This tag is for questions about the general anatomical features of human beings as opposed to the anatomy of non-human animals.

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Mechanism of Tear Gas (chloropicrin/Trichloro methane)

Tear gas (CCl3NO2) makes people cry, and crying doesn't seem to be a simple procedure. There has to be a triggering process somewhere. Can someone explain its mechanism / how it works?
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1answer
1k views

SPINAL CORD: Do the axons from white matter synapse with the cell bodies in grey matter?

After wading through a sea of information, I understand the main differences between the white matter and grey matter of the spinal cord. I know that white matter contains myelinated axons in the ...
3
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1answer
27 views

What are typical values for bone mass in humans?

I wonder what are typical bone mass values for adult males and females? And do they change significantly with workout and diet?
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2answers
98 views

What is the evolutionary purpose of the topology of the human ear?

What is the evolutionary purpose of the topology of human ears? I understand why the ears may have a funnel-like shape but if the various "hills and valleys" do not amplify incoming sound, what ...
3
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1answer
47 views

Is there a way to measure ATP usage in the brain similarly to fMRI?

Is there a way to measure ATP usage in the brain (or anywhere else) similarly to how fMRI works (measuring changes in iron resonance in oxygenated/deoxygenated blood)? Is there some sort of similar ...
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2answers
124 views

How far into a pregnancy is it before visible signs of it is apparent and risk of physical trauma increases

I'm doing research for a series I'm writing. in it the main character is pregnant however goes off to fight a criminal organization who have been killing her friends and i want her appearance to show ...
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1answer
71 views

How do muscle relaxants work?

Do they act directly on the muscle and actually relax muscle tissue and ease spasms, or do they just prevent your brain from receiving signals that inform you of tight muscles? In the latter case, ...
3
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1answer
189 views

Why do I breathe out of BOTH nostrils?

After reading the question why do I only breathe out of one nostril I realized that breathing out of both isn't common. I have always breathed out of both, and when I get a stuffy nose, or a runny ...
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2answers
144 views

Could humans theoretically see infrared better than regular light?

I have noticed that in infrared film, people's eyes reflect that light within their eyes much like nocturnal animals (and many other animals for that matter) do with regular light. I know that this is ...
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3answers
1k views

Why does the apex of the human heart usually point to the left?

In the majority of human beings, the apex of the heart (left ventricle) points towards the left side of the body. Sometimes however (approx. 1/12000 births), a person is born with a condition known ...
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1answer
98 views

Cucumber on the eyes

In many spas and salons I have seen people place a cold cucumber on their eyes. I think this might be for coolness, but why a cucumber? And Is it actually for coolness or for something else (like ...
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2answers
564 views

What happens if a person has the right side of the body totally removed (including the brain)? [closed]

I guess humans could live without just the right lobe of the liver or the right brain. Could a person without the whole right side of body survive? The left brain controls the right side of the ...
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2answers
2k views

Why does the sweat of children not smell like adults?

My kids sweat plenty in this hot heat, but they don't smell afterward. I on the other hand need all kinds of deodorant. Why doesn't kid sweat smell?
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1answer
173 views

Difference between flexion and contraction?

i asked this to my anatomy teacher and he said there is no difference but when it comes to specialy in body building when you say to flex their bicep they freeze their upper limb in order to do that ...
2
votes
1answer
99 views

What is the evolutionary cause for various finger lengths?

Why are the lengths the way they are with middle finger the longest?
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3answers
175 views

Mechanical cause of loss of consciousness

Consciousness is an electrical and chemical interaction in the brain, caused by neurons firing and chemical interactions. How does a mechanical "force" cause this to stop working? i.e. How does a ...
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1answer
14k views

I'm 20. Can I still grow taller? [closed]

I'm 20, in about 6 months I turn 21. For some time I've been wondering whether there are natural, non-surgical and non-pharmaceutical ways that humans can continue to grow after reaching adulthood. ...
2
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1answer
2k views

Which blood vessel carries the most impure blood?

There is a question in my Biology textbook: "Which blood vessel in the human body carries most impure blood after few hours of meal." The answer is given as Renal artery. But I think the ...
2
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1answer
45 views

How small does a nanobot have to be to “swim through the brain” and access any neuron it wants to?

I read on this question What is in the space between neurons in a brain? that there is actually not much empty space in a brain. But my question is slightly different. Is there a visual demonstration ...
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1answer
9k views

Difference between Appendix and the Cecum?

What's the difference between an appendix and a cecum, and what are their functions?
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1answer
59 views

Biology Analogy

In my book are given several paired analogies with me being asked to give reason for them. I could solve all of them except this: liver = thrifty house-keeper I mean, I do not understand why the ...
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1answer
107 views

Scrotal temperature and vascularization

The testes (at least in human males) are vascular organs, the vascularization extending even o the interstitial spaces of the seminiferous tubules. The function of the scrotal sac, is to isolate the ...
2
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1answer
54 views

How do cells figure out the big-picture shape?

