What happens with the nitrogen in blood in membrane oxygenators?

What happens with the nitrogen in blood in membrane oxygenators?

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The air we breathe consists of about 80% nitrogen and 20% oxygen. The oxygen gets diffused into the blood and CO2 out of it, the nitrogen does mostly nothing, as there isn't a partial pressure of nitrogen between the air and your blood.

In membrane oxygenators the blood flows arround small tubes which contain pure oxygen. The oxygen diffuses in your blood en the CO2 diffuses in the tubes, basically doing the same thing lungs does. However, since it's pure oxygen that flows through those tubes, the nitrogen in your blood should get diffused into the tubes.

So is this what happens? Does the nitrogen simply diffuse untill there's nothing left? Isn't that then bad for your body if all the nitrogen is out? Or can't nitrogen pass through the membrane the tubes are made of? Or does it differ wether you use 'true' membrane of microporous membrane?

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 ultrasound (2). These bubbles are mainly nitrogenous. Nitrogen is less soluble in water than oxygen. So during excessive turbulence, temperature changes, or pressure changes, nitrogen is the first gas to come out of the solution. (Ask any knowledgeable diver about the physiology of the bends.) We know these bubbles are mainly nitrogen because when the nitrogen in the patient's blood is off-gassed by breathing 100% oxygen, the cavitated bubbles go away. In one study, the administration of 100% oxygen by facemask reduced the cavitation generation of GME by 98% (3). [Emphasis added]

Can't say it a lot better than that and the rest of the article. When people are breathing de-nitrogenated air, it simply results in nitrogen being diffused out of the blood. So yeah, basically the amount of N2 goes down to 0, at least if they are on it for long enough.

As for it being bad for you, not really, at least not perceptibly: though nitrogen is critical for body function, it's practically useless to the body in the N2 form; it has to be "fixed" to a more reactive form such as ammonia / other nitrogen oxide.


  • Grist G. 2013. Oxygen or Nitrogen: Which Is the Lesser of Two Evils? J Extra Corpor Technol 45(1): 61-63.

  • Sprent JI, Sprent P. 1990. Nitrogen fixing organisms: Pure and applied aspects.

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A: The process of reduction of molecular nitrogen into ammonia is called nitrogen fixation. It can occu.

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Essay question. aqa biology. how many marks

The importance of nitrogen-containing substances in biological systems.

Dna replicates by semi-conservative replication. DNA helicase breaks the hydrogen bonds between base pairs. This allows the dna molecule to unwinds. Free nucleotides are activated. DNA polymerase joins the adjacent nucleotides together and forms the sugar phosphate backbone. Replicated DNA uses the strands as templates. Nucleotides contain bases which contain nitrogen. Bases are very important in DNA replication because without bases, DNA will not be able to divide. This means processes like mitosis will not occur which means we will be able to repair tissues and cells.
Proteins contain nitrogen in the NH2 group. Proteins are very important in biological systems especially enzymes. enzymes act as biological catalysts which speeds ups the rate of the rate of ther reaction. This is done when substrates bind to the active site. The induced fit model states that that the enzyme is not fully complementary to the substrate . when the substrate binds to the activate, it stresses the bonds on the enzyme. This causes an enzyme-substrate complex to be formed which lowers the activation energy. When the activation energy is lowered, this means that less energy is needed to start the reaction. This means that there will be more reactions occurring frequently because of the lower activation energy. Enzymes are therefore important because without enzymes, reactions would have a higher activation energy and would proceed more slowly. Certain examples of reactions which use enzymes is the hydrolysis of atp. Atp to adp and pi. This reaction is catalysed by ATP synthase. This reactions forms ADP quickly and can be used in processes like muscle contration and active transport
Haemoglobin is an important quaternary protein that has 4 binding sites for oxygen. When the first oxygen molecule binds. This slightly changes the quaternaty structure of haemoglibin and uncovers a new binding site. This allows the second oxygen molecule to bind. Oxyhaemoglobin disscoaites to oxgen and haemoglobin at low partial pressure for example in the muscle. The oxygen is used in respiration(oxidative phosphyrlation) which requires oxygen as a final terminal electron acceptor. If this process do not occur, oxygen cannot act as the terminal electron acceptor. This reduces the concentration gradient of protons. This means that less ATP is made. ATP is needed for muscle contraction. Without ATP, there will be no musce contration which means that the animal won&rsquot be able to move. So they won&rsquot be able to hunt for food since this requires muscle contration. There haemoglobin is an important quanternary protein which contains nitrogen because it provides the animal with oxygen which is used in respiration.
mRNA contains adenine,uracil,guanine,cytosine. mRNA is used in translation to produce a polypeptide. Mrna attaches to the ribosome and moves to the start codon. Complementary anticodon on trna binds to codon on mrna. different amino are binded to trna by atp. Amino acids from trna bind to each by peptide bonds. This process keeps repating until ribomose reaches stop codon. Polypeptide then floats away in the cytoplasm. As repeated, the bases of mRNA contain nitrogen. Due to their shape of the bases, they can bind to different bases with a complementary shape. This is important because it allows the condons to bind to the anticonds which leads to amino acids binding together by peptide bonds.
Nitrogen cycle shows how nitrogen is recycled through the food chain. Ammonia is nitrified to nitrite and then nitrified to nitrate. Decomposers break down the nitrogen compounds in dead animals by saprobioitic nutriotion into ammonia. This is then convented into nitrate by nitrifying bacteria. Nitrate also turns into nitrogen gas by denitrification. This happens in water logged soil in anaerobic conditions. Root modules in leguminous plants can convert nitrogen gas into ammonia. The nitrogen cycle shows the transferof nitrogen through the food web. This is important because it shows us that nitrogen is needed in ecosystems.

