117-518: Viatris Inc. is an American global pharmaceutical and healthcare corporation headquartered in Canonsburg, Pennsylvania . The corporation was formed through the merger of Mylan and Upjohn , a legacy division of Pfizer , on November 16, 2020. The name of the corporation comes from the Latin words via , meaning path, and tris , which means three, referring to the path to three main objectives
234-455: A diving chamber or decompression chamber . However, as one rises above sea level the density of the air decreases exponentially (see Fig. 14), halving approximately with every 5500 m rise in altitude . Since the composition of the atmospheric air is almost constant below 80 km, as a result of the continuous mixing effect of the weather, the concentration of oxygen in the air (mmols O 2 per liter of ambient air) decreases at
351-427: A fibrinolytic system that dissolves clots that may have arrived in the pulmonary circulation by embolism , often from the deep veins in the legs. They also release a variety of substances that enter the systemic arterial blood, and they remove other substances from the systemic venous blood that reach them via the pulmonary artery. Some prostaglandins are removed from the circulation, while others are synthesized in
468-405: A partial pressure of carbon dioxide of 5.3 kPa (40 mmHg) (i.e. the same as the oxygen and carbon dioxide gas tensions as in the alveoli). As mentioned in the section above , the corresponding partial pressures of oxygen and carbon dioxide in the ambient (dry) air at sea level are 21 kPa (160 mmHg) and 0.04 kPa (0.3 mmHg) respectively. This marked difference between
585-436: A respiratory acidosis , or a respiratory alkalosis will occur. In the long run these can be compensated by renal adjustments to the H and HCO 3 concentrations in the plasma ; but since this takes time, the hyperventilation syndrome can, for instance, occur when agitation or anxiety cause a person to breathe fast and deeply thus causing a distressing respiratory alkalosis through the blowing off of too much CO 2 from
702-435: A critical role, often then selling the rights to larger companies that have the resources to run the clinical trials. Drug discovery is different from Drug Development. Drug Discovery is often considered the process of identifying new medicine. At the same time, Drug development is delivering a new drug molecule into clinical practice. In its broad definition, this encompasses all steps from the basic research process of finding
819-575: A group of 2245 elderly Americans (average age of 71) surveyed over the period 2010 – 2011, those percentages were 88%, 38%, and 64%. One of the key classifications is between traditional small molecule drugs; usually derived from chemical synthesis and biological medical products ; which include recombinant proteins , vaccines , blood products used therapeutically (such as IVIG ), gene therapy , and cell therapy (for instance, stem cell therapies). Pharmaceuticals or drugs or medicines are classified into various other groups besides their origin on
936-505: A list of essential medicines . A sampling of classes of medicine includes: Pharmaceuticals may also be described as "specialty", independent of other classifications, which is an ill-defined class of drugs that might be difficult to administer, require special handling during administration, require patient monitoring during and immediately after administration, have particular regulatory requirements restricting their use, and are generally expensive relative to other drugs. Drugs affecting
1053-407: A much more even distribution of blood flow to the lungs than occurs at sea level. At sea level, the pulmonary arterial pressure is very low, with the result that the tops of the lungs receive far less blood than the bases , which are relatively over-perfused with blood. It is only in the middle of the lungs that the blood and air flow to the alveoli are ideally matched . At altitude, this variation in
1170-480: A normal mammal, the lungs cannot be emptied completely. In an adult human, there is always still at least 1 liter of residual air left in the lungs after maximum exhalation. The automatic rhythmical breathing in and out, can be interrupted by coughing, sneezing (forms of very forceful exhalation), by the expression of a wide range of emotions (laughing, sighing, crying out in pain, exasperated intakes of breath) and by such voluntary acts as speech, singing, whistling and
1287-428: A partial pressure of CO 2 of also about 6 kPa (45 mmHg), whereas that of the alveolar air is 5.3 kPa (40 mmHg), there is a net movement of carbon dioxide out of the capillaries into the alveoli. The changes brought about by these net flows of individual gases into and out of the alveolar air necessitate the replacement of about 15% of the alveolar air with ambient air every 5 seconds or so. This
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#17328023984411404-452: A process known as reverse pharmacology . Hits from these screens are then tested in cells and then in animals for efficacy . Even more recently, scientists have been able to understand the shape of biological molecules at the atomic level and to use that knowledge to design (see drug design ) drug candidates. Modern drug discovery involves the identification of screening hits, medicinal chemistry , and optimization of those hits to increase
1521-411: A process of identifying a new medicine. Development: Chemicals extracted from natural products are used to make pills, capsules, or syrups for oral use. Injections for direct infusion into the blood drops for eyes or ears. Preclinical research : Drugs go under laboratory or animal testing, to ensure that they can be used on Humans. Clinical testing: The drug is used on people to confirm that it
1638-464: A rise in arterial blood pressure . Large amounts of the angiotensin-converting enzyme responsible for this activation are located on the surfaces of the endothelial cells of the alveolar capillaries. The converting enzyme also inactivates bradykinin . Circulation time through the alveolar capillaries is less than one second, yet 70% of the angiotensin I reaching the lungs is converted to angiotensin II in
1755-424: A single trip through the capillaries. Four other peptidases have been identified on the surface of the pulmonary endothelial cells. The movement of gas through the larynx , pharynx and mouth allows humans to speak , or phonate . Vocalization, or singing, in birds occurs via the syrinx , an organ located at the base of the trachea. The vibration of air flowing across the larynx ( vocal cords ), in humans, and
1872-752: A stake of at least 12.9% in Biocon Biologics. The transaction was completed in November 2022. In November 2022, the business agreed to acquire Oyster Point Pharma and Famy Life Sciences for an aggregate of $ 700–750 million to create an ophthalmology division. The acquisitions closed in January 2023. In 2022 and 2024, Viatris was recognized by Forbes as one of the world's best employers and by Newsweek as one of America's most responsible companies. On April 1, 2023, Scott A. Smith became Viatris' CEO, succeeding Michael Goettler. Smith previously served on
