sexually ...
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Sodium levels and blood pressure

Why does low Na+ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of Na+ cause hypertension or high blood pressure? From what I understand, there are ...
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Euthyrodism and goitre

I read in Tortora and Derrickson that goitre is associated with euthyrodism. How is that possible?
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Giving diuretics to insipidus patient

I read in Tortora and Derrickson that giving diuretics to diabetes insipidus patients may in fact alleviate the symptoms of the disease. How is this possible?
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Growth Hormone and diabetes

Growth hormone and insulin like growth factors are diabetogenic, so I assume that people with high growth hormone (say due to pituitary tumor) may be at high risk for diabetes. Has any correlation ...
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Renin - enzyme or hormone?

Wikipedia says : The kidneys secrete a variety of hormones, including erythropoietin, and the enzyme renin. Can a substance be both an enzyme and a hormone ? Why is renin both an enzyme and a ...
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Which hormones can cross the blood brain barrier?

Can hormones such as testosterone, aldosterone and estrogen cross the blood brain barrier? I looked on Wikipedia and there no mention of it in the testosterone article. Through Googling around I also ...
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Abnormal Prolactin Level [closed]

I want to know what makes the balance of the Prolactin abnormal. Is that related to the presence of a nodule near the pituitary?
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Are there more/less favourable phases of menstrual cycle to donate blood?

I was wondering whether it makes a difference when during the menstrual cycle a female is donating blood in terms of: Blood quality (iron or hormones levels) Her health/safety I am aware that ...
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Do hormones make men think of sex?

I remember hearing a saying that goes like "men think of sex every 7 minutes (or seconds?)". I take this saying to mean that men have sex related thoughts more often than women. I'm interested if ...
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Steroid Hormone Signalling

Can the lipid-soluble hormones (like steroid hormones) go inside every cell, as their particular receptors are located in the cytoplasm or nucleus of the target cells? Is there anything special on the ...
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Diabetes-diabetes comorbidity

Is it possible to have both type-1 (insulin-dependent) and type-2 (non-insulin-dependent) diabetes mellitus? That is, to have both insulin resistance and zero (or negligible) insulin production? If ...
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Can parts of a human brain be asleep independently of each other, or vary in the times required for them to fall asleep?

I know that some birds and marine animals can continue complicated activity (swimming, flying?) while one hemisphere of their brain is asleep. I'm interested if human brain has some parts of it that ...
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Which hormones/factors affect Calcium absorption in the small intestine and its regulation?

I think the question is very broad and cannot find precise mechanisms. I am not sure about the precise mechanisms of the regulation. I think they are at least Vitamin D, diffusion and specific ...
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Why is epinephrine not part of the somatic nervous system?

I learned that the adrenal medulla releases epinephrine, which is a vasodilator of the vessels that lead to the skeletal muscle. I also learned that somatic nervous system only uses Achetycholine as ...
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What is the mechanism by which Melatonin increases dream vividness and intensity in humans?

I'm looking at the wikipedia article on Melatonin and noticed that it mentions vivid dreaming caused by melatonin. I have the "Melatonin and the Biological clock" pamphlet referenced in the article, ...
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146 views

Is there a comprehensive list of human circadian-like processes, hormones or gene expressions?

I'm reading this article onblood sugar and circadian rhythms and the following question popped into my head: a lot of articles mention various diurnal or circadian rhythmicity of biological processes. ...
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What mechanism suppresses melatonin release in humans?

I'm looking at melanopsin, a photo pigment in the human eye. One of its actions is to trigger suprachiasmatic nuclei SCN to suppress melatonin release. I'm interested in learning what is the exact ...
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557 views

What causes humans to be sleepy?

Is there a hormone or group of hormones that regulates when we feel sleepy late at night, or in the morning? Or is sleepiness caused by some other non-hormonal mechanism? (e.g. pure psychological, ...
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Are lactic acid and prolactin rise after exercise connected?

I've been reading about prolactin, a human hormone. Apparently it's levels within the brain can raise after exercise, although the mechanism is not clear to me. I'm interested of there is any ...
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How do circulating androgens contribute to higher rates of hirsuteness in some women?

I was reading up on ethnic groups in which the women are naturally more hirsute (such as South Asian women) in the context of evolving standards of beauty. I came across this statement on a forum: ...
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Prostaglandin F2-alpha production in men

I am trying to find information on Prostaglandin F2-alpha, specificaly production in men. Could somebody explain how this prostaglandin is produced? What types of cells are producing it, production ...
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876 views

Do hormone drugs affect whether a person feels sexual attraction to males or females?

I know that ingesting testosterone and other hormonal drugs may stimulate libido and increase sexual desire. But I wonder, if a man ingests female hormones such as estrogen, will he experience sexual ...
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Is there an entry-level circadian model of serotonin, ghrelin, dopamine and the sense of well being?

I've long been interested in circadian rhythms and recently came across a variety of articles that appear to indicate that the following neurotransmitters, transferases and hormones are connected. ...
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Are there records of monozygotic twins in which one experiences androgen insensitivity syndrome

I have given my high school biology students the thought experiment of "What would happen if a researcher induced twinning of a female zygote and then replaced one of the X Chromosomes with a copy of ...
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Are serotonin levels in humans affected by light?

