The study of the normal function of living organisms and the means by which it is achieved.

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How does having an empty stomach affect absorption of compounds?

From personal experience, compounds such as nicotine, caffeine and alchohol appear to absorb much quicker into the blood on an 'empty' stomach', or after extended periods of fasting. If this is the ...
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1answer
34 views

Why does dehydration lead to low blood pressure

I understand that the two leading causes of death from dehydration is imbalance in electrolytes and loss of blood pressure. I'm trying to understand what role water is playing in these cases and how ...
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21 views

Does too much salt in wound cause problems? [on hold]

OK, everyone has the experience of eating too much salt and getting a slight headache. But assuming somebody's injured and his wound (you can assume however large you want the wound to be) is soaked ...
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43 views

Why is the protein ubiquitin so ubiquitous?

Ubiquitin is a protein tag that is attached to proteins in order to mark them for destruction/proteolysis by the cell. This system is sometimes used for clearing out harmful viral proteins that infect ...
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9 views

How does the Jendrassik's manoeuvre reinforce reflexes? [migrated]

According to Wikipedia, The Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of fingers into a hook-like form and interlocks those sets of ...
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9 views

How long can/will an infant hold his/her breath as part of the dive reflex?

Various other questions on the site have talked about the Diving Reflex, which is also known as the Mammalian Diving Reflex. This reflex is observed in mammals of various species, but also in human ...
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23 views

Reason for variation in the site of onset of edema

What is the reason for the observed clinical difference in the earliest site of onset of edema in cases of different etiologies? For example, in Congestive Heart Failure, it appears initially as ...
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6 views

Ciliary muscle and accommodation

Can anyone explain how contraction of the ciliary muscles causes relaxation of the zonules? Please explain it anatomically i.e. the attachments of ciliary muscles and its relation with the ...
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1answer
14 views

Accommodation mechanism. [closed]

Can anyone explain how contraction of the ciliary muscles causes relaxation of the zonules? Please explain it anatomically i.e. the attachments of ciliary muscles and its relation with the ...
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6 views

Which of the following is an accumulation and release centre of neurohormones?

The options are : a)posterior pituitary b)hypothalamus According to me, it should be 'posterior pituitary' because though neurohormones are produced in hypothalamus but they are temporarily stored in ...
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31 views

What is the circulation that allows for nutrient absorption and excrete of metabolic wastes in humans? [closed]

Pulmonary veins carry oxygenated blood from lungs to heart, while pulmonary arteries carry deoxygenated/CO2 rich blood from heart to lungs. On the other hand, systemic arteries carry oxygen-rich blood ...
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1answer
43 views

Amino Acid requirement + intake in relation to diet + meat type [closed]

I was arguing with a friend: I said: The Yulin festivals cannot be condemned by western culture, as we also kill animals in equally cruel ways. She said: It isn't just that the killing is cruel, ...
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Why do mints make your mouth feel cold?

Why do mints make your mouth feel cold? And specifically, why does your mouth feel so cold if you eat a few mints and then drink a glass of cold water afterwards?
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3answers
104 views

What is the actual storage form of energy in muscles? ATP or Glycogen?

I was asked this question in my latest exam. I think the answer is Glycogen because ATP doesn't store energy for a long time so it isn't the ACTUAL storage of energy. Some classmates argue that in ...
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10 views

Has research indicated how much koinophillia preferences are learned vs insinctual

I'm curious about rather the definition of 'normal', as it affects koinophillia & mate choice, is something instinctual or learned. To clarify I'm not asking if koinophillia itself is ...
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33 views

Would a transparent iris serve its purpose?

The function of the iris is to regulate the aperture of the pupil. How does the iris obstruct light? Is it due to the pigment present in it? Or is it just due to the sheer presence of it? I am doing ...
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1answer
285 views

What's the mechanism for being mentally tired?

