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

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103 views

Missing 4 $\ce{H_2O}$ (per glucose) in Cellular Respiration… Where can they be?

I having trouble understanding the equation of the cellular respiration. The thing that bothers me is the number of $\ce{H_2O}$ molecules. Generally, cellular respiration is written thus : $\ce{C_6H_{...
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0answers
6 views

How does having an empty stomach affect absorption of compounds?

From personal experience, compounds such as nicotine, caffeine and alchohol appear to absorb much quicker into the blood on an 'empty' stomach', or after extended periods of fasting. If this is the ...
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1answer
37 views

Why does dehydration lead to low blood pressure

I understand that the two leading causes of death from dehydration is imbalance in electrolytes and loss of blood pressure. I'm trying to understand what role water is playing in these cases and how ...
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1answer
43 views

Enzyme Inhibition in relation to Aspirin

I've been trying to learn a bit more about pharmacology, so bear with my ignorance. In short, I see that aspirin (in part) works by inhibiting cycloxygenase isoenzymes and that this inhibiting is ...
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0answers
22 views

Does too much salt in wound cause problems? [closed]

OK, everyone has the experience of eating too much salt and getting a slight headache. But assuming somebody's injured and his wound (you can assume however large you want the wound to be) is soaked ...
6
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1answer
55 views

Why don't bacterial cell walls prevent bursting when attacked by the complement?

The complement system creates pores in cell membrane which leads to influx of lots of water thereby causing lysis of bacterial cell. But what I fail to understand is that if bacteria have cell walls ...
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1answer
680 views

Why don't rats have a gallbladder, unlike other rodents?

It has long been known that rats do not have a gallbladder, though other species including humans, monkeys, cows, reptiles, dogs and mice, all have a gallbladder. In this paper from almost 100 years ...
20
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1answer
285 views

What's the mechanism for being mentally tired?

I notice that after long tests, or long periods of critical thinking, my body and mind feel noticeably tired. Why does this happen? Are the neurons in my head not firing as quickly, or is there just a ...
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0answers
43 views

Why is the protein ubiquitin so ubiquitous?

Ubiquitin is a protein tag that is attached to proteins in order to mark them for destruction/proteolysis by the cell. This system is sometimes used for clearing out harmful viral proteins that infect ...
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0answers
9 views

How does the Jendrassik's manoeuvre reinforce reflexes? [migrated]

According to Wikipedia, The Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of fingers into a hook-like form and interlocks those sets of ...
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0answers
27 views

Are there available fluids that can be used in place of blood to facilitate oxygen and carbon dioxide exchange during major surgery/trauma?

Are there any available fluid alternatives that can be used instead of blood replacement that adequately exchange oxygen and carbon dioxide?
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0answers
6 views

Ciliary muscle and accommodation

Can anyone explain how contraction of the ciliary muscles causes relaxation of the zonules? Please explain it anatomically i.e. the attachments of ciliary muscles and its relation with the ...
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0answers
9 views

How long can/will an infant hold his/her breath as part of the dive reflex?

Various other questions on the site have talked about the Diving Reflex, which is also known as the Mammalian Diving Reflex. This reflex is observed in mammals of various species, but also in human ...
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1answer
14 views

Accommodation mechanism. [closed]

Can anyone explain how contraction of the ciliary muscles causes relaxation of the zonules? Please explain it anatomically i.e. the attachments of ciliary muscles and its relation with the ...
4
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0answers
23 views

Reason for variation in the site of onset of edema

What is the reason for the observed clinical difference in the earliest site of onset of edema in cases of different etiologies? For example, in Congestive Heart Failure, it appears initially as ...
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0answers
31 views

What is the circulation that allows for nutrient absorption and excrete of metabolic wastes in humans? [closed]

Pulmonary veins carry oxygenated blood from lungs to heart, while pulmonary arteries carry deoxygenated/CO2 rich blood from heart to lungs. On the other hand, systemic arteries carry oxygen-rich blood ...
4
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1answer
141 views

What causes inhalation during breathing?

