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Not all microorganisms are pathogens Firstly, not all microorganisms are pathogens - some can be harmless and some can be even essential for the host organism functioning (e.g., many microorganisms that are a part of our microbiote). Many pathogens are not microorganisms Here one have to mention viruses and subviral entities (prions, viroids) which are not ...


7

Short answer About 0.79% of the light gets through on average, but there is variability across wavelengths and individuals. (variability between individuals seems to be correlated with density of macromolecules in the eyelid). Long answer: This is called "eyelid spectral transmittance". Lucky for you, Bierman et al (2011) sought to determine the ...


6

Terminology in biology often gets a little fuzzy around the edges, sometimes as a result of overlapping definitions, or the desire to avoid overlap. For whatever reason, many eukaryotic pathogens are more commonly referred to as parasites. This seems to be more common with (though not exclusive to) multicellular parasites, like tapeworms, possibly leading to ...


5

By convention, positive current is assumed to be the direction of flow of positive charges. The trouble is that in many common situations (like this one), the current is actually carried by electrons which are negatively charged. It can be confusing. Blame it on Benjamin Franklin. The convention for current flow was based on his work, before anyone knew ...


4

The tiredness associated with depression/stress is not due to the 'brain power' increasing but due to a change in what parts of the brain are active and/or disrupted sleep. Anxiety can cause issues to the brain and body over time. Brain power is relatively constant For the average adult in resting state the brain consumes about 20% of the body's energy. It ...


3

Tl;DR: Urea is a metabolic waste excreted from human body. As such it does not have any function in human body. It is a major product in the waste excreted from kidneys although trace amounts can be found in sweat. The concentration of urea increases when kidneys fails to function normally. Hence, they are excreted through sweat glands, observed as "...


3

well gastropod mollusks use Epimorphosis, so it is likely cephalopods use the same mechanisms. Basically all triploblastic organisms use this mechanism so phylogenic bracketing points towards it as well. morphallaxis is generally restricted to very simple organisms. Regeneration of the visual system in gastropods (Mollusca) Oksana Tuchina Victor Benno Meyer‐...


3

A Japanese patent filed by Raymond Jay Bergeron, Jr JP2000514089A notes lysoferrin as the siderophore N1, N4-bis (1-oxo-3-hydroxy-3,4-dicarboxybutyl) diaminobutamate. The US counterpart of this patent, jointly filed as US application No. US08/783,306 and later issued as US 5,739,395 covers rhizoferrin in its embodiments. So it seems that the term lysoferrin ...


3

It comes down to the distinction between velocity and flow rate. While you are right that the water would leave a an increased velocity if you put your thumb over the end of the hose, this is deceptive, because the water is exiting the closed system, so it can go absolutely anywhere. So the fact that the velocity is increased could give one the impression ...


3

Yes, birds do have a pharynx. Birds can breathe through the mouth or the nostrils (nares). Air entering these openings (during inspiration) passes through the pharynx & then into the trachea (or windpipe). {1} The larynx can't produce sound -- it's only there for breathing and eating. Instead, birds' sounds are produced at the bottom of the trachea, ...


2

There is no known mechanism for exchange of $\ce{O2}$ and $\ce{CO2}$ in a one-for-one fashion. Their transport across the alveolar membrane takes place by diffusion alone: both of them attain their equilibria with blood independently. Note that it is not necessary for inhaled and exhaled tidal volumes to be the same. In fact, under physiologic conditions, ...


2

Generally textbooks take the following pedagogical flow in basic neurophysiology: Ions flow, so voltage changes propagate This is the "electrotonic part". The key concept is that if you add some ions or change the voltage of one part of a neuron, adjacent areas will also change in voltage as current flows 'passively'. The further away you go, the ...


2

There are 100+ gas phase compounds that come from humans. Find other information about most of these families of compounds from wiki. Full list of compounds is here Methods and findings are here


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A key component of body odour is the volatile thioalcohol, 3-methyl-3-sulfanylhexan-1-ol (3M3SH). The structure may be visualized as hexan-1-ol "substituted by a methyl group and a thiol group at position 3 " (pubchem) A major contributor to the formation of 3M3SH is the commensal bacterium, Staphylococcus hominis, which produces it as a by-...


2

Relaxation of vertebrate skeletal muscle is thought to occur in the absence of ${Ca}^{2+}$ as a result of tropomyosin physically blocking the binding of myosin to actin. This steric blocking model of muscle relaxation predicts that myosin subfragment 1 (S-1) will not bind to actin under conditions where the acto-S-1 ATPase rate is inhibited.[1] However, in ...


