The study of the normal function of living organisms and the means by which it is achieved.
4
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3answers
155 views
Biological Pathway of Lipid Hypothesis
I've read a lot on both sides of the debate of low carb vs low fat diets trying to make some sense of what is being proposed. The lipid hypothesis runs roughly along the lines that we have lots of ...
4
votes
3answers
79 views
Do dogs have something different about their physiology that allows them to pant without hyperventilating?
I was wondering this as I considered how effective panting would be for humans as a means of cooling.
4
votes
2answers
117 views
Extraretinal photoreception in mammals? [duplicate]
A Finnish firm Valkee sells light-ear-plugs against thing such as jetlag. I asked a researcher in Aalto university how do they really work and he responded ...
4
votes
1answer
118 views
Is there a way for a 19th century scientist to prove that the octopus doesn't revive?
Say a sophiscated scientist in the 19th century noted that applying soy sauce on a dead octopus leads to movement of the legs, as a result of the voltage differences resulting from the salt in the soy ...
4
votes
1answer
96 views
Is a raised baseline between T and QRS normal in any ECG lead?
Here are excerpts from an unknown ECG lead. I find it weird that the "baseline" changes after the T wave and doesn't return until after the following QRS complex. Is that normal/expected for any lead?
...
4
votes
1answer
63 views
What is the cause of muscle cramps?
According to wikipedia, muscle cramps are caused by myosin fibers not being able to break free from the actin filaments during contraction, resulting in a prolonged contraction.
Obviously a lack of ...
4
votes
1answer
216 views
Conversion rate of topical Retinol to Retinoic Acid (Tretinoin)?
I'm wondering if someone out there has more information than me. Retinoids have well known metabolic pathways in vivo, and it's usually something like: ...
4
votes
0answers
67 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 ...
4
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1answer
251 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 ...
3
votes
2answers
163 views
Is consuming sugar with food as beneficial as consuming glucose (~half of the amount of sugar)?
A few years back I heard at biology class that sugar's molecule consists of half the number of elements of a glucose molecule. So not counting the energy needed to transform two sugar molecules in one ...
3
votes
2answers
139 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 ...
3
votes
1answer
1k views
Why are (some) cats attracted by bleach?
(Sorry if this question is only partly biological)
I have noticed that several cats (including the one that keeps sleeping in my house), are fond of the odor of bleach (eau de Javel) and chlorine.
...
3
votes
1answer
77 views
How does ethanol interact with insulin?
I know that ethanol increases insulin secretion--could someone explain why?
All I have found till now is experimental data analyses. I am interested in mechanism of alcohol consumption.
3
votes
1answer
43 views
What limits the size of fish compared to marine mammals?
The largest extant fish species is the whale shark (Rhincodon typus). With a length of 13 meters and a mass of about 20-30 metric tons, the whale shark is relatively small compared to the largest ...
3
votes
1answer
390 views
What are the units of Q10 (temperature sensitivity)?
Q10 is the increase in a rate (e.g. activity of an enzyme) observed with a 10 degree temperature increase.
According to Wikipedia:
It is apparent that the units of R (e.g. mol/g/s) cancel out, ...
3
votes
1answer
35 views
What are some examples of scaling laws in biology?
I've seen that metabolic rate scales logarithmically as function of mass for many animals over an extremely large span of parameters. What other scaling laws exist at the individual level?
3
votes
1answer
205 views
Slow-oxidative fibres vs fast-glycotic fibres
Why do slow oxidative muscle fibres contain more mitochondria compared to fast-glycolytic muscle fibres?
3
votes
1answer
93 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 ...
3
votes
2answers
97 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. ...
3
votes
1answer
44 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
votes
1answer
45 views
Why does it hurt more when you touch a nerve directly?
I am not a biologist nor know much about biology (so please explain in layman's terms) however I have always been curious as to why this is.
What causes the difference in pain between touching an ...
3
votes
0answers
452 views
What causes random long white body hairs?
I'm sure many of you have experienced this - you scratch your back or brush your hand over your arm and find a ridiculously long thin white hair, sometimes as long as 3 or 4 inches. I know a few ...
3
votes
2answers
111 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 ...
3
votes
0answers
18 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?
3
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0answers
78 views
what are the mechanics of sweating?
The causes of sweating aside, i.e. I'm not interested in which and how nerve signals are transmitted to sweat glands. But I would like to read a detailed account on what a sweat gland consists of, ...
3
votes
0answers
28 views
Patch-Clamping Neurons Resources
Are there any lectures available on Patch-Clamping?
Were can I find a mathematical model of Patch-Clamp? (that can be easily implemented in matlab).
I have found some step-by-step protocols on ...
3
votes
1answer
88 views
What causes instinctive behaviour?
Some actions, almost behaviour, exist that are common across a species. For instance, based on personal observation, human babies try to taste anything new they encounter until they are a few score ...
2
votes
2answers
81 views
What exothermic reaction distinguishes warm blooded animals?