Water, Carbon and Nitrogen Circulating Throughout Nature

The main biogeochemical cycles studied in ecology are the water cycle, the carbon cycle and the nitrogen cycle.

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2. What is the importance of water, carbon and nitrogen for living organisms?

Water is the main solvent for living organisms and it is necessary for almost all biochemical reactions, including as reagent of photosynthesis. Many properties of water are very important for life.

Carbon is the main chemical element of organic molecules carbon dioxide is also reagent of photosynthesis and a product of the energy metabolism of living organisms.

Nitrogen is a fundamental chemical element of amino acids, the building blocks of proteins that are in turn the main functional molecules of living organisms nitrogen is also part of nucleic acid molecules, which are the basis for reproduction, heredity and protein synthesis.

The Water Cycle

3. What is the water cycle?

The water cycle represents the circulation and recycling of water in nature.

Liquid water on the planet's surface is heated by the sun and turns into water vapor, which enters the atmosphere. In the atmosphere, large volumes of water vapor form clouds that, when cooled, precipitate liquid water as rain. Therefore, water comes back to the planet surface and the cycle is complete. During possible steps of the cycle, water may still be stored in subterranean reserves or in the form of ice in mountains and oceans, and may also be used in the metabolism of living organisms, incorporated into the body of individuals or excreted through urine, feces and sweat.

4. Why is the sun the “motor” of the water cycle?

The sun can be considered the motor of the water cycle because the transformation of liquid water into water vapor depends on its energy. Therefore, the sun is the energy source that causes water to circulate in nature.

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The Carbon Cycle

5. What is the carbon cycle?

The carbon cycle represents the circulation and recycling of the chemical element carbon in nature as a result of the effect of living organisms.

Photosynthetic organisms absorb carbon as carbon dioxide available in the atmosphere and the carbon atoms become part of glucose molecules. During the cellular respiration of these organisms, part of this organic material is consumed to generate ATP and, in this process, carbon dioxide is returned to the atmosphere. The other part is incorporated by the photosynthetic organisms into the molecules that compose their structure. The carbon atoms incorporated into the producers are transferred to the next trophic level and again a portion of them is released by cellular respiration in consumers, another part becomes a component of the consumer's body, and the last part is excreted as uric acid or urea (excretions later recycled by decomposer bacteria). Therefore, carbon absorbed by producers via photosynthesis returns to the atmosphere through cellular respiration along the food chain until reaching the decomposers that also release carbon dioxide in their energy metabolism. Under special conditions, through a process that takes millions of years, carbon incorporated into organisms may also constitute fossil fuels stored in deposits under the surface of the planet as fossil fuels burn. the carbon atoms return to the atmosphere as carbon dioxide or carbon monoxide. The burning of vegetable fuels, such as wood, also returns carbon to the atmosphere.

6. What is the main biological process that consumes carbon dioxide?

The main biological process that consumes carbon dioxide is photosynthesis.

7. How is carbon dioxide made by producers and consumers?

Carbon dioxide is made by producers and consumers through cellular respiration.

8. What are fossil fuels?

Fossil fuels, such as oil, gas and coal, form when organic material is preserved from the complete effect of decomposers, generally buried deep and under pressure over millions of years. Under such conditions, the organic material transforms into hydrocarbon fuels.

Fossil fuels are a natural reservoir of carbon. When oxygen is present, these fuels can be burned and carbon dioxide and carbon monoxide are released into the atmosphere.

The Nitrogen Cycle

9. What is the most abundant form in which nitrogen is found in nature?

The most abundant nitrogen-containing molecule found in nature is molecular nitrogen (N₂). The air is 80% composed of molecular nitrogen.

