Respiratory System
David Sturgeon in Introduction to Anatomy and Physiology for Healthcare Students, 2018
Everybody knows that breathing is an essential requirement for good health and that failure to do so will, in a relatively short period of time, lead to asphyxia and death. However, it is important to recognise that there are three types of respiration occurring simultaneously at different locations within the human body: external, internal and cellular respiration. External respiration describes the process of gaseous exchange that takes place in the lungs. That is to say: oxygen (O2) from the atmosphere is exchanged for carbon dioxide (CO2) from the pulmonary blood supply (capillaries). Internal respiration refers to the process by which oxygen in the blood is made available to the cells and exchanged for carbon dioxide across the plasma membrane. Lastly, cellular respiration refers to the production of energy (ATP) within the cells (by oxidative metabolism) described in Chapter 2 (glucose + O2→ ATP + CO2+ H2O). All three processes are absolutely essential for health and take place at the same time. In general terms, external and internal respiration ensure that the blood is provided with a constant supply of oxygen for cellular metabolism and provide a means for the excretion of carbon dioxide. However, before we look at how the respiratory tract facilitates this process, it is necessary to first consider the air that we breathe.
The immune and lymphatic systems, infection and sepsis
Peate Ian, Dutton Helen in Acute Nursing Care, 2020
Arterial blood gas analysis will not only help evaluate respiratory status, but give information on the metabolic problems as a result of sepsis. Abnormalities in tissue perfusion quickly give rise to a metabolic acidosis, evidenced by a lowered arterial pH and BE/Bicarbonate. In health, aerobic respiration meets oxygen demands, when the body has an increased demand for oxygen, such as in sepsis, the body switches to anaerobic respiration. Elevated serum lactate (the bi-product of anaerobic respiration) of more than 2mmol/L, due to ongoing tissue ischaemia, is the hallmark of sepsis. The increased acid load generated by anaerobic metabolism causes hyperventilation, with a rise in respiratory rate as the body increases carbon dioxide excretion. A chest x-ray will aid medical diagnosis and may reveal areas of patchy consolidation consistent with infection/deteriorating lung function.
Oxidative Stress: Relevance, Evaluation, and Management
Botros Rizk, Ashok Agarwal, Edmund S. Sabanegh in Male Infertility in Reproductive Medicine, 2019
Life evolved in a low-oxygen environment in which carbon dioxide and nitrogen dominated, resulting in mild reducing conditions that provided the energy source for early unicellular organisms. Oxygen was a toxic by-product of this aerobic respiration, leading to the oxygenation of the biosphere [7]. This led to a transformation of the environment and a switch to more oxidizing conditions, which arguably necessitated the evolution of aerobic respiration [8]. The subsequent evolution of mitochondria allowed for the development of aerobic respiration through oxidative phosphorylation, in which simple sugars and long chain fatty acids are transformed into adenosine triphosphate (ATP) [9]. Within this context, aerobic respiration involves a series of redox reactions and the subsequent transfer of electrons through a series of protein complexes known as the electron transfer chain, providing a significant increase in ATP availability, which allowed for the evolution of multicellular life [10].
α-Hederin inhibits the growth of lung cancer A549 cells in vitro and in vivo by decreasing SIRT6 dependent glycolysis
Published in Pharmaceutical Biology, 2021
Cong Fang, Yahui Liu, Lanying Chen, Yingying Luo, Yaru Cui, Ni Zhang, Peng Liu, Mengjing Zhou, Yongyan Xie
Reprogramming energy metabolism is a hallmark of cancer. Energy metabolism is the process in which energy is generated from nutrients, released, stored, and consumed by organisms or living cells. Energy metabolism is divided into glucose metabolism, protein metabolism, and fat metabolism. Under normal conditions, cells generate energy primarily via aerobic respiration. When the oxygen content is insufficient, cells perform glycolysis to generate energy. This process is called anaerobic respiration. Unlike normal cells, tumour cells generate energy primarily via glycolysis, even under aerobic conditions, a phenomenon known as the Warburg effect. Glycolytic capacity is characterized by rapid productivity and low efficiency. The rapid proliferation of tumour cells requires rapid energy consumption. Meanwhile, the lactic acid generated by glycolysis creates an acidic environment for tumour cells, which is conducive to their growth and leads to their rapid proliferation (Zhao et al. 2014; Potter et al. 2016). Sirtuin 6 (SIRT6) protein is a chromatin binding factor that was initially described as an inhibitor of gene instability (Mostoslavsky et al. 2006). During energy metabolism, SIRT6 regulates the fat and glucose metabolism, which is a key regulator of energy stress and is closely related to the process of tumour growth (Sebastián and Mostoslavsky 2015). With the metabolic profile used for energy production is elucidated, regulating tumour metabolism is a new therapeutic strategy to inhibit tumour growth (Zhang and Yang 2013).