I have read here that the two major inhalation muscles are the (1) diaphragm and the (2) external intercostals. Additionally, inhalation can also be caused by (1) expansion of the abdominal cavity, ...
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2answers
195 views

Is Sinus node conduction necessary for heart beating?

Assume a patient with previous cardial infaction which SA node not possible to activate action potential anymore. However, SA trying to beat unsuccessfully repeatedly waisting energy. Therefore, I ...
5
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1answer
179 views

How is adrenaline (also known as “epinephrine”) a ligand?

I keep reading that adrenaline is a ligand, however, from what I understand a ligand is a molecule or ion which donates a pair of electrons to a central transition metal ion in a complex. If this is ...
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2answers
61 views

Do pharmacodynamics and pharmacokinetics of the drug in animals are the same as in human?

I'm trying to understand the purpose of different clinical trial phases, and the following question comes into my mind : Do pharmacodynamics and pharmacokinetics of the drug in animals are the ...
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0answers
6 views

Which of the following is an accumulation and release centre of neurohormones?

The options are : a)posterior pituitary b)hypothalamus According to me, it should be 'posterior pituitary' because though neurohormones are produced in hypothalamus but they are temporarily stored in ...
2
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1answer
663 views

Antihistamine's effect on insulin secretion and tiredness?

Antihistamines are known to cause tiredness. The essential hormones of the body are insulin (glucose), parathyroid hormone (calcium) and aldosterone (Na-K ATPase, sodium). I am thinking how this ...
0
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1answer
43 views

Amino Acid requirement + intake in relation to diet + meat type [closed]

I was arguing with a friend: I said: The Yulin festivals cannot be condemned by western culture, as we also kill animals in equally cruel ways. She said: It isn't just that the killing is cruel, ...
22
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1answer
3k views

Why do mints make your mouth feel cold?

Why do mints make your mouth feel cold? And specifically, why does your mouth feel so cold if you eat a few mints and then drink a glass of cold water afterwards?
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4answers
14k views

Why do men have a higher hematocrit (red blood cell count) than women?

The hematocrit, also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women. so,...
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0answers
64 views

Why do horses recycle their endometrial lining while humans don't?

How does not recycling the endometrial lining of the uterus benefit humans (and other organisms that menstruate), while recycling it is beneficial to horses (and other organisms that undergo estrus ...
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3answers
108 views

What is the actual storage form of energy in muscles? ATP or Glycogen?

I was asked this question in my latest exam. I think the answer is Glycogen because ATP doesn't store energy for a long time so it isn't the ACTUAL storage of energy. Some classmates argue that in ...
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0answers
10 views

Has research indicated how much koinophillia preferences are learned vs insinctual

I'm curious about rather the definition of 'normal', as it affects koinophillia & mate choice, is something instinctual or learned. To clarify I'm not asking if koinophillia itself is ...
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0answers
42 views

When you have your gallbladder removed, how does it affect bile flow into your small intestine?

Cholecystectomy, or surgical removal of the gallbladder, is an extremely common operation around the world. The gallbladder is typically viewed as a storage organ for bile produced by the liver, but ...
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0answers
33 views

Would a transparent iris serve its purpose?

The function of the iris is to regulate the aperture of the pupil. How does the iris obstruct light? Is it due to the pigment present in it? Or is it just due to the sheer presence of it? I am doing ...
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0answers
8 views

will 2,4 Dichlorophenoxy acetic acid be effective as an herbicide against banana and papaya

Since 2,4 D is effective against broad leaved weeds/plants, will it be effective in case of banana and papaya?
2
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1answer
28 views

If targeting a certain daily water intake, do you have to compensate for beverages that promote diuresis?

