DOCSLIB.ORG

The Effect of Anemia on the Ventilatory Response to Transient and Steady-State Hypoxia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Effect of Anemia on the Ventilatory Response to Transient and Steady-State Hypoxia The effect of anemia on the ventilatory response to transient and steady-state hypoxia. T V Santiago, … , N H Edelman, A P Fishman J Clin Invest. 1975;55(2):410-418. https://doi.org/10.1172/JCI107945. Research Article The effects of anemia upon the ventilatory responses to transient and steady-state hypoxia were studied in unanesthetized goats. Responses to transient hypoxia (inhalation of several breaths of nitrogen) were considered to reflect peripheral chemoreceptor and non-chemoreceptor influences of hypoxia upon ventilatory control. In all goats, severe anemia (hemoglobin 3.1-4.8 g/100ml) markedly heightened the responses to transient hypoxia (from a mean of 0.27 to a mean of 0.75 liter/min/percent fall in SaO2). This phenomenon was substantially reversed by alpha-adrenergic blockade (phenoxybenzamine, 5 mg/kg). In contrast, the ventilatory responses to steady-state hypoxia were unaffected by severe anemia. These data suggest that severe anemia enhances the peripheral chemoreceptor-mediated response to hypoxia through a mechanism involving the alpha-adrenergic system. It also appears that a ventilatory depressant effect of hypoxia which is not mediated by the peripheral chemoreceptors is also enhanced by severe anemia, thereby preventing an increase in the steady-state ventilatory response to hypoxia. Finally, experiments involving variation in oxygen affinity of hemoglobin suggested that O2 tension rather than O2 availability in arterial blood is the major determinant of peripheral chemoreceptor activity. Find the latest version: https://jci.me/107945/pdf The Effect of Anemia on the Ventilatory Response to Transient and Steady-State Hypoxia TEODORO V. SANTIAGO, NORMAN H. EDELMAN, and AMnRE P. FISHMAN From the Pulmonary Diseases Division, Department of Medicine of the College of Medicine and Dentistry of New Jersey-Rutgers Medical School, Piscataway, New Jersey 08854, and Cardiovascular-Pulmonary Division, Department of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania 19104 A B S T R A C T The effects of anemia upon the ventila- of arterial blood (1). There is also considerable un- tory responses to transient and steady-state hypoxia were certainty concerning the effects of anemia upon ventila- studied in unanesthetized goats. Responses to transient tion per se and upon the ventilatory response to hypoxia hypoxia (inhalation of several breaths of nitrogen) were (2, 3). This issue is of clinical interest since new modes considered to reflect peripheral chemoreceptor-mediated of therapy for patients with hematologic malignancies reflexes whereas responses to steady-state hypoxia were and chronic renal failure have increased the prevalence considered to reflect both the chemoreceptor and non- of individuals with severe chronic anemia who are likely chemoreceptor influences of hypoxia upon ventilatory to encounter hypoxia-producing respiratory disorders. control. In all goats, severe anemia (hemoglobin 3.1-4.8 One basis for the disparate results obtained in previ- g/100 ml) markedly heightened the responses to transi- ous studies of the ventilatory response to hypoxia in ent hypoxia (from a mean of 0.27 to a mean of 0.75 liter/ anemia may be the use of steady-state methods. This min/percent fall in SaO2). This phenomenon was sub- reservation stems from the fact that ventilatory responses stantially reversed by alpha-adrenergic blockade (phe- to all but exceedingly brief periods of hypoxia prob- noxybenzamine, 5 mg/kg). In contrast, the ventilatory ably reflect the combined effects of stimulation of the responses to steady-state hypoxia were unaffected by peripheral chemoreceptors and of depression of ventila- severe anemia. These data suggest that severe anemia tion via a direct effect upon the central nervous system enhances the peripheral chemoreceptor-mediated re- (4). Anemia