I would appreciate an answer specifically in the form of an exothermic chemical reaction. Namely, the one primarily responsible for generating heat in warm blooded animals that does not take place in ...
2
votes
2answers
42 views
What chemicals can be detected from one's sweat?
This question came to mind after reading this article. The article speaks of inducing sweating to determine by a roundabout fashion the amount of salt therein. I'm no medic but I find myself wondering ...
2
votes
1answer
46 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 ...
2
votes
1answer
110 views
Negative feedback in the fructose metabolism in liver
What happens in liver when large amount of fructose is consumed?
I vaguely remember my biochemistry lecturer telling us that the enzymes that process fructose in the liver does not have negative ...
2
votes
1answer
30 views
Why is the blood pressure in the superior vena cava during inhalation less than during the exhalation?
For further investigation into the progress of the blood pressure, we will measure a patient's blood pressure in the superior vena cava measured during inhalation and during an exhalation. His heart ...
2
votes
1answer
43 views
How much gas is exchanged in one human breath?
When we breathe, our lungs absorb a portion of the oxygen in the air, and replace it with some amount of carbon dioxide and water vapor. Typically, how much $O_2$ (in grams, milliliters, or moles for ...
2
votes
1answer
344 views
What is the “lifecycle” of an average eschar and what types of cells are involved in each stage?
(after some deliberation in the comments, I've decided to make the question more general)
An eschar or "dry scab" often forms at a site of injury over a large cut or sore.
It seems as though the ...
2
votes
1answer
137 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 ...
2
votes
0answers
20 views
Size of classical liver lobule across species
A classical liver lobule is made up of a central vein and the portal triads. A typical human liver weighs around 3 lbs. , while a typical bovine liver weighs around 12 lbs. I was wondering if anyone ...
2
votes
0answers
36 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 ...
2
votes
0answers
18 views
What is the mechanism behind ventilatory acclimatization?
In my respiratory physiology lectures, my professor explained that hypoxia-induced hyperventilation occurs in 2 stages when people try to acclimate at high altitudes. My question is about the ...
2
votes
0answers
35 views
Physiological or molecular difference before and after sleep?
I know that the details of the process of sleep aren't entirely known, but have always wondered why I feel rested after sleep.
Biologically, what differences can be directly observed in the human ...
2
votes
0answers
40 views
Are there any situations in which phenylephrine is preferred to pseudoephedrine?
In the mid 2000s in the US, due to issues of drug enforcement, pseudoephedrine containing medications were brought behind the pharmacy counter and in most cases require ID, and phenylephrine was ...
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vote
3answers
100 views
What difference does it make in the organism's physiology/metabolism whether oxygen binds reversibly or not?
A follow-up to How does hemoglobin-free blood transport oxygen?
I'm unsure about the use of physiology/metabolism in the title there. The question in mind is whether this reversible binding makes an ...
1
vote
2answers
68 views
What organs are absolutely needed by the human body?
The title is my question: what organs are absolutely needed (fatal if injured/removed) by the human body and perhaps animals in general?
I'm not asking which organs are mechanically replaceable, but ...
1
vote
1answer
84 views
What is the energy balance of cooking?
If I cook some food, I get apparently several energetic advantages:
thermal : the temperature of the food is closer or superior to the temperature of my body or internal organs, so I do not have to ...
1
vote
3answers
53 views
Are all healthy animals more likely to defecate near the end of a rest-cycle?
Just what the title states.
It stems from observation & personal experience that a person/dog/cat/monkey is more likely to relieve oneself immediately after it wakes up from the peak-sleep cycle ...
1
vote
1answer
47 views
What could cause hairs to gray at the tips but not the roots?
I have noticed that some of my sporadic gray hairs are gray at the tip side but oddly, not near the roots. Some are even only gray in the middle. I find all of this very counter intuitive, and I ...
1
vote
1answer
25 views
Is stereo olfactory ability restricted to humans?
Most animals I see around seem to have two nostrils - humans, snakes, birds, fish .. and so on. From reading online I see that 2 nostrils provide a stereo olfactory effect. This stereo effect is ...
1
vote
0answers
29 views
Why do ion concentrations change with different secretion rates in pancreatic juice?
Why is it that when secretory rate increases in the pancreas the concentration of chloride ions decreases, and the concentration of bicarbonate increases in the production of isotonic NaCl secretion?
...
1
vote
0answers
43 views
What are the physiological effects of wine?
I have read that alcohol in general and wine in particular can have advantageous as well as detrimental effects on human health. Is this true? What are the physiological effects of consuming wine in ...
1
vote
0answers
70 views
Why is membrane potential not zero at equilibrium?
For the squid giant axon, the membrane potential computed by the Goldman equation is -60mV. And the Nernst potentials are (the differences between the K+ and the Na+'s Nernst potential and the ...
1
vote
0answers
28 views
Where can I find approximate rates of sequestration of CO2 for different species of algae?
For a study, I want to compare the rates of CO2 sequestration and fixation of a few different species of algae.
I could not find any data on the sequestration rates. Any pointers to where I can find ...