1989-499: A suitable molecular target to supporting the drug's commercial launch. Drug development is the process of bringing a new drug to the market once a lead compound has been identified through the process of drug discovery . It includes pre-clinical research (microorganisms/animals) and clinical trials (on humans) and may include the step of obtaining regulatory approval to market the drug. Drug Development Process Discovery: The Drug Development process starts with Discovery,
2106-633: A variety of medicines, with 1,400 approved therapeutic molecules in its portfolio. It owns brands (like Viagra , Xanax , Lipitor ), generics , including branded and complex generics, biosimilars , and over-the-counter (OTC) drugs and active pharmaceutical ingredients . Viatris products cover therapeutic areas including cardiovascular , infectious disease , oncology , immunology , CNS and anesthesia , women's healthcare, diabetes and metabolism , gastroenterology , respiratory and allergy , and dermatology . The following products have been newly launched or received regulatory approvals since Viatris
2223-399: A variety of molecules that aid in the defense of the lungs. These include secretory immunoglobulins (IgA), collectins , defensins and other peptides and proteases , reactive oxygen species , and reactive nitrogen species . These secretions can act directly as antimicrobials to help keep the airway free of infection. A variety of chemokines and cytokines are also secreted that recruit
2340-598: A vein , or by drops put into the ear or eye . A medication that does not contain an active ingredient and is used in research studies is called a placebo . In Europe, the term is "medicinal product", and it is defined by EU law as: In the US, a "drug" is: Drug use among elderly Americans has been studied; in a group of 2,377 people with an average age of 71 surveyed between 2005 and 2006, 84% took at least one prescription drug, 44% took at least one over-the-counter (OTC) drug, and 52% took at least one dietary supplement ; in
2457-419: A watery surface (the water-air interface) tends to make that surface shrink. When that surface is curved as it is in the alveoli of the lungs, the shrinkage of the surface decreases the diameter of the alveoli. The more acute the curvature of the water-air interface the greater the tendency for the alveolus to collapse . This has three effects. Firstly, the surface tension inside the alveoli resists expansion of
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#17328023984412574-559: A wide range of circumstances, at the expense of the arterial partial pressure of O 2 , which is allowed to vary within a very wide range of values, before eliciting a corrective ventilatory response. However, when the atmospheric pressure (and therefore the partial pressure of O 2 in the ambient air) falls to below 50-75% of its value at sea level, oxygen homeostasis is given priority over carbon dioxide homeostasis. This switch-over occurs at an elevation of about 2500 m (or about 8000 ft). If this switch occurs relatively abruptly,
2691-504: Is a medicine or a chemical compound used to treat or cure illness. According to Encyclopædia Britannica , medication is "a substance used in treating a disease or relieving pain ". As defined by the National Cancer Institute , dosage forms of medication can include tablets , capsules , liquids, creams , and patches. Medications can be administered in different ways, such as by mouth , by infusion into
2808-456: Is a sign of, illness. ) It ends in the microscopic dead-end sacs called alveoli , which are always open, though the diameters of the various sections can be changed by the sympathetic and parasympathetic nervous systems . The alveolar air pressure is therefore always close to atmospheric air pressure (about 100 kPa at sea level) at rest, with the pressure gradients because of lungs contraction and expansion cause air to move in and out of
2925-509: Is an important part of the medical field and relies on the science of pharmacology for continual advancement and on pharmacy for appropriate management. Drugs are classified in many ways. One of the key divisions is by level of control , which distinguishes prescription drugs (those that a pharmacist dispenses only on the order of a physician, physician assistant , or qualified nurse ) from over-the-counter drugs (those that consumers can order for themselves). Another key distinction
3042-442: Is at sea level). This reduces the partial pressure of oxygen entering the alveoli to 5.8 kPa (or 21% of [33.7 kPa – 6.3 kPa] = 5.8 kPa). The reduction in the partial pressure of oxygen in the inhaled air is therefore substantially greater than the reduction of the total atmospheric pressure at altitude would suggest (on Mt Everest: 5.8 kPa vs. 7.1 kPa). A further minor complication exists at altitude. If
3159-511: Is between traditional small molecule drugs, usually derived from chemical synthesis , and biopharmaceuticals , which include recombinant proteins , vaccines , blood products used therapeutically (such as IVIG ), gene therapy , monoclonal antibodies and cell therapy (for instance, stem cell therapies). Other ways to classify medicines are by mode of action, route of administration , biological system affected, or therapeutic effects . An elaborate and widely used classification system
3276-426: Is breathed in or out, either through the mouth or nose or into or out of the alveoli are tabulated below, together with how they are calculated. The number of breath cycles per minute is known as the respiratory rate . An average healthy human breathes 12–16 times a minute. In mammals , inhalation at rest is primarily due to the contraction of the diaphragm . This is an upwardly domed sheet of muscle that separates
3393-405: Is determined by the blood gas homeostat , which regulates the partial pressures of oxygen and carbon dioxide in the arterial blood. This homeostat prioritizes the regulation of the arterial partial pressure of carbon dioxide over that of oxygen at sea level. That is to say, at sea level the arterial partial pressure of CO 2 is maintained at very close to 5.3 kPa (or 40 mmHg) under
3510-505: Is divided into an upper and a lower respiratory tract . The upper tract includes the nose , nasal cavities , sinuses , pharynx and the part of the larynx above the vocal folds . The lower tract (Fig. 2.) includes the lower part of the larynx , the trachea , bronchi , bronchioles and the alveoli . The branching airways of the lower tract are often described as the respiratory tree or tracheobronchial tree (Fig. 2). The intervals between successive branch points along
