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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1 answer
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Why are plants classified in living things? [closed]

@Volunteers Beware that I am none of the biological magnates. Nor a philosopher. This is just a sign of curiosity. And, I want only an intuition that enables me to see the difference. As far as I ...
1 vote
0 answers
654 views

Osmosis and hydrostatic pressure

I'm confused about the role of hydrostatic pressure compared to osmotic pressure. Q1:If I have a U-tube with a membrane permeable only to water molecules and equal volumes of water on either side ...
29 votes
3 answers
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Does animal blood, esp. human, really have similar salinity as ocean water, and does that prove anything about evolution?

It is an often-repeated claim that human, and in fact all animal blood is salty because we evolved from aquatic organisms, and that blood has a similar concentration of salts as ocean water, or at ...
0 votes
0 answers
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Why does the LV transmural pressure contribute to afterload?

I've always understood how and why the aortic pressure contributes to afterload on the LV (higher aortic pressure means a greater pressure that the LV must overcome to eject blood; makes sense) ...
1 vote
0 answers
30 views

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 ...
1 vote
0 answers
122 views

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 ...
4 votes
1 answer
79 views

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 ...
78 votes
2 answers
6k views

Do animals exhibit handedness (paw-ness?) preference?

I have been observing my cat and found that when confronted with an unknown item, she will always use her front left paw to touch it. This has me wondering if animals exhibit handedness like humans ...
4 votes
1 answer
634 views

Does food continue to stay sequential once it is inside my body?

I may be very off on many scientific details here, but I'm always all ears. As far as I understand, any food that is eaten goes to the stomach, gets broken down even further into smaller food ...
0 votes
0 answers
24 views

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 ...
1 vote
1 answer
370 views

What triggers the release of gonadotrophin-releasing hormone with the onset of puberty?

I am interested to know the process of development of puberty. During puberty, when boys/girls reache 12-14 (puberty) years of their age, their hypothalamus releases gonadotropin releasing hormone (...
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20 views

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 ...
0 votes
0 answers
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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?
0 votes
1 answer
71 views

How do I classify cytotoxicity values, whether a sample is mildly, moderately, or highly cytotoxic?

I used LDH assay for cytotoxicity testing. I have a plant extract which I tested against HepG2 cancer cells. I did three trials, my results were 2%, 6%, and 8% cytotoxicity, respectively. How do I ...
4 votes
2 answers
965 views

What is the effect of persistent hypothermia on cardiac performance?

I define persistent hypothermia in this thread about the mechanisms of persistent hypothermia. The Graph of Katzung et al. in Pharmacology about Heart Failure: I am thinking which parts here are ...
1 vote
0 answers
22 views

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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0 answers
15 views

What negative effects does heat therapy have on a recently strained muscle?

I've read on the Internet that it is a bad idea to apply heat to a recently strained muscle, and I'd like to understand why -- more precisely, I'd like to understand how the application of heat ...
0 votes
2 answers
52 views

Im struggling to see how these are presynaptic terminals/knobs and not post synaptic

How are these presynaptic terminals ? The action potential is generated at the axon hillock and moves down the axon (in this case to the right) , then at the end of the axon should be axon terminals ...
4 votes
1 answer
572 views

What is the mechanism behind ventilatory acclimatization?

In my respiratory physiology lectures, my professor explained that hypoxia-induced hyperventilation occurs in 2 stages when people try to acclimate at high altitudes. My question is about the long-...
3 votes
1 answer
323 views

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 ...
3 votes
1 answer
69 views

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 ...
15 votes
1 answer
3k views

Do sharks fart?

My son is 5 and I'm encouraging him to be curious and ask questions of the world around him. He asked if sharks fart and how does it smell? He feels that it would smell of fish and be disgusting. He ...
0 votes
3 answers
258 views

How does 2,3 biphosphoglycerate works to release oxygen bound to the hemoglobin?