could complicate the situation by decreas- sponse to hypoxia through a mechanism involving the ing oxygen delivery to both the peripheral chemore- alpha-adrenergic system. It also appears that a ventila- ceptors and the brain. tory depressant effect of hypoxia which is not mediated The protocols of the present study were, therefore, by the peripheral chemoreceptors is also enhanced by designed to evaluate separately the peripheral chemo- severe anemia, thereby preventing an increase in the receptor and the direct central nervous ventilatory ef- steady-state ventilatory response to hypoxia. Finally, ex- fects of hypoxia in intact unanesthetized animals. In periments involving variation in oxygen affinity of hemo- order to make this distinction, we took advantage of the globin suggested that O tension rather than 02 avail- fact that the peripheral chemoreceptor stimulation of ability in arterial blood is the major determinant of ventilation occurs within 2-10 s after exposure to acute peripheral chemoreceptor activity. hypoxia (5), whereas the centrally mediated depression of ventilation by acute hypoxia takes 40-60 s to become INTRODUCTION manifest (6, 7). We, therefore, assessed the peripheral chemoreceptor responses to hypoxia by exposure of un- It has long been known that acute oxygen lack stimulates anesthetized goats to brief inhalations of nitrogen and, in ventilation. However, many facets of this reflex are still the same animals, we considered the responses to steady- obscure. It is not yet clear whether the peripheral ar- state hypoxia to provide a measure of the combined ef- terial chemoreceptors sense oxygen tension or content fects of the peripheral chemoreceptor and central ner- of Received for publication 14 February 1974 and in revised vous effects hypoxia. form 23 September 1974. From these experiments, we have been able to evalu- 410 The Journal of Clinical Investigation Volume 55 February 1975- 410 418 ate the roles of several factors in the overall ventilatory pressure to be recorded simultaneously as blood was with- response to hypoxia during chronic anemia. These in- drawn. It was shown that removal of 30-40 ml as during the transient hypoxia studies was without effect on the clude oxygen content of arterial blood, the degree of ventilation, blood pressure, and heart rate. Separate studies affinity of hemoglobin for oxygen, the level of sympa- comparing the effects of introducing the catheter via the thetic nervous system activity, and the effects of hypoxia carotid artery and the femoral artery also failed to disclose upon tissues other than the peripheral chemoreceptors. any difference in the observed data which might have been attributable to the different sites of cannulation. METHODS Steady-state hypoxia and hypercapnia The experiments were performed on 17 goats which ranged The same valving system was used to deliver air fol- in weight from 30 to 35 kg. 1 wk before the onset of the lowed by a mixture of 12% oxygen in nitrogen for 7 min study, under general anesthesia, an indwelling arterial can- each. Ventilation, blood pressure, and heart rate were re- nula was placed in the descending aorta via a carotid or corded continuously. Arterial blood was collected anero- femoral artery. During the week between the arterial can- bically after 6 min of breathing air and after 1.5 and 6 nulation and the experiments, the animals were trained min of breathing the hypoxic mixture. Expired gas was to the test procedures by exposure to mock experiments and collected for 1 min after 6 min of inhalation of each gas equipment in the laboratory. The animals were studied un- mixture. The blood samples were analyzed within 10 min anesthetized and were lightly restrained by fixing the using appropriate electrodes (Radiometer Co., Copenhagen, horns to a post while standing upright. Denmark) at 370C for Po2, Pco2, and pH. Oxygen satura- The experimental procedure involved the use of a snug tion and hemoglobin content were determined by spectro- mask, with a dead space of 100 ml, fitted to a Rudolph