A hypertrophied bronchial circulatory system may participate in gas exchange

The Lancet ◽  
1998 ◽  
Vol 351 (9096) ◽  
pp. 113 ◽  
Author(s):  
Noreen R Henig ◽  
Robb W Glenny ◽  
Moira L Aitken
Keyword(s):  
Gas Exchange ◽  
Circulatory System

Gas exchange and its control in non-steady-state systems: the consequences of evolution from water to air breathing in the vertebrates

1988 ◽  
Vol 66 (1) ◽  
pp. 109-123 ◽  
Author(s):  
G. Shelton ◽  
P. C. Croghan
Keyword(s):  
Steady State ◽  
Gas Exchange ◽  
Dynamic Models ◽  
Continuous Process ◽  
Circulatory System ◽  
Lung Ventilation ◽  
Burst Duration ◽  
Air Breathing ◽  
Arterial Blood ◽  
Dissociation Curves

Control of breathing and gas exchange has been extensively investigated in unimodal animals, particularly mammals, in which ventilation is characteristically a regular and continuous process and gas exchange approximates to a steady-state system. Both static and dynamic models have been developed in control-theory analyses. Similar analyses are possible in unimodal fish, though few have been carried out. Control in bimodal animals, such as air-breathing fish and amphibians, is more difficult to understand and model. The evolutionary change from water to air breathing in vertebrates involves not only the adjustment of many control processes but also the development, in the early stages, of non steady states in gas exchangers, blood, and tissues. A simple control-system model, differing from mammalian counterparts in its greater emphasis on storage functions and its intermittently activated controller, is described for two suggested stages in the evolution of air breathing. The first of these stages is air gulping, in which a fixed and rather brief pattern of air breathing is activated by internal signals generated as a result of the inadequacy of the gills to provide sufficient oxygen for tissue metabolism. The second stage is that of burst breathing, in which lung ventilation is both begun and ended by internal signals so that burst duration is variable. The effects of adjusting parameters on variables of evolutionary importance, such as dive duration, burst duration, store renewal, and metabolic rate, can be examined in these two versions of the model. Refinements to incorporate arterial and venous compartments in the circulatory system, the shunting of venous and arterial blood streams in the heart, realistic oxygen dissociation curves, controller inputs from a wider range of sources, and the capacity to respond to some conditions with changes in ventilation rate as well as in burst and dive durations, are being developed. They should make the complex, non-steady-state interactions between gas exchangers, circulating blood, and tissues easier to understand and indicate the likely steps toward the evolution of steady-state systems seen in birds and mammals.

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

2004 ◽  
Vol 286 (2) ◽  
pp. H584-H601 ◽  
Author(s):  
K. Lu ◽  
J. W. Clark ◽  
F. H. Ghorbel ◽  
C. S. Robertson ◽  
D. L. Ware ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Cerebral Autoregulation ◽  
Circulatory System ◽  
Open Loop ◽  
Operating Conditions ◽  
Whole Body ◽  
System Control ◽  
The Central Nervous System ◽  
Using Data ◽  
Experimental Findings

The goal of this work is to study the cerebral autoregulation, brain gas exchange, and their interaction by means of a mathematical model. We have previously developed a model of the human cardiopulmonary (CP) system, which included the whole body circulatory system, lung and peripheral tissue gas exchange, and the central nervous system control of arterial pressure and ventilation. In this study, we added a more detailed description of cerebral circulation, cerebrospinal fluid (CSF) dynamics, brain gas exchange, and cerebral blood flow (CBF) autoregulation. Two CBF regulatory mechanisms are included: autoregulation and CO2 reactivity. Central chemoreceptor control of ventilation is also included. We first established nominal operating conditions for the cerebral model in an open-loop configuration using data generated by the CP model as inputs. The cerebral model was then integrated into the larger CP model to form a new integrated CP model, which was subsequently used to study cerebral hemodynamic and gas exchange responses to test protocols commonly used in the assessment of CBF autoregulation (e.g., carotid artery compression and the thigh-cuff deflation test). The model can closely mimic the experimental findings and provide biophysically based insights into the dynamics of cerebral autoregulation and brain tissue gas exchange as well as the mechanisms of their interaction during test protocols, which are aimed at assessing the degree of autoregulation. With further refinement, our CP model may be used on measured data associated with the clinical evaluation of the cerebral autoregulation and brain oxygenation in patients.

