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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What causes the depolarization before Na+ gated channels open? [duplicate]

My book says: "When the membrane potential becomes less negative than during the resting state, rising from −90 millivolts toward zero, it finally reaches a voltage—usually somewhere between −70 and −...
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27 views

Nernst equation and equilibrium potential

Solutions A and B are separated by a membrane that is permeable to Ca2+ and impermeable to Cl−. Solution A contains 10 mM CaCl2 , and solution B contains 1 mM CaCl2. Assuming that 2.3 RT/F = 60 mV, ...
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How is Facilitated Diffusion saturable but simple diffusion not?

In some cases it is pretty clear why Simple diffusion is not saturable but in cases like the movement of molecules through ligand gated channels I'm finding difficult to see how they're not saturable. ...
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14 views

What affects the excitable cell membrane threshold?

What are the factors that affect a cell's membrane threshold? What I think is that it's the nature of voltage-gated sodium channels. But it's said that the density of these channels and the diameter ...
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Do endocrine cells always lie adjacent to capillaries?

The circulatory system transports plasma contents to the body via the interstitial circulatory system, reabsorbed with the lymphatic system. Cell metabolism "waste products" are transported into the ...
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Can horses creep? [closed]

I am wondering whether horses can creep (move on their knees). Based on my experiences with them I would assume they are too weak to put their full weight on them. I could find nothing on Google ...
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104 views

Are there any animals that are unable to hear the human voice?

Humans and animals have different hearing ranges. The frequency range of a human, for example, is stated with 20 Hz to 20 kHz, whereas the fundamental voice frequency is stated with 125 Hz for men, ...
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120 views

Why do patients with type 2 diabetes not show the body wasting seen in type 1 diabetics?

Type 1 diabetes results from the destruction of the cells in the pancreas that produce insulin, while type 2 diabetes is characterized by so-called "insulin resistance", presumably a reduced ...
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25 views

How does chest wall compliance affect functional residual capacity (FRC)?

The functional residual capacity is made up of expiratory reserve volume (ERV) plus the residual volume (RV) - i.e. the volume of air remaining in the lungs after passive expiration. Compliance of ...
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35 views

Why would it be beneficial for cortisol and corticosterone to exhibit pronounced anti-inflammatory activity?

These questions are always a little silly (as we will never truly know), but it always struck me as odd that corticosterone and cortisol exhibit pronounced anti-inflammatory activity. Because these ...
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How does temperature affect metabolism of warm blooded animals (homeotherms)?

In cold blooded animals (Poikilotherms) the temperature has a profound effect on metabolism. When the external temperature is raised a corresponding rise in internal temperature followed by a rise in ...
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Why is arterial pO2 normal in carbon monoxide poisoning?

Arterial blood gas measurements often show that pO2 is 'normal' even though haemoglobin is bound to carbon monoxide with high affinity. Is this because there is still oxygen bound to some subunits of ...
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22 views

Is mucus significantly affected by the presence of ions?

In mucus, there is besides water and the mucins (Proteins for mucus), there are Ions like $Ca^{2+},Na^{+}$, etc. I have read that These Ions can Control the mucus swelling, i.e. the volume that the ...
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36 views

Why does higher venous volume increase atrial pressure?

If the cardiac output stays the same, then why does higher venous volume increase right atrial pressure? Shouldn't the flow rate be conserved (with a constant cardiac output) so that the venous return ...
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What is the human energy consumption by organ?

The human brain uses about 25% of the human body's metabolic energy. How are the other 75% spent, in terms of portioning to its various systems? I thought this could be answered by a simple search, ...
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51 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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1answer
52 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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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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91 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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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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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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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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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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54 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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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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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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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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239 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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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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30 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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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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59 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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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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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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24 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 ...
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1answer
84 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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150 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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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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74 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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413 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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76 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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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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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 ...
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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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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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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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176 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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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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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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509 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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