10. In which form is nitrogen fixed by living organisms?

Most living organisms cannot use molecular nitrogen to obtain nitrogen atoms. Producers fix nitrogen mainly from nitrate (NO₃⁻). Some plants also fix nitrogen from ammonia. Consumers and decomposers acquire nitrogen through digestion of proteins and nucleic acids from the body of other living organisms.

11. What is the nitrogen cycle?

The nitrogen cycle represents the circulation and recycling of the chemical element nitrogen in nature.

The nitrogen cycle basically depends on the effect of specialized bacteria. Bacteria in the soil called nitrogen-fixing bacteria present in plant roots absorb molecular nitrogen from the air and release nitrogen in the form of ammonia. The decomposition of organic material also produces ammonia. In the soil and roots (mainly of leguminous plants), a first group of chemosynthetic bacteria called nitrifying bacteria or nitrosomonas produces energy by consuming ammonia and releasing nitrite (NO₂). The second group of nitrifying bacteria, called nitrobacteria, uses nitrite in chemosynthesis, releasing nitrate (NO₃). In the form of nitrate, nitrogen is then incorporated by plants to be used a component of proteins and nucleic acids, and the element then follows along the food chain. Nitrogen returns to the atmosphere through the effect of denitrifying bacteria that use nitrogen-containing compounds from the soil and release nitrogen gas (molecular nitrogen).

12. Why is leguminous crop rotation used in agriculture?

Leguminous crop rotation and other types of crop rotation are used in agriculture because many bacteria important for the nitrogen cycle live in these plants. Leguminous crop rotation (or਌onjointly with the main crop) helps the soil to become rich in nitrates, which are then absorbed by the plants.

Green manure, the covering of the soil with grass and leguminous plants, is also a way to improve the fixation of nitrogen and is an option for avoiding chemical fertilizers.

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Learn About Yolk Sacs, the Amnion, the Chorion and More

Extraembryonic membranes are membranous structures that appear parallel to the embryo and which play important roles in embryonic development. They form from the embryo but do not become part of the individual organism after its birth.

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2. What extraembryonic membranes are present in vertebrates?

The extraembryonic membranes that may be present in vertebrates are the yolk sac , the amnion, the chorion, the allantois and the placenta.

3. Are extraembryonic membranes the same among all vertebrates?

The presence of each extraembryonic membrane varies according to the vertebrate class.

In fish and amphibians, only the yolk sac is present. In reptiles and birds, in addition to the yolk sac, the amnion, the chorion and the allantois are also present. In placental mammals, in addition to all these membranes, the placenta is also present.

The Yolk Sac

4. How is the yolk sac formed? What is the function of the yolk sac?

The yolk sac is formed from the covering of the vitellus by cells originating from the primitive gut.

The yolk sac stores vitellus, the main source of nutrition for non-placental embryos.

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5. Which extraembryonic membrane has the function of storing the nitrogen wastes of the embryo? Is this function necessary in the embryos of placental mammals?

The allantois is the extraembryonic membrane whose function is to store excretions of the embryo.

In placental mammals, the allantois is present but it does not exert that function, since embryonic wastes are collected by the mother’s body through the placenta.

6. Why can the allantois be considered an adaptation to terrestrial life?

The allantois is an adaptation to dry land because in embryos of oviparous terrestrial organisms, such as reptiles and birds, metabolic wastes cannot be immediately excreted to aquatic surroundings (like fish and amphibian larvae do). Therefore, the appearance of a structure capable of storing embryonic excretions until hatching was necessary.

The Amnion and the Chorion

7. What is the difference between the amnion and the chorion?

The amnion is the membrane that covers the embryo. The chorion is the membrane that covers the amnion, the yolk sac and the allantois. The space delimited by the chorion and the amnion is called the amniotic cavity and it is filled with amniotic fluid. The amniotic cavity has the function of preventing the drying out of the embryo and protecting it against mechanical shocks.

8. Why can the amnion also be considered an adaptation to terrestrial life?

The amnion is also an adaptation to dry land since one of its functions is to prevent the embryo from drying out.

9. What is the chorioallantois membrane present in the embryonic development of reptiles and birds? How does this membrane participate in the energy metabolism of the embryo?

The chorioallantois membrane is formed by juxtaposition of certain regions of the chorion and the allantois. Since it is porous, the chorioallantois membrane allows the passage of gases between the embryo and the exterior, thus making aerobic cellular respiration possible.

The Placenta

10. What types of animals have a placenta? What is its main function?

A true placenta is present in placental mammals.

The placenta is formed from the embryo's chorion and the mother’s endometrium. Its main function is to allow the exchange of substances between the fetus and the mother’s body.

11. What are the main substances transferred from the mother to the fetus through the placenta? And from the fetus to the mother?

From the mother to the fetus, the main substances transferred through the placenta are water, oxygen, nutrients and antibodies. From the fetus to the mother, the main substances transferred are metabolic wastes, including urea (nitrogen waste), and carbon dioxide.

