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

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Voltage-gated Potassium channels in the action potential of cardiomyocyte?

There is one type of potassium voltage-gated channels open in Phase 1 too. Some call them early repolarization channels. I am not convinced that the channels are different in different phases: 0, 2, ...
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45 views

Why is the resting membrane potential of cardiomyocyte more stable than that of Pacemaker in Phase 4?

There must be some channels that keeps this very stable. It seems to be that the resting membrane potential of pacemaker cells is steadily increasing until the threshold voltage. I think the same must ...
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14 views

Why is Aorta sometimes called Compression chamber?

I find this statement that Aorta is called Compression Chamber in my study materials. Aorta can it keeps blood flowing it can accumulate potential energy for bumping and compression However, why ...
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1answer
50 views

Regional circulation and Cardiac output? [closed]

I am reading my study materials and think what is the systemic POV here Regional circulation Blood flow within the tissue/organs based on the functional demands of the tissue. E.g. The ...
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14 views

Characteristics of radius of blood vessel

Which properties do determine the radius of blood vessel? I have these thoughts distension, elasticity, contractility and cross-sectional area of the walls. Is there any other properties?
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12 views

To understand synthesis of e-NOS and n-NOS with respect to Ca and calmodulin

I found this sentence in my notes interesting E-NOS and n-NOS are Ca, calmoduline dependant ferments. They are synthesized from in small conc as response to physiological signals which ...
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24 views

To understand Nitric oxide, iNOS and Tumour cells

I have this figure about nitric oxide and tumor which is for schematic for me to understand it The figure should probably say that tumour cell is induced by NO or alone to go apoptosis and it ...
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2answers
23 views

To understand Second messenger signalling in I/c and E/c

I found this picture in my study materials. I think it is too schematic and ignores the big pictures. I think the thing connected to the hormone is receptor. The second messanger is then connected ...
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2answers
107 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 ...
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1answer
35 views

Can you approximate Cardiac Output by Ohm's law?

I found this sentence from my notes which I cannot understand PR < CO, CO $\uparrow$, PR > CO $\downarrow$ where ...
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1answer
61 views

Is end-systolic volume (ESV) the same as residual volume?

I am reading this site and my study materials. The end-systolic volume (ESV), 50-60 ml, is the volume of blood found in ventricles after systole and contraction of ventricles. I think ESV is the same ...
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121 views

What type of force holds my body rigid & doesn't make it collapse?

My query is that as atoms & its molecules have inter & intra molecular forces,like that only what type of force keeps the cells bonded to each other & prevent it from collapsing ever ...
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16 views

What are the main parameters for systemic circulation?

I have in my notes that main parameters for systemic circulation are ejected blood per minute central venous pressure (in the right atrium) work done by the heart something else What can this ...
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35 views

Normal position of Electrical axis only in the III lead?

I found this sentence in my notes which is not exact enough: Electrical axes Excitatory processes have definite direction and magnitude and could therefore be represented as vectors. At ...
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33 views

ADH Synthesis in Supraoptic and Paraventricular Nuclei of the Hypothalamus

I have this sentence in my notes: Neurons paraventricularis and supraorbitus check the situation and secrete ADH in the nuclei, which by axonal transport → neurohypophysis, where storage take ...
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1answer
37 views

Physiology of skin and leather: why do salt borders occur?

I discussed a leather store about the white border aka salt border on leather shoes. They said that it is due to inner features of leather and you could try to add some fat/cream to push it back ...
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1answer
53 views

Can pheromones in perfume be formulated to cause agitation? [closed]

I generally don't care for female perfume. I have very sensitive olfactory receptors and in general, I just find perfume overwhelming. A couple weeks ago, my wife of almost 14 years and I were ...
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1answer
71 views

Enlargement of thyroid gland

Why does thyroid gland enlarge both in hypothyroidism and hyperthyroidism? Hypothyroid goitre is due to lack of iodine in diet and hyperthyroid goitre (Exopthalmic goitre, Grave's disease) is due to ...
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42 views

Calcium levels and nerve hyperexcitation

Why does lower blood calcium levels (or lower calcium levels in ECF) cause nervous hyperexcitaton? Why does it cause over stimulation of nerves and muscles and spasmic contractions of muscles? This is ...
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232 views

How long can a bee surive in a jar?

So, some people and I encountered an adventure game where you have a bee in a jar and need to move it from place to place before it suffocates, and someone tried to find out how long a bee would ...
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59 views

Counterintuitive action of Vitamin D?

Vitamin D acts in a way which to me is counterintuitive. It functionally supplemets Parathormone. It in the intestinal tract steps up calcium absorption by altering nuclear gene expression and also ...
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1answer
88 views

Disproportion in cranial nerve innervation?

The cranial nerve innervation is highly disproportionate, as far as humans are concerned. I am not sure of the advantage of being innervated by cranial nerve versus being innervated by a normal ...
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1answer
49 views

The arrangement of retinal cells?

The section of retina shows a layered arrangement of the various retinal cells. Starting from the inside (where the light strikes first) is the nerve fibre layer, ganglionic layer, amacrine cell ...
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2answers
56 views

Is the empty GI tract a hollow tube with air inside, or is it generally collapsed until food is eaten?

I have heard that "air in the GI tract" results in flatulence and burping etc, however I initially assumed that the "empty" GI tract was a hollow tube filled with air anyway. So on an empty stomach ...
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152 views

Can humans transdermally absorb minerals from ocean water, and if so how much?

According to several studies quoted here, chemicals can be absorbed by the skin transdermally, at least under certain conditions. When it comes to elements in seawater like sodium, magnesium, ...
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1answer
68 views

The mechanism of mechanoreception?

I am interested in knowing the molecular mechanism behind mechanoreception/mechanotransduction (i.e. mechanism behind receptor potential generation on mechanical stimulation). I know that most ...
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1answer
67 views

Death because of no radio waves

I read somewhere that a man dies if he is isolated from natural electromagnetic fields and waves. (I imply fields of radio frequencies and below.) Is it true?
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105 views

How is membrane capacitance related to the increased speed of saltatory conduction?

Here is the original question which inspired my question below. As explained by the answers there, the reason saltatory conduction in myelinated neurons is faster than non-myelinated conduction is ...
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43 views

How well do we notice asynchronicity?

I'm stopped at a stoplight and, with nothing to do, my thoughts wander to the timed don't-walk sign that governs any pedestrians who might wish to cross the street I'm driving along. I can see two ...
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1answer
168 views

Excretion of various wastes and water requirement

A common fact is that Ammonia, Urea and Uric acid are the most common excreted metabolites and their removal needs varying amount of water, highest for ammonia (hence suited only for aquatic animals) ...
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65 views

Sodium levels and blood pressure

Why does low $\ce{Na+}$ levels cause hypotension (low blood pressure). Alternatively, why does excessive intake of $\ce{Na+}$ cause hypertension or high blood pressure? From what I ...
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2answers
369 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?
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1answer
85 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 ...
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1answer
137 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 ...
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1answer
71 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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19 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. ...
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1answer
62 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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20 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 ...
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1answer
108 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.
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1answer
144 views

Why does caffeine consumption cause one to urinate more?

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

Why does hypertension occur in obstructive sleep apnea?

What is the physiological mechanism behind systemic hypertension resulting from obstructive sleep apnea?
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1answer
53 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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1answer
213 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 ...
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1answer
64 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 ...
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54 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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1answer
2k 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 ...
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1answer
84 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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51 views

Why delayed Power nap might degrade our night sleep?

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. ...
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1answer
54 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 ...
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2answers
241 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 ...