Questions tagged [physiology]

The study of the normal function of living organisms and their anatomical parts and the means by which their normal functioning is achieved.

174 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
5 votes
0 answers
120 views

How is atrophied muscle different than normal muscle in a chemical or biological way?

I am a writer with a question for a story I'm working on. In it, the character suffers from muscle atrophy due to spinal damage. So that I can portray this accurately, what would cause this type of ...
user avatar
4 votes
0 answers
106 views

Optimal carbon dioxide concentration range for the human body

Previously I had thought the maximum concentration of CO2 for human health to be given by the ‘Pettenkofer CO2 level’ with a maximum of 1000 ppm. But according to this post a growing body of ...
4 votes
0 answers
66 views

Are there specific theories as to what causes cold[-water] muscle cramps?

The field of what might cause cramps is quite contested with a lot of controversy around the heat/dehydration cramps, but I find it surprising that no specific theories appear to have been proposed (...
  • 3,042
4 votes
0 answers
72 views

Is there a biological determinant for right- or left-handedness?

When I was very young, I was sent by parents to examination where I was told both my hands are dominant in the same way. My parents preferred to make my life easier and chose to focus on my right hand ...
4 votes
0 answers
123 views

Can you "fight" a coma or serious illness?

In an article about the latest earthquake to strike Mexico, I read that a rescuer said to someone in a gurney, "Fight for your life, please!" I've seen similar things in TV shows and movies where a ...
  • 91
4 votes
0 answers
248 views

Are there predefined implantation sites in mammalian uterus?

I do surgical embryo transfer of genetically modified (microinjected) mouse embryos (at 1 or 2 cell stage). As most of the constructs are new, we expect that it may affect birth rate. In case there ...
4 votes
0 answers
70 views

What could be the reason for the large difference between sodium and potassium blood concentrations?

Reference values for sodium and potassium concentrations in blood tests are usually in the range of 135-145 mEq/L and 3.5-5.1 mEq/L, respectively. My question is what could be the reason for this (...
  • 474
4 votes
0 answers
342 views

What is the lifespan of Skeletal Muscle Cells?

I have read that skeletal muscle cells cannot multiply and are generally not created after early development. However, I have also read that they have a "lifespan" of 10-15 years. Could this lifespan ...
4 votes
0 answers
256 views

What is the essence of difference of how different chemicals affect the same receptor?

It is known that various chemicals can bind to the same receptor type, producing different effects. Be these chemicals agonists or antagonists, there are more variations in how they influence the ...
  • 546
4 votes
1 answer
572 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 long-...
4 votes
2 answers
965 views

What is the effect of persistent hypothermia on cardiac performance?

I define persistent hypothermia in this thread about the mechanisms of persistent hypothermia. The Graph of Katzung et al. in Pharmacology about Heart Failure: I am thinking which parts here are ...
3 votes
0 answers
30 views

Does the kidney regulate sodium balance or total body sodium

Imagine the following situation. You have a person who initially eats 10 mEq/day of salt. He then, at t=0 begins to eat 150 mEq/day of Na, and will continue to do so, because you're forcing them to, ...
3 votes
0 answers
327 views

Why does (insulin induced) hypoglycemia stimulate ADH secretion?

Intuitively, I understand that ADH (Anti Diuretic Hormone) is responsible for maintaining osmolarity, and increased serum osmolarity is a stimulatory factor for its release-- ADH increases water ...
  • 944
3 votes
0 answers
35 views

Hodgkin-Huxley Model and Propagation of Action Potential

I'm studying Hodgkin-Huxley model of action potential, and I have some confusion. In the well-stated HH model, we have time constants for each ion currents, described as the reciprocal of the sum of ...
3 votes
0 answers
407 views

What is blood pH for different animals?

So we all know that humans average blood pH is 7.4. But is it the same for the animals? I need examples of animals with the same blood pH as humans and the ones with different blood pH. I guess dogs ...
  • 39
3 votes
0 answers
38 views

Can Chilopoda "vocalize" or produce sound for the express purpose of communication, as opposed to sound as a byproduct of other movements?

Is there any species of Chilopoda that can "vocalize" or or otherwise produce sound for the express purpose of communication, as opposed to sounds it might create as a byproduct of other movements ...
  • 247
3 votes
0 answers
105 views

How does isometric contraction work?

