This chapter deals with the cardiac system that underpins animal vitality that is more complex than the vegetative one discussed in the previous chapter. The central activity of this system is breathing, and the chapter outlines different types of breathing posited by Galen, the anatomy underpinning them, and his explanation of why the deprivation of breath leads to the loss of life. The chapter also focuses on the three types of pneuma theorized by Galen, discussing their proper activities and properties enabling these activities. The focus on pneuma also brings attention to yet another Galenic division of parts into solids, fluids and pneumata. This division of tissues according to their texture and speed of movement offers an important glimpse into how Galen conceives of interaction between parts. Moreover, the rapid alterations in the pneumatic tissues underpin the physiological understanding of animal vitality.

Dysphagia is a frequent symptom that has an impact on prognosis of the critically ill patient. Studies in unselected ICU patient populations revealed the presence of dyphagia in more than 50% of the patiente, and in patients on neurological ICUs dysphagia is thought to be present in even more than 90% of the patients. Dysphagia in critically ill patients is a significant predictor of complications, especially aspiration pneumonia, reintubation and mortality. Still, the access to adequate diagnostic and therapeutic procedures is often limited. This chapter offers a comprehensive overview of the pathophysiology and the diagnostic and therapeutic approach in neurogenic dysphagia.

Managing the mechanical ventilator in critical illness is far from formulaic. Criteria of intubation are rarely contemplated when a patient is struggling to maintain a patent airway. Once the airway is secured, adjustments in ventilator settings and modes are continuously made, and there is a fair amount of trial and error. Weaning from the ventilator is not standardized (and probably never will be), and protocols (if there are any) are based on consultant preferences and mostly experience. The consensus statement of the European Society of Intensive Care Medicine on mechanical ventilation (MV) in acute brain injury has clearly shown that evidence for certain approaches was either insufficient or lacking and that a substantial amount of research is needed to demonstrate the feasibility, safety, and efficacy of different management approaches in this category of patients.

This chapter reviews considerations in each intervention during the patient’s clinical trajectory of ventilation in the neurosciences ICU. The reader will find that early intubation and mechanical ventilation are initiated because patients cannot protect their airways or have insufficient respiratory drive to maintain oxygenation and normocarbia.

For both developed and developing countries in the world, the twenty-first century will be marked by great challenges for healthcare systems. The overwhelming reason will be aging societies that will face an increase in multimorbid, chronic diseases which will include neurological diseases. The probability of surviving acute illness and the medical opportunities to prolong life in chronic-progressive disease will improve in future. As a result the numbers of neurological patients with respiratory impairment caused by prolonged, chronic or chronic-progressive life-threatening disease will increase. Minimizing dependency on life-supporting technologies and care, stabilizing vital functions, optimizing quality of life and participation and alleviating suffering are paramount goals for these patients. The therapeutic approach therefore must integrate intensive care, neurorespiratory care, rehabilitation and palliative care. Furthermore, patient-centered and family-oriented care, which covers the whole lifespan and bridges the gap between inpatient and outpatient care, is needed.

Sleep is behaviorally defined as a reversible state of reduced motor activity and reaction to sensory stimuli. Although sleep is essential for human survival, its function is still not yet completely understood. Sleep is associated with significant changes in respiratory drive, respiratory muscle tone, respiratory mechanics and ventilation. Therefore, profound knowledge of the interactions between sleep and respiration is indispensable for clinicians and scientists in the field of neurorespiratory medicine. Sleep-related breathing disorders are diagnosed by polysomnography or polygraphy. Alveolar hypoventilation and consecutive hypercapnia become evident in sleep rather than wake state in all clinical conditions. The extent of hypercapnia is stage dependent in many diseases. When hypercapnia is suspected, transcutaneous capnometry and blood gas analysis are suitable diagnostic methods. As sleep deprivation reduces the central respiratory drive, weaning from the respirator always should take place first at daytime. Additionally, any factor causing sleep deprivation should be avoided in patients with increased risk of ventilatory insufficiency and during weaning.

Respiratory regulation comprises respiratory rhythmogenesis, formation of the respiratory motor pattern, control of blood oxygen and carbon dioxide, increase of minute ventilation during physical activity, adaptation of respiration to the sleep-wake cycle, coordination of breathing with swallowing, cough, sneezing, choking and voluntary activity such as speech or singing. Other factors such as growth and maturation, emotion, pregnancy, injury, disease, body temperature, pain and aging lead to changes in respiration. The presence of a respiratory rhythm generator in the brainstem is now known to be a common feature of all vertebrates. Knowledge about respiratory regulation is mainly derived from animal models, but respiratory regulation in humans is subject to an increasing number of physiological, electrophysiological, neuroradiographic, histopathological and genetic studies. This chapter provides an overview of respiratory regulation, focused on neuroanatomical, neurophysiological and clinical apsects.