3627-450: Is fatal. Basic scientific experiments, carried out using cells from chicken lungs, support the potential for using steroids as a means of furthering the development of type II alveolar cells. In fact, once a premature birth is threatened, every effort is made to delay the birth, and a series of steroid injections is frequently administered to the mother during this delay in an effort to promote lung maturation. The lung vessels contain
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3744-570: Is fresh warm and moistened air. Since this 350 ml of fresh air is thoroughly mixed and diluted by the air that remains in the alveoli after a normal exhalation (i.e. the functional residual capacity of about 2.5–3.0 liters), it is clear that the composition of the alveolar air changes very little during the breathing cycle (see Fig. 9). The oxygen tension (or partial pressure) remains close to 13–14 kPa (about 100 mm Hg), and that of carbon dioxide very close to 5.3 kPa (or 40 mm Hg). This contrasts with composition of
3861-441: Is no unidirectional through-flow as there is in the bird lung ). This typical mammalian anatomy combined with the fact that the lungs are not emptied and re-inflated with each breath (leaving a substantial volume of air, of about 2.5–3.0 liters, in the alveoli after exhalation), ensures that the composition of the alveolar air is only minimally disturbed when the 350 ml of fresh air is mixed into it with each inhalation. Thus
3978-423: Is restored. Since the blood arriving in the alveolar capillaries has a partial pressure of O 2 of, on average, 6 kPa (45 mmHg), while the pressure in the alveolar air is 13–14 kPa (100 mmHg), there will be a net diffusion of oxygen into the capillary blood, changing the composition of the 3 liters of alveolar air slightly. Similarly, since the blood arriving in the alveolar capillaries has
4095-485: Is safe to use. FDA Review: drug is sent to FDA before launching the drug into the market. FDA post-Market Review: The drug is reviewed and monitored by FDA for the safety once it is available to the public. The regulation of drugs varies by jurisdiction. In some countries, such as the United States, they are regulated at the national level by a single agency. In other jurisdictions, they are regulated at
4212-523: Is still a lengthy, "expensive, difficult, and inefficient process" with a low rate of new therapeutic discovery. In 2010, the research and development cost of each new molecular entity (NME) was approximately US$ 1.8 billion. Drug discovery is done by pharmaceutical companies, sometimes with research assistance from universities. The "final product" of drug discovery is a patent on the potential drug. The drug requires very expensive Phase I, II, and III clinical trials, and most of them fail. Small companies have
4329-798: Is the Anatomical Therapeutic Chemical Classification System . The World Health Organization keeps a list of essential medicines . Drug discovery and drug development are complex and expensive endeavors undertaken by pharmaceutical companies , academic scientists, and governments. As a result of this complex path from discovery to commercialization, partnering has become a standard practice for advancing drug candidates through development pipelines. Governments generally regulate what drugs can be marketed, how drugs are marketed , and in some jurisdictions, drug pricing . Controversies have arisen over drug pricing and disposal of used Medicine . Medication
4446-493: Is therefore almost the same at the end of exhalation as at the end of inhalation. Thirdly, the surface tension of the curved watery layer lining the alveoli tends to draw water from the lung tissues into the alveoli. Surfactant reduces this danger to negligible levels, and keeps the alveoli dry. Pre-term babies who are unable to manufacture surfactant have lungs that tend to collapse each time they breathe out. Unless treated, this condition, called respiratory distress syndrome ,
4563-406: Is used for euthanasia and physician-assisted suicide . Euthanasia is not permitted by law in many countries, and consequently, medicines will not be licensed for this use in those countries. A single drug may contain single or multiple active ingredients . The administration is the process by which a patient takes medicine. There are three major categories of drug administration: enteral (via
4680-469: Is used per day (e.g., four times a day). It may include event-related information (e.g., 1 hour before meals, in the morning, at bedtime), or complimentary to an interval, although equivalent expressions may have different implications (e.g., every 8 hours versus 3 times a day). In the fields of medicine, biotechnology , and pharmacology , drug discovery is the process by which new drugs are discovered. Historically, drugs were discovered by identifying
4797-434: Is usually some degree of restriction on the availability of certain therapeutic goods depending on their risk to consumers. Respiratory system The respiratory system (also respiratory apparatus , ventilatory system ) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants . The anatomy and physiology that make this happen varies greatly, depending on
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4914-478: Is very tightly controlled by the monitoring of the arterial blood gases (which accurately reflect composition of the alveolar air) by the aortic and carotid bodies , as well as by the blood gas and pH sensor on the anterior surface of the medulla oblongata in the brain. There are also oxygen and carbon dioxide sensors in the lungs, but they primarily determine the diameters of the bronchioles and pulmonary capillaries , and are therefore responsible for directing
5031-494: The Forbes Global 2000 list of the world's largest companies. In October 2023, Viatris reached agreements to divest from almost all of its OTC business, its women’s healthcare business, and its India-based active pharmaceutical ingredients business for a total of about $ 3.6 billion. The following is an illustration of the company's major mergers and acquisitions and historical predecessors: The company produces and sells
5148-506: The affinity , selectivity (to reduce the potential of side effects), efficacy/ potency , metabolic stability (to increase the half-life ), and oral bioavailability . Once a compound that fulfills all of these requirements has been identified, it will begin the process of drug development prior to clinical trials . One or more of these steps may, but not necessarily, involve computer-aided drug design . Despite advances in technology and understanding of biological systems, drug discovery
5265-427: The arterial blood . This information determines the average rate of ventilation of the alveoli of the lungs , to keep these pressures constant . The respiratory center does so via motor nerves which activate the diaphragm and other muscles of respiration . The breathing rate increases when the partial pressure of carbon dioxide in the blood increases. This is detected by central blood gas chemoreceptors on