12. Do the mother and the fetus exchange cells through the placenta?

Under normal conditions, cells do not cross the placenta during gestation. The placenta has smooth mucosa which separate the richly vascularized region in contact with the mother’s endometrium from the umbilical cord in contact with fetal blood. This barrier is known as the placental barrier. Although permeable to some substances (selective permeability), the placental barrier prevents the passage of cells.

13. What are the endocrine functions of the placenta?

The placenta has an endocrine function, since it secretes the hormones progesterone and estrogen, which maintain the endometrium (the internal covering of the uterus) and prevent menses during pregnancy. The placenta also secretes other important hormones for pregnancy regulation.

The Umbilical Cord

14. What is the function of the umbilical cord?

The umbilical cord is a set of blood vessels that connects the fetus with the placenta. In the fetus, one end of the cord is inserted into the center of the abdominal wall (the scar of this insertion is the umbilicus or navel).

The function of the umbilical cord is to allow the transport of substances, nutrients, gases and wastes, between the fetus and the mother’s body.

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Beneficial effect of physical exercise on telomere length and aging, and genetics of aging-associated noncommunicable diseases

Brisamar Estébanez , . María J. Cuevas , in Sports, Exercise, and Nutritional Genomics , 2019 Oxidative stress

Different processes, including oxidative metabolism products of cellular respiration in mitochondria, produce highly reactive ROS, which are able to induce damage on cellular components (proteins, lipids, and DNA) and form molecules that can alter different metabolic pathways. In normal conditions, the effect of these ROS is counteracted by various antioxidant systems however, an excessive accumulation of ROS in cells, tissues or organs can cause oxidative stress, leading to DNA damage ( Arsenis et al., 2017 Chilton et al., 2017 ). In addition, mitochondria with DNA damage produce a greater amount of free radicals, which in turn cause greater deterioration of mitochondrial DNA, thus forming a vicious circle.

In recent decades, one of the most accepted theories of aging is the free radicals or oxidative stress theory. One consistent line of evidence supports that different oxidative-stress genes are linked with both telomere shortening and aging ( Starr et al., 2008 ). Actually, several antioxidant molecules such as glutathione, vitamins, and antioxidant enzymes are associated with longer telomeres, and their content and/or their function decrease with age. In this context, telomeric G triplet is particularly susceptible to oxidative stress ( Hewitt et al., 2012 ). Moreover, the reparation of damaged telomeric DNA is less efficient when compared to coding regions of the genome, leading to shorter telomeres and cumulative and irreparable damage ( Fumagalli et al., 2012 ).

Paradoxically, there is a delicate balance between TL and oxidative stress. While severe oxidative damage can be harmful to telomeres, mild exposure to oxidative stress can play a protective role over TL by enhancing oxidative damage repair systems ( Radák et al., 2003 ), as observed in sperm telomeres ( Mishra et al., 2016 ). In fact, under oxidative conditions, telomerase translocates to the mitochondria where it appears to play a protective role against stress ( Haendeler et al., 2009 ). Additionally, a certain amount of ROS may also be protective by increasing antioxidant defense systems ( Chilton et al., 2017 ). In this sense, overexpression of the antioxidant enzyme superoxide dismutase reduces telomere shortening in human fibroblasts ( von Zglinicki et al., 2000 ). In conclusion, it appears that, as long as ROS concentration is maintained within a determined threshold, ROS can aid in telomere maintenance.

22.4 Gas Exchange

The purpose of the respiratory system is to perform gas exchange. Pulmonary ventilation provides air to the alveoli for this gas exchange process. At the respiratory membrane, where the alveolar and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting. It is through this mechanism that blood is oxygenated and carbon dioxide, the waste product of cellular respiration, is removed from the body.

Gas Exchange

In order to understand the mechanisms of gas exchange in the lung, it is important to understand the underlying principles of gases and their behavior. In addition to Boyle’s law, several other gas laws help to describe the behavior of gases.

Gas Laws and Air Composition

Gas molecules exert force on the surfaces with which they are in contact this force is called pressure. In natural systems, gases are normally present as a mixture of different types of molecules. For example, the atmosphere consists of oxygen, nitrogen, carbon dioxide, and other gaseous molecules, and this gaseous mixture exerts a certain pressure referred to as atmospheric pressure (Table 22.2). Partial pressure (Px) is the pressure of a single type of gas in a mixture of gases. For example, in the atmosphere, oxygen exerts a partial pressure, and nitrogen exerts another partial pressure, independent of the partial pressure of oxygen (Figure 22.21). Total pressure is the sum of all the partial pressures of a gaseous mixture. Dalton’s law describes the behavior of nonreactive gases in a gaseous mixture and states that a specific gas type in a mixture exerts its own pressure thus, the total pressure exerted by a mixture of gases is the sum of the partial pressures of the gases in the mixture.

