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Questions tagged [physiology]

The study of the normal function of living organisms and the means by which it is achieved.

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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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47 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 ...
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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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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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7 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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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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99 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
130 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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51 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
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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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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
113 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
26 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
114 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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29 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 ...
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1answer
41 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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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
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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
32 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 ...
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1answer
56 views

What is the difference between optokinetic and vestibular nystagmus?

Optokinetic nystagmus is for stabilising the pictures we see when we are observing moving objects for example if we are rotating on an office chair. If we wear a mask while rotating however, the ...
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1answer
211 views

Why does sympathetic activity constrict pulmonary vessels?

I don't know understand why sympathetic stimulation constricts pulmonary vessels? I thought that the sympathetic nervous system activated the body for physical activity. Physical activity would need ...
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1answer
21 views

Does focusing on a certain part of the body increase electrical activity in that region?

I am batting around ideas for master's thesis topics and was wondering whether or not just focusing on an area of the body would cause of boost of neuronic activity? Not sure whether this would fall ...
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1answer
42 views

Blood pressure in various blood vessels and heart

What are the typical systolic and diastolic blood pressure in arteries,capillaries, veins and the heart? I know it must be highest in the arteries. arteries>capillaries>veins Arteries: 120-80mmHg (...
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2answers
282 views

What causes “ear rumbling”?

The video Ear rumbling happens below the range of human hearing demonstrates that the "ear rumbling" sound is actual sound and can be recorded by a sensitive microphone near the ear. What is it ...
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1answer
37 views

How does vasoconstriction increase the pressure of blood?

Is the increase of pressure due to the decrease in volume? Wouldn't the decrease in volume push the components of blood closer to one another resulting in an increase of repulsive forces, thus ...
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0answers
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What is the optimal time to implant embryo in uterus for in vitro fertilization?

What is the best time to implant an embryo in the uterus. I was under the impression that the earlier the better and more natural, but also if you wait until the blastocyst age, it may be better to ...
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0answers
15 views

How do booklice avoid dessication?

I often find booklice (aka psocids) in old paper notes I have in semi-storage. These pages of paper are intentionally left in dry conditions on my desk to avoid damage. However, if the psocids live ...
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0answers
62 views

Why does water stress lead to alkalinity of xylem sap in plants?

I was reading this book: Plant Physiology and Development, Sixth Edition by Lincoln Taiz, Eduardo Zeiger, Ian M. Møller, and Angus Murphy when this doubt came to my mind. Abscisic acid, the stress ...
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0answers
15 views

Etymology of eccentric/concentric contractions

I was wondering if anyone knew why the terms eccentric and concentric were chosen to refer to lengthening and shortening muscle contractions? The basic etymology of the words are to do with ...
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1answer
42 views

When muscles contract is the process similar to how non-newtonian fluids react?

I'm trying to understand how muscles contraction/tension works but getting loss in on the cellular level. From my understanding, when muscle tissue need to contract, the cells are flooded with calcium?...
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2answers
416 views

Wim Hof Method claims Alkaline Blood is Good. Contradictions? Counterproof?

The Wim Hof Method claims, that it is beneficial to have alkaline blood. On the other site there is the medical claim that if the pH-value is not within the range of 7.36 – 7.42, enzyms are ...
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0answers
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When we laugh or run for sport which autonomic system works?

When we laugh or run for sport which autonomic system takes place in this time? While I am not sure what happens in heart while laughing (tachycardia or bradycardia), but for sport running I'm sure ...
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1answer
106 views

Continuous (yeast) culture system satisfying multiple criteria

There are multiple ways yeast cells can be grown in liquid cultures. Batch cultures are easy to prepare but cell density, medium composition and physiology change over time Chemostats allow to ...
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3answers
1k views

Public database of animal specifications

I'm a math teacher looking for data to help my students interested in biology complete a quantitatively flavored study of animals. (As a math person, I apologize if I'm not using discipline-...
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1answer
60 views

Is there a name for the use of sunlight in metabolic processes?

"Photosynthesis" is what is used to describe how plants use sunlight to synthesize sugars, but, I also heard some animals like humans use sunlight in the process of creating vitamin D. Is there a ...
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1answer
103 views

Do sharks fart?

My son is 5 and I'm encouraging him to be curious and ask questions of the world around him. He asked if sharks fart and how does it smell? He feels that it would smell of fish and be disgusting. He ...
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0answers
45 views

Why is the glomerular filtrate isotonic to the blood in the capillaries?

How can the osmolarity of the filtrate be the same as the blood in the peritubular capillary when there is no red blood cells filtered?
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1answer
183 views

What are the limiting factors of human stamina?

What are the limiting factors of (human) stamina? Let's define stamina as the capacity to continue doing a physical activity. We clearly have our limits, so what aspects of physiology impose a limit ...
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1answer
120 views

Why do musk deer have the smallest red blood cells and amphibians have the largest?

What is the reason that musk deer have the smallest red blood cells and amphibians have the largest? Should they not be proportionate to the size of the organism?
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0answers
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What is the benefit of reducing inflammation when producing antibodies?

We just learned in lecture that IL-10 promotes the formation of plasma cells over memory cells. Which seemed strange to me as IL-10 also reduces inflammation, and I figure you would want inflammation ...
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2answers
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Why is wombat excreta shaped like cubes?

I've heard that wombat excreta is cube shaped, but I don't understand how that can happen. Has anyone studied the phenomenon? What would the evolutionary pressure have been to cause this?
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1answer
61 views

How does vasodilation slow blood flow?

During inflammation, cytokines and histamine cause vasodilation to increase blood flow to the inflamed area. However, it is also said that vasodilation slows blood flow which facilitates the adhesion ...
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1answer
37 views

Common english name for tissues which are separated from the blood by blood-tissue barriers

Which general term is used to denote such organs/tissues as: brain, testis, thymus etc., which are separated from the blood by blood-tissue barriers?
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1answer
74 views

What physiological processes give rise to a linear cell survival curve?

If we plot the number of surviving cells in a structure over time (assuming no replacement), the shape of that curve should imply something about the underlying process responsible for cell death. For ...
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2answers
39 views

Cross-species infections

I’ve heard that HIV developed from SIV, etc. I’ve also heard that most species (including most monkeys) can’t get a common cold like humans. So then what causes infections to be able to travel ...
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1answer
33 views

What is (are) the medium of conduction for an electrical current with an external source in the human body?

I am trying to get some background for some personal research I am doing into the effects of Electro Convulsive Therapy. I don't understand how electric current from an external household source, say, ...
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1answer
246 views

Why do crocodiles have a high concentration of lactic acid in their blood?

Crocodilians have high concentration of lactic acid in their blood. This is the cause that prevents them from prolonged intense activity, since prolonged intense activity causes the muscles to secrete ...