Questions tagged [endocrinology]

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

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1answer
603 views

How to measure GnRH in menstrual cycle?

I am interested in pulse frequencies of GnRH (gonadotropin-releasing hormone) in the menstrual cycle (MC) i.e. 28 +/- 7 days. I would like to study its pulsatile nature i.e. within one MC, not same ...
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1answer
351 views

Where exactly is 'Colloid' with regards to synthesis of thyroid hormones?

I've researched colloid and it seems to be a substance of microfibres and thin films in which thyroid hormones may be synthesised, but I was wondering where this exactly is... I think it could be in ...
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1answer
555 views

Corpus luteum during the luteal phase and gonadotropins

Does the corpus luteum operate independently of the hypothalamic-hypophyseal-ovarian axis? I know that hCG sustains the corpus luteum in the absence of FSH and LH, but in an ovarian cycle where there ...
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1answer
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How can hyperthyroidism induce osteoporosis?

It says in my physiology notes that hyperthyroidism can cause osteoporosis. I've been trying to figure out how this could be possible for a little more than an hour now. Every article that I look at ...
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1answer
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How does the pancreatic beta-cell know how much insulin to secrete in response to glucose?

How do $\ce\beta$-cells know how much glucose is in the blood? I know that when glucose enters a beta cell it triggers the cell to produce insulin. $\ce\beta$-cells trap glucose by converting it into ...
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Target cells of adrenaline?

I have been thinking about how adrenaline increases blood sugar levels, but have not been able to find an answer to the target cells. Does it affect the hepatocytes and muscle cells, like glycogen? ...
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0answers
125 views

Nail polish toxicity studies?

Are there any well-founded studies that authoritatively demonstrate negative effects from the use of nail polish, particularly in children? I've been brought into the fray of a couple of folks who ...
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1answer
624 views

If so many different hormones/molecules work by activating adenylyl cyclase, how do they have different effects?

It seems that many hormones and molecules work by activating adenylyl cyclase to convert $\text{ATP}$ to $\text{cAMP}$, such as adrenaline and glucagon. Both of these seem to bind to $\text G$ protein ...
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1answer
952 views

Effects of HRT on transgender(M to F) physiology and athleticism.

I often heard of athletes in the Olympics who would be accussed of having an advantage because they were intersexed. Now I know transgenderism and being intersexed are not the same thing, but they ...
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1answer
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How is adrenaline (also known as “epinephrine”) a ligand?

I keep reading that adrenaline is a ligand, however, from what I understand a ligand is a molecule or ion which donates a pair of electrons to a central transition metal ion in a complex. If this is ...
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1answer
381 views

Difference between the inactivation of neurotransmitters and hormones

Neurotransmitters must be somehow removed from the synapse once they’ve produced a post-synaptic potential, whether it be through enzymatic breakdown, diffusion, reuptake or another mechanism. However,...
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2answers
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Why would glucocorticoids promote glycogenesis and not glycogenolysis?

I read in a textbook that glucocorticoids can stimulate the synthesis of glycogen. I do not understand this at all—shouldn’t glucocorticoids try to increase the blood level of glucose? Why would they ...
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332 views

Why would growth hormone (somatotropin) cause both lipid AND glucose release?

GH increases lipolysis (lipid breakdown) and the release of fatty acids from adipocytes into the blood. Fatty acids then can be used as energy sources to drive chemical reactions, including ...
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549 views

Proteases in the blood

I’m reading on hormones and the book talks about how peptide or amine hormones are easily broken down by proteases present in the blood plasma. This has led me to question the interactions between ...
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53 views

How are steroid hormones secreted? [closed]

Peptide hormones for example tend to be secreted by Ca2+ mediated exocytosis following depolarisation and are secreted in vesicles. How are steroid hormones secreted and what stimulates their ...
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2answers
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Why does depolarisation by high intracellular K+ trigger calcium channels opening?