one- photometry (CO-Oximeter, Instrumentation Laboratory way breathing valve (0. C. Rudolph and Sons Inc., Cald- Inc., Lexington, Mass.). The volume of expired gas was well, N. J.). Wide-bore tubing at both ends of the valve measured with a calibrated dry-gas meter and samples made possible a switch from one inspired gas to another, were collected anerobically for determination of Po2 and or the collection of expired gas, without disturbing the Pco2 (Radiometer Co.). The accuracy of the analyzers was goat. Ventilation was measured using a Fleisch pneumo- checked periodically using the micro-Scholander technique tachograph that was interposed in the inspiratory line and (10). Oxygen consumption, carbon dioxide production, and attached to a differential pressure transducer (Statham respiratory quotient were calculated in the usual way (11). PM-15, Statham Instruments, Inc., Oxnard, Calif.). The The ventilatory response to inspired C02 was determined pressure signal was converted to a signal proportional to by administering an inspired gas mixture of 5% CO2 in tidal volume using an integrator circuit and records were 30% 02 plus N2 after a period of breathing a mixture of made using an oscilloscopic recorder (Electronics for Med- 30% 02 in N2. Each period lasted for 10 min. Expired icine, Inc., White Plains, N. Y.). Calibrations of volume gas and arterial blood were sampled during the last minute were made using a 2-liter syringe; these calibrations were of each period. The volume of expired gas and the pH, repeated three times during each experiment. Each calibra- Pco2, and Po2 of the arterial blood were measured as above. tion deviated by less than 10% from the average value. The ventilatory response to CO2 was expressed as the ratio of the increase in ventilation to the increase in arterial Transient hypoxia Pco:. The method for determining the ventilatory response to Groups of studies transient hypoxia was a modification of that originally described by Dejours (8). Before the start of the ex- Four groups of studies were done: (a) determination of perimental procedure, the goats were anticoagulated with the effects of anemia upon the ventilatory responses to heparin (2 mg/kg) administered i.v.
Load more

Recommended publications
  • Human Physiology an Integrated Approach
    Gas Exchange and Transport Gas Exchange in the Lungs and Tissues 18 Lower Alveolar P Decreases Oxygen Uptake O2 Diff usion Problems Cause Hypoxia Gas Solubility Aff ects Diff usion Gas Transport in the Blood Hemoglobin Binds to Oxygen Oxygen Binding Obeys the Law of Mass Action Hemoglobin Transports Most Oxygen to the Tissues P Determines Oxygen-Hb Binding O2 Oxygen Binding Is Expressed As a Percentage Several Factors Aff ect Oxygen-Hb Binding Carbon Dioxide Is Transported in Three Ways Regulation of Ventilation Neurons in the Medulla Control Breathing Carbon Dioxide, Oxygen, and pH Infl uence Ventilation Protective Refl exes Guard the Lungs Higher Brain Centers Aff ect Patterns of Ventilation The successful ascent of Everest without supplementary oxygen is one of the great sagas of the 20th century. — John B. West, Climbing with O’s , NOVA Online (www.pbs.org) Background Basics Exchange epithelia pH and buff ers Law of mass action Cerebrospinal fl uid Simple diff usion Autonomic and somatic motor neurons Structure of the brain stem Red blood cells and Giant liposomes hemoglobin of pulmonary Blood-brain barrier surfactant (40X) From Chapter 18 of Human Physiology: An Integrated Approach, Sixth Edition. Dee Unglaub Silverthorn. Copyright © 2013 by Pearson Education, Inc. All rights reserved. 633 Gas Exchange and Transport he book Into Thin Air by Jon Krakauer chronicles an ill- RUNNING PROBLEM fated trek to the top of Mt. Everest. To reach the summit of Mt. Everest, climbers must pass through the “death zone” T High Altitude located at about 8000 meters (over 26,000 ft ). Of the thousands of people who have attempted the summit, only about 2000 have been In 1981 a group of 20 physiologists, physicians, and successful, and more than 185 have died.