I read on Wikipedia that 2,3 BPG binds with the deoxygenated state of hemoglobin and helps in stabilizing it. It was also written that it helps release remaining oxygen from the hemoglobin. How? ...
3 votes
1 answer
48 views

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 ...
8 votes
2 answers
39k views

Why can I raise my left eyebrow independently from the other but not the right?

I've seen the same question on other forums, but have not come across any definitive explanation. The non-cited answers seem to fit into three categories: It is due to greater muscle dexterity on ...
0 votes
1 answer
232 views

Does estrogen increase muscular growth in females?

Regarding humans it is said that most psychological effects caused in men by testosterone are caused in women by estrogens. There are many studies on that, particularly regarding temporary shifts of ...
0 votes
0 answers
52 views

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 ...
5 votes
2 answers
3k views

Why does sympathetic activity constrict pulmonary vessels?

I don't know understand why sympathetic stimulation constricts pulmonary vessels? I thought that the sympathetic nervous system activated the body for physical activity. Physical activity would need ...
4 votes
2 answers
2k views

Correlation between muscle size and absolute strength

Is there a linear connection between muscle size and the power it can produce? If not, why? And what is the true correlation if any, can it be described with an appropriate function? What other ...
0 votes
0 answers
18 views

Why do rock monitors have such large snouts?

I'm looking into the anatomy of different types of African monitors. I came across the rock monitor, one of the largest lizards in Africa. One of the defining characteristics of this species is it's ...
0 votes
1 answer
380 views

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 ...
12 votes
2 answers
2k views

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 ...
5 votes
0 answers
120 views

How is atrophied muscle different than normal muscle in a chemical or biological way?

I am a writer with a question for a story I'm working on. In it, the character suffers from muscle atrophy due to spinal damage. So that I can portray this accurately, what would cause this type of ...
2 votes
0 answers
48 views

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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Glomerular capillary blood pressure is not very location dependent, why?

Question about kidneys. Let Pc; glomerular capillary hydrostatic pressure Pbc; Bowman's sac hydrostatic pressure πc; glomerular capillary colloid osmotic pressure πbc; Bowman's sac colloid osmotic ...
4 votes
1 answer
68 views

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-...
1 vote
4 answers
2k views

Resilience to the neurotoxins of Indian King Cobra

I read on Wikipedia about this: King Cobra - Wikipedia In Thailand, a concoction of alcohol and the ground root of turmeric is ingested, which has been clinically shown to create a strong ...
9 votes
3 answers
2k views

What triggers meiosis in gonadal cells?

What specific biochemical processes are involved in inducing meiosis rather than mitosis? Why are gonadal cells the only cells in the human body which do undergo meiosis?
0 votes
1 answer
31 views

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 ...
8 votes
1 answer
63k views

Why are (some) cats attracted by bleach?

(Sorry if this question is only partly biological) I have noticed that several cats (including the one that keeps sleeping in my house), are fond of the odor of bleach (eau de Javel) and chlorine. ...
6 votes
2 answers
16k views

Does NADH inhibit gluconeogenesis?

I was told in a physiology lecture that alcohol inhibits gluconeogenesis because 'NADH produced from ethanol catabolism leads to product inhibition'. But is NADH not a reactant coenzyme of ...
1 vote
0 answers
24 views

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 ...
0 votes
1 answer
478 views

Nernst equation and equilibrium potential

Solutions A and B are separated by a membrane that is permeable to Ca2+ and impermeable to Cl−. Solution A contains 10 mM CaCl2 , and solution B contains 1 mM CaCl2. Assuming that 2.3 RT/F = 60 mV, ...
2 votes
0 answers
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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, ...
0 votes
0 answers
42 views

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 ...
2 votes
1 answer
544 views

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 ...
7 votes
2 answers
2k views

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....
4 votes
1 answer
493 views

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 ...
1 vote
1 answer
71 views

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 ...
5 votes
1 answer
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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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