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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.

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1answer
40 views

Mithradates - Developing immunity to poison?

According to legend, Mithridates studiously researched and examined all known toxins and experimented with potential remedies by using prisoners as his guinea pigs. Supposedly, Mithridates’ toils paid ...
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29 views

Are chordae tendinae capable of healing?

I haven't found anything on this question. Generally the sources say the heart cannot heal but that's contradictory. Has there been any cases of chordae tendinae rupture healing?
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1answer
44 views

How does an electrical impulse spread in a muscle fiber spread from the motor end plate?

Does this impulse in skeletal muscle spread much in the same way it does in neurons, with an initial potential change that spreads to its immediate surroundings and is then re-amplified or is it the ...
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10 views

Does increasing contractility increase LV ESP?

I see many PV diagrams showing a negligible difference in the ESP when contractility increases. I'm wondering why this is the case, because if more blood is being pumped out into the aorta, the MAP ...
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1answer
70 views

Can all animals breathe manually?

Originally I was pondering about why we have the ability to breathe manually. I couldn't think of any tangible advantage, given that the body can develop mechanisms to regulate the rate of breathing ...
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3answers
6k views

Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?

It is an often-repeated claim that human, and in fact all animal blood is salty because we evolved from aquatic organisms, and that blood has a similar concentration of salts as ocean water, or at ...
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12 views

How much does Scolopendra gigantea weigh?

For somewhat understandable reasons, most references I've found related to "size" of Scolopendra gigantea, and centipedes in general, seem to focus on length. There are numerous sites, blogs, etc., ...
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18 views

How does the descending branch of the loop of Henle equilibrate concentration?

I'm learning physiology and I have a hard time figuring out how the cortico-papillary gradient is created. Most explanations go as follow: 1) Sodium is pumped out the ascending branch into the ...
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0answers
18 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 ...
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1answer
52 views

Why is there a mass limit on biological powered flight?

So, this is one thing I never fully understood. There are a lot of reasons for a flying creature to be limited in mass, from energy consumption to material strength. However there seems to be a reason ...
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8 views

Is atrial natriuretic peptide relased when we drink water?

I know that osmolarity is controlled by the hypothalamus and recover by ADH which reabsorb water. It also can be released when ECV is very low. ECV/salt is controlled by aldosterone/atrial ...
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1answer
61 views

Can stress and arousal be independent?

I'm trying to figure out if it's possible to have a stress response without being initially, or simultaneously aroused. I'm defining stress to be physiological stress (ie. release of cortisol) and ...
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0answers
19 views

Vasoconstriction and blood flow

The resistance in a blood vessel is equal to the pressure difference divided by the blood flow. Let us now say that a sympathomimetic causes vasoconstriction which increases the resistance. Does this ...
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1answer
59 views

What is the difference between transpiration and evapotranspiration?

According to my point of view transpiration and evapotranspiration are different things, but i am confused about this topic. After great effort, I found a major difference between it. Transpiration: ...
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8 views

Using EMG to measure increases in strength

I have a DIY EMG kit and I know it can be used to measure muscle activation. I am wondering, is there a relationship between muscle strength and the value obtained from the EMG sensors measuring on ...
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0answers
28 views

What adaptations does the human body have to handle frequent and sustained changes in orientation?

Most animals are horizontal with the ground. When they lie down, they get closer to the ground, but their orientation does not change. Humans, on the other hand, stand up straight and tall, ...
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54 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 ...
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1answer
55 views

What differentiates neurons in different parts of the brain?

For example: what makes a neuron in the hippocampus of the brain different from a neuron in, say, the amygdala, or the frontal lobe, or anywhere else in the brain? Do neurons in different parts of the ...
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29 views

How to troubleshoot in vitro formaldehyde fixation for nucleosomes?

For an experiment, I am trying to fix the mononucleosomes (100ng) using formaldehyde as crosslinking agent in HEPES buffer. I have been using 2% formaldehyde in a reaction buffer containing 1mM EDTA, ...
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15 views

Is chlorine a good activator of osteoblasts?

I have read on the internet that Fluorine, which is a group 17 element is a good activator of osteoblasts. Since elements down the same group has similar properties, I’m wondering if Chlorine is a ...
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1answer
21 views

Does the frequency discrimination of the outer hair cells of the ear increase with sound pressure?

I'm wondering whether the frequency resolution of the inner ear increases/decreases with the volume level (caused by sound pressure $(N/m^2)$. My assumption would be that as long as the pressure ...
2
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1answer
82 views

How does a nerve cell adjust if O2 diffusion is interrupted?

What effects would it have on a nerve if the oxygen supply is cut off? Is there any data on this? Does the nerve conductance velocity increase? What about the Amplitude and receptor-channels on/in ...
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0answers
101 views

Why does K+ going out of the cell cause hyperpolarization?

I'm really confused by how the terms Hyperpolarization and Depolarization are used in Cell biology and hope somebody can enlighten me hopefully. Here's what they mean for me so far: Depolarization ...
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0answers
54 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 ...
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1answer
71 views

Why didn't these scientists restore electrical activity in this pig's brain?

This experiment was published in Nature Magazine: Pig brains kept alive outside body for hours after death. The researchers used a system called BrainEx to revive certain metabolic and physiological ...
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1answer
260 views

Why does histamine cause bronchoconstriction?

What purpose does histamine-caused constriction serve in lungs during allergies and such, since it's vasodilator in other parts of body. Wouldn't it be more practical to vasodilate lungs so that white ...
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1answer
74 views

Why does muscle blood flow decrease during exercise?