    [Show full text]
  • Absolute Measurements of Cerebral Perfusion and Oxygenation in Rats with Near-Infrared Spectroscopy Bertan Hallacoglu1, Angelo Sassaroli1, Irwin H
    Absolute measurements of cerebral perfusion and oxygenation in rats with near-infrared spectroscopy Bertan Hallacoglu1, Angelo Sassaroli1, Irwin H. Rosenberg2, Aron Troen2 and Sergio Fantini1 Tufts University Department of Biomedical Engineering, Medford, MA (1) and USDA Human Nutrition Research Center on Aging, Boston, MA (2) Brain microvascular pathology is a common finding in Alzheimer’s disease and other dementias. However, Figure 2 – Time traces of [Hb], [HbO2], [HbT], StO2 and SaO2 during the hypoxia and hypercapnia protocols 10 and 20 weeks after Figure 3 – Illustration of the differences in animal groups and the extent to which microvascular abnormalities cause or contribute to cognitive impairment is unclear. the start of folate deficient diet (blue and red lines represent the mean values for each dietary group, whereas, dashed lines indicate changes within each group between weeks 10 and 20 in Dietary vascular risk factors, including poor folate status are potentially modifiable predictors of cognitive the range corresponding to ± one standard error from the mean). A first striking result is the consistency of baseline values across cerebral tissue saturation (StO2) and concentration of impairment among older adults. Folate deficiency in rat impairs cognition and causes cerebral animals within a group (control or folate deficient), and the reproducibility of baseline values measured at weeks 10 and 20. hemoglobin ([HbT]), blood concentration of hemoglobin ([HbT]b), microvascular damage, without concomitant neurodegeneration [1]. We hypothesized that folate Absolute brain total hemoglobin concentration ([HbT]) and tissue oxygen saturation (StO2) are significantly reduced by folate and partial blood volume (Vb/Vt) Eq. (1). FD rats have deficiency might result in functional decrements in cerebral oxygen delivery and vascular reactivity.
    [Show full text]
  • Respiration the Main Function of the Respiratory System Is Gas Exchange
    Respiration The main function of the respiratory system is gas exchange. Gas exchange is achieved through a process called respiration, or breathing. The cardiovascular system and the respiratory system work together to accomplish respiration. External Respiration During external respiration, fresh oxygen from outside the body fills the lungs and alveoli, and carbon dioxide is transported from the body tissues to the lungs. For oxygen to reach the body’s tissues and carbon dioxide to leave the body, gas exchange must occur in the alveolar capillary membrane. The alveoli and the capillaries that surround them make up the alveolar (al-VEE-oh-lar) capillary membrane (Figure 9.5 in the textbook). The alveolar capillary membrane is built for gas exchange, as explained by Fick’s Law. Fick’s Law states that the diffusion of oxygen and carbon dioxide between the capillaries and the alveolar sacs is proportional to the surface area (S.A.) of the lungs, the diffusion constant (D) of each gas, and the difference in partial pressure between each capillary and alveolar sac (P1-P2). According to this law, the diffusion of gases is also inversely related to the thickness of the tissues (T) involved. In simpler terms, thin-walled tissues allow for easier gas exchange. Diffusion = Therefore, oxygen easily diffuses across the membrane of the alveolar sacs and into the capillaries. Carbon dioxide passes from the capillaries into the alveolar sacs, where it can be expelled from the body via the lungs (Figure 9.5). How fast does gas exchange occur in the lungs? Faster than you might think.
