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For questions on the biochemical, physical, and mechanical functioning of humans in good health including their organs and cells.

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18 views

What is (are) the medium of conduction for an electrical current with an external source in the human body?

I am trying to get some background for some personal research I am doing into the effects of Electro Convulsive Therapy. I don't understand how electric current from an external household source, say, ...
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0answers
16 views

Caloric deficit effect on muscle fibers

Can muscle fibers grow in size after stimulation if the body is in a caloric deficit? More details: 80 kilogram human male -500 kilocaries deficit
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1answer
26 views

Is there muscle hyperplasia or hypertrophy after surgery?

After exercise there is hypertrophy only. I am curious, if a surgery removes muscle, will there be hyperplasia or hypertrophy to restore it?
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33 views

does being battered build muscle?

My crude understanding of how people normally go about building muscle is something like this following 2 step process: 1) a person can lift weights (for example), which tears muscle and stimulates ...
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14 views

Once neurotransmitters bind to its receptors, how does the post synaptic neuron “know” when to start a new action potential?

My textbook seems to gloss over this subject. Once the post-synaptic receptors are activated, do they cause particular ion channels to open, letting positive charge into the cell and inching the ...
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0answers
29 views

Interstitial volume

In the literature, studies mention that the interstitial space surrounding cells varies in each tissue. Are there references from which one can obtain the values of interstitial volume in each tissue?...
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2answers
91 views

Why exactly does the immune system weaken with age?

Why does the immune system become weaker with age in humans and in some other mammals? Let's try to be more specific than just "everything degrades with age."
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0answers
24 views

Why do humans lose subcutaneous fat from the extremities with age?

Why does fat tissue die and shrink on the hands, knees, and lower legs of most people as they age, even when they are overweight? In most people, their bone definition becomes much more visible around ...
4
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1answer
70 views

Why do humans lose subcutaneous fat tissue with age?

Why exactly do humans lose subcutaneous fat tissue with age? It appears that we either lose fat cell volume or we might actually be losing the number of fat cells with age. One hypothesis is that as ...
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0answers
21 views

What is the purpose of chloride ions in the stomach

Why are chloride ions secreted into the gastric pits in addition with hydrogen ions? Why can't the parietal cells simply secrete hydrogen ions for an acidic effect?
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0answers
28 views

Why do I have super vision in purely red light?

I installed some RGBW led strips in my apartment recently.. by some I mean everything is now lit by led strips and there isn't a single light bulb left. One thing I've noticed over the last few days ...
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2answers
42 views

How does 2,3 biphosphoglycerate works to release oxygen bound to the hemoglobin?

I read on Wikipedia that 2,3 BPG binds with the deoxygenated state of hemoglobin and helps in stabilizing it. It was also written that it helps release remaining oxygen from the hemoglobin. How? ...
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1answer
144 views

Spermatogenesis question

I found this diagram in my textbook regarding the process of spermatogenesis. But, I doubt if the labelling done is correct or not. Especially, I can't figure out any difference between the cells ...
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1answer
78 views

What is the benefit of oxygen tanks to persons trappped in an enclosed space?

When people are enclosed in an air-tight space, the levels of carbon dioxide will rise to lethal levels (hypercapnia) long before the oxygen is exhausted (hypoxia). For example, the astronauts of ...
4
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1answer
232 views

Immune System - B-cell receptors

How do the B-cells, which are a part of our body, develop antibodies against antigens of outside world (outside of our body), which they don't even know about? Is it just a random match?
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1answer
27 views

Is the serum concentration of calcitriol different at different times in the day?

Given that calcitriol has a relatively short half-life in adults it would be possible that the serum concentration is at different times of the day different if it gets produced in different ...
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1answer
36 views

Is the heart more relaxed when stretched or contracted, and how does it affect cross-bridge interactions?

In the heart, are stretched muscles during the diastole more relaxed or are the contracted muscles more relaxed? Depending on the answer, are there then more cross-bridge interactions in cardiac ...
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1answer
28 views

Which components grow in size but not in number and which grow in number but not in size?