My questions semi-relates to these two items: Where does extra blood come from to fill your muscles during exercise? , and Blood pressure during exercise . While reading Exercise Physiology by Dr. ...
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1answer
124 views

Coronary circulation

It is said that the coronary artery that gives the posterior descending artery(PDA) determines if the heart is right dominant(most cases) or left dominant. Is there any reason to this? Why PDA?
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1answer
68 views

Is it correct that the nicotinic acetylcholine receptor has nothing to do with Dopamin?

As I know Dopamine is almost exclusively produced via metabotropic receptors, is it possible for a nicotinic ACH receptor to influence a dopamineric neuron? Can a nicotinic ACH receptor cause a ...
2
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0answers
120 views

Living potato clock? [duplicate]

Could a potato stay alive and power a clock while growing in the ground? I know how a potato clock works as a electrochemical cell and involves chemistry, but I am only interested in a growing ...
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0answers
19 views

Is it possible for a human being to live on a different day cycle?

I am considering writing a story where a character lives on a 30-hour day cycle. That is, this person sleeps for 9.5 hours and is awake for 20.5 hours. Then this person repeats the schedule. I'd ...
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0answers
27 views

In oscillometric blood pressure measurement, why do we assume that highest oscillations correspond with mean arterial pressure?

As far as I've seen, the point on the oscillometric curve where there are greatest oscillations represents the mean arterial pressure (MAP). My question is - why? What is the logic behind this ...
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4answers
162 views

What's the benefit of the average human body temperature?

Why would the body choose a resting temperature of 36.1c to 37.2c? It seems a very inefficient mechanism of survival considering the typical ambient temperatures on Earth. If there is a benefit to ...
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0answers
23 views

What is the net effect of pancreatic somatostatin and how is it regulated?

I've read the following facts about pancreatic somatostatin released from delta cells of the islets of Langerhans: Blood glucose, fatty acids, and plasma amino acids stimulate somatostatin ...
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0answers
11 views

What's the significance of independent control of glomerular capillary pressure and plasma flow, via efferent arteriole?

As I understand, the renal efferent arteriole, when constricted, allows an increase in glomerular capillary pressure, but a decrease in blood flow. This allows an independent control of renal plasma ...
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0answers
29 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 (...
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1answer
435 views

Why is the ingestion of salt and water beneficial to muscle cramp

According to Wikipedia, muscle cramps are caused by the inability of myosin fibers to break free from the actin filaments during contraction, resulting in a prolonged contraction. A lack of ATP would ...
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2answers
163 views

Why do fruit flies go so close to large reservoirs of liquid when they are likely to fall in due to surface tension?

I had accidentally left out half a glass of red wine by the windowsill when I went to sleep. As anyone knows, if you do this with a window cracked you will get quite a few fruit flies near it in that ...
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0answers
181 views

How can we smell odor direction if we breathe through one nostril at a time?

It's known that humans breathe mostly through one nostril at a time. How can we then perceive the direction the smell is coming from? Some articles claim similarity between olfactory and auditory ...
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1answer
125 views

Do animals with their eyes ~180 degrees apart have depth perception?

Lots of animals have their eyes more on the side of their head, like an octopus or a parrot. Are animals with eyes more on the side able to tell the depth of objects at different distances? It seems ...
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0answers
11 views

Is creb level linked to cancer

I am just wondering if there is any evidence the overall proteome CREB transcript level is linked to cancer. Most likely since it is so Central to the underlying pH driven process.
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2answers
215 views

Why does the seed of the coconut tree have a liquid in it?

What is the purpose of water in the coconut seed? The reason I ask this is that I was reading about coconut water and all the benefits it has for us Humans. But why does the tree put a liquid in the ...
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1answer
32 views

Effect of the same caloric intake of different macronutrients on body weight

To gain weight, caloric intake > caloric expenditure. To lose weight, caloric intake < caloric expenditure. But what is the effect of the type of macronutrient ? That is to say : does the same ...
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3answers
197 views

Why do our bodies maintain blood pressure but not the flow rate?

This might be a silly question but i'm not not clear I'm always told that blood pressure is homeostatic parameter and can't not be changed but isn't what important is the flow rate to the organs? ...
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1answer
39 views

Why does carbon dioxide diffuse easier through the bilipid layer than oxygen?

When gas exchange occurs during respiration, the pressure of oxygen in alveoli is around 105 mmHg, whereas in the blood vessels in close contact with alveoli is 40 mmHg. For carbon dioxide the values ...
2
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1answer
46 views

How does a decrease in free Ca2+ result in nerve/muscle overexcitability?

I have in my notes that a decrease in free Ca2+ increases membrane permeability to Na+ so that it is brought closer to threshold, but no further details. So how does this work?
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18 views

Muscular tetany and hypocalacemia

Decreased serum calcium level leads to increased excitability of neuron and at same time decreases the contractibilityof the muscle fibres.But still its causing tetany.Wouldn't these two counteract to ...
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3answers
216 views

Why did a lot of common insects evolve such a thin waist?

Something that doesn't quite make sense to me is why lots of insects like ants, bees and wasps have a such a small petiole when it connects many major organs to the rest of their body from a suddenly ...
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0answers
38 views

Why is the V/Q Ratio 0.8 not 1?

According to: https://en.wikipedia.org/wiki/Ventilation/perfusion_ratio the ideal V/Q Ratio would be 1.0 because 1 L of blood can hold about 200 mL of oxygen and 1L of humidified air has about 200 mL ...