Questions tagged [human-physiology]
For questions on the biochemical, physical, and mechanical functioning of humans in good health including their organs and cells.
388
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Fasting gastric pH versus normal gastric pH
I want to know if someone is fasting (no food or drink for a whole day) will they have a higher or lower pH than a person who is eating regularly? If so what is an estimate of both of those pH's in ...
3
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1
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Renorenal Reflex
According to this:
The kidney contains afferent sensory nerve fibers that are located primarily in the renal pelvic wall where they sense stretch.
I think the stretch is due to urine. If I am ...
3
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1
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What are some characteristics of venules and arterioles?
I know that the vascular system of the human body is organized in the
two, "ever branching", structures of the veins and the arteries. These two
structures stem from their connections to the heart and ...
3
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1
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Why do we make T4 if we only use T3?
So, recently, I learnt that T4 and T3 are both released into circulation but only T3 is the active form. Why then, do we make T4 in the first place? I read that T4 has a higher half-life, which might ...
3
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1
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Hypothalamus and posterior pituitary gland in ADH production
Concerning the role of hypothalamus and the posterior pituitary gland in osmoregulation and especially when water potential of the blood is low,
When the osmoreceptors in the hypothalamus detect the ...
3
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2
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Reaction of the body to heat
In massage school we are being taught hydrotherapy -- applying cold and heat to specific areas.
It says that when applying cold, first the body goes through vasoconstriction, and then later ...
3
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1
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Are there official criteria for an experiment to be considered statistically robust for publication in a decent scientific journal?
For a high school project, I investigated the effect of breathing meditation on teenagers. 15 students were asked to follow specific directions and meditate for 10 minutes a day for 8 weeks. Each week,...
3
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1
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How do sarcomeres coordinate contraction?
As can be seen from the figure
if myosins from both sides apply equal force then how does muscle contract? And also how do actins resist tearing?
Is there any kind of coordination between different ...
3
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1
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Do pet animals and humans perceive good and bad smells differently
As the title says, just wondering if there is a difference in what animals like dogs and cats perceive as good smell vis a vis humans. Example : Smell of some flowers - great . Fart smells - bad.
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How is circadian rhythm of gastric acid secretion regulated?
Gastric acid secretion shows a circadian rhythm where acid production in the morning is minimal and it reaches a maximum towards the evening.
How is this process regulated?
3
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1
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Are the intestinal microbiota substantially different within a diverticulum of the colon?
From the Wikipedia page for the vermiform appendix:
This proposal is based on a new understanding of how the immune system supports the growth of beneficial intestinal bacteria, in combination with ...
3
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0
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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 ...
3
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What is the average volume of the human Psychic tear? ("emotional tear")
My goal is to find out the volume of the average human "emotional tear" (Psychic tear - sadness, happiness), specifically when crying. I found a lot of information about Basal tears (constant ...
3
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0
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What's the ratio of saturated to unsaturated fatty acids in human cell membrane?
It's well established that the fluidity of a cell is largely dependent upon the ratio of saturated to unsaturated fatty acids that exist within the membrane, but, what exactly are the values for this ...
3
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Plant vs animal protein digestibility?
The protein scoring methodologies ( https://en.wikipedia.org/wiki/Protein_Digestibility_Corrected_Amino_Acid_Score) rate plant proteins of a lower quality than animal proteins. Now I can understand ...
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What are the most efficient heat exchange sites on the human body?
Where on the body would be the best place to achieve the greatest cooling effect with a "cooling undergarment"? Concentrated over the kidneys, groin, inside the wrists, back of the neck?
3
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Empty room, Room full with stuffs & Auditory adaptation to reflection of sounds
Background
When a room is full with stuffs like furniture, electronic utilities, books etc. it's hard to hear reflections of sounds made by us (talking, playing an instrument, sound from falling ...
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Pee Shiver: Any reliable research about this phenomenon?
I came across 2 webpages about the science of pee shiver.
Link 1
Link 2
I wonder if there any reliable scientific research about this phenomenon. The 2 webpages I have hyperlinked attribute this to ...
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Physiological effects of electrical shocks on human body depending on the energy
When discussing safety of electricity, one usually considers a constant DC or AC current with constant amplitude over a longer time. It is easy to find tables in books or in the web which lists ...
3
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0
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Changes in spongy urethra during tumescence
How does the columnar cells of spongy urethra expand during tumescence(erection of penis)?
If we assume that the urethra has the length, long enough to sustain tumescence without expansion of cells, ...
3
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0
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Why are adults so suceptible to dizziness?
I have a child and she, like pretty much all the others it seems, loves spinny rides in the park. Adults often can't stand them.
In fact, I recall going from loving to hating dizziness over the space ...
3
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0
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Coagulation of blood in small intestine due to trypsin
Trypsin is secreted in the small intestine to convert proteins into dipeptides i.e. to carry out digestion of proteins. However, it is also a coagulating agent which coagulates blood by hydrolysing ...
3
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Why is there a structural difference between the bicuspid and tricuspid valve?
There are three cusps in the tricuspid valve and only two in the bicuspid valve? Why is there such a structural difference? Does it have anything to do with that there is oxygenated blood on the left ...
3
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0
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How do we sneeze?
When a stimulus triggers the sneezing pathway, known as the trigenimal nerve network, how do the droplets from a sneeze get created within the nose? What affects the size of these droplets?
3
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When a muscle contracts, but not all the muscle fibers are activated, what happens to the remaining muscle fibers?
I understand how motor neurons work, but I would like clarification on what exactly is going on when a muscle contracts. For the sake of simplicity, let's just use the bicep as an example. If I do a ...
