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130

Apparently you're not the first person to notice this; in 1895, a German nose specialist called Richard Kayser found that we have tissue called erectile tissue in our noses (yes, it is very similar to the tissue found in a penis). This tissue swells in one nostril and shrinks in the other, creating an open airway via only one nostril. What's more, he found ...


62

This is natural phenomenon called the nasal cycle. It is discussed in this paper by Telles et al. (1994), among many others. The nostrils are used on an alternating cycle of about 2-3 hours, controlled by the autonomic nervous system. If you notice alternating congestion, that also seems to be coupled to the nasal cycle (Hasegawa and Kern 1977, 1978). ...


18

As others have said, this phenomena is called the nasal cycle, a process controlled by the autonomic nervous system that alternants congestion between your nostrils. Mentalfloss of all places has an article about this that explains: ...it makes our sense of smell more complete. Different scent molecules degrade at different rates, and our scent ...


14

Hemoglobin molecules used to manufacture these products are not contained by a red cell membrane, and when released into the vasculature, these molecules rapidly scavenge nitric oxide.This can result in systemic vasoconstriction, decreased blood flow, increased release of proinflammatory mediators and potent vasoconstrictors, and a loss of ...


13

Developmentally, the urinary and genital systems (typically you will hear them referred to as "urogenital system") are derived from the same embryonic tissue, the intermediate mesoderm. The embryonic kidneys are drained by the mesonephric duct in both females and males. This embryonic tissue also gives rise to the ovaries and testes. The mesonephric duct ...


10

The female breast is composed primarily of fat and connective tissue plus lobules and ducts for milk production and delivery. The pectoralis muscles form a thin layer beneath the breast, as seen in the figure in the link. An athletic female can enlarge the size of the pectoralis muscle and the laterals muscles, just as male athletes can enlarge their "pecs" ...


9

The concept of transgenders has nothing to do with sexual organs at birth. Transgenders is a concept that has to do with sociology, not biology. See the wiki link. Hermaphroditism (sometimes called intersex) has to do with biology. The wiki link makes a great job at defining intersex. In short: A transgender person is born anatomically either male or ...


8

Short answer: The genes that encode eye color do not change, but the pigments in the eye can change due to external factors like diseases of medication. Long answer: Yes, it is possible that the eye color of adults can change, and it can also only happen to one eye. It is then called Heterochromia. There are two possibilities for different colored eyes, ...


8

Individuals have not only hand dominance but also a dominant foot, eye and ear. There has also been a belief that this sidedness applies to chewing as well. However, the short answer is that no one is sure, but that it may be related to handedness. I only looked at studies done after 2000. One large study[1] found a questionable to weak correlation, not ...


8

Anatomical terms must be able to fit a wide variety of organisms, from insects to fish, dogs, horses, chimpanzees to humans. That's why the terms are sometimes confusing to people who are thinking only of bipedal humans. In anatomy, the dorsum is the upper side of animals that typically run fly, swim or crawl in a horizontal position. In vertebrates the ...


7

Questions of the type, "why does organism X have feature A?" invite teleological (just so) explanations which are difficult to substantiate. For example, the number of teats on a cow are difficult to explain in terms of providing milk to humans! We should look to evolutionary history to explain human traits, not "just so" stories. The simple answer is that ...


7

It is logically clear that the ankle could only partly be analyzed in the group of joints that are below its height. There is no direct way to measure the pressure on ankle joint (on talus bone), but from the logic it is clear that it should be the point of highest pressure in the group of points lister in the question, however the pressure is distributed ...


6

This is a well worded question. There are more reasons than the following but the most apparent is hemoglobin production and its transport. The erythrocyte is a cell whose structure is optimal for its function-the production and transport of hemoglobin. It lacks a nucleus and organelles so that it can devote almost 100% of its energy to hemoglobin ...


6

Here is my overly succinct answer. I doubt we will ever know this for sure. But, it basically comes down to ancestral bilateral symmetry in development; this defaults to two organs and is broadly symmetrical except where the organs are central. Further exceptions to symmetry occur where evolution pressured the body into not bothering to grow the second of ...


6

feel the tip of your nose. Mush it around, It's got a certain stale gummy bear feeling to it. Now feel your ears, all over. The outer edge, the back, the hard part in the front where the ear meets the face. Feel your adam's apple. This is cartilege. When you feel your penis, does anything even feel close? Nope. It's just soft. Soft tissue, to be precise. ...


