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15

summary: O2 could form a linear complex with the Fe atom, but then it would start to look more like a mineral Fe=O...O bond - a linear bond would be like a transition state to an iron oxide (rust). An Fe-O-O bent bond preserves more of the electronic character of the O2 molecule and promotes strong but reversible binding to Hemoglobin. The oxygen ...


8

Terrestrial crustaceans are land animals that use gills (or gill-like structures) for gas exchange, though these gills must be kept moist for efficient respiration. Specifically, animals like hermit crabs have a branchiostegal lung that looks like gill tissue but is better adapted for absorption of oxygen from air instead of water.


7

To learn obstructive/restrictive lung diseases, I find it easiest to think in extremes at first, with vivid descriptions of why. So in obstructive lung diseases, like COPD/emphysema: Total volume increases because so many of the walls of the alveoli have been destroyed, they are like giant floppy bags instead of nice firm bubbles. There's more empty space,...


7

This reference from CHEST lists 21 clinically measured peak flow rates during various modes of coughing. Of these patients, and for unassisted cough, the highest peak flow is about 4 liters/sec. The human trachea ranges from 13 to 27 mm diameter. The relationship between velocity, $V$ and flow $Q$ is $$ V=\frac{Q}{A}$$ Assume the 4 liters/sec = 4000 cm^3/...


7

Some terrestrial hermit crabs (genus Coenobita) have gills, but these are only partially responsible for their respiration1. These animals carry around water with them in the snail shell they 'wear'. Amphibious land snails in the genus Pomatiopsis have gills2. Finally, a terrestrial amphipod known as a "sand hopper" Talitrus saltator also has gills3. ...


6

There are at least two things to consider. First, ability to limit airflow is a defense mechanism for animal. Imagine getting into area of some sort of toxic evaporation, e.g. CO2 cloud near volcano , then it makes sense to decrease delivery of toxin via lungs to minimum. As I understand, that is what an allergic asthma attack. (Sorry for not providing good ...


6

I like it that nitrogen came to your mind ;) I guess in school they didn't tell you about the nitrogen at all, for the matter of simplification, because it is of no function in the body and the $O_{2}$ and $CO_{2}$ are the important gasses for biological function of breathing. However, all of these small gas molecules are very small and generally the ...


6

Alveolar tree is like a bunch of grapes. If you put a bunch of grapes into a plastic bag and put this bag into another bag, you can imagine how the lungs are covered. Alveoli form the surface of the lungs. There is a membrane called visceral (or pulmonary) pleura that covers the alveoli and this membrane continues into another sheet called parietal (or ...


5

People can drown because of aspired food. If they don't then it can cause diseases, for example pneumonia. In extreme cases a tree can grow in the lungs. There are other aspiration/inhalation related diseases like silicosis or asbestos lung cancer. So it depends on the composition of the object (or liquid or powder) and other factors whether it causes a ...


5

It gets diffused out, like you expected. Grist (2013) writes about this in relation to "the bends," which has already been mentioned by user1136. He writes: Cavitation of blood containing normal oxygen and nitrogen levels by mechanical heart valves after implantation generates bubbles that can be detected in the brain using transcranial Doppler ...


4

nuhcole is mostly correct. Airborne particles first pass through the nasal passageways and/or mouth and throat and many are caught, but those that enter the lungs become trapped in mucus. Your cilia act like a constant escalator, bringing up that mucus from your lungs 24/7. You reflexively swallow it without even realizing it. That is why when you are ...


4

Quick clarification firstly, the main change in thoracic volume that causes inspiration is not as a result of the alveoli expanding - they have no smooth muscle lining therefore are unable to spontaneously contract. They do have some elastic fascia however their expansion is passive. The change is mainly as a result of the diaphragm contracting to become ...


4

Oxygen masks can provide up to near 100% oxygen, whereas the atmosphere contains only ~20%. Typically, oxygen is provided in cases where patients' blood oxygen saturation is low or is likely to be low. Giving a patient supplemental oxygen helps them to achieve oxygen saturation even if their breathing or circulation is impaired, and allows slightly more ...


4

"Reflected" here describes the relationship between the continuous, but differently named parts of the pleura. The parietal pleura lines the chest wall and mediastinum (costal, cervical, mediastinal, and diaphragmatic areas marked in the image below). The visceral pleura covers the surface of the lungs (orange area below). There is a transition point at the ...