5382-3535: The central nervous system include psychedelics , hypnotics , anaesthetics , antipsychotics , eugeroics , antidepressants (including tricyclic antidepressants , monoamine oxidase inhibitors , lithium salts , and selective serotonin reuptake inhibitors (SSRIs)), antiemetics , anticonvulsants /antiepileptics, anxiolytics , barbiturates , movement disorder (e.g., Parkinson's disease ) drugs, nootropics , stimulants (including amphetamines ), benzodiazepines , cyclopyrrolones , dopamine antagonists , antihistamines , cholinergics , anticholinergics , emetics , cannabinoids , and 5-HT (serotonin) antagonists . The main classes of painkillers are NSAIDs , opioids , and local anesthetics . For consciousness (anesthetic drugs) Some anesthetics include benzodiazepines and barbiturates . The main categories of drugs for musculoskeletal disorders are: NSAIDs (including COX-2 selective inhibitors ), muscle relaxants , neuromuscular drugs , and anticholinesterases . Antibiotics , sympathomimetics , antihistamines , anticholinergics , NSAIDs , corticosteroids , antiseptics , local anesthetics , antifungals , and cerumenolytics. Bronchodilators , antitussives , mucolytics , decongestants , inhaled and systemic corticosteroids , beta2-adrenergic agonists , anticholinergics , mast cell stabilizers , leukotriene antagonists . Androgens , antiandrogens , estrogens , gonadotropin , corticosteroids , human growth hormone , insulin , antidiabetics ( sulfonylureas , biguanides / metformin , thiazolidinediones , insulin ), thyroid hormones , antithyroid drugs, calcitonin , diphosphonate , vasopressin analogues . Antifungal , alkalinizing agents , quinolones , antibiotics , cholinergics , anticholinergics , antispasmodics , 5-alpha reductase inhibitor , selective alpha-1 blockers , sildenafils , fertility medications . NSAIDs , anticholinergics , haemostatic drugs , antifibrinolytics , Hormone Replacement Therapy (HRT), bone regulators, beta-receptor agonists , follicle stimulating hormone , luteinising hormone , LHRH , gamolenic acid , gonadotropin release inhibitor , progestogen , dopamine agonists , oestrogen , prostaglandins , gonadorelin , clomiphene , tamoxifen , diethylstilbestrol . Emollients , anti-pruritics , antifungals , antiseptics , scabicides , pediculicides , tar products, vitamin A derivatives , vitamin D analogues , keratolytics , abrasives , systemic antibiotics , topical antibiotics , hormones , desloughing agents, exudate absorbents, fibrinolytics , proteolytics , sunscreens , antiperspirants , corticosteroids , immune modulators. Antibiotics , antifungals , antileprotics , antituberculous drugs , antimalarials , anthelmintics , amoebicides , antivirals , antiprotozoals , probiotics, prebiotics, antitoxins , and antivenoms. Vaccines , immunoglobulins , immunosuppressants , interferons , and monoclonal antibodies . Anti-allergics , antihistamines , NSAIDs , corticosteroids . Tonics, electrolytes and mineral preparations (including iron preparations and magnesium preparations ), parenteral nutrition , vitamins , anti-obesity drugs , anabolic drugs , haematopoietic drugs, food product drugs. Cytotoxic drugs , therapeutic antibodies , sex hormones , aromatase inhibitors , somatostatin inhibitors, recombinant interleukins , G-CSF , erythropoietin . Contrast media . A euthanaticum
5499-463: The endothelial cells of the alveolar capillaries (Fig. 10). This blood gas barrier is extremely thin (in humans, on average, 2.2 μm thick). It is folded into about 300 million small air sacs called alveoli (each between 75 and 300 μm in diameter) branching off from the respiratory bronchioles in the lungs , thus providing an extremely large surface area (approximately 145 m ) for gas exchange to occur. The air contained within
5616-410: The human gastrointestinal tract ), injection into the body, and by other routes ( dermal , nasal , ophthalmic , otologic , and urogenital ). Oral administration , the most common form of enteral administration, can be performed using various dosage forms including tablets or capsules and liquid such as syrup or suspension. Other ways to take the medication include buccally (placed inside
5733-410: The red blood cells . The reaction can go in both directions depending on the prevailing partial pressure of CO 2 . A small amount of carbon dioxide is carried on the protein portion of the hemoglobin molecules as carbamino groups. The total concentration of carbon dioxide (in the form of bicarbonate ions, dissolved CO 2 , and carbamino groups) in arterial blood (i.e. after it has equilibrated with
5850-405: The skin plays a vital role in gas exchange. Plants also have respiratory systems but the directionality of gas exchange can be opposite to that in animals. The respiratory system in plants includes anatomical features such as stomata , that are found in various parts of the plant. In humans and other mammals , the anatomy of a typical respiratory system is the respiratory tract . The tract
5967-509: The trachea or nose , respectively. In this manner, irritants caught in the mucus which lines the respiratory tract are expelled or moved to the mouth where they can be swallowed . During coughing, contraction of the smooth muscle in the airway walls narrows the trachea by pulling the ends of the cartilage plates together and by pushing soft tissue into the lumen. This increases the expired airflow rate to dislodge and remove any irritant particle or mucus. Respiratory epithelium can secrete
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#17328023984416084-428: The ventilation/perfusion ratio of alveoli from the tops of the lungs to the bottoms is eliminated, with all the alveoli perfused and ventilated in more or less the physiologically ideal manner. This is a further important contributor to the acclimatatization to high altitudes and low oxygen pressures. The kidneys measure the oxygen content (mmol O 2 /liter blood, rather than the partial pressure of O 2 ) of
6201-460: The 19.7 kPa of oxygen entering the alveolar air. (The tracheal partial pressure of oxygen is 21% of [100 kPa – 6.3 kPa] = 19.7 kPa). At the summit of Mt. Everest (at an altitude of 8,848 m or 29,029 ft), the total atmospheric pressure is 33.7 kPa , of which 7.1 kPa (or 21%) is oxygen. The air entering the lungs also has a total pressure of 33.7 kPa, of which 6.3 kPa is, unavoidably, water vapor (as it
6318-437: The actions of the intercostal muscles (Fig. 8). These accessory muscles of inhalation are muscles that extend from the cervical vertebrae and base of the skull to the upper ribs and sternum , sometimes through an intermediary attachment to the clavicles . When they contract, the rib cage's internal volume is increased to a far greater extent than can be achieved by contraction of the intercostal muscles alone. Seen from outside