I notice that after long tests, or long periods of critical thinking, my body and mind feel noticeably tired. Why does this happen? Are the neurons in my head not firing as quickly, or is there just a ...
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8 views

will 2,4 Dichlorophenoxy acetic acid be effective as an herbicide against banana and papaya

Since 2,4 D is effective against broad leaved weeds/plants, will it be effective in case of banana and papaya?
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27 views

Are there available fluids that can be used in place of blood to facilitate oxygen and carbon dioxide exchange during major surgery/trauma?

Are there any available fluid alternatives that can be used instead of blood replacement that adequately exchange oxygen and carbon dioxide?
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1answer
28 views

If targeting a certain daily water intake, do you have to compensate for beverages that promote diuresis?

Please forgive my ignorance on the topic and I hope this is a "on topic" question here. It was a toss up between this SE and Physical Fitness SE but I want a more scientific answer. I came at a ...
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0answers
64 views

Why do horses recycle their endometrial lining while humans don't?

How does not recycling the endometrial lining of the uterus benefit humans (and other organisms that menstruate), while recycling it is beneficial to horses (and other organisms that undergo estrus ...
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0answers
17 views

What is the evidence that mammals are unable to process excess sodium chloride?

I grew up hearing the mantra excess salt causes heart disease I had a vague understanding that it caused deposits in the body or something. Now that I give it more thought - I come up with three ...
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1answer
32 views

Resting stage of primary oocytes

In my biology textbook, I read that the primary oocyte gets arrested in the early stages of meiosis in prophase I (diplotene stage). I wanted to know why this is so. I searched google, and this ...
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26 views

How do organoarsenics improve digestion efficiency in poultry?

It struck me as very surprising that these organoarsenic compound with structure looking not very compatible with living system is widely used as food additive to increase weight gain and improve food ...
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2answers
59 views

How does the muscle return to its resting state after muscle contraction?

I know that when ADP binds to the myosin head, it moves along and as it does so, it releases the ADP. The ATP attaches to the myosin head and releases the myosin head from the actin filament. Then the ...
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1answer
45 views

How does an octopus eye react in free fall?

according to Wikipedia: Attached to the brain are two special organs, called statocysts, that allow the octopus to sense the orientation of its body relative to horizontal. An autonomic response ...
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1answer
50 views

Evolution & Celluar Chemistry [closed]

I'm new to this site but had a question on evolution, apologies if some of these questions seem basic but they are from a book i am reading challenging the role of chance in evolution. Taking the ...
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1answer
54 views

Why don't bacterial cell walls prevent bursting when attacked by the complement?

The complement system creates pores in cell membrane which leads to influx of lots of water thereby causing lysis of bacterial cell. But what I fail to understand is that if bacteria have cell walls ...
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52 views

Why do some men have patchy beards?

Why do some men have patchy beards? Or more specifically, why would some hair follicles lack sufficient 5-alpha reductase while others nearby don't when their genetic code is identical and they are ...
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1answer
43 views

Enzyme Inhibition in relation to Aspirin

I've been trying to learn a bit more about pharmacology, so bear with my ignorance. In short, I see that aspirin (in part) works by inhibiting cycloxygenase isoenzymes and that this inhibiting is ...
2
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1answer
258 views

Where does female ejaculate actually originate from?

It's common knowledge that it's released via the urethra, but where does it originate? If it doesn't come from a part of the clitoris, then why is the clitoral glans called the clitoral glans? How ...
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1answer
41 views

A state model of sodium channels

I am studying by myself Human Physiology. I have encountered the following question: In the following given model of sodium channel with 3 states open closed blocked (which I assume means inactivated)...
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0answers
27 views

Bilirubin metabolism and UGT1A1 inhibition in human vs. monkey?

In human UGT1A1 seems to be the only relevant enzyme to glucuronidate unconjugated bilirubin into excreted forms. Is the pathway the same for e.g. the Cynomolgus monkey (Macaca fascicularis) in vivo? ...
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1answer
43 views

Question about radiation and how it affects biological systems

I'm doing research on the effects of radiation, and specifically UV, X-Ray and Gamma radiation, on biological systems at the cellular level and beyond. I understand that radiation types can be ...
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1answer
28 views

Is H antigen considered as an agglutinogen?

