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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35 views

Odd- and even-sneezers

There's an anecdotal claim that people exhibit clear pattern when clearing their nose: Usually sneezing once (odd-sneezers) Usually sneezing twice (even-sneezers) Usually making a long series of ...
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15 views

Do factors other than concentration gradient and membrane permeability affect the diffusion potential?

If, hypothetically, the concentration gradients and the permeability of 2 different ions (Na+ and K+ for example) in 2 separate solutions are the same, will the diffusion potentials be different? I'm ...
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47 views

What causes paresthesia from compression?

Compression of a nerve causes loss of afferent and efferent information in it. What is the physiological basis of this?
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58 views

If you only ate fruits, vegetables or smoothies would you be able to skip drinking water?

If you only ate fruits, vegetables or smoothies would you be able to skip drinking water? I do not see some animals (like squirrels) drinking water daily (doesn't mean they don't have a water source) ...
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1answer
37 views

How do birds eliminate oxygen free radicals [closed]

Birds breathe in a lot. Do they produce a lot more of oxygen free radicals than mammals? And how do they cope with oxydative stress? Thanks!
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Why is wombat scat (feces) shaped like cubes?

I've heard that wombat scat 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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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 ...
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1answer
38 views

Why does increasing the space constant increase conduction velocity in myelinated neurons if nodes of Ranvier are constantly spaced?

If depolarisation at one node of Ranvier triggers, by passive conduction, an action potential at the next node of Ranvier, why does increasing the space constant increase conduction velocity? Surely ...
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Does Darwin's Theory of Evolution refute Terence McKenna theory “Stoned Ape” theory of human evolution?

I haven't read it but I'm asking for a quick answer. As far as I know, Terence McKenna's theory of evolution in humans main concept is that a hominid has tried in their diet psilocybin mushrooms, and ...
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1answer
13 views

Does a tubular sodium reabsorption cause a stimulation of β2-adrenergic receptors?

I read the study "The Role of Aldosterone in Obesity-Related Hypertension" and there is one thing I didn't understand. They write: "According to norepinephrine-induced tubular sodium reabsorption, ...
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Is my understanding of the Bergmann's rule correct? (mass is secondary)

According to Wikipedia, Bergmann's rule applies because animals living in colder areas have greater surface-area-to-volume ratio. If I understand that correctly, the advantage of the bulkier bodies ...
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1answer
101 views

What is Lysoferrin?

I was going though my Guyton and Hall Medical Physiology when I came across the name of an antibacterial lysosomal enzyme - Lysoferrin. It said that Lysoferrin "binds to iron and other metals ...
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Why is phagocytosis not included as a type of receptor-mediated endocytosis?

A common classification of endocytotic processes groups them into Phagocytosis, Pinocytosis, and receptor-mediated endocytosis (1) & (2). But Phagocytosis involves the use of specific receptors ...
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2answers
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Garden Hose Analogy for Blood Vessel Resistance

I've been trying to reconcile the resistance component of Poisseuille's law with a mental analogy of a garden hose; specifically, I had assumed that the effects of reducing the radius of a blood ...
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1answer
50 views

Why is the ratio between action potential and threshold value called the 'safety factor'?

"All­or­Nothing Principle. Once an action potential has been elicited at any point on the membrane of a normal fiber, the depolarization process travels over the entire membrane if conditions are ...
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1answer
104 views

Osmosis and hydrostatic pressure

I'm confused about the role of hydrostatic pressure compared to osmotic pressure. Q1:If I have a U-tube with a membrane permeable only to water molecules and equal volumes of water on either side ...
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Why is the brain dependent on glucose?

The strict dependence of the (human) brain on glucose has always been puzzling to me. While ketones can substitute for a portion of the brain's energy needs, it cannot substitute completely: blood ...
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1answer
24 views

How can the pressure during contraction vary between the left and right ventricles?

After reading this passage from my physiology textbook (Vanders Physiology p. 384), I'm confused about how exactly the right and left ventricle can create markedly different pressures as they pump ...
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Getting confused by neutralizer, fixator and stabilizer muscles

I know that neutralizers may also be classified as stabilizers because it is their ability to keep joints balanced that holds motion along a specific path. A fixator muscle is a stabilizer that acts ...
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1answer
522 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-...
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1answer
177 views

Does estrogen increase muscular growth in females?

Regarding humans it is said that most psychological effects caused in men by testosterone are caused in women by estrogens. There are many studies on that, particularly regarding temporary shifts of ...
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2answers
6k views

Do animals exhibit handedness (paw-ness?) preference?

I have been observing my cat and found that when confronted with an unknown item, she will always use her front left paw to touch it. This has me wondering if animals exhibit handedness like humans ...
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1answer
85 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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1answer
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Why do people's hands get cold for the first half an hour and then suddenly they are warm when they are doing exercise outdoors in winter? [closed]

When people do exercise outdoors in winter at temperatures less than zero degree celsius, their hands are quite cold and hurt for about half an hour. Then, there is a sudden rush of blood into the ...
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What gaseous substances do humans emit?