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Why does an increased heart rate mean increased blood pressure?
Say a person starts exercising. If their cardiac volume remains the same but their heart rate increases so that the overall result is an increase in cardiac output, will their blood pressure increase ...
2
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1
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Does LSD "stay" in your fat storage and then "returns" back?
This rumor was told me by a very anti-drug person. A stance I agree with only lightly.
The rumor was that when you take LSD, it stores itself in your fat storage, and then returns back in 3-6 months, ...
2
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1
answer
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Why does exhaled air still contain oxygen?
If the partial pressure of oxygen in the atmosphere is 159 mmHg and that inside human alveoli is 104 mmHg, and if these values are fixed or don't change very much, then why does exhaled air have ...
2
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1
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Will a 0.2g/mL sugar concentration cause vomiting in humans? [closed]
This infographic claims that the sugar content in a can of Coca Cola would cause vomiting if not for the phosphoric acid.
In The First 10 minutes: 10 teaspoons of sugar hit your system. (...
2
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2
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Do afterload and stroke volume form part of a negative feedback loop in blood pressure regulation?
Blood pressure is the product of cardiac output and total peripheral resistance:
$\text{BP} = \text{CO} \times \text{TPR}$
Since cardiac output is the product of heart rate and stroke volume, we have:
...
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1
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What is meant with “the chest wall and lungs are coupled together”?
Since the lung and chest are elastic, we can represent them with springs. Under normal conditions, they are coupled together: the “lung” springs are stretched and the “chest” springs are compressed. ...
2
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Could humans breathe if the average methane content of the atmosphere increased to 1%?
Below is a table of atmospheric composition. Could humans breathe if the average methane content of the atmosphere increased to 1%?
Table 7a-1: Current Average composition of the atmosphere up to ...
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Can you build muscles from watching point of view videos of people weightlifting?
According to this, "new research has found that viewing other people exercise actually increases your heart rate and other physiological measures, just as if you were working out yourself".
This got ...
2
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2
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How is CO2 and O2 separated in our body during gas exchange?
https://www.msdmanuals.com/home/lung-and-airway-disorders/biology-of-the-lungs-and-airways/exchanging-oxygen-and-carbon-dioxide
The image in the above link shows that CO2 and O2 both pass through the ...
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2
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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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Medical term for "holding urine for a long time"
Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity?
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Anti malarial drugs and g6pd deficiency
Why does antimalarial drugs causes hemolysis in g6pd deficiency patients?
I know that g6pd protects the cell from oxidative stress by maintaining glutathione in reduced state but how does the ...
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2
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Does every nerve ending send information to the brain separately?
Does every nerve ending send information to the brain separately? Is there a nerve path (I don't know their scientific name) from every nerve ending to the brain; or are they sent to brain from the ...
2
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1
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Nernst Equation and Membrane Potential
I am a bit confused on how to use the Nernst equation to determine polarization.
I saw in the textbook that if potassium channels were open in a neuron cell, there will be a net diffusion of $\ce{K+}$ ...
2
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1
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Is Pars intermedia functional in humans?
My textbook says, "Pars intermedia secretes only one hormone called melanocyte stimulating hormone (MSH)."
My teacher says that in humans MSH is secreted by the anterior lobe because the ...
2
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1
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RE: Fasting gastric pH vs Normal gastric pH
If fasting gastric pH values are more acidic then why is it recommended to eat no more than three hours before bed time to prevent reflux. It seems at some point during sleep the stomach would become ...
2
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1
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896
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Causes of Back Dimples
What are the causes of the dimples commonly found above the buttocks? They seem to be in line with the sacroiliac joints. Do the joints have anything to do with them?
2
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what is the difference between pituitary dwarfism and thyroid dwarfism? [closed]
My book (Comprehensive Biology class XI, by J P Sharma ) mentions of two kinds of dwarfism- "Pituitary Dwarfism" and "Thyroid Dwarfism" but does not provide any details about the matter. so please ...
2
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Are receptors integral membrane proteins or peripheral membrane proteins?
Integral membranes proteins serve as transporters. Peripheral proteins serve as cell adhesion molecules, antigens and enzymes. So what about receptors? Which proteins carry out the duty of receptors?
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Chloride Clamp and Nernst potential
The Nernst potential for chloride is -70 mV. The neuronal Resting Membrane Potential (RMP) is -70 mV. Under this condition, if the chloride channels are open (as it happens in Inhibitory Post Synaptic ...
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Why is the resting membrane potential of excitable tissue not affected by the extracellular sodium concentration?
I know that the resting membrane potential for excitable tissue (eg, nerve) is primarily determined by the electronegative difference between the inside and the outside of the membrane for potassium ...
2
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Can some colours be processed faster/more accurately than others?
Is the human visual / motor system able to track, and move in response to, objects of certain colours more quickly and reliably than for others? By more reliably, I mean with greater accuracy in ...
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Ejaculation without orgasm: is this possible to do it at will without external stimulation?
I know that ejaculation without orgasm is possible for human males with external stimulations, e.g. prostate massage.
My question is, can a human male perform full ejaculation without reaching orgasm ...
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How does motor nerve innervation determine type of muscle fibre?
Muscle fibres are of two types - type I and type II. They differ from each other in various properties. Even the underlying biochemical processes are different to suit their function (slow vs fast)
...
2
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How fast is the patellar reflex?
I have found a lot of content on the patellar reflex, but I cannot find any studies on how fast the reflex is, from onset of stimulus to innervation of muscles. Does anyone know of either a study or ...