2

As @Roshelle Perera points out, the textbook reason for differential solute and water movement in different parts of the LoH is osmolarity, which is nicely explained in this wikipedia article. Coming to an interesting point, about the movement of water across cell membranes through aquaporins, this is helpful:{1} The discovery of aquaporin membrane water ...


2

Water across cell membranes occurs due to osmosis( which is based on a concentration gradient). so water diffuses through the cell membrane. sometimes water channels called aquaporins can be found. https://www.anaesthesiamcq.com/FluidBook/fl1_2.php https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/aquaporin In the loop ...


2

Cold extremeties are a reaction of endotherms where they reduce warm blood circulation to prevent losing core body temperature, otherwise the cold blood in your hands would lower your central blood pressure from 37'C, which makes the body less efficient and at risk of catching colds. The reaction is called vasoconstriction. quote: Active cutaneous ...


2

Synaptic vesicles are on the order of tens of nanometers (for example Zhang et al give a mean diameter around 40 nm). Gap junctions are much smaller, on the order of 1-2 nm. Maeda et al measure one at 1.4 nm. Peptides the size of oxytocin present in the cytosol could theoretically travel through gap junctions. Vesicle-packaged peptides or molecules of any ...


1

The GHK voltage equation also known as just "Goldman equation" is always valid for determining the voltage at which the net current is zero, given internal/external ion concentrations and their permeabilities. This includes times during the action potential, though the result you get from GHK will be changing faster than the actual membrane ...


1

You can determine the diffusion potential mathematically with the Nernst equation. If it's not in the Nernst equation, it's not necessary. The charge of the ion matters (including valance), the temperature matters. Some universal constants are in the equation but these don't vary. Other factors that potentially matter are found in the other parameters, like ...


1

A good number of vegetables and fruits have >90% water contents; this includes cucumber, watermelon, etc. Even oranges, broccoli etc. have >80%. So it would not be hard to have enough water intake if the veggie/fruit/smoothie diet is not restricted to particular fruits or veggies. Slightly less detailed, but more reliable source agrees:


1

At a constant volumetric flow-rate, the product of velocity and vesicle cross-section area is constant. In a real-life scenario, the volumetric flow-rate decreases when you hold your finger over the opening. So while water exits 'faster', at higher velocity, you would fill less bottles of water per minute.


1

The key is vascular resistance. Pumps like the heart don't move fluid, they exert force ("push") on it, increasing the pressure. The movement happens subsequently because there is somewhere for the fluid to go, so it moves down the pressure gradient from a place of high pressure to a place of lower pressure. If you clamped their outputs (increased ...


1

I think that it is missing some details. Note that the vast majority of urobilinogen (~80%) is actually eliminated via fecal elimination. I would recommend looking at the article on enterohepatic circulation, which provides more context on this issue. Basically, bile salts can be useful (even or especially after metabolism by bacteria), so a fraction is ...


1

Action potentials usually maintain muscle tone in skeletal muscles, but muscle cells are affected by other influences that can affect their contraction and thus the tone of the muscle. Smooth muscle occurs in the walls of hollow organs, most notably the blood vessels and the GI tract, and in a few other places. Contraction of smooth muscle is generally ...


1

I am not sure if you are referring to a mechanochemical cycle of "stepping" of a myosin molecule along an actin filament, or a cycle of contraction and relaxation of a muscle cell as a whole. These take place on completely different timescales and control the binding and unbinding of the two proteins in entirely different ways. In the ...


1

I think the simplest answer to your question is that you're correct in thinking passive flow would be what changes, but the reason behind it is important to understand. I'd recommend looking at UT Health's neuroscience online resource where they break down action potential propagation in an understandable way. The main takeaway is that the space constant is ...


1

Here is how I think of the issue. First, keep in mind over the course of the action potential, ion concentrations on both the outside and inside of the neuron remain relatively unchanged. You can think of the Nernst potential as a charged battery, and they keep their concentrations relatively constant. Currents will flow, and the voltage will change, but ...


1

Although the OP might no longer be active, I'm comming back to this question, because there is a new study on this released in "Soft Matter". With simulations Yang et al., 2021, describe how corners of these almost perfect cubes might be formed. From the abstract: Using histology and tensile testing, we discover that the cross-section of the ...


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