3

We don't really know. Several theories have been put forward over the years. Here are a few: contractions to assist exhalation or mucus propulsion promoting lymphatic and venous flow ventilation/perfusion matching stabilizing airways enhancing the effectiveness of cough optimizing anatomic dead space volume None of them have a huge amount of evidence or ...


3

You cannot change the oxygen concentration of inhaled air in the absence of an external source of oxygen. However, you can use your lungs at their maximum capacity doing this: breathe deeply: =increase tidal volume. Your muscles will inflate your lungs as much as they are able to, inflating parts of the lungs that were not fully inflated (atelectases) in ...


3

From your examples only the first is really true. Exercise leads to better physical abilities (within some boundaries). Sunlight on the other hand is always potentially dangerous, depending on the dose. But the damages accumulate over the years which finally lead to the so called senile lentigos (others call them aging spots) occuring in sun exposed skin ...


3

Cough-variant asthma is a common cause for a non-productive dry cough. Asthma is not a single condition involving bronchospasm and with associated wheezing - there is a variant that is primarily or only coughing. There are different inciting factors that bring on symptoms cough-variant asthma. Most commonly they are exercise-induced, cold-induced, ...


3

When we eat the architecture makes sure most if not all the food ends up in our foodpipe rather than our windpipe. This is aided by a structure called the epiglottis. However frequently foods may be inhaled, for example if a drink is sucked through a straw more if it gets into the lungs compared to if we drink it. Occasionally we will inhale a peanut or ...


3

I agree with Jan's answer generally, but thought I'd clarify a few points. What fills the space between the alveoli in the lungs? As Jan says, alveoli are packed together. In most cases, the thing next to any particular alveolus is another alveolus. In this case, the space between them is the alveolar wall, which (generally) consists of a pneumocyte and ...


2

You asked the single most difficult questions ever, so be proud of yourself! I've spent some time in the lab with a post doctorate trying to answer that particular question. It all is based on something called the hygiene hypothesis: the belief that as we are getting cleaner we are seeing less and less bacteria and so our immune system isn't working as it ...


2

20-30 seconds is all it takes to reach the brain, then levels continue to increase with a peak at around 15 minutes and normal levels by about 2 hours (hence the craving). Smoking increases your heart rate directly and also indirectly through reducing the oxygen levels in your blood so your body compensates by increasing heart rate as well as makes each beat ...


2

In a cold climate, do people often blow out the air from their lungs a lot when living in the cold condition to keep their lungs warm? No, and it wouldn't make any sense: breathing more means inhaling more cold air that needs to be warmed up, so the result is a heat loss. The more so, as cold air (< 0°C) has a low water vapor pressure, while the lung ...


2

Long-term exposure to excessive oxygen will lead to damage in pulmonary tissue. This damage resembles the same damage which is seen in patients with Acute Respiratory Distress Syndrome (ARDS). In these patients surfactant specific proteins are damaged by proteolysis. This proteolysis is caused by the neutrophil elastase enzyme, after a massive influx of ...


2

Trying to rephrase the question If I understand the question (and what you missunderstand) correctly, I think one could rephrase the post as When one spends some time under water and come back to the surface, one usually breath out and then breath in. This is surprising to me because I would expect the person to be out of air and therefore wouldn't need to ...


2

COPD is not caused by an infection (which would require a pathogen) but by the inflammation reaction the body triggers because of the tar particles. Thus the statement "mucus accumulated causing infection" does not correctly describe the effect of tar on the lung. Consequently, B and C are incorrect.


2

More basic answer; the asbestos crystals have hooks. So the cilia in the lungs have difficulty moving them out with the other dust. This irritates the tissue causing the effects of the first answer. So it is a matter of time and number of asbestos particles that increases the probability of a cancer. Decades ago , the asbestos miners in Africa typically ...


2

Short answer: Hilum is an area(has only 2 dimensions) where as root is a body( has 3 dimensions). The root of lung is a short broad pedicle connecting the medial surface of the lung with the mediastinum. It consists of structures entering and leaving the lung at hilum. The root of lung is surrounded by a tubular sheath derived from the mediastinal pleura. ...


2

Deep inhalation and deep exhalation are informal terms and cannot be defined by lung volumes, because saying deep by itself does not tell how deep. In the first part of the question deep refers to maximal: Deep inhalation that means inhaling the air with effort as much as possible = maximal inhalation Deep exhalation that means exhaling the air with ...


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