6

Citing your source would help to answer. In order to test an elastic modulus, you need to apply some non-zero strain. If the strain is infinitesimal, then compression and stretch modulus will be equal. But if it is finite, then there can be a difference due to the structure of the material. In bone, I believe porosity will provide most of the dissymetry ...


5

They don’t meet. Some framework: Spinal nerves contain motor, sensory, and autonomic fibers. Each of these have different pathways. Spinal nerves don’t go to the brain. Rather, they synapse in the spinal cord with other neurons which in turn go to the brain (sometimes requiring one more synapse). In the case of motor neurons, we talk about upper and ...


5

Is there a visual demonstration I can see of approximately how "packed full of cells" the brain actually is? Yes. You can inject tracers in the CSF (Cerebrospinal fluid) or in the ventricles and monitor them. In this study, the authors have injected a fluorescent tracer in the CSF and used a direct imaging. We used in vivo two-photon imaging to ...


5

Via deep scientific analysis (i.e. trying it myself 5 seconds ago), I have determined that you can in fact speak while breathing in, it just sounds funny. Think of the vocal chords as being like the body of a flute. As air passes by them, they vibrate and make sounds. Through careful modulation of their shape, specific sounds can be reproducibly made (this ...


5

As part of your question, you ask if other animals can create sound without continuous airflow. Many insects (e.g. cicadas and moths) do exactly this by using tymbals. A tymbal/timbal is an external membrane organ that is controlled by muscles or wing movements, that cause the membrane to flip back and forth, creating clicks or other sounds. So in many ways ...


5

This doesn't really answer the question and I only post it at the asker's request. NASA has measured the dimensions of the back in 40 year old American males and 40 year old Japanese females in the year 2000 at 1G. Of course gravity matters to NASA… From figure 3.3.1.3-1 (American male). All data in centimetres: 921 Waist back 5th percentile: 43.7 ...


5

It is impossible at present to reproduce all the conditions of a womb. A womb is more than a warm fluid-filled home for nine months. A few days after fertilization, the trophoblast portion of the conceptus attaches itself to the uterine wall where it develops into a placenta and umbilical cord while the rest (the epiblast) becomes the baby. Throughout the ...


5

Artificial amniotic fluid has been used on goats, and for premature human babies. In the 1996 experiment, Thomas Shaffer, a scientist at Temple University, used an oxygenated liquid in a clinical trial with thirteen infants born at twenty-three to twenty-four weeks who were not expected to survive, and seven babies were discharged healthy. Jonathan Knight, ...


5

Sounds such as certain phonemes are made merely with the use of air flow and movement of the lips or tongue, without the need for action of the vocal chords. Think of 'f', 's', 't', k in the English language. These are called unvoiced phonemes in phoniatrics (see the phonemic chart). Also, clicking sounds and whistling can be made without use of the vocal ...


5

Anatomically speaking, the palate is the roof of the mouth, separating the oral cavity (mouth) from the nasal cavity (inner nose). While the palate may be sensitive to heat and spiciness (via the capsaicin receptor, for example), it does not contain any taste buds, which are located on the tongue, and are part of the taste-sensing system. The other part of ...


5

Yes, such a conditions exists. It is called "situs inversus" (literally "inverted sites"). All major organs are placed on the opposite site, the condition is relatively rare with an incidence rate of 1:10.000. There are some even rarer forms occuring, when the organs are flipped, but the heart is still on the left side (levocardia) as opposed to the case ...


5

"Position of the pelvis" is pretty vague, but there are very clear differences in pelvic morphology between females and males. This sexual dimorphism looks like: Female pelves are wider and flatter, which I think you could tell from surface anatomy. Of course if you could palpate, then you could tell for sure.


4

Limb lengthening surgery is usually used to treat sequelae caused by bone disease, trauma, pygmyism or inflammation. I personally do not recommend to use surgical methods to increase height. Typically Limb Lengthening requires Achilles pre-lengthening surgery and a lot of postoperative rehabilitation. Moreover, Limb lengthening surgery may cause pain, ...


4

Vision deteriorates for both reasons, but I'm not quite sure how to separate the effects of aging from wear and tear. Cataracts are the leading cause of blindness in the world. Ways in which environment (which falls under the category of wear and tear in my book) affects cataract formation: UV light: people living at high altitudes (e.g. Tibet) have ...



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