6435-643: The active ingredient from traditional remedies or by serendipitous discovery. Later chemical libraries of synthetic small molecules , natural products , or extracts were screened in intact cells or whole organisms to identify substances that have a desirable therapeutic effect in a process known as classical pharmacology . Since sequencing of the human genome which allowed rapid cloning and synthesis of large quantities of purified proteins, it has become common practice to use high throughput screening of large compound libraries against isolated biological targets which are hypothesized to be disease-modifying in
6552-423: The adult human has a volume of about 2.5–3.0 liters (Fig. 3). Resting exhalation lasts about twice as long as inhalation because the diaphragm relaxes passively more gently than it contracts actively during inhalation. The volume of air that moves in or out (at the nose or mouth) during a single breathing cycle is called the tidal volume . In a resting adult human, it is about 500 ml per breath. At
6669-423: The air into close contact with the blood. These air sacs communicate with the external environment via a system of airways, or hollow tubes, of which the largest is the trachea , which branches in the middle of the chest into the two main bronchi . These enter the lungs where they branch into progressively narrower secondary and tertiary bronchi that branch into numerous smaller tubes, the bronchioles . In birds ,
6786-453: The alveolar air) is about 26 mM (or 58 ml/100 ml), compared to the concentration of oxygen in saturated arterial blood of about 9 mM (or 20 ml/100 ml blood). Ventilation of the lungs in mammals occurs via the respiratory centers in the medulla oblongata and the pons of the brainstem . These areas form a series of neural pathways which receive information about the partial pressures of oxygen and carbon dioxide in
6903-460: The alveolar partial pressure of carbon dioxide has returned to 5.3 kPa (40 mmHg). It is therefore strictly speaking untrue that the primary function of the respiratory system is to rid the body of carbon dioxide "waste". The carbon dioxide that is breathed out with each breath could probably be more correctly be seen as a byproduct of the body's extracellular fluid carbon dioxide and pH homeostats If these homeostats are compromised, then
7020-423: The alveoli during inhalation (i.e. it makes the lung stiff, or non-compliant). Surfactant reduces the surface tension and therefore makes the lungs more compliant , or less stiff, than if it were not there. Secondly, the diameters of the alveoli increase and decrease during the breathing cycle. This means that the alveoli have a greater tendency to collapse (i.e. cause atelectasis ) at the end of exhalation than at
7137-454: The alveoli has a semi-permanent volume of about 2.5–3.0 liters which completely surrounds the alveolar capillary blood (Fig. 12). This ensures that equilibration of the partial pressures of the gases in the two compartments is very efficient and occurs very quickly. The blood leaving the alveolar capillaries and is eventually distributed throughout the body therefore has a partial pressure of oxygen of 13–14 kPa (100 mmHg), and
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#17328023984417254-400: The ambient atmospheric pressure is about 100 kPa, the moistened air that flows into the lungs from the trachea consists of water vapor (6.3 kPa), nitrogen (74.0 kPa), oxygen (19.7 kPa) and trace amounts of carbon dioxide and other gases (a total of 100 kPa). In dry air the partial pressure of O 2 at sea level is 21.0 kPa (i.e. 21% of 100 kPa), compared to
7371-414: The animal is provided with a very special "portable atmosphere", whose composition differs significantly from the present-day ambient air . It is this portable atmosphere (the functional residual capacity ) to which the blood and therefore the body tissues are exposed – not to the outside air. The resulting arterial partial pressures of oxygen and carbon dioxide are homeostatically controlled . A rise in
7488-454: The anterior surface of the medulla oblongata . The aortic and carotid bodies , are the peripheral blood gas chemoreceptors which are particularly sensitive to the arterial partial pressure of O 2 though they also respond, but less strongly, to the partial pressure of CO 2 . At sea level, under normal circumstances, the breathing rate and depth, is determined primarily by the arterial partial pressure of carbon dioxide rather than by
7605-473: The antero-posterior diameter is increased by the so-called pump handle movement shown in Fig. 4. The enlargement of the thoracic cavity's vertical dimension by the contraction of the diaphragm, and its two horizontal dimensions by the lifting of the front and sides of the ribs, causes the intrathoracic pressure to fall. The lungs' interiors are open to the outside air and being elastic, therefore expand to fill
7722-439: The arterial partial pressure of oxygen , which is allowed to vary within a fairly wide range before the respiratory centers in the medulla oblongata and pons respond to it to change the rate and depth of breathing. Exercise increases the breathing rate due to the extra carbon dioxide produced by the enhanced metabolism of the exercising muscles. In addition, passive movements of the limbs also reflexively produce an increase in
7839-435: The arterial blood. When the oxygen content of the blood is chronically low, as at high altitude, the oxygen-sensitive kidney cells secrete erythropoietin (EPO) into the blood. This hormone stimulates the red bone marrow to increase its rate of red cell production, which leads to an increase in the hematocrit of the blood, and a consequent increase in its oxygen carrying capacity (due to the now high hemoglobin content of
7956-447: The arterial partial pressure of CO 2 and, to a lesser extent, a fall in the arterial partial pressure of O 2 , will reflexly cause deeper and faster breathing until the blood gas tensions in the lungs, and therefore the arterial blood, return to normal. The converse happens when the carbon dioxide tension falls, or, again to a lesser extent, the oxygen tension rises: the rate and depth of breathing are reduced until blood gas normality
8073-399: The basis of pharmacological properties like mode of action and their pharmacological action or activity, such as by chemical properties , mode or route of administration , biological system affected, or therapeutic effects . An elaborate and widely used classification system is the Anatomical Therapeutic Chemical Classification System (ATC system). The World Health Organization keeps
8190-538: The belly to bulge outwards to the front and sides, because the relaxed abdominal muscles do not resist this movement (Fig. 7). This entirely passive bulging (and shrinking during exhalation) of the abdomen during normal breathing is sometimes referred to as "abdominal breathing", although it is, in fact, "diaphragmatic breathing", which is not visible on the outside of the body. Mammals only use their abdominal muscles during forceful exhalation (see Fig. 8, and discussion below). Never during any form of inhalation. As