I'm reading this Wikipedia article on light therapy and noticed a peculiar statement: The production of the hormone melatonin, a sleep regulator, is inhibited by light and permitted by darkness ...
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Insulin and monoclonal antibody production

When producing insulin, the gene for its production is inserted into the plasmid of a bacterium that is allowed to replicate freely. Why can't the same thing be done with antibodies (as I understand ...
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Is Leptin Stimulated by Insulin Alone?

What is the mechanism of insulin stimulation in the human body? Is leptin release stimulated by circulating insulin directly? Which other factors are involved in the level of insulin release? My goal ...
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Why do drugs which are hormones have long half-life?

Hormones normally have short half-life. How is it possible that they have long-life in drugs?
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Genetic engineering for insulin production

In order to put human DNA inside a bacteria in order to have it create Insulin, from what type of cell would you need to take the gene for insulin? I thought it should be from any somatic cell, since ...
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circulating microRNAs are functional?

In plasma and other body fluids, miRNAs can be found. They not only originate from dying cells but also from active secretion and are usually 'packed' into vesicles/lipo-proteic structures (i.e. ...
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How are melatonin levels measured in humans?

I'm wondering how it is possible to measure diurnal variations of melatonin levels in humans. I keep reading that there should be a large difference in amplitude between melatonin levels measured at ...
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Are there yearly variations in HIOMT (HydroxyIndole-O-MethylTransferase) availability?

I'm reading a booklet on melatonin published in 1996, titled "Melatonin and the Biological Clock". And see the following statement: HIOMT (HydroxyIndole-O-MethylTransferase), one of enzymes of ...
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What light intensity determines the start/end of a photoperiod in humans?

I'm reading this article, which discusses the influence of Long Photoperiod (LP) and Short Photoperiod (SP) on melatonin production: HIOMT drives the photoperiodic changes in the amplitude of the ...
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Is there a relationship between Melatonin, Norepinephrine and depression in humans?

I'm reading a booklet on melatonin published in 1996, titled "Melatonin and the Biological Clock". This particular paragraph caught my attention and I would like to better understand what it means: ...
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What determines testosterone exposure in womb, baby's genetics or mom's body?

I read this article which has the following quote: The ratio between index and ring finger is believed to be linked to exposure to the male hormone testosterone in the womb. And I wonder what ...
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From which ancestor species did humans inherit orgasm?

From what ancestors did humans inherit orgasm? Do fish experience orgasm? Are the male and female orgasm the homologues that can be traced to the time when there was no difference in sex between ...
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Biological Pathway of Lipid Hypothesis

I've read a lot on both sides of the debate of low carb vs low fat diets trying to make some sense of what is being proposed. The lipid hypothesis runs roughly along the lines that we have lots of ...
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What gaseous substances do humans emit?

Other than CO₂ and Methane what other gases do humans produce or emit? For example, does skin decomposition, or aerobic respiration emit any special gases that people don't normally realize or know ...
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What is the mIU unit as used in hCG hormone levels?

My girlfriend is in her very early pregnancy, and has provided several blood samples by now where the doctors measure her hCG levels. The hCG hormone level is measure in a unit called ...
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Do men have significant hormonal cycles?

I know there's a similar question here. But that discussion dissolved into lunar cycle and a correlation with it. I want to find more towards the original question of is there a periodic hormone ...
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What is the purpose of the adrenal medulla?

The adrenal medulla is less of a 'real' endocrine organ like the others in the endocrine system and much more an extension of the sympathetic nervous system. In fact, its chromaffin cells are modified ...
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Why are some menstrual cycles irregular?

A friend of mine asked me this today, and I didn't know. I remember studying the menstrual cycle a few years ago, but I can't remember the details (other than it was very hormone-related), and so I ...
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Is it purely the nervous system causing vaginal lubrication (arousal)?

My girlfriend was watching some documentary on TLC about a paralyzed woman getting pregnant. I believe that woman still has some feeling, as she spoke about feeling the effects of a bladder ...
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Is there such thing as a generic “metabolic type”?

A while ago I picked up a book called "Eat right for your metabolic type". The book discussed the effects of the endocrine system on the overall shape and the speed of metabolism. The book outlined ...
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What happens to a human body once a sugary snack is consumed?

I'm looking to understand the effects of sugary snacks and/or drinks on a human body. I'm particularly interested in the timing of the ingestion versus various hormonal levels that may be circadian in ...
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Do any animals other than humans undergo menopause?

Do any animals other than humans undergo menopause? Also, is there any difference between animals in captivity and animals in the wild as regards menopause? For example, even if menopause has been ...
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Does testosterone increase female sexual behavior?

According to my lecture notes testosterone generally increases sexual behavior. Given that it's generally thought to be the male hormone I'm not quite sure whether they mean that it also increases ...
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Single hormone opposite effects

Often, a smooth response to a hormone means that some processes must be sped up and others must be slowed down. How can a single hormone have opposite effects like this?
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Which human body hormonal systems exhibit 24 hour diurnal cyclical activity?

I'm researching the possible connection between the dream content and the activity of various organ or hormonal systems within the human body. I'm looking for information on biological cycles within ...