During growth of an individual animal some components of the body grow in size but not in number (type 1) while some others increase in number but not in size (type 2). Which of the following is ...
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1answer
25 views

Why does the right bundle branch not have any terminal filaments in the IVS of the human heart?

Dubin's "Rapid Interpretation of EKG's" briefly describes this part of human physiology but doesn't explain the reason behind it. Is there a specific advantage of the human heart having this ...
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0answers
36 views

How can there not be purpose movement in the fetus until week 18 when a fetus can open its mouth and suck its fingers at week 11?

According to Fetal Movement According to an overview produced by the Royal College of Physicians of Edinburgh, purposive movement begins at about 18 weeks, gradually replacing reflex movements ...
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1answer
62 views

Causes of Back Dimples

What are the causes of the dimples commonly found above the buttocks? They seem to be in line with the sacroiliac joints. Do the joints have anything to do with them?
2
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1answer
32 views

Do fruit juices have a diuretic effect & what governs this?

Was just contemplating this. Juices tend to contain a lot of sugar. Does the body absorb all the sugar in juices? If the body does not, that sugar must be excreted by the kidneys alongside water ...
3
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0answers
53 views

What is the average volume of the human Psychic tear? (“emotional tear”)

My goal is to find out the volume of the average human "emotional tear" (Psychic tear - sadness, happiness), specifically when crying. I found a lot of information about Basal tears (constant ...
3
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1answer
55 views

How is it possible to breathe perflurocarbon?

I have heard of liquid breathing, where an organism, usually a person, would be breathing in perflurocarbon. Now I looked up perflourocarbon on wikipedia and I noticed, no oxygen at all, but fluorine ...
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1answer
336 views

Ventricular Filling : Systole or Diastole?

As the Blood goes down from the Atrium to the Ventricles: The Tricuspid Valve ( Right Atrioventricular Valve) Bicuspid Valve (Mitral Valve ) The atrial pressure is INCREASES WHEN ATRIA ( THE ATRIA ...
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2answers
30 views

Is the glomerular filtration rate, per kidney or for both?

We say in a healthy human being the average glomerular filtration rate is about 120 mL/min. Is that for both kidneys together (60+60), or just one kidney? Pardon me if this makes me sound like an ...
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0answers
57 views

How does the stomach differentiate between liquids and solids to initiate churning?

Or maybe it doesn't at all. Can the stomach tell the difference between liquids and solids and change its churning process accordingly despite that it has no nerves? Because liquids don't need to be ...
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1answer
46 views

does the amount of blood circulate in a body is same before and after amputation?

if a person loose his hand in an accident do the blood flows through his body is equal to the volume of blood before accident? how human body manage with that blood which is deserved by the missed ...
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0answers
16 views

How to obtain normalised ECG given ECG readings across lead 1, 2, and 3?

I saw this youtube video on ECG readings and cardiac dipole vector locus of the heart across the three leads. Posting screenshots from it: My question is how to obtain the graph (2nd image) from the ...
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1answer
33 views

Nonpancreatic digestion of tryglicerides

In an answer about coconut oil I can read the digestion of coconut oil does not involve in the Pancreatic digestive enzyme system In both primary and secondary school I have learned that fat needs ...
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0answers
45 views

How can diving with 100% oxygen not destroy your lungs? [closed]

It is possible this should be moved to physics, depending on the nature of the answer (i.e. if the reason is physical). But I suspect the explanation is biological, so I posted it here. Sometimes ...
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1answer
32 views

Why doesn't patients with chronic acne's body lower sebum production itself?

Background My cousin has had nodular acne for at least 9 years. Her sebum plugs usually causes bumps on, and inflame, the skin, before the sebum emerges or can be extracted with a comedo extractor. ...
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2answers
63 views

Are all of our hormones synthesized in the same gland that they are secreted from?

For example, growth hormone is secreted from the anterior pituitary; is it also synthesized there?
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0answers
19 views

How do (commensal and mutualist) microorganisms colonize the seminal vesicles?

Human's seminal fluid has it's own microbiome (Javurek et al. 2016). How do species of this microbiome (bacteria and eukaryotes) colonize the seminal vesicles? It is possible that different species ...
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0answers
48 views

What's the ratio of saturated to unsaturated fatty acids in human cell membrane?