I have learnt that in pancreatic beta cells, glucose being metabolised in the cell causes a high ATP level, which triggers ATP-dependent potassium channels to close. This means that potassium can't ...
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1answer
183 views

Is there a blood panel lab test that measures all the hormone-producing glands?

I understand that there are gland-specific hormone tests, such as: Secretin: for the pancreas; and Prolactin/ACTH: for the pituitary; and PTH: for the payathyroid, etc. However, are there any "...
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1answer
284 views

Does exercise really reduce stress in the biological meaning?

It is a very widespread claim, that movement in general helps body to get out stress hormones. It is used as a warning for long sitting at the computer and I also heard it as a pro-vegan argument (We ...
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3answers
13k views

What are the differences between how glucagon and cortisol work to increase blood sugar?

As I understand, both cortisol and glucagon cause an increase in blood sugar concentrations. However I don't understand how they work differently or why they work separately. I would be very grateful ...
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78 views

Artificial Adrenalin

I was watching Sherlock Holmes - A Game of Shadows yesterday. I saw that he had developed a serum that causes a person to react like he has been injected with adrenalin. Watsons's dog fainted, I ...
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1answer
4k views

If a human is stranded with beer but no water, should they drink it? [duplicate]

TL;DR: At what percent (if any) will alcohol dehydrate you more/faster than drinking nothing? Let's contrive a situation for dramatic effect... A human goes out on a boat for a nice sail in the sea. ...
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124 views

Root etiology of non-pituitary low T4 and low TSH

Please note: I'd like to preface this question by stating that this is neither homework nor me seeking medical advice. I am simply trying to understand the biological, physiological root etiology ...
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1answer
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What is the antagonist of epinephrine?

Norepinephrine and epinephrine have similar stimulant properties on the nervous system and the body. I was wondering which hormone is the antagonist of epinephrine?
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1answer
386 views

How do signal transduction pathways utilize transcription factors to express a specific gene?

I have an inquiry regarding the regulation of genes via extracellular signaling. To my knowledge, in autocrine, paracrine, and endocrine cellular communication, large protein ligands that cannot ...
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0answers
768 views

What's the feedback regulation of Thyroid diseases and body temperature?

While going through the feedback regulation, the control of blood glucose level by insulin and glucagon is quite discussed in multiple materials including the textbook. I also understand the basic ...
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What is basis of multifunctionality of “master glands” in the endocrine system?

I have just started reading about the endocrine system and I am having some difficulty understanding the basis of distribution of glands and associated hormones. I am using multifuntionality to ...
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3answers
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Why does the face turn pale in dangerous situations?

I know what the effects are of a dangerous situation on the brain, i.e., an activation of the hypothalamic-pituitary-adrenal (HPA) axis which eventually results in an increased heart rate and elevated ...
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1answer
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How do female hormones cause blood to clot?

On most female-hormone supplements you get a warning that is something like this: The use of a combination hormonal contraceptives (CHC), like NuvaRing, is associated with increased risks of ...
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2answers
273 views

Leptin and fat mass?

I am interested in the relationship between blood leptin concentration and fat mass. It is well known that as fat mass increases, leptin increases. Have there been studies that look into whether the ...
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1answer
754 views

Can androgen-insensitive genetic-males get pregnant?

According to the linked report, people with androgen insensitivity syndrome appear as male, but have both feminine and masculine outer genitalia. However, I was not able to find out whether their ...
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345 views

Is hunger pushing cognitive ability in humans? [closed]

We have a lot of those questions here that base on personal anecdotes and I try to avoid asking any of those. Still, after skipping breakfast and an extremely effective work day so far I started ...
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1answer
482 views

Do humans have skin cells that trigger oxytocin release in the brain?

I was reading an article by Montgomery on the therapeutic effect of pets (Boston Globe, January 12, 2015), and I found this quote: All animals appear to have cells directly under the skin that ...
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1answer
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How does visual sexual arousal work between the eyes, brain, and genitals/gonads? [closed]

When many people look at sexual images, they often can become sexually aroused, including full genital arousal, and feel urges, known more often used as "horny" as slang/urban usage. How does this ...
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1answer
754 views

Over what range do Thyroid Stimulating Hormone (TSH) levels tend to fluctuate over the course of a day?

