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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Do women REALLY get more cortisol than men, when they see domestic clutter?
I'm reading a book "The Organized Mind: Thinking Straight in the Age of Information Overload" by Daniel Levitin.
At the beginning of chapter "Organizing our homes" he says that ...
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If a bowhead whale can break through thick ice, why can't a sperm whale (able to sink ships without significant harm) able to do the same thing?
A sperm whale is unable to ram through thick ice unlike bowhead whales. But it can ram ships and sink them without harm. There are no instances of a bowhead ramming a ship and sinking it, but there a ...
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Are Reproductive Hormones produced in both males and females identical or are they slightly chemically distinct?
Are Oestrogen, Testosterone, Luteinizing Hormone, and Follicle Stimulating Hormone exactly identical in both males and females?
For example, I know both males and females produce Follicle Stimulating ...
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Why both with the hypothalamus in the thyroid-hormone secretion pathway?
The release of thyroid hormones into the blood is controlled by the hypothalamic-pituitary-thyroid (HPT) axis. Briefly:
Cell bodies in the paraventricular nucleus of the hypothalamus detect low ...
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Why do damaged joints or ligaments experience inflammation? Why do physiotherapists try to stop inflammation as part of the healing process?
I have had the repeated experience of going to physiotherapists with injuries to ligaments or joints and they all expressly aim to reduce inflammation.
I don’t understand this. Our mammalian (and ...
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What happens to the gamma motor neuron during too much contraction of a muscle?
Suppose a muscle is contracting too much, so we need a reflex to stop it from contracting too much.
Contraction of a muscle causes the muscle spindle to go slack, hence the Ia axons and II-axons do ...
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What elements are affected when dehydrated?
I know that the blood vessels constrict and there is a decrease in water in the blood. Are there any other elements that increase or decrease when the human body is dehydrated?
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Does this explanation hold good even in case of Mitotracker red?
When the fluorescence intensity is higher when the depolarization is high?
The more damage to the mitochondria, the more mitochondrial dysfunction and therefore more fluorescence intensity. So, in ...
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How are on and off bipolar cells of the retina arranged?
In the retina, there are both on and off bipolar cells. But how are they spread out in the retina? Are they so, that there is one of each after one another? Or are there areas where there are clusters ...
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Will a 5nm diameter uncharged object make it through the renal glomerular filtration apparatus in humans?
Will a 5nm diameter uncharged object make it through the glomerular filtration apparatus in humans? I think that it should as I have read that the smallest fenestrations are about 10-15nm in size and ...
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Tardigrade scaling and survival
Tardigrades have attracted the attention of researchers with their amazing endurance. They withstand enormous temperatures, high doses of ionizing radiation, resistant to harsh atmospheric factors and ...
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What is total body water and why is it inversely proportional to fat content of body?
In my textbook "Physiology" by 'Linda S. Costanzo' its written that total body water is the amount of fluid present in the body. So my question is that is it just the water content it means ...
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Why does hyperventilation make you feel like you need to breathe more?
Calm Clinic claims:
"The problem is that hyperventilation makes your body feel like you're not getting enough oxygen. Essentially, it makes you feel like you need to take deeper breaths and take ...
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Why is iron transported across membranes in the ferrous form?
Iron in the diet of animals is predominantly in the ferric form, but it must be reduced to the ferric form by a specific ferrireductase before it can be transported across the cell membrane into the ...
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Why do animals excrete excess nitrogen instead of recycling it?
I am aware of the different ways animals excrete excess nitrogen (mainly ammonium, urea, uric acid). My question is: why do we excrete excess nitrogen instead of recycling it? How can we explain that ...
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Why does hypercalcemia cause muscle weakness, yet hyperkalemia causes muscle excitation?
The reasoning I've been given is that high extracellular $[K^+]$ increases the $E_v$ of potassium; therefore, membrane potential increases and the threshold for action potentials is more easily ...
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Do whales really sleep "head down"?
