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

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Case Study and speculations of Edward Mordake

I am very interested in the case of the man named Edward Mordake who lived in the 19th century. In particular, he had two faces. If you have not heard of this man, please, search this up as there are ...
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110 views

Dimensionless number for blood volume

Comments from the question How is the blood volume of a living organism measured without killing it? by @Nico discussed that the time of blood recirculation scales with the size of the organism. I was ...
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452 views

Does Amphibian embryo's blastocoel become a primitive yolk sac without yolk?

The mammalian blastocoel becomes yolk sac without yolk according to my professor. I have not found any evidence that such a thing happens in amphibians like frog. I need to be able to compare and ...
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103 views

Why can't we defibrillate the heart within 1 minute after ventricular fibrillation by electroshock?

We mostly can defibrillate the heart before 1 min of ventricular fibrillation by electroshock.Then we often can't do defibrillate it with electroshock. What's the reason and What's the best way to ...
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395 views

Why is the frog genome so much larger than a fish's?

As we have heard in the summaries of the human ENCODE project, 80 per cent of junk DNA appears to have an essential function. Many fish have a genome with only one tenth the size of a usual vertebrate ...
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1k views

The number of nipples (breasts) a species has?

Only mammals have mammaries and mammary glands. What evolutionary factors determines the number of mammaries (nipples/teats/breasts) a species has? Is it always an even number?
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88 views

Is vision a vestigial sense for deep ocean species?

Sunlight doesn't penetrate beyond a couple of hundred feet from the surface of the ocean. Species that exist at greater depth probably live in a state of perpetual night; yet from a quick google image ...
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1answer
99 views

Why do people in the scientific community use terminology such as renal, hepatic, cardiac instead of kidney, liver and heart? [closed]

Why is there the need to map these everyday words into another set of words, it seems to complicate matters. Is it done mostly out of tradition or is there some logical basis to it?
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129 views

What is lack in sense of smell called?

People who lack the sense of hearing, vision and speaking are called Deaf, Blind and Mute. But what is the person called if he/she lacks the sense of smell? Is there any case like that?
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100 views

What’s the reason for isovolumic contraction and isovolumic relaxation?

During cardiac cycle, there are two periods in which the heart volume doesn’t change, but there is a change in tension/pressure. It takes about 0.25-0.35 second to achieve this change. I searched in ...
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139 views

What are the factors that control the speed of propagation of neuronal signals?

If we consider an analogy between a wire and a neuron there may be some resemblance between the factors controlling the data flow rate. For example the increased width of wire leads to decreased ...
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1answer
77 views

Do people with gout live longer?

Antioxidants reduce damage to tissue (by scavenging the free radicals) and thus may reduce ageing.It is known that Uric acid is a very good antioxidant. People with gout have excess accumulation of ...
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83 views

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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170 views

Hydrogen Peroxide on Open Wounds

I know that H2O2 is a chemical with high oxidative potential. It can deliver nascent oxygen which can destroy bacteria. I understand that open wounds have cells that are dividing at a fast rate to ...
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1answer
74 views

Do human visual functions degenerate due to genetic factors or by external factors?

Does eyesight primarily deteriorate 'naturally' due to genetics (genomic/epigenomic factors), or due to external factors such as normal wear and tear, or disease? By normal wear and tear I include ...
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1answer
375 views

NADH inhibits gluconeogenesis?

I was told in a physiology lecture that alcohol inhibits gluconeogenesis because 'NADH produced from ethanol catabolism leads to product inhibition'. But is NADH not a reactant coenzyme of ...
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1answer
54 views

What is the reason behind more severe proteinuria in nephrotic syndrome than in nephritic syndrome?

Why is there less protein loss via urine in case of nephritic syndrome than in case of nephrotic syndrome?
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1answer
71 views

How does regurgitated food go to the 3rd stomach chamber instead of going to the 1st?

Ruminants are known for their regurgitation of food; the food goes through the 1st and 2nd stomach chambers, then returns to the oral cavity in cuds. The cuds then come back into the stomach, but this ...
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2answers
5k views

How does extracellular potassium ion concentration and calcium ion concentration affect the excitability of a cell?

When extracellular $K^+$ concentration increase by a certain amount, excitability of cells is higher because the resting potential shifts toward a higher equilibrium potential of $K^+$, therefore ...
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1answer
63 views

Alternating Ovulation

I have often heard that right and left ovaries alternate in releasing ovum. Is it always true? What controls this rhythm? Is it simply because the other ovary is unresponsive to LH or FSH? If so, ...
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1answer
68 views

Difference in reptile inner ear and otosclerosis

In reptiles, the sound is conducted from the tympanic membrane to the inner ear by a single bone. In the disease otosclerosis the stapes of humans become fused to the other middle ear bones( or to ...
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1answer
2k views

What are the units of Q10 (temperature sensitivity)?

$Q_{10}$ is the increase in a rate (e.g. activity of an enzyme) observed with a 10° temperature increase. According to Wikipedia: ...
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1answer
238 views

Antihistamine's effect on insulin secretion and tiredness

Antihistamines are known to cause tiredness. The essential hormones of the body are insulin (glucose), parathyroid hormone (calcium) and aldosterone (Na-K ATPase, sodium). I am thinking how this ...
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1answer
23 views

Polarized epithelium and localization of ion channels

I'm trying to learn more about polarized epithelial cells of the gut. I am familiar with classic brush border transporters localized to the apical memebrane to facilitate nutrient absorption. I am ...
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2answers
102 views

What are the physiological roles of Hydrogen sulfide?

I am thinking why hydrogen sulfide has its effects in the body. For instance, it is one Salmonella's virulence factor. I am not sure if such a balance equations holds H2O + H2S ←→ ... Actually, I ...
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1answer
291 views

Is there a maximum pain threshold?