Glutathione reductase and catalase as potential biomarkers for synergistic intoxication of pesticides in fish
Published in Biomarkers, 2019
Ankur Khare, Naina Chhawani, Kanchan Kumari
Contrary to LDH activity, a sudden decrease in SDH activity was seen in the study period in all the groups. Succinate dehydrogenase is the only mitochondrial metabolic enzyme and the only one which is involved in both TCA cycle and electron transport chain as it couples the conversion of succinate to fumarate with reduction of ubiquinone to quinone for energy generation. It is also associated with oxygen sensing and aerobic respiration in the tissues. The sharp decrease in SDH levels in this study justifies the fact that anaerobic respiration was favored in contrast to aerobic respiration due to the oxygen debts. This decreased level of SDH indicates inhibition of SDH at mitochondrial level alternatively enhancing different pathways for carbohydrate metabolism (Srivastava et al.2016). The oxygen debt experienced by fishes was much greater in carbaryl exposure in comparison to methyl parathion alone and synergistic effect of carbaryl and methyl parathion as reflected by the SDH activity. Contrary to increase in LDH activity, decrease in the activity of SDH was accounted which indicates that the metabolism of the fish body is shifting towards anaerobic respiration under stress condition caused by toxicants. A strong negative correlation of −0.91 was accounted between the increase in LDH and decrease in SDH activity, depicts that pesticides are capable of inducing oxidative stress. A significant and progressive increase in LDH serum was observed in entire study.
Acute exposure to C60 fullerene damages pulmonary mitochondrial function and mechanics
Published in Nanotoxicology, 2021
Dayene de Assis Fernandes Caldeira, Flávia Muniz Mesquita, Felipe Gomes Pinheiro, Dahienne Ferreira Oliveira, Luis Felipe Silva Oliveira, Jose Hamilton Matheus Nascimento, Christina Maeda Takiya, Leonardo Maciel, Walter Araujo Zin
Similar to other nanomaterials, fullerene exposure has been strongly related to mitochondrial dysfunction by means of different toxic mechanisms (Freyre-Fonseca et al. 2011; Liu et al. 2019; Santos et al. 2014; Dong et al. 2016; Xu et al. 2016). Mitochondria play an essential, but not unique, role in cellular respiration, where oxygen is consumed and adenosine triphosphate (ATP) is produced during oxidative phosphorylation. Indeed, during this process superoxide anion (O2−) is also generated and converted into hydrogen peroxide (H2O2) by manganese superoxide dismutase (MnSOD), which crosses the mitochondrial membrane (Spinelli and Haigis 2018). An impaired oxidative phosphorylation may lead to mitochondrial dysfunction and trigger an oxidative imbalance, which can be used to gauge the toxicity (Moreno et al. 2007; Yang et al. 2016). C60 and derivatives can induce cytotoxicity, trigger apoptosis by the increase in reactive oxygen species (ROS), and reduce mitochondrial membrane potential and capacity (Jacobsen et al. 2008; Lee et al. 2011). However, most studies investigate isolated mitochondrial activity or on the cellular level, with no further detail about the possible change at the organ level, especially those broadly exposed to nanopollutants, as the lung.
Related Knowledge Centers
- Combustion
- Oxygen
- Metabolism
- Catabolism
- Oxidation State
- Adenosine Triphosphate
- Cell
- Nutrient
- Redox
- Sugar