    [Show full text]
  • Oxygen Transport During Ex Situ Machine Perfusion of Donor Livers Using Red Blood Cells Or Artificial Oxygen Carriers
    International Journal of Molecular Sciences Review Oxygen Transport during Ex Situ Machine Perfusion of Donor Livers Using Red Blood Cells or Artificial Oxygen Carriers Silke B. Bodewes 1,2 , Otto B. van Leeuwen 1,3, Adam M. Thorne 1,3, Bianca Lascaris 1,3, Rinse Ubbink 3, Ton Lisman 2 , Diethard Monbaliu 4,5 , Vincent E. De Meijer 1 , Maarten W. N. Nijsten 6 and Robert J. Porte 1,* 1 Section of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; [email protected] (S.B.B.); [email protected] (O.B.v.L.); [email protected] (A.M.T.); [email protected] (B.L.); [email protected] (V.E.D.M.) 2 Surgical Research Laboratory, Department of Surgery, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; [email protected] 3 Organ Preservation & Resuscitation Unit, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; [email protected] 4 Department of Abdominal Transplantation Surgery and Coordination, University Hospitals Leuven, 3000 Leuven, Belgium; [email protected] 5 Transplantation Research Group, Department of Microbiology, Immunology, and Transplantation, Katholieke Universiteit Leuven, 3000 Leuven, Belgium 6 Department of Critical Care, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands; [email protected] * Correspondence: [email protected]; Tel./Fax: +31-50-3611745 Abstract: Oxygenated ex situ machine perfusion of donor livers is an alternative for static cold preservation that can be performed at temperatures from 0 ◦C to 37 ◦C.
    [Show full text]
  • Hemoglobin/Myoglobin Robert F.Diegelmann, Ph.D
    Hemoglobin/Myoglobin Robert F.Diegelmann, Ph.D. OBJECTIVES 1. Describe the interactions of heme, globins and oxygen. 2. Discuss the mechanism responsible for Sickle­Cell Anemia. 3. Understand the clinical significance of A1C hemoglobin. 4. Describe the basic biochemical mechanisms of O2 delivery & CO2 removal. RECOMMENDED RESOURCES Lehninger, Principles of Biochemistry, 5th edition, Chapter 5 Molecular Cell Biology, 5th edition; Lodish et al., page 67 http://web.indstate.edu/thcme/mwking/hemoglobin­myoglobin.html#hemoglobin Myoglobin (muscle) & Hemoglobin (Red Blood Cells) were the first proteins for which three­ dimensional structures were determined. Professor Max Perutz and his colleagues at Cambridge University determined Hemoglobin’s three dimensional structure in the late 1950s Therefore Hemoglobin is one of the most studied & best understood proteins. Figure 1. The Evolution of the Globin protein family Figure 2. Structural similarity of the Globin proteins Figure 3 Below is the basic heme group structure. It consists of a complex organic ring structure named Protoporphyrin. NOTE: Heme metabolism will be covered in more detail in another lecture. Protoporphyrin prosthetic group Porphyrin ring Fe binding site Methene bridge Substitution sites Figure 4 Oxygen is not very soluble in aqueous solutions and therefore needs a special molecule to be carried to tissues and cells. The Protoporphyrin ring structure of Heme binds a single iron atom in its ferrous (Fe 2+) . The iron atom has six coordination bonds, four are found bound to the nitrogens in the Porphyrin ring system and two additional sites perpendicular to the Porphyrin. The Cytochromes (a, b & c) are proteins that also consist of porphyrin structures.
    [Show full text]
  • Prognostic Value of the Hemoglobin/Red Cell Distribution Width Ratio in Resected Lung Adenocarcinoma
    cancers Article Prognostic Value of the Hemoglobin/Red Cell Distribution Width Ratio in Resected Lung Adenocarcinoma Francesco Petrella 1,2,* , Monica Casiraghi 1 , Davide Radice 3, Andrea Cara 1, Gabriele Maffeis 1, Elena Prisciandaro 1, Stefania Rizzo 4,5 and Lorenzo Spaggiari 1,2 1 Department of Thoracic Surgery, IEO European Institute of Oncology IRCCS, 20141 Milan, Italy; [email protected] (M.C.); [email protected] (A.C.); [email protected] (G.M.); [email protected] (E.P.); [email protected] (L.S.) 2 Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, 20141 Milan, Italy 3 Department of Biostatistics, IEO European Institute of Oncology IRCCS, 20141 Milan, Italy; [email protected] 4 Department of Radiology, Ente Ospedaliero Cantonale (EOC) Istituto di Imaging della Svizzera Italiana (IIMSI), 6903 Lugano, Switzerland; [email protected] 5 Facoltà di Scienze Biomediche, Università della Svizzera italiana, via Buffi 13, 6900 Lugano, Switzerland * Correspondence: [email protected] or [email protected]; Tel.: +39-025-748-9362; Fax: +39-029-437-9218 Simple Summary: Low hemoglobin (Hb) values—indicating a condition of anemia—are related to impaired nutrition and immune system status, suggesting reduced tolerance to therapies in oncologic patients. In fact, it has been shown that pre-treatment anemia predicts poor outcomes in many neoplastic diseases. Similarly, red cell distribution width—which is a measure of the size of variation of circulating erythrocytes—has been shown to be closely related to poor prognosis Citation: Petrella, F.; Casiraghi, M.; both in cardiovascular and in oncologic diseases.