Currently there is a broadcast in German TV (see https://en.wikipedia.org/wiki/The_Swarm_(TV_series)) where there was a scene of multiple whales sleeping in suspended state, vertically heads down.
The ...
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If the Z-line is pulled from both sides , how does it move to shorten the sarcomere?
When I was considering muscle contraction as a whole, this issue came to mind.
Which side should the Z-line of myofibrils shift to when it is being pulled by actin filaments on both sides to which it ...
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Confusion regarding the role of the capacitor in the electrical equivalent of a membrane
I am having trouble understanding the electrical equivalent of a cell mebrane as it is shown in this picture taken from Kandel:
What I cannot understand is the capacitor in the specific image. Why is ...
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Why does the Left Ventricle transmural pressure contribute to afterload?
I've always understood how and why the aortic pressure contributes to afterload on the left ventricle (LV) as follows: a higher aortic pressure means a greater pressure that the LV must overcome to ...
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Does all CO2 from the blood leave the body through the respiratory system?
I know that the primary way that CO2 leaves a healthy human’s body from the blood is by diffusing into the lungs during gas exchange and then being exhaled. Is there any other way in which CO2 from ...
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What happens if we lose voluntary control of our breathing?
Breathing can be controlled voluntarily, even though it is automatic. What happens if a person loses voluntary control of their breathing? How much would it effect day-to-day life? What are its ...
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NMDA receptor depolarization
I learnt that two factors for NMDA receptor channels opening are:
1)Binding of glutamate
2)Depolarization of postsynaptic cell (to remove the Mg+2 block)
Given that depolarization starts in axon ...
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Through what mechanism does ingesting Saturated Fat (but not Mono unsaturated Fat/PUFA) increase Serum Cholesterol.?
I know that the saturated fats you ingest is broken down in the intestines by the bile acids from liver and then re synthesized as triglycerides after crossing the enterocytes. Then these ...
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Can color-blind people see the effect of combining red, green, and blue light beams?
When combined, red, green, and blue light beams result in white light. This effect is observed by most of us, but can color-blind people also see this effect?
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What is the actual molecular mechanism for muscle relaxation?
A number of my students asked what happens to the sliding filaments when muscles relax. For example, in an individual sarcomere, do all myosin heads release all at once or one/few at a time?
More ...
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Electronic properties of neurons [closed]
This is about the electronic properties of neurons.
When a signal is sent from 1 part of the brain due to a stimulus,are neurons considered voltage or current sources?
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Why does a non-functional retinoblastoma protein cause tumours in the cells of the retina specifically?
I know that the name of the protein itself is the retinoblastoma protein - but that's only because the result of a pathogenic variant is retinoblastoma. I'm trying to kind of reverse engineer the name ...
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Why does there have to be two muscles to control the size of the pupil?
In dim light, the circular muscles relax and radial muscles contract to allow more light to enter the eye, and vice versa in bright light.
Why is there the need to have two muscles when probably the ...
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Simultaneous activation of myosin kinase (MLCK) and myosin phosphatase (MLCP)
Reading about smooth muscle cells, I stumbled upon this sentence in Guyton & Hall, Textbook of Medical Physiology (14th ed):
When the myosin kinase and myosin phosphatase enzymes are both ...
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Pulse pressure, vascular physiology
I always though compliance of a vessel is a thing that prevents systolic pressure to goes up a lot and also prevents the diastolic pressure to goes down a lot, and that works because in ...
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Solar Celiac Plexus location in body
Where is the Solar (Celiac) Plexus located in relation to the ribcage? I am reading this on the internet, and trying to learn more.
"The solar plexus — also called the celiac plexus — is a ...
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How is the Staverman's reflection coefficient in the Stirling equation determined?
The Stirling equation is expressed as follows
$J = Kf ([Pc-Pi] - σ [πc - πi])$
Here, capillary hydrostatic pressure (Pc) and Bowman's space oncotic pressure (πi) favor filtration into the tubule, and ...