Gas Percent of total composition Partial pressure
(mm Hg)
Nitrogen (N2) 78.6 597.4
Oxygen (O2) 20.9 158.8
Water (H2O) 0.4 3.0
Carbon dioxide (CO2) 0.04 0.3
Others 0.06 0.5
Total composition/total atmospheric pressure 100% 760.0

Partial pressure is extremely important in predicting the movement of gases. Recall that gases tend to equalize their pressure in two regions that are connected. A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower. In addition, the greater the partial pressure difference between the two areas, the more rapid is the movement of gases.

Solubility of Gases in Liquids

Henry’s law describes the behavior of gases when they come into contact with a liquid, such as blood. Henry’s law states that the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas. The greater the partial pressure of the gas, the greater the number of gas molecules that will dissolve in the liquid. The concentration of the gas in a liquid is also dependent on the solubility of the gas in the liquid. For example, although nitrogen is present in the atmosphere, very little nitrogen dissolves into the blood, because the solubility of nitrogen in blood is very low. The exception to this occurs in scuba divers the composition of the compressed air that divers breathe causes nitrogen to have a higher partial pressure than normal, causing it to dissolve in the blood in greater amounts than normal. Too much nitrogen in the bloodstream results in a serious condition that can be fatal if not corrected. Gas molecules establish an equilibrium between those molecules dissolved in liquid and those in air.

The composition of air in the atmosphere and in the alveoli differs. In both cases, the relative concentration of gases is nitrogen > oxygen > water vapor > carbon dioxide. The amount of water vapor present in alveolar air is greater than that in atmospheric air (Table 22.3). Recall that the respiratory system works to humidify incoming air, thereby causing the air present in the alveoli to have a greater amount of water vapor than atmospheric air. In addition, alveolar air contains a greater amount of carbon dioxide and less oxygen than atmospheric air. This is no surprise, as gas exchange removes oxygen from and adds carbon dioxide to alveolar air. Both deep and forced breathing cause the alveolar air composition to be changed more rapidly than during quiet breathing. As a result, the partial pressures of oxygen and carbon dioxide change, affecting the diffusion process that moves these materials across the membrane. This will cause oxygen to enter and carbon dioxide to leave the blood more quickly.

Gas Percent of total composition Partial pressure
(mm Hg)
Nitrogen (N2) 74.9 569
Oxygen (O2) 13.7 104
Water (H2O) 6.2 40
Carbon dioxide (CO2) 5.2 47
Total composition/total alveolar pressure 100% 760.0

Ventilation and Perfusion

Two important aspects of gas exchange in the lung are ventilation and perfusion. Ventilation is the movement of air into and out of the lungs, and perfusion is the flow of blood in the pulmonary capillaries. For gas exchange to be efficient, the volumes involved in ventilation and perfusion should be compatible. However, factors such as regional gravity effects on blood, blocked alveolar ducts, or disease can cause ventilation and perfusion to be imbalanced.

The partial pressure of oxygen in alveolar air is about 104 mm Hg, whereas the partial pressure of oxygenated blood in pulmonary veins is about 100 mm Hg. When ventilation is sufficient, oxygen enters the alveoli at a high rate, and the partial pressure of oxygen in the alveoli remains high. In contrast, when ventilation is insufficient, the partial pressure of oxygen in the alveoli drops. Without the large difference in partial pressure between the alveoli and the blood, oxygen does not diffuse efficiently across the respiratory membrane. The body has mechanisms that counteract this problem. In cases when ventilation is not sufficient for an alveolus, the body redirects blood flow to alveoli that are receiving sufficient ventilation. This is achieved by constricting the pulmonary arterioles that serves the dysfunctional alveolus, which redirects blood to other alveoli that have sufficient ventilation. At the same time, the pulmonary arterioles that serve alveoli receiving sufficient ventilation vasodilate, which brings in greater blood flow. Factors such as carbon dioxide, oxygen, and pH levels can all serve as stimuli for adjusting blood flow in the capillary networks associated with the alveoli.

Ventilation is regulated by the diameter of the airways, whereas perfusion is regulated by the diameter of the blood vessels. The diameter of the bronchioles is sensitive to the partial pressure of carbon dioxide in the alveoli. A greater partial pressure of carbon dioxide in the alveoli causes the bronchioles to increase their diameter as will a decreased level of oxygen in the blood supply, allowing carbon dioxide to be exhaled from the body at a greater rate. As mentioned above, a greater partial pressure of oxygen in the alveoli causes the pulmonary arterioles to dilate, increasing blood flow.