    [Show full text]
  • Improved Oxygen Release: an Adaptation of Mature Red Cells to Hypoxia
    Improved oxygen release: an adaptation of mature red cells to hypoxia Miles J. Edwards, … , Carrie-Lou Walters, James Metcalfe J Clin Invest. 1968;47(8):1851-1857. https://doi.org/10.1172/JCI105875. Research Article Blood from patients with erythrocytosis secondary to arterial hypoxemia due either to congenital heart disease or to chronic obstructive pulmonary disease was shown to have a decreased affinity for oxygen; the average oxygen pressure required to produce 50% saturation of hemoglobin with oxygen was 29.8 mm Hg (average normal, 26.3 mm Hg). Such a displacement of the blood oxygen equilibrium curve promotes the release of oxygen from blood to the tissues. Studies were also performed upon blood from a man with complete erythrocyte aplasia who received all of his red cells by transfusion from presumably normal persons. With mild anemia (hematocrit, 28%), the affinity of his blood for oxygen was slightly diminished (an oxygen pressure of 27.0 mm Hg was required to produce 50% saturation of hemoglobin with oxygen). With severe anemia (hematocrit, 13.5%), however, his blood had a markedly decreased oxygen affinity (an oxygen pressure of 29.6 mm Hg was required to produce 50% saturation of hemoglobin with oxygen). We conclude that patients with various conditions characterized by an impairment in the oxygen supply system to tissues respond with a diminished affinity of their blood for oxygen. Although the mechanism which brings about this adaptation is not known, the displacement of the oxygen equilibrium curve is associated with an increase in heme-heme interaction. The decrease in blood oxygen affinity […] Find the latest version: https://jci.me/105875/pdf Improved Oxygen Release: an Adaptation of Mature Red Cells to Hypoxia MUas J.
    [Show full text]
  • A Carbon Monoxide Transport Model of the Human Respiratory System Applied to …
    A Carbon Monoxide Transport Model of The Human Respiratory System Applied to … A Carbon Monoxide Transport Model Cyro Albuquerque Neto of the Human Respiratory System [email protected] Applied to Urban Atmosphere Jurandir Itizo Yanagihara Senior Member, ABCM Exposure Analysis [email protected] The aim of this work is to analyze the carbon monoxide (CO) transport in the human body submitted to several physical activity levels. A complete mathematical model of the human respiratory system was developed, considering the exchanges of CO, oxygen (O2) and Fábio Turri carbon dioxide (CO2) in the lung, blood and tissues. The human body was divided in the [email protected] following compartments: alveolar, pulmonary capillaries, arterial, venous, tissue capillary University of Sao Paulo - USP and tissues. The gas transport in the blood and tissues is represented by empirical Escola Politécnica equations. The physiological parameters were described in function of physical activity. Department of Mechanical Engineering The model was validated by comparing its results with experimental data of controlled CO 055809-900 São Paulo, SP, Brazil exposition. The agreement was excellent. CO concentration curves for critical days of São Caetano do Sul city (SP, Brazil) atmosphere were used as model input. The simulation results for some physical activities show that the more intense the activity, the larger the blood carboxyhemoglobin (COHb) level variations. The COHb level was compared with a CO quality air criteria, which showed to be adequate for low and moderate physical activity levels. Keywords: compartment model, carbon monoxide, gas transport, respiratory system, air pollution The models of Selvakumar, Sharan and Singh (1992) and Introduction Sharan and Selvakumar (1999) divide the lung into compartments, one alveolar and several pulmonary capillaries.