8307-451: The blood into the outside air. Oxygen has a very low solubility in water, and is therefore carried in the blood loosely combined with hemoglobin . The oxygen is held on the hemoglobin by four ferrous iron -containing heme groups per hemoglobin molecule. When all the heme groups carry one O 2 molecule each the blood is said to be “saturated” with oxygen, and no further increase in the partial pressure of oxygen will meaningfully increase
8424-449: The blood). In other words, at the same arterial partial pressure of O 2 , a person with a high hematocrit carries more oxygen per liter of blood than a person with a lower hematocrit does. High altitude dwellers therefore have higher hematocrits than sea-level residents. Irritation of nerve endings within the nasal passages or airways , can induce a cough reflex and sneezing . These responses cause air to be expelled forcefully from
8541-425: The body, the lifting of the clavicles during strenuous or labored inhalation is sometimes called clavicular breathing , seen especially during asthma attacks and in people with chronic obstructive pulmonary disease . During heavy breathing, exhalation is caused by relaxation of all the muscles of inhalation. But now, the abdominal muscles, instead of remaining relaxed (as they do at rest), contract forcibly pulling
8658-405: The breathing cycle, drawing air in and out of the lungs. The volume of air moved in or out of the lungs under normal resting circumstances (the resting tidal volume of about 500 ml), and volumes moved during maximally forced inhalation and maximally forced exhalation are measured in humans by spirometry . A typical adult human spirogram with the names given to the various excursions in volume
8775-418: The breathing rate. Information received from stretch receptors in the lungs' limits tidal volume (the depth of inhalation and exhalation). The alveoli are open (via the airways) to the atmosphere, with the result that alveolar air pressure is exactly the same as the ambient air pressure at sea level, at altitude, or in any artificial atmosphere (e.g. a diving chamber, or decompression chamber) in which
8892-406: The bronchioles are termed parabronchi . It is the bronchioles, or parabronchi that generally open into the microscopic alveoli in mammals and atria in birds. Air has to be pumped from the environment into the alveoli or atria by the process of breathing which involves the muscles of respiration . In most fish , and a number of other aquatic animals (both vertebrates and invertebrates ),
9009-400: The cheek), sublingually (placed underneath the tongue), eye and ear drops (dropped into the eye or ear), and transdermally (applied to the skin). They can be administered in one dose, as a bolus . Administration frequencies are often abbreviated from Latin, such as every 8 hours reading Q8H from Quaque VIII Hora . The drug frequencies are often expressed as the number of times a drug
9126-510: The combination, the company began trading on the NASDAQ using the ticker symbol VTRS. In December 2020, the company announced a cost-reducing restructuring plan that would impact up to 20% of its global workforce, or 9,000 jobs at its facilities around the world. In 2021, Viatris was ranked 5th by Fortune on its annual "Change the World" list for having "transformed the treatment of HIV around
9243-499: The commercialization rights to Phase 3 pharmaceuticals selatogrel , a cardiac medication, and cenerimod, a novel immunology medication used to treat systemic lupus erythematosus . The agreement includes the potential to add more assets in the future. Pharmaceutical A medication (also called medicament , medicine , pharmaceutical drug , medicinal drug or simply drug ) is a drug used to diagnose , cure , treat, or prevent disease. Drug therapy ( pharmacotherapy )
9360-531: The company worked with Sesame Workshop to create resources to help children and their caregivers manage their social and emotional needs impacted by the COVID-19 pandemic. In April 2021, the company partnered with Atomo Diagnostics and Unitaid to expand access to HIV self-testing to 135 countries and lower the price of the tests by around 50%. In February 2024, Viatris entered into an agreement with Idorsia to collaborate on global research and development and
9477-514: The company's board since 2022. In April 2023, Viatris was recognized by LinkedIn as one of the 25 best companies to work for in India, and one of the 25 best companies offering career development in Ireland. In May 2023, USA Today included Viatris in its list of 400 US companies that have reduced their greenhouse gas emissions intensity from 2019 to 2021. In June 2023, Viatris was named to
9594-406: The composition of the alveolar air and that of the ambient air can be maintained because the functional residual capacity is contained in dead-end sacs connected to the outside air by fairly narrow and relatively long tubes (the airways: nose , pharynx , larynx , trachea , bronchi and their branches down to the bronchioles ), through which the air has to be breathed both in and out (i.e. there
9711-482: The corporation set: expanding access to medicines, meeting patient needs through innovation, and earning the trust of the healthcare community. Viatris ranked 254th on the 2021 Fortune 500 rankings of the largest United States corporations based on its 2020 total revenue. On November 16, 2020, Upjohn merged with Mylan in a Reverse Morris Trust transaction and changed its name to Viatris. At that time, Michael Goettler became chief executive officer . Following
9828-399: The diaphragm contracts, the rib cage is simultaneously enlarged by the ribs being pulled upwards by the intercostal muscles as shown in Fig. 4. All the ribs slant downwards from the rear to the front (as shown in Fig. 4); but the lowermost ribs also slant downwards from the midline outwards (Fig. 5). Thus the rib cage's transverse diameter can be increased in the same way as
9945-432: The dry outside air at sea level, where the partial pressure of oxygen is 21 kPa (or 160 mm Hg) and that of carbon dioxide 0.04 kPa (or 0.3 mmHg). During heavy breathing ( hyperpnea ), as, for instance, during exercise, inhalation is brought about by a more powerful and greater excursion of the contracting diaphragm than at rest (Fig. 8). In addition, the " accessory muscles of inhalation " exaggerate
10062-419: The end of exhalation, the airways contain about 150 ml of alveolar air which is the first air that is breathed back into the alveoli during inhalation. This volume air that is breathed out of the alveoli and back in again is known as dead space ventilation, which has the consequence that of the 500 ml breathed into the alveoli with each breath only 350 ml (500 ml – 150 ml = 350 ml)