Is there a maximum threshold of pain a Human can experience, beyond which point there is no noticeable difference? I ask this question in part to better understand the definition of pain and its ...
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1answer
88 views

Why does hypertension occur in obstructive sleep apnea?

What is the physiological mechanism behind systemic hypertension resulting from obstructive sleep apnea?
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2answers
184 views

How does Humira work when injected into patients with rheumatoid arthritis?

OK, I have rheumatoid arthritis and I've been injecting Humira 2 times a month for the last 8 months. As far as I know rheumatoid arthritis is simply an immune system disorder which makes the immune ...
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50 views

Effect of arteriole dilation on vein

If an arteriole leading to a capillary bed is dilated will the pressure in the vein coming out from the bed decrease ? Will the velocity of blood in the vein change ?
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2k views

What is the genetic basis of blood type (ABO) system?

What is the genetic basis of the A/B/B+/O/etc. blood type system? Are there definitive loci that correspond to each or can multiple different genotypes produce the same antigen profile? Also, is the ...
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1answer
2k views

Slow-oxidative fibres vs fast-glycotic fibres

Why do slow oxidative muscle fibres contain more mitochondria compared to fast-glycolytic muscle fibres?
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1answer
104 views

Are ectopic beats considered sinus rhythm for pNN50 purposes?

One quantification of the heart rate variability of an ECG is pNNx, i.e. the proportion of consecutive NN distances that differ by at least 50 ms. When a premature beat occurs, the preceding and ...
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45 views

Why do the size of the phase 1 notch vary among cardiac cells?

The size of the phase 1 notch varies among cardiac cells. It is prominent in myocytes in the epicardial and midmyocardial regions of the left ventricular wall and in ventricular Purkinje fibers. ...
3
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1answer
57 views

Mechanisms of bone growth

The length of a bone is caused by growth of hyaline cartilage which is then replaced by bone tissue. How do cells know whether they should grow the hyaline cartilage? What are the key molecules that ...
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157 views

Electronic cigarettes (e-cigs), any health risks?

Background: An electronic cigarette (e-cig or e-cigarette) is a battery-powered device which simulates tobacco smoking patented in 1963 by Herbert A. Gilbert. It generally uses a heating element ...
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1answer
294 views

What are the highest and lowest possible pH, paCO2 and HCO3 in the blood of living human?

What are the highest and lowest possible values of pH, $paCO_2$, and $HCO_3$ in the (arterial or venous) blood of a living human being?
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111 views

Attachment of muscles during molting in insects

Normally, insects' muscles are attached to their exoskeleton but what happens to this attachment when they are moulting? Sorry if this is an extremely silly question but I have wondered about it for ...
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2answers
1k views

Ill effects of urea and NH₃ on metabolism

What exactly does urea do that harms our body? Does it interfere with our cellular processes or disturbs the colloidal onchotic pressure of our blood? I have heard that NH3 damages the brain. What ...
3
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1answer
88 views

How is olfactory acuity rated/measured?

Acuity of one's sight is rated on the 20/20 scale. An online search appeared to indicate there is no comparable 'standard' to rate olfactory acuity. How is acuity of the olfactory system rated?
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1answer
60 views

What is the impact of stress on the human body?

Can stress trigger any changes in the human body? I'd like to know more about things less commonly known than, for example: sweating and tiredness. What are the long term risks of chronic stress? Do ...
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1answer
119 views

How are arms different than legs?

Ok, this is a bit of a tangent question, but it came up yesterday and I didn't know the answer: How are arms and legs defined physiologically? For example, we say humans have two arms and two legs, ...
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1answer
53 views

Hypersensitivity Simultaneously in Ear canals

I got experimental data where hypersensitivity (i.e. tonic pain when touching ear canal) was recognised for about 100 minutes. I do not know which type of hypersensitivity is this one. IgM can ...
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1answer
113 views

Elevated position effect on recovery times from upper respiratory infections at rest?

In nursing school, they advice for people with upper respiratory infections to be in a slightly elevated position at the head region when sleeping. My intuition of the reason is that the lymphatic ...
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2answers
88 views

Why do humans circulate monosaccharides instead of disaccharides as in plants?

Plants transport food mostly in the form of disaccharides like sucrose but humans transport them in the form of a monosaccharide - glucose. What is the reason behind this ?
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1answer
612 views

How is Hypertonic Urine Produced in a Mammalian Kidney?

I know that the ascending loop of Henle is impermeable to water and ions, and, by end of the ascending limb, the osmolarity of the tubular fluid is very low due to the active transport of ions out ...
3
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2answers
967 views

Physiological indicators of happiness and well being

If I understand it correctly, levels of serotonin in the brain can indicate if a person is happy. What other physiological measures indicate happiness or well being for a humans? I am looking for ...
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2answers
197 views

Why is most tissue cellular?

Most tissue is comprised of cells. Why? It would seem inefficient to have so many individual nucleus, membranes, etc.? Specifically: Not all tissue is cellular. Much tissue is extracellular matrix. ...
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1answer
48 views

Is there such thing as “biological cycles” of activity/performance/etc in mammals?

I'm looking for some information about the cycles of increased/decreased activity, mental performance or endurance that are related to a mammal's age and the time of a season. First of all, I'm not ...
3
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1answer
275 views

Why apes started to contemplate and become altruistic? [closed]

I was asking this first on philosophy forums, but it is suggested, that answer could be found from evolutionary view of point, so here we go: Again my question raised when thinking of myths, their ...
3
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1answer
19 views

Why Doesn’t Hypercalcemia Cause Muscle Spasms?

If you have more calcium in the cell, wouldn’t more attach to troponin and initiate muscle contraction? Why does hypercalcemia cause muscle weakness instead of spasms?