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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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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Why do I feel funny in my tummy when riding a virtual roller coaster?
I've ridden a virtual roller coaster on an Oculus Rift. I felt tension as I went up to the top, but more interestingly I actually felt my stomach drop when I went down the steep drop on the other side....
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Which mammal produces the most milk?
I'm searching for the mammal species that can produce the most milk during lactation. I Googled it, but it says dairy cattle which biologically speaking is not right answer, because a baby whale can ...
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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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How are arms different from legs?
How are arms and legs defined physiologically? For example, we say humans have two arms and two legs, while cats have four legs, and some monkeys (appear) to have four arms (although I guess they ...
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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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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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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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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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Why do some mammals not have testes in a scrotum?
Coming from an evolutionary approach, Is the only purpose of a scrotum to regulate the temperature of the testes?
Knowing all mammals are warm blooded, shouldn't all mammals have testes in a scrotum?...
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How does UV light damage the DNA when the chromosomes are deep inside the cell?
When UV light falls on the skin it has to go through the cell membrane and the nuclear membrane to reach the chromosomes. So it looks like that the DNA is protected but it probably isn't. Won't ...
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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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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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Why nerve fibre is infatiguable?( is my conjecture correct?)
According to this:
A nerve fibre cannot be fatigued, even if it is stimulated for a long time. This property of infatiguability is due to absolute refractory period.
How is refractory period ...
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Why does K+ going out of the cell cause hyperpolarization?
I'm really confused by how the terms Hyperpolarization and Depolarization are used in Cell biology and hope somebody can enlighten me hopefully.
Here's what they mean for me so far:
Depolarization ...
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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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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 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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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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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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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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Do insomniacs yawn?
According to wikipedia, the jury is still out on the function a yawn serves. The article referenced above however writes to say
Yawning most often occurs in adults immediately before and after ...
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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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Why does distention of the veins not decrease their resistance in the first case but decrease it in the second?
Here are two quotes from Guyton and Hall Textbook of Medical Physiology, Chapter 20 (emphasis mine):
Why is venous resistance so important in determining the resistance to venous return? The answer ...
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Why does vasodilation increase blood flow in the capillaries, but decrease it in the chest during inspiration?
From Guyton and Hall Textbook of Medical Physiology:
Every time a person inspires, the pressure in the thoracic cavity becomes more negative than usual, causing the blood vessels in the chest to ...
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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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Which processes are during the latent period of ventricular contraction?
The latent period is the time between the start of depolarisation and the start of contraction.
I know that the contraction of ventricles starts after sufficient influx of Ca2+ and threshold ...
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Why is Heart Rate Recovery after exercise reasonably well described by a mono-exponential decay?
I have been measuring my heart rate recovery after exercise and I see that it can be fit reasonably well using a single exponential:
$HeartRate(t) = HR_{max} \times e^{-t/\tau} + HR_{resting}$
This ...
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After digesting food, where does the energy go before being stored by the body?
I'm trying to piece together a simplified model on how the energy flows in the human body.
From what I understand:
We store enough ATP for around 2 seconds of maximum exertion
We store enough ...
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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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How does Humira work when injected into patients with rheumatoid arthritis?
OK, I have rheumatoid arthritis and I've been injecting Humira 2 times a month for the last 8 months.
As far as I know rheumatoid arthritis is simply an immune system disorder which makes the immune ...
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How much percentage of substance does liver take in one pass?
The portal vein system is to feed the absorbed nutrition and toxin (defined as "substance" here) to liver first for it to take them up as fast as possible, before they reach other organs ...
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Medical Physiology
I've come across the topic of the influence of inhaled ammonia (caustic ammonia) on breathing rate and some cardiovascular changes. All of this stuff is thought to be mediated through the fifth ...
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Wheatgrass in thalassaemia
In local newspapers there was a not so recent story about wheatgrass juice being "curative" in thalassaemia. Although I do not take the article at face value, it would be enlightening to know if there ...
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Why do people make "aaagh" noises when they make an effort (e.g. trying to hit a ball hard)?
I'm referring to, for instance, grunting in tennis. It refers to how many tennis players make loud "aaagh" noises when hitting a ball. In daily life, people often also do this when trying to ...
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Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)
Reading this question, Why are there no wheeled animals?, I wondered why no organisms seem to make use of the tensile and other strengths of metal, as we do in metal tools and constructions. I am ...
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Why does the time to reach equilibrium across a membrane decrease with concentration?
We're learning about flux and Fick's law and there's one point I'm having trouble understanding. Assuming we have a higher concentration of a species on one side of a membrane, I understand that ...
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Is Haemoglobin a positively charged Sol?
My book NCERT(Class 12, Surface chemistry) claims that hemoglobin is a positively charged sol
The cytosolic pH in human cells is around 7.4, but fluctuates as the cell is replicating
according to ...
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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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Why does (insulin induced) hypoglycemia stimulate ADH secretion?
Intuitively, I understand that ADH (Anti Diuretic Hormone) is responsible for maintaining osmolarity, and increased serum osmolarity is a stimulatory factor for its release-- ADH increases water ...
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What are the roles of ATP and ADP in muscle contraction?
I've always known that the hydrolysis of ATP generates ADP, P, and energy, so I'd assume that if energy is necessary in a given process, ATP hydrolysis should occur (or another exothermic process).
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If blood vessels mostly aren't supplied by parasympathetic nerves, how effects through M3-ACh receptors are mediated?
Blood vessels throughout the body mostly aren't supplied by any parasympathetic fibres. But the effects of ACh through M3-ACh receptors would infact release NO (which acts on VSM and causes ...
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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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Which processes in the human body depend on natural selection among cells?
Are there processes in the human body which occur via natural selection among cells? Could anyone provide examples?
E.g. when tissues are conditioned to be stronger, such as a rock climber's skin ...
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Pathogens vs Microbes and the Immune System
I hope my question isn't too basic or silly. I am currently learning about infectious diseases in Year 11 Biology right now, and I'm stuck at the concept of pathogens and micro-organisms. Whenever I ...
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Is there a function for urea in sweat?
In ureotelic organisms, ammonia is converted to urea for excretion primarily in the liver and, to a lesser extent, in the kidneys. However, sweat also contains trace amounts of urea. Is this small ...
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Is the swimming pool water harmful to frogs who jump in? If so, how?
Here is an odd question:
Frogs have permeable skin. Indeed, via capillary action, frogs absorb water through their skin.
Chlorine is in principle a harmful substance. I am sure what percentage of ...
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How much heat can a human sustain?
For how long can a human sustain a temperature of 180 degrees Fahrenheit (82oC) without damage in a confined place?
For instance, suppose a person is sitting in a steam-filled room, without external ...
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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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