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 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 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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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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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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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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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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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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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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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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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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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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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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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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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 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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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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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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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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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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How many cells are there in the apical meristematic tissue?
How many cells are there in the apical meristematic tissue?
Looking at this picture...
, I would tend to think that there are few hundreds cells in the meristem tissue. But I guess this is a picture ...
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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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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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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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How does lactulose cause the removal of ammonia from the colon?
Lactulose is also used to reduce the amount of ammonia in the blood of patients with liver disease. It works by drawing ammonia from the blood into the colon where it is removed from the body.
[Source]...
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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 µm?
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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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Does posture matter while drinking water?
I have heard a lot of people (where I am from, India) say that one must drink water sitting, not standing. Recently, I also came across a video that said the same thing (link). The reason given is ...
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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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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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Why does higher venous volume increase atrial pressure?
If the cardiac output stays the same (hypothetically, although obviously it doesn't stay the same), then why does higher venous volume increase right atrial pressure? Shouldn't the flow rate be ...
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What are some good books on oncology?
I'm looking for some book suggestions on oncology, preferably I want them to be fairly recent. I am not worried if they are fairly technical, as long as they have good accurate content and layout.
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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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Why is there a mass limit on biological powered flight?
So, this is a thing I never fully understood. There are a lot of reasons for a flying creature to be limited in mass (though I'm unsure if I'm familiar with all of them), from energy consumption to ...
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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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Enlargement of thyroid gland
Why does thyroid gland enlarge both in hypothyroidism and hyperthyroidism?
Hypothyroid goitre is due to lack of iodine in diet and hyperthyroid goitre (Exopthalmic goitre, Grave's disease) is due to ...
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Are there neuron mediated reactions faster than reflexes?
I'm interested in how fast the human body can respond to a stimulus. I know the fastest reflex, the blink reflex, operates around 100ms from stimulus to reaction. I also know that the blink reflex ...
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Is breathing a reflex action or is it an intrinsic process?
The process of breathing is controlled by respiratory centers in the brain stem. Do these centers have an innate activity, i.e., just send out signals to breathing muscles intrinsically, and have the ...