Gas Exchange

Gas exchange occurs at two sites in the body: in the lungs, where oxygen is picked up and carbon dioxide is released at the respiratory membrane, and at the tissues, where oxygen is released and carbon dioxide is picked up. External respiration is the exchange of gases with the external environment, and occurs in the alveoli of the lungs. Internal respiration is the exchange of gases with the internal environment, and occurs in the tissues. The actual exchange of gases occurs due to simple diffusion. Energy is not required to move oxygen or carbon dioxide across membranes. Instead, these gases follow pressure gradients that allow them to diffuse. The anatomy of the lung maximizes the diffusion of gases: The respiratory membrane is highly permeable to gases the respiratory and blood capillary membranes are very thin and there is a large surface area throughout the lungs.

External Respiration

The pulmonary artery carries deoxygenated blood into the lungs from the heart, where it branches and eventually becomes the capillary network composed of pulmonary capillaries. These pulmonary capillaries create the respiratory membrane with the alveoli (Figure 22.22). As the blood is pumped through this capillary network, gas exchange occurs. Although a small amount of the oxygen is able to dissolve directly into plasma from the alveoli, most of the oxygen is picked up by erythrocytes (red blood cells) and binds to a protein called hemoglobin, a process described later in this chapter. Oxygenated hemoglobin is red, causing the overall appearance of bright red oxygenated blood, which returns to the heart through the pulmonary veins. Carbon dioxide is released in the opposite direction of oxygen, from the blood to the alveoli. Some of the carbon dioxide is returned on hemoglobin, but can also be dissolved in plasma or is present as a converted form, also explained in greater detail later in this chapter.

External respiration occurs as a function of partial pressure differences in oxygen and carbon dioxide between the alveoli and the blood in the pulmonary capillaries.

Although the solubility of oxygen in blood is not high, there is a drastic difference in the partial pressure of oxygen in the alveoli versus in the blood of the pulmonary capillaries. This difference is about 64 mm Hg: The partial pressure of oxygen in the alveoli is about 104 mm Hg, whereas its partial pressure in the blood of the capillary is about 40 mm Hg. This large difference in partial pressure creates a very strong pressure gradient that causes oxygen to rapidly cross the respiratory membrane from the alveoli into the blood.

The partial pressure of carbon dioxide is also different between the alveolar air and the blood of the capillary. However, the partial pressure difference is less than that of oxygen, about 5 mm Hg. The partial pressure of carbon dioxide in the blood of the capillary is about 45 mm Hg, whereas its partial pressure in the alveoli is about 40 mm Hg. However, the solubility of carbon dioxide is much greater than that of oxygen—by a factor of about 20—in both blood and alveolar fluids. As a result, the relative concentrations of oxygen and carbon dioxide that diffuse across the respiratory membrane are similar.

Internal Respiration

Internal respiration is gas exchange that occurs at the level of body tissues (Figure 22.23). Similar to external respiration, internal respiration also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the respiratory membrane. The partial pressure of oxygen in tissues is low, about 40 mm Hg, because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue. Hemoglobin that has little oxygen bound to it loses much of its brightness, so that blood returning to the heart is more burgundy in color.

Considering that cellular respiration continuously produces carbon dioxide, the partial pressure of carbon dioxide is lower in the blood than it is in the tissue, causing carbon dioxide to diffuse out of the tissue, cross the interstitial fluid, and enter the blood. It is then carried back to the lungs either bound to hemoglobin, dissolved in plasma, or in a converted form. By the time blood returns to the heart, the partial pressure of oxygen has returned to about 40 mm Hg, and the partial pressure of carbon dioxide has returned to about 45 mm Hg. The blood is then pumped back to the lungs to be oxygenated once again during external respiration.

Everyday Connection

Hyperbaric Chamber Treatment

A type of device used in some areas of medicine that exploits the behavior of gases is hyperbaric chamber treatment. A hyperbaric chamber is a unit that can be sealed and expose a patient to either 100 percent oxygen with increased pressure or a mixture of gases that includes a higher concentration of oxygen than normal atmospheric air, also at a higher partial pressure than the atmosphere. There are two major types of chambers: monoplace and multiplace. Monoplace chambers are typically for one patient, and the staff tending to the patient observes the patient from outside of the chamber (Figure 22.24). Some facilities have special monoplace hyperbaric chambers that allow multiple patients to be treated at once, usually in a sitting or reclining position, to help ease feelings of isolation or claustrophobia. Multiplace chambers are large enough for multiple patients to be treated at one time, and the staff attending these patients is present inside the chamber. In a multiplace chamber, patients are often treated with air via a mask or hood, and the chamber is pressurized.