The bottom line

2019 ◽  
pp. 192-196
Author(s):  
Steven F. Perry ◽  
Markus Lambertz ◽  
Anke Schmitz
Keyword(s):  
Gas Exchange ◽  
Structure Function ◽  
Functional Result ◽  
Circulatory System ◽  
Arms Race ◽  
Food Sources ◽  
Bottom Line ◽  
Function Unit ◽  
Counter Current ◽  
Line P

This chapter summarizes the most important aspects of the entire book. Writing an abstract of a summary can result in a ‘bouillon cube’ of information that is nearly incomprehensible, so this sticks to the most far-reaching observations and conclusions. The structure–function unit referred to here as the respiratory faculty did not just suddenly appear, but rather bits and pieces of it are recognizable even in most basally branching metazoan lineages. The use of mitochondria in an aerobic atmosphere to produce large amounts of energy-carrying molecules precipitated a kind of arms race, whereby the individuals that could compete better for food sources or become predatory could become part of an evolutionary cascade. These new animals moved into another realm, but the old ones did not necessarily disappear: they just did what they always did, maybe a little better. In the most diverse lineages of invertebrates and craniotes we see similar changes appearing: gills with counter-current exchange, highly specialized oxygen-carrying proteins, a partly or completely closed circulatory system that includes the gas exchange organs, lungs. The more extreme the grounds for specialization, the more similar are these structures and functions. Often the functional result remains unchanged or becomes improved while the anatomical cause changes dramatically, but just as often structures change little but minor functions become major ones: a phenomenon called exaptation. This book has looked at most major animal groups and these principles turn up everywhere. It talks about multidimensional forces at work in a multidimensional world, and respiration is the keystone to it all.

New Dimensions for the Vital Storage of Microsurgical Free Flaps: An Experimental Approach

1993 ◽  
Vol 109 (4) ◽  
pp. 690-692 ◽  
Author(s):  
Berndt Mayer ◽  
Hans Von Baeyer ◽  
Uwe Kaiser
Keyword(s):  
Electron Microscopy ◽  
Gas Exchange ◽  
Aqueous Phase ◽  
Cold Storage ◽  
Experimental Approach ◽  
Circulatory System ◽  
Free Flaps ◽  
Nutritive Medium ◽  
Microsurgical Free Flaps

A Revolutionary Circulatory System Has Been Developed To Nourish Big, Free Osteomusculocutaneous Flaps Extracorporally. Thus We Will Be Able To Transplant The Free Flaps To Defect Areas That Have No Sufficient Vascular Situation. In Respect To The Cold Storage Of Microsurgical Free Flaps, To Date Maximal Periods Of Ischaemic Tolerance Have Been Considerably Exceeded; The Maximal Period Is Currently 168 Hours. The Vitality Of The Flap Is Monitored Through Parameters Setting Forth The Consumption Of Oxygen Together With Histology And Electron Microscopy. The Oxygenation Of The Nutritive Medium Is Achieved Through An Aqueous Phase Gas Exchange.

Gas exchange and the circulatory system

1995 ◽  
pp. 96-125 ◽  
Author(s):  
Q. Bone ◽  
N. B. Marshall ◽  
J. H. S. Blaxter
Keyword(s):  
Gas Exchange ◽  
Circulatory System

Angiogenesis in bronchial circulatory system after unilateral pulmonary artery obstruction

1997 ◽  
Vol 82 (1) ◽  
pp. 284-291 ◽  
Author(s):  
Nirmal B. Charan ◽  
Paula Carvalho
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Pulmonary Artery ◽  
Pulmonary Arteries ◽  
Left Lung ◽  
Circulatory System ◽  
Control Group ◽  
Sheep Model ◽  
Pulmonary Artery Obstruction ◽  
Artery Obstruction

Charan, Nirmal B., and Paula Carvalho. Angiogenesis in bronchial circulatory system after unilateral pulmonary artery obstruction. J. Appl. Physiol. 82(1): 284–291, 1997.—We studied the effects of left pulmonary artery (LPA) ligation on the bronchial circulatory system (BCS) by using a sheep model. LPA was ligated in the newborn lambs soon after birth ( n = 8), and when the sheep were ∼3 yr of age anatomic studies revealed marked angiogenesis in BCS. Bronchial blood flow and cardiac output were studied by placing flow probes around the bronchial and pulmonary arteries in four adult sheep. After LPA ligation, bronchial blood flow increased from 35 ± 6 to 134 ± 42 ml/min in ∼3 wk ( P < 0.05). We also studied gas-exchange functions of BCS ∼3 yr after the ligation of LPA in newborn lambs ( n = 4) and used a control group ( n = 12) in which LPA was ligated acutely. In the left lung, O2 uptake after acute ligation was 16 ± 3 ml/min and was similar to the chronic model, whereas CO2 output in the control group was 27 ± 3 ml/min compared with 79 ± 12 ml/min in the chronic preparation ( P < 0.05). We conclude that LPA ligation causes marked angiogenesis in BCS that is capable of performing some gas-exchange functions.

