The study of the normal function of living organisms and the means by which it is achieved.
23
votes
1answer
369 views
What is itching?
What exactly at the molecular level is itching? What physiological function does itching serve, if any? I cant remember the reference but a PLCb3 null mice lost the itch phenotype, so presumably it is ...
17
votes
2answers
241 views
How does the microbial environment in your gut initiate?
Clearly, a zygote does not harbor any microbes. As it develops, and the alimentary canal tissue is differentiated, I logically assume that there is still no microbial activity in the fetus's gut. I'm ...
16
votes
3answers
205 views
How is the blood volume of a living organism measured without killing it?
How is the blood-volume of an organism measured without killing it? NOTE: The blood-volume of an organism is defined as the total volume of blood present inside that organism.
15
votes
2answers
2k views
What is the mechanism behind “acquired” alcohol tolerance?
I can understand natural variation in alcohol dehydrogenase (ADH) in a population leading to variation in rate of inebriation (after controlling for other variables -- e.g., mass, food consumption, ...
14
votes
3answers
308 views
Are human fetuses more likely to be male?
Question: From a physiological point of view, when sex is determined in a human fetus, is it equally likely to be male or female?
Studies in this area typically measure age at birth, where the data ...
14
votes
1answer
6k views
Why is coffee a laxative?
How does caffeine (or any additional agents) act as a laxative when ingested? I'm interested in the metabolic/signaling pathway.
14
votes
2answers
955 views
What actually happens when my leg 'falls asleep'?
Most people have experienced the temporary loss of feeling and tingling in their leg resulting from sitting in an abnormal position for a short while. Usually you get a loss of feeling in your leg ...
12
votes
1answer
479 views
Why do some mammals not have testes in a scrotum?
Coming from an evolutionary approach, Is the only purpose of a scrotum to regulate the temperature of the testes?
Knowing all mammals are warm blooded, shouldn't all mammals have testes in a ...
12
votes
2answers
217 views
Is there any reason for the variation in mitochondrial DNA size?
As my textbook An Introduction to Genetic Analysis points out, yeast mitochondrial DNA has approximately 78 kb of genetic data, while the human mitochondrial DNA contains 17 kb. Is there any evolution ...
12
votes
3answers
104 views
How are long time periods measured in biological systems?
Biological systems are pretty good at measuring fairly long times, for example, menstrual cycles (month), or puberty (years). Counting days or years seems to be implausible, and chemical concentration ...
11
votes
2answers
203 views
Is the 'fluttering feeling' when under stress neurological or physical?
I'm sure that everyone is familiar with the sensation commonly known as "butterflies in the stomach". It is commonly experienced during periods of anxiety or stress (e.g. before high stakes job ...
11
votes
2answers
827 views
How do insects breathe?
Do ants even breathe? If they don't, how do they stay alive? On what resources do they depend upon to stay alive? How are they different form mammals?
11
votes
3answers
255 views
How did the huge dinosaurs cope with gravity and loads on bones, etc.?
It's very costly to be a huge animal. Your mass grows in cube when you scale up, but you still only have two/four legs to support the same weight. This increases the pressure that your body needs to ...
10
votes
1answer
104 views
Does stress physically age our body?
Going by the assumption that stress eventually triggers a flight/fight response, and the subsequent realization that flight/fight puts the body in a system of readiness to use it's available resources ...
9
votes
2answers
194 views
Where do the bacteria within the vagina originate from?
I understand that it's feasible the bacteria within the gastrointestinal tract originate from the food we eat and air we breath, but where does this population of microbes originate from?
9
votes
1answer
280 views
Is trembling an advantageous response during periods of anxiety?
I originally had planned to ask about whether there was any biological truth in the popular phrase "shivering with fright". However, after doing a fair bit of googling it seems that there is a lot ...
9
votes
1answer
76 views
To which distinctions does the term “hymenoptera” refer?
Hymenoptera is an order of insects that includes bees, ants, and wasps. A quick search gives the following etymological analysis of the term hymenoptera.
hymen (membrane) + pteron (wing)
Does ...