In times past, an inquisitive physician-scientist must have pondered these questions: How do we unknowingly breathe? What brain structures control our breathing? Why is breathing so perfectly rhythmic? Is there a lung-brain communication, and if so, how? But an even more fundamental question must have been: how much brain injury can one sustain before breathing stops?

It took two centuries (more or less) to answer the above-mentioned questions and gradually add small pieces to a large (still incomplete) puzzle. The respiratory center in the brainstem was identified and characterized in the late 1800s and early 1900s. Similarly, the function of the respiratory muscles and its neural connection with cranial nerves (CN) became better known.

This chapter recounts the history of the neurology of breathing and, thus, the discovery of the respiratory center and the respiratory mechanics. Sections of the chapter review experimental and clinical discoveries of those parts of the central and the peripheral nervous system involved with breathing while acknowledging their interplay.

Coughing is essential for survival as it clears secretions and foreign bodies from the central airways. Insufficient cough flows and aspiration of saliva are frequent problems in neurological illness and lead to tracheobronchial retention of secretions. Comorbidities like chronic obstructive pulmonary disease, certain medications and failure to adequately humidify the lower airways can lead to hypersecretion, thick and tenacious secretions and ciliary dysfunction, respectively. This can further aggravate any bronchopulmonary retention of secretions, finally leading to atelectasis, pneumonia, respiratory failure as well as death. Noninvasive ventilatory support is effective only if accompanied by adequate management of secretions. This chapter provides a comprehensive overview of the neuronal control, physiology and pathophysiology of coughing and bronchopulmonary retention of secretions as well as effective techniques to reduce secretions and to eliminate them from the airways.

This chapter highlights the most important neuromuscular disorders affecting respiration, discusses their clinical characteristics and provides a guide to management. Respiratory involvement is common in many neuromuscular disorders (NMDs) to a variable degree. In most NMDs, hypoventilation is due to insufficient respiratory muscle pump and results in reduced quality of life and increased morbidity and mortality. Moreover, upper airway muscles and brain can be involved resulting in obstructive sleep apnea, central sleep apnea or central hypoventilation syndrome. Especially in congenital neuromuscular diseases with early disease onset, skeletal deformities reduce thoracic compliance with resulting restrictive ventilatory pattern. In some neuromuscular disorders, more than one system can be affected with the need for an individual diagnostic and therapeutic approach. Intensive care and long-term management of these conditions are discussed.

Comprehensive knowledge of the anatomy and physiology of the respiratory system is crucial in respiratory medicine. A profound understanding of physiology allows the practitioner to deduce pathological processes and initiate therapeutic steps based on rational decisions. The choice of a suitable ventilation mode or setting typically stems from an understanding of the pathophysiological processes. Understanding the respiratory chain at the cellular level, ventilation and perfusion, as well as the delicate interplay of macroscopic and microscopic mechanisms, supports the development of precise and individualized ventilation strategies. Knowledge of mucociliary clearance and the various lung volumes is also crucial to ensure optimal management of tracheobronchial secretions, oxygen supply and CO2 elimination.

This chapter plays an important role in the argument of the book. It shows that there is room in Aristotle’s life for a study of what is common to animals and plants in addition to separate studies of animals and plants. At the same time, it shows that what Aristotle is able, or willing, to say in common for animals and plants is truly limited. By the end of the chapter the reader will see that the Peripatetic study of life is a complex scientific endeavor consisting of at least three components: a study of what is common to animals and plants followed by separate yet coordinated studies of animals and plants. What Aristotle is able, or willing, to say in common for animals and plants is to be found within the boundaries of project of the Parva naturalia.

In a well-known passage (Juv. 13 (7).473a15–474a24), Aristotle preserves a fragment of Empedocles’ poem dealing with respiration, in which the clepsydra is used as a model for breathing. Although there is a substantial literature on this subject, most scholars have focused on explaining Empedocles’ account of the mode of operation of the clepsydra as well as on assessing the extent to which Aristotle’s interpretation does justice to Empedocles’ fragment. What has received little attention is the fact that Aristotle begins his criticism of Empedocles by offering a specific counterproposal of his own, one that rests on the idea that the mechanism of respiration can be explained in a much clearer fashion through the analogy of a forge bellows. References to bellows are actually already traceable to Homer. At the same time, the bellows–lungs analogy continued to be used for centuries after Aristotle. The aim of this chapter is to provide an overview of the existing literary and archaeological evidence about bellows in Greek antiquity in order to build a complete picture of its function and hence clarify Aristotle’s theory of respiration.

