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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What inhibits linkage between actin and myosin filaments

What is the mechanism behind the inhibition for cross-bridge linkage between actin and myosin filaments in the binding-tilting cycle? There are 2 possible ways that are in my mind: a. Tn-I (tropnin-I)...
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What is the difference between muscle contracture and muscle rigor

My text says muscle contracture is a state of sustained muscle contraction due to depletion of energy. And muscle rigor is the stiffening of muscles when they're depleted of energy. So, what exactly ...
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Question on myosin power stroke

I am wondering what really powers the myosin head to undergo the power stroke to push the actin filaments towards the M-line. I have 2 thoughts: when ATP in the myosin head gets hydrolyzed, the ...
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Does electrotonic spread/conduction occur in saltatory conduction?

Even as textbooks, and almost all web pages I've seen so far, explain electrotonic spread/conduction as the passive current flow along an axon, they do so with continuous conduction only. Apart from ...
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Do birds have pharynx like mammals?

I saw this in Wikipedia: Birds do have a larynx, but unlike in mammals, it does not vocalize. And this pdf in Google. It claims that birds do have a pharnyx. Do birds have a structure called pharnyx?...
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Why does increasing concentration of extracellular sodium have no effect on electrical gradient of potassium? [duplicate]

I learnt that the permeability of an ion across the membrane contributes to the membrane potential as much as(or even more than) its concentration and electrical gradients. And so far I've made peace ...
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Will renal blood flow decrease in response to dehydration?

If dehydrated, does the correction of ECF osmolarity happen slowly enough for ECF (and therefore plasma) volume to be temporarily depleted and therefore reduce renal blood flow? If dehydration is ...
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Why does increasing the space constant increase conduction velocity in myelinated neurons if nodes of Ranvier are constantly spaced?

If depolarisation at one node of Ranvier triggers, by passive conduction, an action potential at the next node of Ranvier, why does increasing the space constant increase conduction velocity? Surely ...
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Over-consumption of water in a short period of time

With too much water consumption at once, the blood will become much more hypotonic. Therefore, a larger amount of water will remain in the blood as the kidneys cannot ultrafiltrate all water out from ...
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Why does glomerular filtration result in a filtrate with the same osmolality as plasma?

Unlike the plasma, the ultrafiltrate has no proteins which are prevented from filtering out. Shouldn't the loss of these proteins result in a loss of oncotic pressure and thus a different overall ...
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Can severe vasoconstriction increase systolic blood pressure?

I know that, vasoconstriction results in increased total peripheral resistance which is responsible for the rise in diastolic blood pressure. Also, cardiac output is responsible for the systolic blood ...
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How does noradrenaline result in rise of systolic blood pressure even when the cardiac output is decreasing?

Systolic blood pressure[SBP] depends on the cardiac output. When Nor adrenaline is given there is vasoconstriction due to alpha-1 action on blood vessel, vasoconstriction results in increased total ...
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is ventricular depolarisation same as depolarisation during nerve impulse conduction? [closed]

Does the change in membrane charge accumulation occur in a similar way in heart and nerves cells?
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Na+ / K+ ATPase: How does it restore resting membrane potential? [duplicate]

Could not find any sources talking about this (in a clear manner). If the Na+ / K+ ATPase pumps 3 Na+ out for every 2 K+ it pumps in, thus making the cell more negative, why is the Na+ / K+ ATPase ...
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At small axon diameters (<1 µm), why does myelination not increase neuronal conduction velocity?

As per the diagram below (and other graphs available online), why do unmyelinated fibres have a higher conduction velocity than myelinated fibres when the axon diameter is less than around 1 µm?
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Asexual Reproduction Of sponges through endogenous or exogenous budding?

I was studying asexual reproduction in sponges and came across two website Wikipedia of Gemmule and there is a line.... Only Endogenous Types of Buds develop into New Sponges. Then as I was reading ...
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Taking cold shower / drinking cold water after / during training

(I am a new-comer in biology SE so sorry if violated any rules) Effect of cold showers after intense training I have read the answer to this question, but it seems there are discussions on the ...
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Why largest cats so much larger than canids?

It is striking to me that there is no dog-like creature larger than a wolf while there are at least two species, tigers and lions, many (at least twice and probably 3 or 4) times the size of the ...
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Is faster breathing during exercise linearly more efficient?

Evolution's an amazing thing. It has this incredible ability to optimize variables, and often these optima can then be learned by people to gain insight into various biological phenomena. In exercise, ...
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What is the pH of cytosol? And plastids?

My teacher ask this question, and I answered 7 to 7.4, but she said it's wrong. I read a lot and found the same answer (wikipedia) I'm here asking for confirmation of this and the pH inside & ...
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Does hypokalemia increase sodium concentration in cells?

In hypokalemia, when intracellular potassium is low, does intracellular sodium increase?
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Humans best at long distance running: purely physiological or is it a function also of ability to pace?

I have read that although certainly other land animals are much faster over short distances, a human can run down any other animal over time, so that if a human is hunting like a gazelle, etc. ...
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What happens to intrinsic factor exactly at the terminal ileum, where B12 is absorbed?

IF is very important for IF-dependent B12 absorption in the terminal ileum, the mechanism by which most of dietary B12 is absorbed. The B12-IF complex bind to IF receptors on enterocytes, but does the ...
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What causes paresthesia from compression?