    [Show full text]
  • Myoglobin/Hemoglobin O2 Binding and Allosteric Properties
    Myoglobin/Hemoglobin O2 Binding and Allosteric Properties of Hemoglobin •Hemoglobin binds and transports H+, O2 and CO2 in an allosteric manner •Allosteric interaction - a regulatory mechanism where a small molecule (effector) binds and alters an enzymes activity ‘globin Function O does not easily diffuse in muscle and O is toxic to biological 2 2 systems, so living systems have developed a way around this. Physiological roles of: – Myoglobin • Transports O2 in rapidly respiring muscle • Monomer - single unit • Store of O2 in muscle high affinity for O2 • Diving animals have large concentration of myoglobin to keep O2 supplied to muscles – Hemoglobin • Found in red blood cells • Carries O2 from lungs to tissues and removes CO2 and H+ from blood to lungs • Lower affinity for O2 than myoglobin • Tetrameter - two sets of similar units (α2β2) Myo/Hemo-globin • Hemoglobin and myoglobin are oxygen- transport and oxygen-storage proteins, respectively • Myoglobin is monomeric; hemoglobin is tetrameric – Mb: 153 aa, 17,200 MW – Hb: two α chains of 141 residues, 2 β chains of 146 residues X-ray crystallography of myoglobin – mostly α helix (proline near end of each helix WHY?) – very small due to the folding – hydrophobic residues oriented towards the interior of the protein – only polar aas inside are 2 histidines Structure of heme prosthetic group Protoporphyrin ring w/ iron = heme Oxygenation changes state of Fe – Purple to red color of blood, Fe+3 - brown Oxidation of Fe+2 destroys biological activity of myoglobin Physical barrier of protein
    [Show full text]
  • Respiratory System.Pdf
    Respiratory System Respiratory System - Overview: Assists in the detection Protects system of odorants Respiratory (debris / pathogens / dessication) System 5 3 4 Produces sound (vocalization) Provides surface area for gas exchange (between air / blood) 1 2 For the body to survive, there must be a constant supply of Moves air to / from gas O2 and a constant exchange surface disposal of CO 2 Marieb & Hoehn (Human Anatomy and Physiology, 8th ed.) – Table 19.1 Respiratory System Respiratory System Functional Anatomy: Functional Anatomy: Trachea Epiglottis Naming of pathways: • > 1 mm diameter = bronchus Upper Respiratory • Conduction of air • < 1 mm diameter = bronchiole System • Gas exchange Primary • < 0.5 mm diameter = terminal bronchiole Bronchus • Filters / warms / humidifies Lower Respiratory Bronchi System incoming air bifurcation (23 orders) 1) External nares 5) Larynx 2) Nasal cavity • Provide open airway Green = Conducting zone • Resonance chamber • channel air / food Purple = Respiratory zone 3) Uvula • voice production (link) 4) Pharynx 6) Trachea 7) Bronchial tree • Nasopharynx Bronchiole 8) Alveoli • Oropharynx Terminal Bronchiole Respiratory Bronchiole • Laryngopharynx Alveolus Martini et. al. (Fundamentals of Anatomy and Physiology, 7th ed.) – Figure 23.1 Martini et. al. (Fundamentals of Anatomy and Physiology, 7th ed.) – Figure 23.9 Respiratory System Respiratory System Functional Anatomy: Functional Anatomy: Respiratory Mucosa / Submucosa: How are inhaled debris / pathogens cleared from respiratory tract? Near Near trachea alveoli Nasal Cavity: Epithelium: Particles > 10 µm Pseudostratified Simple columnar cuboidal Conducting Zone: Particles 5 – 10 µm Cilia No cilia Respiratory Zone: Mucus Escalator Particles 1 – 5 µm Mucosa: Lamina Propria (areolar tissue layer): Mucous membrane (epithelium / areolar tissue) smooth smooth muscle muscle Mucous No glands mucous glands Cartilage: Rings Plates / none Macrophages Martini et.