What exactly happens to myosin during isometric contraction? I suspect that either myosin heads just "freeze" in the middle of crossbridge cycle, or go through full crossbridge cycles repeatedly at ...
  • 71
3 votes
0 answers
322 views

Affinity for oxygen and carbon dioxide in animals

I'm currently reading Treatise on Invertebrate Paleontology (A) and don't understand the following fragment: The affinity for oxygen in lower animals is many times that in higher ones, whereas ...
  • 39
3 votes
0 answers
726 views

Physiological effects of electrical shocks on human body depending on the energy

When discussing safety of electricity, one usually considers a constant DC or AC current with constant amplitude over a longer time. It is easy to find tables in books or in the web which lists ...
  • 131
3 votes
0 answers
79 views

What is the evidence that mammals are unable to process excess sodium chloride?

I grew up hearing the mantra excess salt causes heart disease I had a vague understanding that it caused deposits in the body or something. Now that I give it more thought - I come up with three ...
  • 939
3 votes
0 answers
165 views

What happens to the cell during post-hypothermia?

A friend of mine said that the cell membrane somehow changes after rewarming from hypothermia and that the body does not recognize it's own cells, thus leads the immune system to attack it self. Is ...
  • 31
3 votes
0 answers
324 views

How does glucose delivered intraperitoneal (i.p.) get into the peripheral circulation?

Intraperitoneal delivery of drugs or fluids is something that occurs much more frequently in veterinary medicine than clinical medicine. In veterinary medicine or scientific studies using animals, ...
3 votes
0 answers
1k views

Skin extra sensitive to heat after burn

I just got my finger burnt (first degree burn $\Rightarrow$ I didn't even bother to bear the wound). It didn't hurt much, even when I pressed the wound. However, when exposed to heat (hot water, but ...
  • 143
3 votes
0 answers
1k views

Which types of blood vessels can regenerate in humans/mammals?

Which types of blood vessels can regenerate in humans/mammals? From what I understand, arteries and arterioles can be created later in life, while this is not necessarily the case with veins. However ...
  • 161
3 votes
0 answers
79 views

Are small CO₂ concentrations devastating to certain cognitive tasks?

A new study shows strong effects of what should be a negligible CO2 concentration. The paper "Is CO2 an Indoor Pollutant? Direct Effects of Low-to-Moderate CO2 Concentrations on Human Decision-Making ...
3 votes
0 answers
125 views

A day in Beijing is like smoking Only one sixth of a cigarette

This is the title of this blog post followed by this other good post. I'm particularly anti-tobacco-smoke, at the point of not always considering other pollution, and this article shows how this kind ...
  • 181
3 votes
0 answers
77 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
0 answers
48 views

How is the Staverman's reflection coefficient in the Stirling equation determined?

The Stirling equation is expressed as follows $J = Kf ([Pc-Pi] - σ [πc - πi])$ Here, capillary hydrostatic pressure (Pc) and Bowman's space oncotic pressure (πi) favor filtration into the tubule, and ...
  • 31
2 votes
0 answers
41 views

Why does the Corpus Luteum produce more Progesterone than Estrogen?

In the human ovarian cycle, follicular cells produce only Estrogen in high concentrations (to my knowledge). Yet after ovulation and formation of CL, which should be the remnant follicular cell mass, ...
2 votes
0 answers
16 views

What benefit do cardiomyocytes accrue by requiring calcium induced calcium release (relative to skeletal myocytes)?

According to 2 sources I've read, in contrast to skeletal myocytes, cardiac myocytes need calcium to diffuse in to result in contraction. One source says that they need large amounts of calcium to ...
2 votes
0 answers
97 views

Why does distention of the veins not decrease their resistance in the first case but decrease it in the second?

Here are two quotes from Guyton and Hall Textbook of Medical Physiology, Chapter 20 (emphasis mine): Why is venous resistance so important in determining the resistance to venous return? The answer ...
  • 193
2 votes
0 answers
65 views

Is there any animal known to produce structures of both keratin and chitin?

I began with thinking about the similarities between keratin in its hardest form (fingernails, horn sheaths) and the chitin that composes the exoskeletons of some few beetles I've seen in my life. To ...
2 votes
0 answers
64 views

Is it incorrect to assume alveoli as spherical and distinct, especially when analysing lung inflation/deflation?

I have recently read the paper "Laplace’s Law and the Alveolus: A Misconception of Anatomy and a Misapplication of Physics". To summarise it, here is a section from its abstract: The ...
2 votes
0 answers
53 views

Why doesn't the concentration of one ion affect the concentration gradient of another ion across a plasma membrane?