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Ischemia-induced deploarization in excitable cells
I have read in many sources that ischemia-induced depolarization is due to the opening of ATP-sensitive potassium channels and inactivation of Na/K exchangers [1,2]. However, K-atp channels are inward-...
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How does a stimulus causes a voltage change in nerve cell?
I know about the opening of voltage gated sodium channels and then how the membrane becomes depolarized when the rise of potential greater than threshold occurs.
But what happens initially after the ...
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What are the implications for a small bird flying at high altitudes?
Are the aerodynamics of a bird flying at high altitude significantly different than a bird flying at low altitude? I would imagine a bird adapted for low, short flights (such as between bushes and ...
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Why does the Corpus Luteum produce more Progesterone than Estrogen?
In the human ovarian cycle, follicular cells produce only Estrogen in high concentrations (to my knowledge). Yet after ovulation and formation of CL, which should be the remnant follicular cell mass, ...
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Why does the sympathetic nervous system constrict in heart failure?
As I learn about heart failure in medical school, we are consistently taught that one of the compensatory responses to heart failure (and the accompanying reduction in cardiac output) is for the ...
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How could microplastics accumulate in the bodies of marine mammals?
I have read several literature reviews and studies on the effects of microplastic particles on fish and invertebrates (one example includes the review by Franzellitti et al. (2019)) and there are ...
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Entry of particulate pollutants into the nasal cavity
NCERT Chemistry of Grade XII (India) writes
Particulate pollutants bigger than 5 microns are likely to lodge into the nasal passage, whereas particles about 10 microns enter the lungs easily.
I'm ...
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Which animal has the smallest percentage of their body mass made up of water?
It's a "well known" and interesting "fact" that the human body is made up of "mostly water". With percentages from 65% to 90% often being repeated as if they were exact ...
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Does the kidney regulate sodium balance or total body sodium
Imagine the following situation. You have a person who initially eats 10 mEq/day of salt. He then, at t=0 begins to eat 150 mEq/day of Na, and will continue to do so, because you're forcing them to, ...
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What benefit do cardiomyocytes accrue by requiring calcium induced calcium release (relative to skeletal myocytes)?
According to 2 sources I've read, in contrast to skeletal myocytes, cardiac myocytes need calcium to diffuse in to result in contraction. One source says that they need large amounts of calcium to ...
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What are the possible causes of Lactase persistence?
Lactase enzyme which is responsible for the digestion lactose (a disaccharide milk sugar) normally its production decreases when a young mammal is weaned but mostly Humens continue to produce this ...
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Why does damage to myelin sheath in multiple sclerosis lead to a decrease in information reaching the brain from sensory receptors?
In multiple sclerosis(MS), myelin sheath is attacked and damaged. When this happens, there is a decrease in the amount of information reaching the brain from sensory receptors. How and why does a ...
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Can mosquitoes be attracted by our voice?
In the dark, mosquitoes use CO2 to find blood host like us. However, 1) they are known to have excellent auditory organs (ref1, ref2) and 2) sound can be heard from any directions, contrary to odors ...
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Where does nitrogen go or come from as its partial pressure in different parts of the lungs decreases or increases?
Here's a table from Guyton and Hall Textbook of Medical Physiology showing the partial pressures of gases in different types of air:
We can see that as the partial pressures of some gases decrease or ...
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Does an "empty stomach" have acid in it?
I know that the pH of the acid in an empty stomach is higher than a stomach with food.
I was trying to understand how water passes through stomach to intestines with the absence of food.
But this ...
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Why do blobfish become bloated when they are brought to the surface?
There are several things that can happen to deep sea creatures that are brought up to the surface, but none of them explain why the blobfish becomes deformed. Blobfish don't have swim bladders, so ...
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Effects of high extracellular fluid calcium ion concentration - what's the reason behind it?
The Guyton and Hall Textbook of Medical Physiology, p. 76, says:
For example, a high extracellular fluid calcium ion concentration decreases membrane permeability to sodium ions and simultaneously ...
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