The climate benefit of forests is mostly recognized in their removal of carbon dioxide from the atmosphere. Over the course of a tree’s lifetime, the accumulated carbon in biomass is carbon removed from the atmosphere. Species differ in growth rate, size at maturity, and longevity, but the basic principle of biomass accumulation over the lifetime of a tree is the basis for using forests to remove carbon dioxide from the atmosphere. Decomposition of organic material in the soil emits carbon dioxide and reduces the net carbon gain by forests. Wildfires, insect outbreaks, logging, and other disturbances also release carbon dioxide to the atmosphere. The combination of these processes – carbon gain from biomass growth; carbon loss from the soil and from disturbances – makes some forests a sink for atmospheric carbon; the forests have a net gain of carbon annually. Other forests are a source of carbon, in which there is a net loss of carbon to the atmosphere. Forests are, at a global scale, an annual carbon sink, which reduces the accumulation of carbon dioxide in the atmosphere. Nature-based solutions to mitigate climate change aim to enhance the carbon sink.

Regulation of the cardiovascular system, the respiratory system and the gastrointestinal tract (GIT) is represented in the lower brain stem. These control systems require precise coordination and are closely integrated, which is reflected in the anatomy and physiology of the neural substrates of these control systems. Included in this integration are the final autonomic pathways, the enteric nervous system and the spinal autonomic circuits. The circuits in the medulla oblongata are under the control of the upper brain stem, hypothalamus and telencephalon. Neurons involved in regulation of arterial blood pressure and respiration are situated in rostrocaudally organized columns of neurons in the ventrolateral medulla (VLM). The rostral VLM is a sympathetic cardiovascular premotor nucleus mediating reflexes to sympathetic cardiovascular preganglionic neurons such as arterial baroreceptor, arterial chemoreceptor and other reflexes. The caudal raphe nuclei of the medulla oblongata are involved in thermoregulation and regulation of energy balance. The respiratory pattern in cardiovascular neurons is generated by the "common cardiorespiratory network" in the VLM. Neural control of the GIT by the lower brain stem is exerted by multiple reflex circuits consisting of vagal afferents from the GIT, neurons in the nucleus tractus solitarii and parasympathetic preganglionic neurons projecting to the GIT.

Speech physiology consists of the articulatory structures, including the respiratory system, the larynx and various vocal tract articulators, plus the sensory organs, which provide auditory, somatosensory and visual inputs that map the feature space in which speech is produced and perceived. In this chapter the focus is on the neurophysiology of the articulatory structures. The acoustic characteristics of speech sounds are determined by changes in the length and tension of muscles, coordinated, at the lowest level, by interlinked clusters of motor neurons and interneurons in the brainstem which are themselves directed by excitation from cortical and midbrain structures. This chapter provides a brief foundation to these systems and structures, taking a functional perspective. The progressive nature of research into the anatomy and physiology of speech continues to generate new discoveries, and advances in modelling and mapping of biomechanical and neural control promise new avenues for phonetic research.

Chapter 7 presents the soil carbon cycle. The chapter largely by-passes the still uncertain processes that occur at the molecular scale. The focus is on macroscopic properties and how they vary with space and time. Soil C storage is first examined from a box model perspective, which introduces mass balance equations and how they are useful, when coupled with data, in beginning to understanding soil C dynamics. The chapter includes an introductory perspective on the vertical trends in soil C and the transport-reaction models that are needed to fully explain these patterns. Soil organic C is largely removed from soil as CO2, and production-diffusion models are introduced to explain observable CO2 depth profiles and to calculate the fluxes to the atmosphere. Diffusion impacts the C isotope composition of soil CO2 and any CaCO3 minerals that subsequently form. These are examined through the lens of diffusion modeling, which is now common, and critical, in any examination of soil properties with depth.

Lennox explores the role of cooling in the regulation of natural heat and the preservation of life with special interest in methodological questions about how Aristotle arrived at his views about the critical role of cooling in the lives of blooded animals and why he insists that both the brain and the lungs are involved in moderating the animal’s heat. Lennox concludes that Aristotle was somewhat perplexed by the brain, and that his changing views about its presence in the cephalopods may be an indication of that perplexity.