Hyperbaric chamber treatment is based on the behavior of gases. As you recall, gases move from a region of higher partial pressure to a region of lower partial pressure. In a hyperbaric chamber, the atmospheric pressure is increased, causing a greater amount of oxygen than normal to diffuse into the bloodstream of the patient. Hyperbaric chamber therapy is used to treat a variety of medical problems, such as wound and graft healing, anaerobic bacterial infections, and carbon monoxide poisoning. Exposure to and poisoning by carbon monoxide is difficult to reverse, because hemoglobin’s affinity for carbon monoxide is much stronger than its affinity for oxygen, causing carbon monoxide to replace oxygen in the blood. Hyperbaric chamber therapy can treat carbon monoxide poisoning, because the increased atmospheric pressure causes more oxygen to diffuse into the bloodstream. At this increased pressure and increased concentration of oxygen, carbon monoxide is displaced from hemoglobin. Another example is the treatment of anaerobic bacterial infections, which are created by bacteria that cannot or prefer not to live in the presence of oxygen. An increase in blood and tissue levels of oxygen helps to kill the anaerobic bacteria that are responsible for the infection, as oxygen is toxic to anaerobic bacteria. For wounds and grafts, the chamber stimulates the healing process by increasing energy production needed for repair. Increasing oxygen transport allows cells to ramp up cellular respiration and thus ATP production, the energy needed to build new structures.

Introduction to Mass Spectrometry

A diagram of a conventional mass spectrometer is depicted in Figure (PageIndex<1>).

Figure (PageIndex<1>). Conventional Mass spectrometer 2

As shown, the mass spectrometer consists of a sample input, an ionization chamber, accelerator, defector, detector, and an amplifier. In brief, the sample of interest is injected into the mass spec and ionized to form charged particles. The charged particles are then accelerated by increasing the kinetic energy of the particles. As shown in the Figure, there are three plates with slits in the acceleration region these plates all vary in potential allowing for the particles to increase in kinetic energy and form a finely tuned beam as they pass through each slit. This beam consists of a mixture of different ions before hitting the deflector. The deflector takes this mixture and separates the ions based on mass to charge ratio (m/z) this is done by applying a magnetic field. Figure (PageIndex<2>) presents a diagram of what occurs in the deflector.

Figure (PageIndex<2>). Deflector of a Mass spectrometer

Different ions interact differently with the magnetic field. In Figure (PageIndex<2>) for example, the ions from steam B are ions that have a low m/z ratio. This means that the ions that compose this beam either have a low mass or a high charge or both. On the other hand ions from stream C hardly interact with the magnetic field applied meaning they have a high m/z ratio. The ions in steam B, however, interact with the magnetic field in such a way that the ions pass through to the detector. The magnetic field can be altered to select a desired m/z range. For example, if one were to want to detect the higher mass ranges (steam C), the magnetic field would need to be larger in order to deflect the ions more. Equations 1 (Lorentz Force) and 2 (Newton&rsquos second law of motion) are crucial in understanding how partials move in an electric or magnetic field.

Where (Q) is the ion charge, (F) is the force applied on the ion, (v imes B) is the cross product of the velocity and magnetic field, (m) is the mass and a is the acceleration.

Equating the two equations then gives the following differential (Equation ef<3>)

Once the selected ions pass the deflector the ions travel towards a detector were there m/z is recorded. In short, when the ions strike the metal detector, a current from the movement of electrons is produced which can then be recorded as a signal. Because the electrons affected by this collision are typically very few, amplification of the signal is almost always necessary. Ions in the gas phase are typically very reactive and have a short lifetime thus it is important that the instrument in run in high vacuum (typically from 10 &minus3&thinsp torr to 10 &minus6 &thinsptorr pressure).

There are several different mass spectrometers commercially available that tailor to different needs, such as quantifying data, qualifying data, protein sample analysis, small sample analysis, etc. Ionization techniques have been key to determining what types of samples can be analyzed by mass spectrometry. 3

Before going into detail about the different ionizations methods it is important to understand two main categories that ionization falls under, hard and soft ionization. 4

  1. Hard ionization- hard ionization evokes larger amounts of energy to the sample of interest in order to ionize the sample. Due to the larger amount of energy the bonds within the molecule tend to break more, resulting in an increase in fragmentation. Hard ionization techniques typically yield in a larger number of lower mass fragments as oppose to higher mass.
  2. Soft ionization- Soft ionization methods use smaller amounts of energy to ionize the sample, causing a decrease in fragmentation. This technique yields a larger amount of high mass fragments.

Key Terms

  • osmosis: the net movement of solvent molecules from a region of high solvent potential to a region of lower solvent potential through a partially permeable membrane
  • hypotonic: Having a lower osmotic pressure than another.
  • isotonic: Having the same osmotic pressure.
  • hypertonic: Having a greater osmotic pressure than another.
  • halophile: Organisms that thrive in high salt concentrations.

