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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If a grizzly bear puts on 500 lbs of fat in preparation of hibernation, is he any stronger?
Let's say that at the end of Spring a male grizzly bear is at 500 lbs. By the end of Autumn he has gained another 500 lbs of fat in preparation for the winter hibernation.
Is he any stronger than when ...
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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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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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66 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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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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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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23 views
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
65 views
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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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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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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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
45 views
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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2answers
56 views
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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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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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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46 views
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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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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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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2answers
68 views
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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36 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 ...
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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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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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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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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 / ...
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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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1answer
27 views
What inhibits linkage between actin and myosin filaments
What is the mechanism behind the inhibition for cross-bridge linkage between actin and myosin filaments in the binding-tilting cycle? There are 2 possible ways that are in my mind:
a. Tn-I (tropnin-I)...
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What is the difference between muscle contracture and muscle rigor
My text says muscle contracture is a state of sustained muscle contraction due to depletion of energy. And muscle rigor is the stiffening of muscles when they're depleted of energy.
So, what exactly ...
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1answer
27 views
Does electrotonic spread/conduction occur in saltatory conduction?
Even as textbooks, and almost all web pages I've seen so far, explain electrotonic spread/conduction as the passive current flow along an axon, they do so with continuous conduction only. Apart from ...
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1answer
51 views
Do birds have pharynx like mammals? [closed]
I saw this in Wikipedia:
Birds do have a larynx, but unlike in mammals, it does not vocalize.
And this pdf in Google.
It claims that birds do have a pharnyx.
Do birds have a structure called pharnyx?...
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17 views
Why does increasing concentration of extracellular sodium have no effect on electrical gradient of potassium? [duplicate]
I learnt that the permeability of an ion across the membrane contributes to the membrane potential as much as(or even more than) its concentration and electrical gradients. And so far I've made peace ...
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Will renal blood flow decrease in response to dehydration?
If dehydrated, does the correction of ECF osmolarity happen slowly enough for ECF (and therefore plasma) volume to be temporarily depleted and therefore reduce renal blood flow?
If dehydration is ...
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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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Over-consumption of water in a short period of time
With too much water consumption at once, the blood will become much more hypotonic. Therefore, a larger amount of water will remain in the blood as the kidneys cannot ultrafiltrate all water out from ...
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Why does glomerular filtration result in a filtrate with the same osmolality as plasma?
Unlike the plasma, the ultrafiltrate has no proteins which are prevented from filtering out. Shouldn't the loss of these proteins result in a loss of oncotic pressure and thus a different overall ...
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Can severe vasoconstriction increase systolic blood pressure?
I know that, vasoconstriction results in increased total peripheral resistance which is responsible for the rise in diastolic blood pressure. Also, cardiac output is responsible for the systolic blood ...
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1answer
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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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48 views
is ventricular depolarisation same as depolarisation during nerve impulse conduction? [closed]
Does the change in membrane charge accumulation occur in a similar way in heart and nerves cells?
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Na+ / K+ ATPase: How does it restore resting membrane potential? [duplicate]
Could not find any sources talking about this (in a clear manner). If the Na+ / K+ ATPase pumps 3 Na+ out for every 2 K+ it pumps in, thus making the cell more negative, why is the Na+ / K+ ATPase ...
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At small axon diameters (<1 µm), why does myelination not increase neuronal conduction velocity?
As per the diagram below (and other graphs available online), why do unmyelinated fibres have a higher conduction velocity than myelinated fibres when the axon diameter is less than around 1 Āµm?
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Asexual Reproduction Of sponges through endogenous or exogenous budding?
I was studying asexual reproduction in sponges and came across two website
Wikipedia of Gemmule and there is a line....
Only Endogenous Types of Buds develop into New Sponges.
Then as I was reading ...
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Taking cold shower / drinking cold water after / during training
(I am a new-comer in biology SE so sorry if violated any rules)
Effect of cold showers after intense training
I have read the answer to this question, but it seems there are discussions on the ...
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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 ...
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Is faster breathing during exercise linearly more efficient?
Evolution's an amazing thing. It has this incredible ability to optimize variables, and often these optima can then be learned by people to gain insight into various biological phenomena.
In exercise, ...
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1answer
64 views
What is the pH of cytosol? And plastids?
My teacher ask this question, and I answered 7 to 7.4, but she said it's wrong.
I read a lot and found the same answer (wikipedia)
I'm here asking for confirmation of this and the pH inside & ...
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22 views
Does hypokalemia increase sodium concentration in cells?
In hypokalemia, when intracellular potassium is low, does intracellular sodium increase?
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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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1answer
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What happens to intrinsic factor exactly at the terminal ileum, where B12 is absorbed?
IF is very important for IF-dependent B12 absorption in the terminal ileum, the mechanism by which most of dietary B12 is absorbed. The B12-IF complex bind to IF receptors on enterocytes, but does the ...
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44 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?