    [Show full text]
  • Tissue Hypoxia: Implications for the Respiratory Clinician
    Tissue Hypoxia: Implications for the Respiratory Clinician Neil R MacIntyre MD FAARC Introduction Causes of Hypoxia Hypoxemia Oxygen Delivery Oxygen Extraction/Utilization Compensatory Mechanisms for Hypoxia Current and Future Clinical Implications Summary Oxygen is essential for normal aerobic metabolism in mammals. Hypoxia is the presence of lower than normal oxygen content and pressure in the cell. Causes of hypoxia include hypoxemia (low blood oxygen content and pressure), impaired oxygen delivery, and impaired cellular oxygen up- take/utilization. Many compensatory mechanisms exist at the global, regional, and cellular levels to allow cells to function in a hypoxic environment. Clinical management of tissue hypoxia usually focuses on global hypoxemia and oxygen delivery. As we move into the future, the clinical focus needs to change to assessing and managing mission-critical regional hypoxia to avoid unnecessary and potential toxic global strategies. We also need to focus on understanding and better harnessing the body’s own adaptive mechanisms to hypoxia. Key words: hypoxia; hypoxemia; alveolar ventila- tion; ventilation/perfusion matching; diffusion; hemoglobin binding; hemoglobin-oxygen binding; re- gional oxygenation; oxygen extraction; oxygen utilization; hypoxia-inducible factors. [Respir Care 2014;59(10):1590–1596. © 2014 Daedalus Enterprises] Introduction with oxygen to produce energy (converting adenosine 5Ј- Ј diphosphate to adenosine 5 -triphosphate) along with CO2 Oxygen is essential for normal aerobic metabolism in and
    [Show full text]
  • Anemia and Hemoglobin Testing
    Hematology Anemia and hemoglobin testing Hematology Our mission Contents EKF Hematology aims to make blood 1. What is anemia? donation and anemia screening easier, more affordable and more accessible 2. Causes of anemia than ever before. 3. Symptoms and health consequences Our diagnostic tests deliver fast and reliable results for hemoglobin 4. Patients at risk and hematocrit that provide both practitioner and patient with the 5. Blood donation information they need to make clinical 6. Treatment of anemia or lifestyle decisions in seconds. 7. Methods of testing Hb/Hct 8. Factors influencing the measurement 9. References and units Pharmacies Blood banks • Health check • Donor check Maternity care Hospitals • Anemia testing • Dialysis units H • Emergency rooms • OBGY • Critical care • Operating theatres GP surgeries Field clinics • Anemia testing • Anemia screening • Malnutrition programmes • HIV and malaria programmes 1 What is anemia? Anemia is a condition in which the gender, altitude, smoking behavior number of healthy red blood cells or the and different stages of pregnancy. availability of hemoglobin falls below The volume percentage of red blood the body’s physiologic needs. cells in a blood sample is called hematocrit (Hct), also known as packed Hemoglobin (Hb) is a protein based cell volume (PCV). component and is the main part of red blood cells. It binds oxygen Hemoglobin or hematocrit tests are to transport around the body and the main blood tests used to diagnose ensures sufficient supply to tissues and anemia. Anemia can be caused by poor organs. Hemoglobin also helps in the nutrition or various diseases. transportation of carbon dioxide and hydrogen ions back to the lungs.
    [Show full text]