The study of the normal function of living organisms and the means by which it is achieved.

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2answers
774 views

The number of nipples (breasts) a species has?

Only mammals have mammaries and mammary glands. What evolutionary factors determines the number of mammaries (nipples/teats/breasts) a species has? Is it always an even number?
4
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1answer
174 views

Body size, what are the evolutionary trade-offs?

Background Considering just the "Kingdom Animalia" branch of organisms. It is clear that bigger does not necessarily mean better - there is large variation in body size... From the 94 µm long ...
3
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1answer
216 views

Is there a maximum pain threshold?

Is there a maximum threshold of pain a Human can experience, beyond which point there is no noticeable difference? I ask this question in part to better understand the definition of pain and its ...
5
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1answer
92 views

By what mechanism can hypoglycemia induce fainting?

Hypoglycemia (Low blood sugar) is said to be among the potential causes of human-faintings. I was wondering by which mechanism this happens. Google search results are abundant; there are lists of ...
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1answer
20 views

Order of events in hibernation

Arrange this in sequence : i. Heat loss exceeds heat production. ii.As body temperature falls, heat loss decreases. iii.Body temperature equals environmental temperature. ...
1
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1answer
76 views

(Web)app to search metabolic/signalling pathways

I'm looking for an application where you can find pathways by selecting a chemical occurring in it. So, for example, selecting 6-phosphogluconolactone brings up the pentose phosphate pathway or any ...
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1answer
27 views

Amphibian blood circulation

In an amphibian blood entering the right atrium shows higher levels of oxygenation than that in left atrium when : A.It is hyperactivated B.it is hibernating C.it is submerged D.it is in the ...
0
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1answer
166 views

Why can CO₂ be transported dissolved in plasma?

Is it because CO2 is more soluble in water or has it got to do with the alkaline pH of plasma ?I here mean only aqueous CO2 transport from body cells to lungs.
2
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1answer
232 views

Why does caffeine consumption cause one to urinate more?

What is the physiological mechanism behind the diuretic effect of caffeine?
3
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1answer
80 views

Why does hypertension occur in obstructive sleep apnea?

What is the physiological mechanism behind systemic hypertension resulting from obstructive sleep apnea?
2
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1answer
66 views

What happens during a Raynauds episode?

Raynaud's phenomenon can be a serious health issue, as the blood flow to the extremities, mainly the fingers is compromised, causing fingers to blanche, and then turn blue. Severe Raynaud's can cause ...
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vote
1answer
465 views

What is the physiological difference between snorting/swallowing cocaine

I know that mucosa inside the nose absorbs cocaine molecules when snorting cocaine, but what difference is there compared to swallowing? Also more cocaine administration equals more cocaine molecules ...
3
votes
1answer
80 views

Attachment of muscles during molting in insects

Normally, insects' muscles are attached to their exoskeleton but what happens to this attachment when they are moulting? Sorry if this is an extremely silly question but I have wondered about it for ...
5
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1answer
79 views

Competition for mates in sea horses

This source here ...research has shown that it is STILL the males that compete for females. says that male sea horses compete for mates but this source here Females exhibit a ...
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2answers
3k views

How does extracellular potassium ion concentration and calcium ion concentration affect the excitability of a cell?

When extracellular $K^+$ concentration increase by a certain amount, excitability of cells is higher because the resting potential shifts toward a higher equilibrium potential of $K^+$, therefore ...
3
votes
2answers
146 views

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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0answers
67 views

Why delayed Power nap might degrade our night sleep? [closed]

Recently in the research areas we come across the term "Power Nap" which says after a nice lunch it would be nice to get a nap for 20-30 minutes which will make the body relaxed and fresh afterwards. ...
4
votes
1answer
60 views

How much can you learn about species variation from a skeleton?

I just read about the discovery of the 1.8-million-year-old human skull in Georgia, and how it suggests that early humans were all one species instead of distinct ones. Would an archaeologist ...
2
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2answers
288 views

Do brain cells shrink during REM sleep or a lucid dream?

In this BBC news article a study shows that during sleep brain cells shrink to open up the gaps between neurons and allow fluid to wash the brain clean. But do the cells shrink and undergo the whole ...
0
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1answer
110 views

cellular respiration

What are the effects of addition of these chemicals to actively respiring cells ? Which of them would lead to INHIBITION of aerobic respiration ? Would cytochromes be actually taken up by cells ? ...
2
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1answer
55 views

Antibody production in secondary immune response

Can IgG antibodies be produced in the secondary immune response without the help of T cells? Is the affinity of antibody for antigens higher during secondary immune response?
3
votes
1answer
60 views

Alternating Ovulation

I have often heard that right and left ovaries alternate in releasing ovum. Is it always true? What controls this rhythm? Is it simply because the other ovary is unresponsive to LH or FSH? If so, ...
4
votes
1answer
42 views

What are the molecular mechanisms that make the turtle brain more resistant to hypoxia?

I know that turtle brains, particularly those of individual species that hibernate and burrow are particularly resilient to hypoxia and any tissue damage secondary to a hypoxic event. What are the ...
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vote
3answers
1k views

Does Darwin's Theory of Evolution refute Terence McKenna theory “Stoned Ape” theory of human evolution?