I'm wondering what makes cells to divide (and stop) in such a way that they make our hands the shape that our hands are...
2
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1answer
573 views

Circulation through the liver in light of drug metabolism

I have a lingering question which stems from an answer that I gave to What hydrolyses aspirin within the digestive tract and blood stream? When a drug or any other substance is absorbed into the ...
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1answer
31 views

Relieving pain by massage

How come the pain in our body, primarily due to excessive physical exercises, vanishes after having a massage? What is the mechanism?
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1answer
1k views

Function of the Auricle in heart

What is the function of the auricles (conical appendages through the atria) present in the heart? Do they have any other function than increasing the volume of blood the heart can hold?
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1answer
100 views

Development of vitreous humor

I have tried reading about development of vitreous humor but it is all very confusing. When does it first developed ? Does it renew itself ? Please provide reliable sources..
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1answer
151 views

Do people of the same height walk at the same speed?

I'm working on a project that concerns movement and the human body. Before I begin to experiment, I need an answer to a question I'm sure has an answer, but doesn't Google well. What I need to know ...
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1answer
107 views

Why do genitals feel frozen when freefalling?

I don't want to add much more about that. Since childhood I noticed a chilling effect, even when doing rollercoaster-type activities.
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1answer
803 views

Is it possible to still grow taller after grow plates have been closed?

In addition, when do we know we stop growing taller? Or we keep growing taller? To the first question: Recently, I went to a doctor to have a check up, he said that my growth plates are closed and ...
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1answer
20 views

Why is the vermis of the cerebellum associated with speech?

I've found multiple sources claiming that damage or impairment as a result of alcohol to the vermis of the cerebellum results in speech impairment. I find this a bit surprising, since the only areas I ...
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1answer
372 views

Are Asian people shorter than Europeans?

People in different countries have different average heights. For example, Wikipedia's article on human height states that Australian men have an average height of 177.8 cm, and Australian women 163.8 ...
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1answer
33 views

Does digit 1 have an extensor sheath?

Extensor digitorum and extensor digiti minimi both insert into the extensor hoods of digits 2-5 (or just 5 in the case of e. digiti minimi). In every source that I can find, extensor pollicis longus ...
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1answer
33 views

What are the criteria for determining the origin and end of muscle anatomically?

For example the pectoralis muscle starts from sternum region and ends on the acromion or coracoid process. Why you can't say that it starts acromion process and ends on the sternum?
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1answer
71 views

Average face shape

I am doing face detection application where every face detected is inside a rectangle. The rectangle always contains some background behind the face and now I need to extract as much of the face as ...
2
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1answer
144 views

Why don't we have more cone cells (bigger fovea)?

Background Apart from being able to sense color, cone cells are able to perceive finer detail and more rapid changes in images, because their response times to stimuli are faster than those of rods. ...
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1answer
2k views

What negative effects can pinhole glasses have on the body?

While shopping in the local supermarket yesterday, I was surprised to find this display on one of the shelves. I also realize that I should have taken a pamphlet with me, as well as a picture of ...
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1answer
71 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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0answers
52 views

What causes headaches (biologically)? What does it mean directly? [closed]

Even though your brain can't feel pain, thingies in your head are installed to compensate for that. Once I thought your head starts to hurt when your brain is tired. I can't believe this any more. ...
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0answers
35 views

Questions regarding Scapulohumeral Rhythm

I'm actually an artist, but I wanted to ask this because it will help a lot in my figure drawings. My artistic anatomy teacher taught me about the Scapulohumeral Rhythm. He said that in during the ...
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0answers
111 views

Human female chest model or data representation?

I am looking for professionally used representation of female chest (I know how it sounds ;). Generally - a model comprehensive enough to effectively represent human chest, with focus on breasts. ...
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0answers
579 views

What is a lip? (upper lip and lower lip)

Everyone knows what a lip is but I'm asking from a technical and anatomical standpoint. Actually what we call "lip" is "vermilion" in medical terminology. But I want to ask if my understanding is ...
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0answers
40 views

How much does a human brain's metabolic rate vary? [duplicate]

Possible Duplicate: How does brain energy consumption depend on mental activity? Our brains consume about 20% of our energy when we're at rest. How variable is a human brain's energy ...
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3answers
230 views

What does orbital mean in orbital frontal cortex?

Orbital frontal cortex is where decisions are made. What does the word orbital there mean? I looked around in wikipedia and never find it.
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1answer
3k views

How are the paranasal sinuses linked with the capillaries in the ear canals?

Sinus congestion often seems to be accompanied by excess pressure on the outer ears (as anyone who has shared a transcontinental flight with an infant can attest to) or fluid buildup in the canals. ...
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1answer
66 views

Is the human collarbone supposed to break?

I've read it in a book and have heard people mention it, but I can't find any documentation about it. But the point being made is this: The human collarbone acts as a shock absorber for impact on ...
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1answer
35 views

What does it mean to have different “metabolism”?

We hear talk of different body types, and that it is more difficult for certain people to lose weight than others. On the other hand, when my physician recommends that I lose weight, they say that it ...
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1answer
367 views

Why do we suffer abdominal pain after we get very angry or stress?

You also realize probably, when we get so much anger or high levels of stress, after some point we have terrible stomach ache, like really heavy pain. Why is that? How stress or anger can effect our ...
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1answer
61 views

Why are new vessels more permeable in microvasculature?

I know for microvasculature New microvasculature (arterioles, venules) are always more permeable as they lack pericytes. and then I have this sentence about new blood vessels (not specific) ...
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1answer
114 views

Breathing in and out

I was reading my textbook and it says that breathing involves inhaling and exhaling but it doesn't say whether they happen simultaneously or sequentially. Also is my overall understanding of ...