Please forgive my ignorance on the topic and I hope this is a "on topic" question here. It was a toss up between this SE and Physical Fitness SE but I want a more scientific answer. I came at a ...
2
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0answers
17 views

What is the evidence that mammals are unable to process excess sodium chloride?

I grew up hearing the mantra excess salt causes heart disease I had a vague understanding that it caused deposits in the body or something. Now that I give it more thought - I come up with three ...
1
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1answer
32 views

Resting stage of primary oocytes

In my biology textbook, I read that the primary oocyte gets arrested in the early stages of meiosis in prophase I (diplotene stage). I wanted to know why this is so. I searched google, and this ...
2
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3answers
7k views

What organs are absolutely needed by the human body?

The title is my question: what organs are absolutely needed (fatal if injured/removed) by the human body and perhaps animals in general? I'm not asking which organs are mechanically replaceable, but ...
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0answers
26 views

How do organoarsenics improve digestion efficiency in poultry?

It struck me as very surprising that these organoarsenic compound with structure looking not very compatible with living system is widely used as food additive to increase weight gain and improve food ...
17
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1answer
647 views

How fast can a human run?

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly ...
4
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1answer
85 views

What causes anorexia nervorsa?

I've heard of anorexia nervosa being a severe loss of appetite. I'm wondering what causes such disease in humans?
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2answers
59 views

How does the muscle return to its resting state after muscle contraction?

I know that when ADP binds to the myosin head, it moves along and as it does so, it releases the ADP. The ATP attaches to the myosin head and releases the myosin head from the actin filament. Then the ...
3
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1answer
45 views

How does an octopus eye react in free fall?

according to Wikipedia: Attached to the brain are two special organs, called statocysts, that allow the octopus to sense the orientation of its body relative to horizontal. An autonomic response ...
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1answer
51 views

Evolution & Celluar Chemistry [closed]

I'm new to this site but had a question on evolution, apologies if some of these questions seem basic but they are from a book i am reading challenging the role of chance in evolution. Taking the ...
4
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1answer
129 views

What is the impact of stress on the human body?

Can stress trigger any changes in the human body? I'd like to know more about things less commonly known than, for example: sweating and tiredness. What are the long term risks of chronic stress? Do ...
7
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1answer
107 views

Blood clumping in mosquitos

Will a mosquito die due to blood clumping if it sucks blood from two persons having different blood group? What will happen in its gut? Is there any mechanism to avoid clumping ? Or mosquitos know ...
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0answers
31 views

Why do the vines change their spinning direction?

Look at the vines holding onto the lattice. The "vine springs" change their spinning direction in the middle. Why? And how do they achieve this? (By the way, what's the name for this plant? Is is ...
7
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1answer
9k views

How much gas is exchanged in one human breath?

When we breathe, our lungs absorb a portion of the oxygen in the air, and replace it with some amount of carbon dioxide and water vapor. Typically, how much $O_2$ (in grams, milliliters, or moles for ...
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5answers
19k views

What is the cause of muscle cramps?

According to wikipedia, muscle cramps are caused by myosin fibers not being able to break free from the actin filaments during contraction, resulting in a prolonged contraction. Obviously a lack of ...
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0answers
53 views

Why do some men have patchy beards?

Why do some men have patchy beards? Or more specifically, why would some hair follicles lack sufficient 5-alpha reductase while others nearby don't when their genetic code is identical and they are ...
2
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1answer
258 views

Where does female ejaculate actually originate from?

It's common knowledge that it's released via the urethra, but where does it originate? If it doesn't come from a part of the clitoris, then why is the clitoral glans called the clitoral glans? How ...
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1answer
1k views

How are arms different than legs?

Ok, this is a bit of a tangent question, but it came up yesterday and I didn't know the answer: How are arms and legs defined physiologically? For example, we say humans have two arms and two legs, ...
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1answer
41 views

A state model of sodium channels

I am studying by myself Human Physiology. I have encountered the following question: In the following given model of sodium channel with 3 states open closed blocked (which I assume means inactivated)...