I haven't read it but I'm asking for a quick answer. As far as I know, Terence McKenna's theory of evolution in humans main concept is that a hominid has tried in their diet psilocybin mushrooms, and ...
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vote
1answer
120 views

Need of Creatinine Phosphate

In muscle cells most of the ATP's phosphate is with creatinine phosphate. So why is the displacement of the phosphate group done ? Is it because creatinine phosphate would give it's phosphate more ...
3
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1answer
50 views

Effect of arteriole dilation on vein

If an arteriole leading to a capillary bed is dilated will the pressure in the vein coming out from the bed decrease ? Will the velocity of blood in the vein change ?
2
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1answer
380 views

Which is the tissue damaging agent in krokodil (street desomorphine)

I've just read about krokodil and saw some quite hideous pictures about what it does to the human body. I guess just desomorphine alone wouldn't have this effect. Which ingredient(s) causes the ...
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0answers
69 views

Harmful effects of radiation from cell phone towers? [closed]

As per this article - http://www.thehindu.com/news/national/mumbai-citizens-link-cancer-to-cell-phone-towers/article5139166.ece , people living adjacent to cell phone towers claim to have developed ...
3
votes
1answer
65 views

Difference in reptile inner ear and otosclerosis

In reptiles, the sound is conducted from the tympanic membrane to the inner ear by a single bone. In the disease otosclerosis the stapes of humans become fused to the other middle ear bones( or to ...
2
votes
1answer
166 views

What happens in the synapse when cocaine administration occurs in the human brain

As far as i know when you accept cocaine in your blood some cocaine molecules reach some synapses in your brain and fill some Reuptake tunnels preventing the cell to simply "do not know that fired ...
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vote
1answer
72 views

What stops the coagulation process?

Whenever there are minor/major injury to blood vessels, the platelets, fibrin, thrombin, etc. are recruited. They then seal the wound and block bleeding. What tells them that their job is done?
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1answer
57 views

Which fish will have more developed gills?

A fish lives at the depth of 1000-2000m and another at the depth of 200-700m. Which of them would have a more developed gill system ?
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1answer
156 views

Is the resting state of the forearm in the pronated or supinated position?

It seems to me that my forearm is naturally in a more pronated position than the anatomic (supinated) position and that it actually takes work to make it hold the supinated position. Anyone an expert ...
15
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3answers
2k views

Is there any use of CO₂ in human body?

We all know CO₂ as a waste product of metabolism . Does CO₂ have any helpful role , apart from having a role in pH of blood ?
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1answer
536 views

Can food swallowed when a person is upside down reach the stomach?

If a person positions himself upside down and swallows food, will it reach the stomach against gravity? If so how?
0
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1answer
106 views

Why do bats huddle during late fall?

In the late fall, bats hibernate in clusters with many bats pressed together and holding on to one another. Which of the following supposed advantages of huddling behavior is, in reality, not true? ...
3
votes
2answers
2k views

What is the genetic basis of blood type (ABO) system?

What is the genetic basis of the A/B/B+/O/etc. blood type system? Are there definitive loci that correspond to each or can multiple different genotypes produce the same antigen profile? Also, is the ...
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1answer
1k views

Are there more/less favourable phases of menstrual cycle to donate blood?

I was wondering whether it makes a difference when during the menstrual cycle a female is donating blood in terms of: Blood quality (iron or hormones levels) Her health/safety I am aware that ...
8
votes
1answer
93 views

Why pouring salt in the wounds is painful?

Pouring salt in the wounds is so painful. I am sure you all experienced this. whats happend there?
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0answers
1k views

What are potential side effects of myostatin inhibitors?

Myostatin inhibitors, which are being developed to treat muscle wasting diseases like muscular dystrophy, are likely to be abused by athletes. What are the potential long-term side-effects of taking a ...
0
votes
1answer
119 views

All or none phenomenon

Let's say that the threshold potential of a neuron is +40 mV to make a muscle twitch. Now suppose we have two signals of +20 mV. So, this signal will cause the twitch in muscle because it has reached ...
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vote
2answers
175 views

What use a pair of lips?

Pardon my ignorance ... A lip is apparently a very sensitive tactile device - as it at-least serves to warn it's owner they may just be about to consume something that could cause injury. Primates ...
18
votes
3answers
987 views

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 ...
17
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3answers
1k views

Do animals exist with an uneven total number of digits?

I recently finished reading Contact by Carl Sagan. In the book they talk about a pattern in the transcendental number like pi or e, and comment that it is found in base 10 or however many fingers the ...
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2answers
231 views

What gases are needed for humans to breathe?

I will be beginning a science project about sustaining life on space stations. I already know that pure oxygen is harmful for humans but would $O_2$ + $CO_2$ be enough for humans to breathe in or do ...
2
votes
1answer
1k views

fibroblast cells and fibers

I am interested in fibroblast cells in human arteries. Here are the things that I am not clear at the moment and I could not find any answer from the literature: What are the dimensions of these ...
2
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1answer
51 views

Deep diving in mammals

Mammals like seals often dive and can remain under water for more than 70 minutes. How do seals know when is it the time to come up?
7
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1answer
70 views

Excretion of monovalent and divalent ions in sharks

I have heard that sharks excrete $\ce{Na+}$ and $\ce{Cl-}$ by their gill surfaces but divalent ions like magnesium are excreted through feces. What could be the reason behind this?
0
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1answer
53 views

What is a good review article source for Physiology?

I am looking review articles for Physiology. For instance, Physiological explanation of steps of measurement of the metabolism by Douglas-Haldane. There is no section for Physiology or metabolism in ...
5
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1answer
116 views

Would my hands sweat this much if I wasn't wearing gloves?

I've wondered about this for a long time, and hopefully someone here has a reasonable answer. I'm a cell and molecular biologist, and much of my time at the bench is spent wearing (usually nitrile) ...