A and B antigens which have the potential to cause agglutination in certain cases are called agglutinogens. But, as far as I know, H antigen cannot give rise to agglutination. So can it be said that H ...
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41 views

Why do Arctic predators accumulate vitamin A?

Top predators in the Arctic are known to accumulate vitamin A, often to levels that are toxic for human consumption. A 2012 study by Senoo, Imai, et al. found that the livers of several predator ...
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1answer
111 views

What keeps organs suspended in the body?

I'm a bit confused what prevents our organs from not collapsing into a heap or putting pressure on each other. I have a 3D anatomy app and have been studying the relationship between the organs. ...
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2answers
437 views

Why does haemoglobin's affinity to oxygen decrease at high altitudes?

My class 12 NCERT book says, Pg 226 The body compensates low oxygen availability by increasing red blood cell production, decreasing the binding affinity of haemoglobin and by increasing breathing ...
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1answer
113 views

What determines whether a substance can diffuse across the blood-brain-barrier?

What determines whether a chemical substance is able to cross the blood-brain-barrier via passive, transmembrane diffusion? What structurally differentiates these chemicals?
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1answer
106 views

Why is it always Sodium that we talk of in blood pressure?

Why is that we emphasize so much on sodium in blood pressure? I understand that it is a major extracellular ion, but, it also is tightly regulated. So when something is that tightly regulated, won't ...
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1answer
129 views

Doesn't the sarcomere contract during isometric contraction?

During muscle contraction, the lenght of the sarcomere changes, length of myocyte changes and so does the length of muscle. However, if the length of muscle is not changing length as in isometric ...
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1answer
122 views

What happens when our muscle tense? [closed]

Is the tensing of muscles equivalent to stretching them? I am trying to understand what tensing of the muscles means.
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0answers
27 views

What happens to the cell during post-hypothermia?

A friend of mine said that the cell membrane somehow changes after rewarming from hypothermia and that the body does not recognize it's own cells, thus leads the immune system to attack it self. Is ...
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1answer
679 views

Why don't rats have a gallbladder, unlike other rodents?

It has long been known that rats do not have a gallbladder, though other species including humans, monkeys, cows, reptiles, dogs and mice, all have a gallbladder. In this paper from almost 100 years ...
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Is the amount of blood same in the pulmonary and systemic foetal circulation?

We learn that the stroke volume is the same for the right and left side of the heart. So the amount of blood in either circulations should also be the same. (is it? I myself doubt this statement. As ...
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0answers
42 views

When you have your gallbladder removed, how does it affect bile flow into your small intestine?

Cholecystectomy, or surgical removal of the gallbladder, is an extremely common operation around the world. The gallbladder is typically viewed as a storage organ for bile produced by the liver, but ...
3
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1answer
76 views

What is the oxygen carrying capacity of reticulocytes?

What is the oxygen carrying capacity of immature red blood cells, or reticulocytes? Is there any difference between oxygen carrying capacity of mature and immature red blood cells?
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0answers
17 views

How is the side-polarity of the myosin filament in myofibril maintained?

If myosin molecules are the properly oriented relative to their position in the the myosin filaments, the sarcomere is not functional. But how is the orientation of the myosin molecules determined? ...
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44 views

How does glucose delivered intraperitoneal (i.p.) get into the peripheral circulation?

Intraperitoneal delivery of drugs or fluids is something that occurs much more frequently in veterinary medicine than clinical medicine. In veterinary medicine or scientific studies using animals, ...
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1answer
47 views

Do goosebumps always appear in the same spots on the skin?

Often one gets goosebumps when one is cold. I am curious whether the precise location of the goosebumps on, say, one's leg changes from occurrence to occurrence or not? In case if their precise ...