9
votes
1answer
94 views
Were dinosaurs 'hot-blooded' or 'cold-blooded'?
Were dinosaurs hot-blooded or cold-blooded? NOTE: The popular term 'hot-blooded' means having an internally maintained average body temperature, which is generally more than that of the surroundings, ...
9
votes
1answer
128 views
Does the oxygen concentration equilibrate between red blood cells in the liver sinusoids?
In the sinusoids of the liver, venous blood from the hepatic portal system mixes with arterial blood from the hepatic arteries.
Do oxygen molecules move between oxygenated RBCs and non-oxygenated ...
8
votes
3answers
222 views
What triggers meiosis in gonadal cells?
What specific biochemical processes are involved in inducing meiosis rather than mitosis? Why are gonadal cells the only cells in the human body which do undergo meiosis?
8
votes
2answers
1k views
How do the lungs act as a sieve to trap blood clots?
Does anyone know? I'm curious to find out as my human anatomy and physiology book doesn't go into much detail on how the lungs function as such
8
votes
2answers
216 views
Below which temperature human muscles don't work?
When one exposes theirs body parts to cold environment (especially foot and hands), they may be numb, with temporarily blocked both muscles.
What is typical body temperature below which human muscles ...
8
votes
1answer
115 views
What are the effects of caffeine on the mammalian circulatory system?
A friend of mine told me an anecdote about his mother, who drank too much caffeine, to the point she became hypotensive and would pass out. Because caffeine acts as a stimulant, I'm assuming the ...
8
votes
3answers
179 views
Why is blood pressure higher the more distal an artery is?
Why is blood pressure generally higher in more distal arteries?
7
votes
1answer
129 views
How can an albatross stay airborne for months?
Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes. They range widely in the Southern ...
7
votes
1answer
80 views
Are cerebellar basket and stellate neurons actually different cell types?
The title more or less says it all, but to contextualise a bit:
Cerebellar molecular layer interneurons have been classified, probably since Cajal, into the basket cells, which synapse onto the soma ...
7
votes
1answer
863 views
Effects of beer on muscle recovery after exercise
I noticed it several times that when I drink beer (even one bottle) after some heavy workout, the next day my muscles are more stiff than other times, and not the same way... Is it because that ...
7
votes
1answer
142 views
Why are some menstrual cycles irregular?
A friend of mine asked me this today, and I didn't know. I remember studying the menstrual cycle a few years ago, but I can't remember the details (other than it was very hormone-related), and so I ...
6
votes
3answers
309 views
Do men have more extreme variations than women?
This question was considered unsuitable for Skeptics and I think it is more suited to BIology than Cognitive Sciences
I was reading this article which I found interesting. It is not supported with ...
6
votes
1answer
112 views
Understanding Membrane / Resting Potential from the perspective of ions?
From wikipedia article RESTING potential: "there is no actual measurable charge excess in either side. That occurs because the effect of charge on electrochemical potential is hugely greater than ...
6
votes
1answer
321 views
What happens to a human body once a sugary snack is consumed?
I'm looking to understand the effects of sugary snacks and/or drinks on a human body. I'm particularly interested in the timing of the ingestion versus various hormonal levels that may be circadian in ...
6
votes
1answer
123 views
Can oxygen diffuse out through the lungs?
Let's say you accidentally walk into a room pressurized with pure nitrogen (or you're jettisoned into space). Within a couple of seconds, the partial pressure of oxygen within your lungs drops to 0. ...
6
votes
3answers
100 views
What gaseous substances do humans emit?
Other than CO2 and Methane what other gases do humans produce or emit?
For example, does skin decomposition, or aerobic respiration emit any special gases that people don't normally realize or know ...
6
votes
1answer
152 views
Can I estimate leaf temperature from air temperature? What other information would be required?
Physiological measurements such as respiration rate and assimilation rate depend on temperature.
Most papers report tissue temperature (e.g. leaf temperature for leaf measurements), although some ...
6
votes
1answer
71 views
How does one maintain balance sleepwalking?