10179-405: The end of inhalation. Since surfactant floats on the watery surface, its molecules are more tightly packed together when the alveoli shrink during exhalation. This causes them to have a greater surface tension-lowering effect when the alveoli are small than when they are large (as at the end of inhalation, when the surfactant molecules are more widely spaced). The tendency for the alveoli to collapse
10296-513: The example given. The differences between the atmospheric and intrapulmonary pressures, driving air in and out of the lungs during the breathing cycle, are in the region of only 2–3 kPa. A doubling or more of these small pressure differences could be achieved only by very major changes in the breathing effort at high altitudes. All of the above influences of low atmospheric pressures on breathing are accommodated primarily by breathing deeper and faster ( hyperpnea ). The exact degree of hyperpnea
10413-425: The flow of air and blood to different parts of the lungs. It is only as a result of accurately maintaining the composition of the 3 liters of alveolar air that with each breath some carbon dioxide is discharged into the atmosphere and some oxygen is taken up from the outside air. If more carbon dioxide than usual has been lost by a short period of hyperventilation , respiration will be slowed down or halted until
10530-402: The hyperpnea at high altitude will cause a severe fall in the arterial partial pressure of carbon dioxide, with a consequent rise in the pH of the arterial plasma . This is one contributor to high altitude sickness . On the other hand, if the switch to oxygen homeostasis is incomplete, then hypoxia may complicate the clinical picture with potentially fatal results. There are oxygen sensors in
10647-416: The increased space, pleura fluid between double-layered pleura covering of lungs helps in reducing friction while lungs expansion and contraction. The inflow of air into the lungs occurs via the respiratory airways (Fig. 2). In a healthy person, these airways begin with the nose . (It is possible to begin with the mouth, which is the backup breathing system. However, chronic mouth breathing leads to, or
10764-418: The individual is breathing freely. With expansion of the lungs the alveolar air occupies a larger volume, and its pressure falls proportionally , causing air to flow in through the airways, until the pressure in the alveoli is again at the ambient air pressure. The reverse happens during exhalation. This process (of inhalation and exhalation) is exactly the same at sea level, as on top of Mt. Everest , or in
10881-430: The lower edges of the rib cage downwards (front and sides) (Fig. 8). This not only drastically decreases the size of the rib cage, but also pushes the abdominal organs upwards against the diaphragm which consequently bulges deeply into the thorax (Fig. 8). The end-exhalatory lung volume is now well below the resting mid-position and contains far less air than the resting "functional residual capacity". However, in
10998-476: The lungs and released into the blood when lung tissue is stretched. The lungs activate one hormone. The physiologically inactive decapeptide angiotensin I is converted to the aldosterone -releasing octapeptide, angiotensin II , in the pulmonary circulation. The reaction occurs in other tissues as well, but it is particularly prominent in the lungs. Angiotensin II also has a direct effect on arteriolar walls , causing arteriolar vasoconstriction , and consequently
11115-585: The lungs can undergo is illustrated below (Fig. 3): Not all the air in the lungs can be expelled during maximally forced exhalation ( ERV ). This is the residual volume (volume of air remaining even after a forced exhalation) of about 1.0–1.5 liters which cannot be measured by spirometry. Volumes that include the residual volume (i.e. functional residual capacity of about 2.5–3.0 liters, and total lung capacity of about 6 liters) can therefore also not be measured by spirometry. Their measurement requires special techniques. The rates at which air
11232-437: The lungs during breathing rarely exceeding 2–3 kPa. During exhalation, the diaphragm and intercostal muscles relax. This returns the chest and abdomen to a position determined by their anatomical elasticity. This is the "resting mid-position" of the thorax and abdomen (Fig. 7) when the lungs contain their functional residual capacity of air (the light blue area in the right hand illustration of Fig. 7), which in
11349-455: The opposite direction, through orifices in the pelvic floor. The abdominal muscles contract very powerfully, causing the pressure inside the abdomen and thorax to rise to extremely high levels. The Valsalva maneuver can be carried out voluntarily but is more generally a reflex elicited when attempting to empty the abdomen during, for instance, difficult defecation, or during childbirth. Breathing ceases during this maneuver. The primary purpose of
11466-446: The oxygen concentration of the blood. Most of the carbon dioxide in the blood is carried as bicarbonate ions (HCO 3 ) in the plasma. However the conversion of dissolved CO 2 into HCO 3 (through the addition of water) is too slow for the rate at which the blood circulates through the tissues on the one hand, and through alveolar capillaries on the other. The reaction is therefore catalyzed by carbonic anhydrase , an enzyme inside
11583-479: The playing of wind instruments. All of these actions rely on the muscles described above, and their effects on the movement of air in and out of the lungs. Although not a form of breathing, the Valsalva maneuver involves the respiratory muscles. It is, in fact, a very forceful exhalatory effort against a tightly closed glottis , so that no air can escape from the lungs. Instead, abdominal contents are evacuated in
11700-519: The respiratory system consists of gills , which are either partially or completely external organs, bathed in the watery environment. This water flows over the gills by a variety of active or passive means. Gas exchange takes place in the gills which consist of thin or very flat filaments and lammellae which expose a very large surface area of highly vascularized tissue to the water. Other animals, such as insects , have respiratory systems with very simple anatomical features, and in amphibians , even
11817-443: The respiratory system is lined with mucous membranes that contain mucosa-associated lymphoid tissue , which produces white blood cells such as lymphocytes . The lungs make a surfactant , a surface-active lipoprotein complex (phospholipoprotein) formed by type II alveolar cells . It floats on the surface of the thin watery layer which lines the insides of the alveoli, reducing the water's surface tension. The surface tension of