Osmotic pressure is an important factor that affects cells. Osmosis is the net movement of solvent molecules through a partially permeable membrane into a region of higher solute concentration. The intent of osmosis is to equalize the solute concentrations on the two sides. Osmosis is essential in biological systems because biological membranes are semi permeable. In general, these membranes are impermeable to large and polar molecules such as ions, proteins, and polysaccharides. However, they are permeable to non-polar and/or hydrophobic molecules like lipids as well as to small molecules like oxygen, carbon dioxide, nitrogen, nitric oxide, etc. Osmosis provides the primary means by which water is transported into and out of cells. Osmoregulation is the homeostasis mechanism of an organism to reach balance in osmotic pressure.

Having the correct osmotic pressure in the culture medium is essential. A cell can be influenced by a solution in three ways. Suppose a cell is placed in a solution of sugar or salt water. If the medium is hypotonic &mdash a diluted solution with a higher water concentration than the cell &mdash the cell will gain water through osmosis. If the medium is isotonic &mdash a solution with exactly the same water concentration as the cell &mdash there will be no net movement of water across the cell membrane. If the medium is hypertonic &mdash a concentrated solution with a lower water concentration than the cell &mdash the cell will lose water by osmosis.

Figure: Osmotic Pressure on Red Blood Cells: Effect of different solutions on blood cells.

Essentially, this means that if a cell is put in a solution that has a solute concentration higher than its own, then it will shrivel up. If it is put in a solution with a lower solute concentration than its own, the cell will expand and burst.

What happens with the nitrogen in blood in membrane oxygenators? - Biology

1. Describe the basic molecular structure and primary function of lipids.
2. Relate the molecular structure of saturated and unsaturated fats to their health implications.
3. Recognize a phospholipid and understand why phospholipids in a plasma membrane are arranged in a phospholipid bilayer structure. Explain the fluid mosaic model.
4. Understand the process of diffusion.
5. Distinguish between the four methods by which materials enter and exit a cell, and explain the role of the plasma membrane as a selective barrier in each case.
6. Be able to identify solutions as hypertonic, hypotonic, or isotonic. Know what a concentration gradient is.
7. Be able to illustrate and explain what happens to a cell in solutions of different concentrations as a consequence of osmosis.

Active Transport
Concentration Gradient
Facilitated Diffusion
Fluid Mosaic Model
Hypertonic Solution
Hypotonic Solution
Isotonic Solution
Phospholipid Bilayer
Saturated and Unsaturated Fat
Semipermeable or Selectively Permeable Membrane
Simple Diffusion

Sample MCAS Questions
1. Which of the following functions does active transport perform in a cell?
A. Packaging proteins for export from the cell.
B. Distributing enzymes throughout the cytoplasm.
C. Moving substances against a concentration gradient.
D. Equalizing the concentration of water inside and outside the cell.

2. The diagram below shows a cross section of part of a cell membrane.

a. Describe the basic structure of the cell membrane.
b. Describe two primary functions of the cell membrane.
c. Explain how the structure of the cell membrane allows it to perform the functions
described in part (b).

3. The table below lists the concentrations of water inside and outside a cell under four different conditions.

Water Concentration In Cell
Water Concentration in Environment

Under which condition will the cell experience a net loss of water to the environment?
A. Condition 1
B. Condition 2
C. Condition 3
D. Condition 4

4. A diagram of an organic molecule is below.

Which element is found at positions marked by the dots in the diagram?
A. Carbon
B. Nitrogen
C. Phosphorus
D. Sulfur

5. If an animal cell is placed in distilled water, it will swell and burst. This bursting is a result of which biological process?
A. Active transport
B. Enzyme activity
C. Osmosis
D. Respiration

6. One category of organic compounds contains molecules composed of long hydrocarbon chains. The hydrocarbon chains may be saturated or unsaturated. Which of the following categories of organic compounds contains these molecules?
A. carbohydrates
B. lipids
C. nucleic acids
D. proteins

7. Which of the following statements best explains why oxygen diffuses from the alveoli into the blood?
A. The diaphragm draws oxygen into the alveoli at a rapid speed.
B. Alveoli cells contain hemoglobin to transfer gases to the blood.
C. The concentration of oxygen is greater in the alveoli than in the blood.
D. Red blood cells move one at a time through the capillaries surrounding the alveoli.

1. C
2. Examples of student responses can be found here . Pay attention, of course, to the responses that garnered scores of 4.
3. C In condition 3, the water inside the cell is less concentrated than the water outside the cell. Osmosis will occur, with more water leaving the cell than entering.
4. A As you can tell by its chain structure, this is a lipid. The trademark of a lipid is a chain of carbon, surrounding by hydrogens.
5. C Pure distilled water is invariably hypotonic relative to the inside of a cell. Because water is more concentrated outside the cell than inside, it diffuses (diffusion of water = osmosis) into the cell, causing the cell to swell and burst.
6. B
7. C

Watch the video: Hämoglobin einfach erklärt (August 2022).