It's well established that the fluidity of a cell is largely dependent upon the ratio of saturated to unsaturated fatty acids that exist within the membrane, but, what exactly are the values for this ...
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1answer
34 views

Is there gas exchange in the fingers?

I saw A documentary many years ago that said that hemoglobin will take in O2 in the fingers and toes. I have Not been able to find any information on this. But it would seem that being so close to the ...
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0answers
10 views

How to estimate equivalence units of short-acting insulin in long-acting insulin?

You have a combination insulin therapy for DM2: metformin + two long-acting insulin medications A and B. There is no A in the pharmacy, and you have blood glucose 6 now, for instance (over 5). You ...
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0answers
35 views

effect of arterial vasocontriction on the pressure in arteries

if experimentally one induces smooth muscle contraction on an artery and cause it to constrict, keeping the cardiac output same and also the arteriolar resistance(total peripheral resistance) the same ...
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1answer
40 views

Required energy to metabolize fat

Tl;dr: What is the net joule value of fat if used for energy provision, compared to e.g. carbohydrates. So does 1 Joule Fat intake result in 1 - X Joule energy provided to the cell, or does it work in ...
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2answers
5k views

Why don't chilli peppers taste as hot in space?

The following commentator writes: Chili peppers don’t taste as hot in space as they do on Earth. Nobody knows why. We know that the 'hot' feeling of chilli peppers is caused by Capsaicin. We read: ...
3
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1answer
30 views

Are there official criteria for an experiment to be considered statistically robust for publication in a decent scientific journal?

For a high school project, I investigated the effect of breathing meditation on teenagers. 15 students were asked to follow specific directions and meditate for 10 minutes a day for 8 weeks. Each week,...
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1answer
63 views

Why do fat people and thin people get hungry at the same time? [closed]

Say a fat person and a thin person take breakfast at the same time. Around lunchtime, they'll both be hungry. Why? After all, the fat person theoretically has lots of body fat the body can consume ...
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3answers
51 views

How do our sensory organs work automatically without our conscious effort? [closed]

I wonder how our different sensory organs (e.g., eyes, nose, ears, etc.) work automatically without our conscious efforts or without our command. We don't have to tell our eyes how to see, our ears ...
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1answer
371 views

Why is the body cooled during cardiac surgery?

When undergoing cardiac surgery, the heart is disconnected from the blood circulation and blood is passed through a heart-lung machine and cooled so that the body temperature of the patient is reduced....
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1answer
151 views

How does kissing burst a person's ear drum?

A young Chinese woman was left partially deaf following a passionate kiss from her boyfriend. .. The kiss reduced pressure in the mouth, pulled the eardrum out and caused the breakdown of the ear. ...
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1answer
55 views

Viability of argon-oxygen atmosphere

Can humans breathe an Argon-Oxygen atmosphere, where Argon substitutes the inert Nitrogen gas which currently populates our atmosphere? I didn't quite know which forum to stick this one in; I put it ...
3
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0answers
151 views

Plant vs animal protein digestibility?

The protein scoring methodologies ( https://en.wikipedia.org/wiki/Protein_Digestibility_Corrected_Amino_Acid_Score) rate plant proteins of a lower quality than animal proteins. Now I can understand ...
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0answers
181 views

What is exact relationship between blood pressure, colloid osmotic pressure and hydrostatic pressure?

According to basic explanation : The blood pressure is the pressure of circulating blood on the walls of blood vessels. Also we know in blood there is colloid osmotic pressure(oncotic pressure) and ...
2
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1answer
324 views

What is the function of the Hyoepiglottic ligament?

The hyoepiglottic ligament (ligamentum hyoepiglotticum) is an elastic band that connects the epiglottis to the hyoid bone. Although I can find information about the clinical significance of this ...
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0answers
38 views

Contribution of major nutrients to energy in the human body

What is the contribution of the major nutrients -- glucose, fat and protein -- to the human body's energy requirements, in normal conditions? For some tissues, the fuel preference is known ...