11934-417: The respiratory system is the equalizing of the partial pressures of the respiratory gases in the alveolar air with those in the pulmonary capillary blood (Fig. 11). This process occurs by simple diffusion , across a very thin membrane (known as the blood–air barrier ), which forms the walls of the pulmonary alveoli (Fig. 10). It consists of the alveolar epithelial cells , their basement membranes and
12051-428: The same amount of oxygen to the lungs at altitude as at sea level. During inhalation, the air is warmed and saturated with water vapor during its passage through the nose passages and pharynx . Saturated water vapor pressure is dependent only on temperature. At a body core temperature of 37 °C it is 6.3 kPa (47.0 mmHg), irrespective of any other influences, including altitude. Thus at sea level, where
12168-539: The same change in lung volume at sea level results in a 50 kPa difference in pressure between the ambient air and the intrapulmonary air, whereas it result in a difference of only 25 kPa at 5500 m. The driving pressure forcing air into the lungs during inhalation is therefore halved at this altitude. The rate of inflow of air into the lungs during inhalation at sea level is therefore twice that which occurs at 5500 m. However, in reality, inhalation and exhalation occur far more gently and less abruptly than in
12285-480: The same rate as the fall in air pressure with altitude. Therefore, in order to breathe in the same amount of oxygen per minute, the person has to inhale a proportionately greater volume of air per minute at altitude than at sea level. This is achieved by breathing deeper and faster (i.e. hyperpnea ) than at sea level (see below). There is, however, a complication that increases the volume of air that needs to be inhaled per minute ( respiratory minute volume ) to provide
12402-413: The same route. A system such as this creates dead space , a volume of air (about 150 ml in the adult human) that fills the airways after exhalation and is breathed back into the alveoli before environmental air reaches them. At the end of inhalation, the airways are filled with environmental air, which is exhaled without coming in contact with the gas exchanger. The lungs expand and contract during
12519-422: The segmental bronchi (1 to 6 mm in diameter) are known as 4th order, 5th order, and 6th order segmental bronchi, or grouped together as subsegmental bronchi. Compared to the 23 number (on average) of branchings of the respiratory tree in the adult human, the mouse has only about 13 such branchings. The alveoli are the dead end terminals of the "tree", meaning that any air that enters them has to exit via
12636-408: The size of the organism, the environment in which it lives and its evolutionary history. In land animals , the respiratory surface is internalized as linings of the lungs . Gas exchange in the lungs occurs in millions of small air sacs; in mammals and reptiles, these are called alveoli , and in birds, they are known as atria . These microscopic air sacs have a very rich blood supply, thus bringing
12753-445: The small airways lacking any cartilaginous support. The first bronchi to branch from the trachea are the right and left main bronchi. Second, only in diameter to the trachea (1.8 cm), these bronchi (1–1.4 cm in diameter) enter the lungs at each hilum , where they branch into narrower secondary bronchi known as lobar bronchi, and these branch into narrower tertiary bronchi known as segmental bronchi. Further divisions of
12870-408: The smaller bronchi and bronchioles . In response to low partial pressures of oxygen in the inhaled air these sensors reflexively cause the pulmonary arterioles to constrict. (This is the exact opposite of the corresponding reflex in the tissues, where low arterial partial pressures of O 2 cause arteriolar vasodilation.) At altitude this causes the pulmonary arterial pressure to rise resulting in
12987-521: The state level, or at both state and national levels by various bodies, as is the case in Australia. The role of therapeutic goods regulation is designed mainly to protect the health and safety of the population. Regulation is aimed at ensuring the safety, quality, and efficacy of the therapeutic goods which are covered under the scope of the regulation. In most jurisdictions, therapeutic goods must be registered before they are allowed to be marketed. There
13104-409: The thoracic cavity from the abdominal cavity. When it contracts, the sheet flattens, (i.e. moves downwards as shown in Fig. 7) increasing the volume of the thoracic cavity in the antero-posterior axis. The contracting diaphragm pushes the abdominal organs downwards. But because the pelvic floor prevents the lowermost abdominal organs from moving in that direction, the pliable abdominal contents cause
13221-487: The traditional immune cells and others to the site of infections. Surfactant immune function is primarily attributed to two proteins: SP-A and SP-D. These proteins can bind to sugars on the surface of pathogens and thereby opsonize them for uptake by phagocytes. It also regulates inflammatory responses and interacts with the adaptive immune response. Surfactant degradation or inactivation may contribute to enhanced susceptibility to lung inflammation and infection. Most of
13338-473: The various branches of "tree" are often referred to as branching "generations", of which there are, in the adult human, about 23. The earlier generations (approximately generations 0–16), consisting of the trachea and the bronchi, as well as the larger bronchioles which simply act as air conduits , bringing air to the respiratory bronchioles, alveolar ducts and alveoli (approximately generations 17–23), where gas exchange takes place. Bronchioles are defined as
13455-444: The volume of the lungs were to be instantaneously doubled at the beginning of inhalation, the air pressure inside the lungs would be halved. This happens regardless of altitude. Thus, halving of the sea level air pressure (100 kPa) results in an intrapulmonary air pressure of 50 kPa. Doing the same at 5500 m, where the atmospheric pressure is only 50 kPa, the intrapulmonary air pressure falls to 25 kPa. Therefore,
13572-435: The world in the [previous] five years through the first low-cost antiretroviral drug for first-line treatment of HIV and a children's version in the form of fruit-flavored tablets that dissolve in liquid. In February 2022, Viatris announced an agreement where it will contribute to Biocon Biologics its biosimilars portfolio and related commercial and operational capabilities in exchange for up to $ 3.335 billion, including
13689-742: Was established include: Following the formation of Viatris, the company became a member of the Biosimilars Forum, a trade organization that advocates for greater biosimilar usage. Viatris partnered with the American College of Cardiology , the NCD Alliance , and the World Heart Federation to create the NCD Academy, a platform to help fight non-communicable diseases around the world. In December 2020,
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