Anectodal. Feel free to shoot it down.
Walking is an acquired skill; As far as I'm concerned exhaustion causes disorientation. Even after waking up it sometimes takes a second or so to get balanced.
...
5
votes
3answers
157 views
Why does having cold hands hurt?
(1). Why does having cold hands create a painful sensation?
Is it a physical effect, maybe a protection mechanism from evolution?
(2). Why, if one's hands are cold, does it feel as if they are more ...
5
votes
1answer
237 views
What causes the characteristic 'gleam' in the eye of a living being?
The title is pretty much what I seek to know.
Unless the other person is play-acting, one can often make out the eye of a living person has a shine-of-life to it; a cadaver does not. Similarly the ...
5
votes
1answer
300 views
The genetic and physiological origins of laughter?
This Wikipedia article defines laughter in many terms, such as...
"a visual expression of happiness, or an inward feeling of joy"
and
"a part of human behavior regulated by the brain, ...
5
votes
1answer
196 views
Is it purely the nervous system causing vaginal lubrication (arousal)?
My girlfriend was watching some documentary on TLC about a paralyzed woman getting pregnant. I believe that woman still has some feeling, as she spoke about feeling the effects of a bladder ...
5
votes
1answer
971 views
Do hot drinks cool you down?
It is quite the old wives tale that drinking a hot drink cools you down. If you don't really think about it it does seem somewhat logical: increasing temperature will cause your body to try and cool ...
5
votes
2answers
246 views
How are the gene sequences of individual sperm and egg cells “randomized”?
What I mean by "randomized" is, in the place where an egg cell or sperm cell is made, what is the mechanism by which each one is not made identically? Though I am a layman, I'm pretty sure that if the ...
5
votes
1answer
53 views
Would muscle fatigue still occur if aerobic conditions for a working muscle is maintained?
Put another way if the muscle is given everything it needs to contract and do work will it ever get tired or have a reduction in energy efficiency?
As far as I understand muscles depend upon a ...
5
votes
1answer
114 views
Do mosquitoes need to pump blood out of the host?
Many species of mosquitoes have bloodsucking females.
When they bite a host, do they need to pump? Or does the sheer blood pressure combined with capillary action suffice to make the blood rush into ...
5
votes
1answer
53 views
Does the human ear adapt to noise levels?
I have noticed lately that if I go to sleep, when I have my radio running, it is on lowest volume, I still consider it kind of loud.
In the morning, when being on the edge of waking up, I hear the ...
5
votes
2answers
79 views
What metabolic activities are performed by a developing human fetus's liver?
I understand that organ function varies with the stages of development. Does a fetal liver EVER perform lipogenesis, gluconeogenesis, make bile, etc? Or does it only begin performing these actions ...
5
votes
1answer
99 views
Why is the human body able to repair a broken bone and not a heart muscle?
The human body can repair skin/organ laceration, fractures, even repair nerves - albeit the duration and rate of recovery differ. For instance:
The burn scar on my arm from the hot soldering iron ...
5
votes
1answer
134 views
What really happens when a body is tired?
This may be anecdotal; please feel free to vote to close.
After staying awake for an extended duration, I usually find myself having to take extra effort to focus my eyes on an object. Similarly ...
5
votes
1answer
42 views
functional hypocholesterolemia due to very high HDL or low LDL?
Nutritional and medical recommendations about cholesterol seem to focus exclusively on hypercholesterolemia, and as such, they provide only a maximum desirable level for LDL and a minimum for HDL. ...
5
votes
0answers
66 views
How is hibernation/aestivation different from anesthesia?
How do hibernation/aestivation happen?
I read on wikipedia that a squirrel injected with the body fluids of a hibernating fellow is more prone to hibernation. If hibernation/aestivation are driven ...
4
votes
1answer
82 views
What protocol does the nervous system use?
I just read How does an inhibitory synapse communicate to the cell body of a neuron? and found myself asking this question ... hopefully I'm not asking the same thing
Any body possessed of a nervous ...