Oxygen transport in invertebrates

1985 ◽  
Vol 248 (5) ◽  
pp. R505-R514 ◽  
Author(s):  
C. P. Mangum
Keyword(s):  
Gas Exchange ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Respiratory Function ◽  
Heme Proteins ◽  
Circulatory System ◽  
O2 Transport ◽  
Phylogenetic Level ◽  
Fluid Compartments ◽  
O2 Binding

The distribution of the O2 carrying proteins suggests that the original transport system was a hemoglobin similar to the alpha-chain of hemoglobin A and packaged in a nucleated red blood cell. These molecules, which occur in large open fluid compartments, function as O2 stores for regular periods of hypoxia as well as carriers between sites of gas exchange. When the closed circulatory system first arose, the red blood cell was abandoned in favor of extracellular heme proteins, and the O2 storage function became less important. Alternative O2 carriers, hemerythrins, appear in the blood at about the same phylogenetic level as the intracellular hemoglobins, and their respiratory functions appear to be similar. The presence of hemoglobins instead of hemerythrins in the vertebrates may be an evolutionary accident. Still other O2 carriers, hemocyanins, arose separately in two specialized groups that left no descendants. Their O2 binding has all the adaptive features of vertebrate hemoglobin O2 binding, with unique features also. The respiratory function of the hemocyanins is largely limited to O2 transport, which makes a far greater contribution to aerobic metabolism than the O2 carriers found in simpler systems.

The sites of respiratory gas exchange in the planktonic crustacean daphnia magna: an in vivo study employing blood haemoglobin as an internal oxygen probe

1999 ◽  
Vol 202 (22) ◽  
pp. 3089-3099 ◽  
Author(s):  
R. Pirow ◽  
F. Wollinger ◽  
R.J. Paul
Keyword(s):  
Gas Exchange ◽  
Oxygen Saturation ◽  
Daphnia Magna ◽  
Ambient Medium ◽  
Circulatory System ◽  
Convective Transport ◽  
Transport Systems ◽  
Respiratory Gas Exchange ◽  
Ambient Oxygen

Recent studies on Daphnia magna have revealed that the feeding current is important for uptake of oxygen from the ambient medium. Respiratory gas exchange should therefore mainly occur within the filtering chamber, whose boundaries are formed by the trunk and the extended carapace shell valves. The precise site of gas exchange in the genus Daphnia is, however, a matter of conjecture. We have developed a method of imaging the haemoglobin oxygen-saturation in the circulatory system of transparent animals, which provides an opportunity to localize oxygen uptake from the environment and oxygen release to the tissues. Experiments were carried out at 20 degrees C on 2.8-3.0 mm long parthenogenetic females maintained in hypoxic culturing conditions, which had resulted in an increased haemoglobin content in the haemolymph. In lateral views of D. magna, the highest values of haemoglobin oxygen-saturation occurred near the posterior margin of the carapace and, surprisingly, in the rostral part of the head. The ambient oxygen partial pressures at which haemoglobin was half-oxygenated were 15 mmHg (2.0 kPa) for the posterior carapace region and 6 mmHg (0.8 kPa) for the rostrum. Although not all parts of the circulatory system could be analyzed using this technique, the data obtained from the accessible regions suggest that the inner wall of the carapace is a major site of respiratory gas exchange. Taking the circulatory pattern and the flow pattern of the medium in the filtering chamber into consideration, it becomes clear that the haemolymph, after passing from the limbs to the carapace lacuna, becomes oxygenated while flowing through the ventral part of the double-walled carapace in a posterior direction. The laterally flattened rostral region, where sensory and central nervous system structures are located, seems to have direct diffusive access to ambient oxygen, which could be especially advantageous during severe hypoxia when the convective transport systems fail to supply enough oxygen to that region.

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