Compression of a nerve causes loss of afferent and efferent information in it. What is the physiological basis of this?
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Why don't our tongue receptors for salt and sugar adapt to them, like the ones for pepper do?

Many (most?) physiological receptors adapt to the substance they bind to, leading to higher dosages required to elicit the same response. In pharmacology, it’s called “drug tolerance”. In physiology, ...
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Why does arterial chemoreceptor reflex “override” cardiac vagal C-fibre reflex?

During haemorrhage, why does activation of the arterial chemoreceptor reflex, and the resultant tachypnoea, "mask" the bradycardia induced by the cardiac vagal C-fibre reflex? Struggling to ...
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What are some good books on oncology?

I'm looking for some book suggestions on oncology, preferably I want them to be fairly recent. I am not worried if they are fairly technical, as long as they have good accurate content and layout.
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How can Saccharomyces cerevisiae live in a dried state for long periods of time?

I want to know how can the Saccharomyces can live for so long in dried form. I am talking about the dried yeast used in baking .
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What is blood pH for different animals?

So we all know that humans average blood pH is 7.4. But is it the same for the animals? I need examples of animals with the same blood pH as humans and the ones with different blood pH. I guess dogs ...
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Kidney: Is added resistance on proximal tubules a function of the narrowness of the descending limb?

The efferent arteriole has a smaller diameter than the afferent arteriole. This forces the part of the blood that is able to leave the blood vessels of the glomeruli (excludes large bodies like blood ...
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Water used in excretion in ureotelism vs ammonotelism

Ureotelism is an adaptation to conserve water, less water is needed to excrete nitrogen compared to in ammonotelism. Is the water usage more or less exactly proportional to the number of nitrogen ...
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If heparin is an anticoagulant, how is its effect nullified upon exposure to air?

First of all, does heparin always remain in circulation? Or is it specifically released by the mast cells and basophils upon activation? Adding to that, if it always stays in circulation, why is its ...
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How we regard bone a connective tissue

Connective tissue is a tissue which connects one tissue to other eg tendon which connect bone to muscle or blood which carry chemicals from one tissue to other where needed. Then how we regard bone a ...
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Is breathing a reflex action or is it an intrinsic process?

The process of breathing is controlled by respiratory centers in the brain stem. Do these centers have an innate activity, i.e., just send out signals to breathing muscles intrinsically, and have the ...
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Does a tubular sodium reabsorption cause a stimulation of β2-adrenergic receptors?

I read the study "The Role of Aldosterone in Obesity-Related Hypertension" and there is one thing I didn't understand. They write: "According to norepinephrine-induced tubular sodium reabsorption, ...
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Electrical transmission vs Chemical transmission

"The advantage of electrical transmission, apart from speed, is it can favour synchrony in firing. For example, in the brain stem a nucleus called the inferior olive can generate oscillations due to ...
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Which results in greater energy expenditure: consecutive actions, or non-consecutive actions?

Is there a difference in energy expenditure when performing the same set of movements consecutively vs non-consecutively? Example: You jump in-place 1 time, stand motionless for 1 minute, and then ...
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What does sympathetic and parasympathetic 'tone' mean?

My professor's lecture notes say that " The basal rate of firing is called “sympathetic tone” and 'parasympathetic tone" , but a table I found on the internet says that the parasympthetic system has ...
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Is there any case in which excitability increases with lowering the RMP?

My professor says , at a more negative RMP, less sodium ion channels are inactivated, so if you take 2 of the exact same neuron with the same threshold potentials, and try to excite them starting from ...
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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 ...
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Why is the ratio between action potential and threshold value called the 'safety factor'?

"All­or­Nothing Principle. Once an action potential has been elicited at any point on the membrane of a normal fiber, the depolarization process travels over the entire membrane if conditions are ...
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Help me understand Voltage Patch Clamping please?

Before I type my question it is important to know that I already tried looking this up on my own and could not find an answer because the answers are all in complicated physics terms and this topic is ...
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What was the evolutionary benefit of enclosing hemoglobin in cells?

The ancestral solution to oxygen transport is with hemoglobin (or, similar proteins) dissolved in blood (or, "hemolymph", but, basically, dissolved in water. ) What was the advantage of enclosing the ...
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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 ...
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Are ligand gated channels saturable?

A major difference between simple diffusion and facilitated diffusion is that facilitated diffusion has a maximum transport and velocity; the rate of diffusion is limited, whereas in simple diffusion, ...
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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, ...
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What affects the excitable cell membrane threshold?

What are the factors that affect a cell's membrane threshold? What I think is that it's the nature of voltage-gated sodium channels. But it's said that the density of these channels and the diameter ...
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Do endocrine cells always lie adjacent to capillaries?

The circulatory system transports plasma contents to the body via the interstitial circulatory system, reabsorbed with the lymphatic system. Cell metabolism "waste products" are transported into the ...
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Are there any animals that are unable to hear the human voice?

Humans and animals have different hearing ranges. The frequency range of a human, for example, is stated with 20 Hz to 20 kHz, whereas the fundamental voice frequency is stated with 125 Hz for men, ...
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Why do patients with type 2 diabetes not show the body wasting seen in type 1 diabetics?

Type 1 diabetes results from the destruction of the cells in the pancreas that produce insulin, while type 2 diabetes is characterized by so-called "insulin resistance", presumably a reduced ...

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