In the initial stages, some ion channels across the plasma membrane open to allow for ions to flow down their concentration gradient into or out of the cell. I understand that each ion's overall ...
2 votes
0 answers
27 views

Do the posterior legs of mosquito plays the role of antenna?

I have had this question for years and this stems from the observation that when I bring my hand close to a mosquito lying on some surface (e.g : wall) I see its posterior legs - which are in a ...
2 votes
0 answers
34 views

How to estimate oxygen consumption of an average human during different activities?

I've tried to find some resource on the internet but had little luck. I'm looking to see if there's any data on average oxygen consumption of average to well trained humans during different activities....
  • 121
2 votes
0 answers
145 views

Does The Sympathetic Nervous System Increase or Decrease Urination?

According to my book: Sympathetic nervous system stimulation, leads to the release of Norepinephrine(Noradrenaline), priming the body for the "Fight or Flight" response. It is also stated ...
2 votes
0 answers
263 views

Summation on muscles

I am learning myology and encountered 2 problems in tetanus and summation: Unfused tetanus is just a continual summation of twitches if I am not mistaken. However, is it a MUST for summation / ...
  • 153
2 votes
0 answers
39 views

Why largest cats so much larger than canids?

It is striking to me that there is no dog-like creature larger than a wolf while there are at least two species, tigers and lions, many (at least twice and probably 3 or 4) times the size of the ...
  • 287
2 votes
0 answers
74 views

Hematuria due to Nitric Oxide

Drug interactions between properly dosed NO and other medications are not expected, but side effects may include noisy breathing, hematuria, or possibly atelectasis. (pg.no:577; Goodman and Gilman ...
  • 4,746
2 votes
0 answers
418 views

What do Caucasians see in their peripheral vision, and how is their visual field?

I am an Asian who has no idea how much of their nose Caucasians (especially for those with extremely deep-set eyes, very prominent and low brow ridges, and high noses like Brian Shimansky or Rishi ...
2 votes
0 answers
48 views

Does dreaming have any physiological impact on our body?

Personally speaking, when I wake up after a really good dream, I feel really happy, similar to how I would feel if something good has happened in reality. This makes me wonder if we are actually going ...
  • 295
2 votes
0 answers
206 views

Alpha-gamma co-activation

I am having trouble visualizing/grasping the necessity of alpha-gamma co-activation. My understanding is the following: When an external load causes stretching of the sensory muscle spindles, the 1a ...
2 votes
0 answers
51 views

What is the biggest structure in nature for structural coloration?

I'm interested in the actual sizes behind structural coloration: I find it fascinating and I think it may have a couple very nice applications. The problem is I couldn't find anything but vague ...
  • 21
2 votes
0 answers
39 views

How urination prior to blood test may give error?

Source: Textbook of Practical Physiology, 4th Edition according to it urination within 30 minutes is a precollection factor that may alter the results of blood test. I am unable to comprehend how ...
  • 4,746
2 votes
0 answers
334 views

Why are many unable to defecate and urinate simultaneously?

Many people (including myself) do not defecate and urinate simultaneously, but rather in succession. Only after one is completed, the other commences. I have noticed this in myself, but the internet ...
  • 473
2 votes
0 answers
131 views

Origin of melatonin: oxidative stress defense OR circadian rhythm?

Question Which functional role of melatonin came first? Regulation of the circadian rhythm Defense against oxidative stress Other Background I was well aware of the important role melatonin plays ...
  • 21
2 votes
0 answers
94 views

How much do arteries expand during pulse?

Arteries expand during a pulse. The amount of expansion may differ from artery to artery. How much do arteries expand? I understand it might be a range. Inform the same. Even values specific to some ...
  • 21
2 votes
0 answers
46 views

Does human skeletal muscle fascia grow new additional collagen in response to increases in skeletal muscle size?

For example, if a human skeletal muscle is growing repeatedly due to periodic weightlifting, does the fascia eventually respond to the increasing volume by growing more quantities of collagen or other ...
2 votes
0 answers
230 views

Why does fetal distress (hypoxia) cause bradycardia?

In a non stress test performed in the labor room, fetal bradycardia is a danger sign indicating fetal distress (hypoxia). Why does fetal hypoxia cause bradycardia while hypoxia in adults cause ...
  • 3,647