Other than CO₂ and Methane what other gases do humans produce or emit? For example, does skin decomposition, or aerobic respiration emit any special gases that people don't normally realize or know ...
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Is there any correlation between animal diet and blood pH?

The alkaline diet claim that as we humans have a slightly basic pH we shouldn't eat acidic food like meat (I think they claim that meat ashes are acid). I was wondering that if carnivores animals ...
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1answer
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What's so special about Chassaignac tubercle?

1-How does massaging of carotid artery at chassaignac tubercle( anterior tubercle of transverse process of C6 vertebra ) can relieve the symptoms of Supraventricular Tachycardia? My attempt: I think ...
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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 ...
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How does noradrenaline result in rise of systolic blood pressure even when the cardiac output is decreasing?

Systolic blood pressure[SBP] depends on the cardiac output. When Nor adrenaline is given there is vasoconstriction due to alpha-1 action on blood vessel, vasoconstriction results in increased total ...
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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 ...
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Quantitative Physiology Textbooks Recommendations?

I am currently completing a 2nd year (UK) Mamamilian Physiology Module and a Neuroscience Module. However, my degree is also 40% Maths and Statistics. So in order to learn the content better, I am ...
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Why is urobilinogen reabsorbed from the gut just to be excreted via the kidneys?

The Wikipedia article on Urobilin states: Bilirubin is... excreted as bile, which is further degraded by microbes present in the large intestine to urobilinogen... Some is reabsorbed into the ...
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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 ...
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How does gas equilibration occur in the alveolus, numerically?

I am attempting to model gas exchange across the alveolar membrane. My main question is there a direct exchange of O2 molecules for CO2 molecules? If so, then my model predicts (assuming alveolar ...
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1answer
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Why Can't Muscles Push When They Return To Their Original Length?

I understand that muscles can only contract and shorten and thus can only pull, but why can't a muscle push when it relaxes and returns to its initial length?
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Specific and non-specific endocytosis

I am confused as to what endocytic processes are termed specific and non-specific. I am only sure of pinocytosis as a non-specific process but I can't successfully put phagocytosis in the right ...
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1answer
71 views

Humans best at long distance running: purely physiological or is it a function also of ability to pace?

I have read that although certainly other land animals are much faster over short distances, a human can run down any other animal over time, so that if a human is hunting like a gazelle, etc. ...
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What is the physiological function of the CoV-2 targeted ACE2-Mas receptor pathway on lung/nasal epithelial cells?

CoV-2 targets ACE2 receptor on epithelial cells, pneumocytes, as well as nasal cells which seem to be cells of the nervous system (loss of smell is a symptom of Covid). ACE2-Receptor is rather well ...
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1answer
127 views

What stops myosin during muscle relaxation?

I understand that when the muscle is relaxed tropomyosin blocks myosin binding sites on actin filaments thereby preventing muscle contraction. What I am concerned with however, is whether myosin ...
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1answer
47 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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1answer
91 views

Why is the current flow shown to be flowing from the negative area towards the positive area?

When I was studying the ECG chapter in the book "Guyton and Hall Textbook of Medical Physiology", I noticed something odd in one of the pictures: As you can see the current is shown to be ...
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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....
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2answers
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Is water movement across cell membrane purely diffusive or it always requires channels?

If we see nephrons, in the descending part of Loop of Henle (LoH), water movement is allowed but solute movement is not. On the contrary, in ascending LoH, solute movement is allowed but not water. ...
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Why do I see different hues of colors between each of my eyes?

Frequently, I see colors with a slightly different hue when looking through my eyes individually. The right eye is more red-tinted ('warmer' hued) and the left is typically more blue-tinted ('cooler' ...
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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 ...
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1answer
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What does sympathetic and parasympathetic 'tone' mean?

My professor's lecture notes say that " The basal rate of firing is called “sympathetic tone” and 'parasympathetic tone" , but a table I found on the internet says that the parasympthetic system has ...
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1answer
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Question on thick filaments

In this photo, I know that the arrows pointing towards the M-line of sarcomere on actin filaments are due to the power strokes of myosin heads. However, what I don't understand are the arrows on the ...
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Why does dryness irritate mucosal surfaces, and what exactly is this “irritation”?

The mucosal surfaces of the body function to moisten the epithelial linings and keep them from becoming dry. Why is this important? As an example, the respiratory tract moistens and warms the air that ...
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2answers
52 views

Understanding muscle tone

I am relatively new to Physiology, and I've just learnt about muscle tone. I however find it difficult to understand the electrical changes that initiate (and/or accompany) muscle tone in smooth ...
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what powers power strokes

I am wondering what really powers the myosin head to undergo the power stroke to push the actin filaments towards the M-line. I have 2 thoughts: when ATP in the myosin head gets hydrolyzed, the ...

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