I understand that the majority of doctors consider the TSH test "the gold standard" for measuring thyroid function (examples stating that literally are here and here). The reference range for what is ...
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304 views

Is there any biological support for the concept of “chakras”? [closed]

Is there any support in modern biology for the ancient concept of "Chakras"? I've seen the concept of 7 chakras linked to the major endocrine glands in the human body (pineal,thyroid, adrenal, testes,...
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1answer
430 views

Does hypothalamus regulate posterior pituitary gland?

We have the hypothalamus-anterior pituitary-endocrine axis, but is there a similar chain of command for posterior pituitary gland such that oxycotin and vasopressin are regulated by some tropic ...
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3answers
1k views

What does it mean for a hormone to be “active”

In my textbook it is stated that the T3 hormone produced at the thyroid gland is 3-5 times more biologically active than T4. How is being active defined and how can this effect be measured?
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Question about epinephrine

In my class we were told that adrenaline (or epinephrine) causes vasoconstriction. My question was I had always thought that people took this via an EpiPen when they were having an allergic reaction. ...
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2answers
4k views

When glucose production is low, the brain begins using ketoacids as energy… how does that work?

Can someone very generally describe how the brain consumes ketoacids/ketone bodies when blood glucose has been completely depleted?
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2answers
458 views

Is it possible for a human to wake up in a wrong way?

There's an old folk saying that goes like "He got out of bed on a wrong foot" - to indicate that the person's day is going poorly because of the way that person woke up. Is it is possible for a human ...
5
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1answer
377 views

Can we artificially increase human growth using HGH?

Robert Pershing Wadlow was a man who lived in the first half of the twentieth century. He had hyperplasia of his pituitary gland, which caused him over-produce human growth hormone (HGH), and as a ...
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272 views

How does estrogen influence collagen synthesis?

Through what mechanisms does estrogen interact with collagen synthesis? Especially in the context of elevated estrogen levels and genesis of purpura simplex .
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1answer
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Pituitary giants - is the fusing of growth plates dependent on amount of growth hormone in blood?

I wanted to ask a couple questions related to pituitary giants (people who are giants because of some anomaly, such as a tumor, in their pituitary gland). Some of these giants seem to keep growing ...
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4answers
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Why do men have a higher hematocrit (red blood cell count) than women?

The hematocrit, also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women. so,...
7
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1answer
669 views

When did our ancestors switch to a menstrual cycle instead of the estrous cycle?

The Wikipedia page on the Estrous cycle says: Humans have menstrual cycles instead of estrous cycles. They shed their endometrium instead of reabsorbing it. Unlike animals with estrous cycles, ...
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Why do Sorghum Bicolor leaves roll up?

In A level Bio today we talked about abcesic acid as a stress hormone, and its ability to reduce osmotic potential around guard cells to close stomata. My question is, is abscesic acid in sorghum ...
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What is the biological basis of “energy” that extraverted humans draw from social engagements and introverts expend?

This question is related to this question about introverts becoming exhausted after extended social events on cognitive sciences stack exchange. As I read more on the topic of human extraversion-...
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1answer
809 views

Why is LH level much higher than FSH level at ovulation?

My teacher showed us an elaborate collection of graphs with one of them showing FSH and LH plasma levels during the menstrual cycle. LH level was almost 3 times higher than FSH level. Why? Does this ...
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1answer
74 views

Would constant light or fading light be registered as more wakefulness promoting by the Supra Chiasmatic Nucleus?

During the fall and winter season, a number of people are experiencing Seasonal Affective Disorder. One of the way it has traditionally been treated is with a dedicated lightbox - a very high ...
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1answer
77 views

Help me understand how the thyroid secretes

Please have a look at this close up light microscopic image of a thyroid gland: So I'm guessing the cubic epithelial cells surrounding this big red pulp are the secreting cells...? If so, is the red ...