Internal environments

BNA California Environment Daily BNA Chemical Regulation Daily BNA Chemical Regulation Reporter BNA Daily Environment Report BNA Environmental Law Database BNA Environmental Law Update BNA International Environment Daily CELDS Environmental Regulations... 

In addition to considering the external environment, recommendations for the internal environment have been set. Every room in which human activity is required has maximum limits for noise (85—90 dB), carbon dioxide, solvents, radiation, temperature, etc. 

As a result of the concentration of acidic species, such as chloride and sulfate, material scraped from the inside of tubercles is virtually always acidic when mixed with water. Acidity varies not only from tubercle to tubercle but also from place to place in a given tubercle. Acidity is greatest near the corroded metal surface. The size of the fluid-filled cavity can indicate acidity. The larger the cavity, the more acidic the internal environment. 

Pipework is the item of plant that is most usually buried in soil. In addition to the internal environment, the soil can present a significant corrosion hazard. 

When an implant is surgically inserted into the human body, the internal environment is greatly disturbed. Haematomas are likely to collect around the implant, resulting in a lowered pH. Laing observed pH values as low as 4-0 in healing wounds. The low pH usually persists until the haematomas are reabsorbed after several weeks ... 

As illustrated in Table 41-1, the internal environment is rich in K+ and and phosphate is its major... 

The multiple human variants of G-6-PD and the relationship of their kinetic properties to the presence of hemolytic anemia under conditions which closely simulate the erythrocyte internal environment have been elegantly studied by Yoshida (112). This author found that those enzyme variants with significantly reduced physiological activity are those associated with hemolytic anemia. 

The mucosa of the GIT represents an interface between the external and internal environments. The expansive surface area is necessary for the efficient hydrolysis of foodstuffs and the absorption of energy and nutrients. The mucosa also influences the systemic availability of non-nutrient compounds in the diet, both beneficial and detrimental. Digestion and absorption of glucosinolates are critical determinants of health benefits (see Chapter 4) Similarly, the bioavailability and health benefits of phytoestrogens, such as genistein (see Chapters 5 and 10) are at least partly dependent on the carrier-mediated processes of absorption associated with the GIT (Oitate et al, 2001). Moreover, the metabolic activities of the mucosa can influence the systemic concentrations and forms of dietary phytochemicals, as exemplified by research with soy isoflavones (Andlauer et al., 2000). 

Physiology is the study of the functions of the human body. In other words, the mechanisms by which the various organs and tissues carry out their specific activities are considered. Emphasis is often placed on the processes that control and regulate these functions. In order for the body to function optimally, conditions within the body, referred to as the internal environment, must be very carefully regulated. Therefore, many important variables, such as body temperature, blood pressure, blood glucose, oxygen and carbon dioxide content of the blood, as well as electrolyte balance, are actively maintained within narrow physiological limits. 

The study of physiology includes study not only of how each of these systems carries out its functions, but also of the mechanisms involved that regulate these activities in order to maintain homeostasis under a variety of conditions. For example, the body s needs are very different during a resting state compared to that of exercise. How do organ systems adjust their activities in response to varied levels of physical exertion or when confronted with altered internal and external environments In order to maintain homeostasis, the body must be able to monitor and sense changes in the internal environment. It must also be able to compensate, or make adjustments, for these changes. 

Many different types of sensory receptors are located throughout the body. These receptors monitor the status of the internal environment or that of the surroundings. Sensory receptors are sensitive to specific types of stimuli and measure the value of a physiological variable. For example, arterial baroreceptors measure blood pressure and chemoreceptors measure the oxygen and carbon dioxide content of the blood. The information detected by these sensors then travels by way of afferent neuronal pathways to the central nervous system (CNS). The CNS is the integrative portion of the nervous system and consists of the (1) brain and the (2) spinal cord. 

Heat of vaporisation. Water has a very large heat capacity (a large amount of energy has to be removed to lower the temperature by 1°C) and a large heat of vaporisation. This means that the temperature in solution is stabilised by the thermochemical properties of the water as a solvent. All life forms on Earth stabilise their internal environments with respect to temperature and composition so that the internal chemistry or metabolism is kept constant - a process called homeostasis. It would, however, be possible to learn to live in an environment that was fluctuating more wildly and develop a unique evolutionary niche. 

In this paradigm both processes, i.e. the controlled process and the controlling process, are influenced by their external and internal environment as Wiener (Wiener,... 

In parallel with improvements in chemical sensor performance, analytical science has also seen tremendous advances in the development of compact, portable analytical instruments. For example, lab-on-a-chip (LOAC) devices enable complex bench processes (sampling, reagent addition, temperature control, analysis of reaction products) to be incorporated into a compact, device format that can provide reliable analytical information within a controlled internal environment. LOAC devices typically incorporate pumps, valves, micromachined flow manifolds, reagents, sampling system, electronics and data processing, and communications. Clearly, they are much more complex than the simple chemo-sensor described above. In fact, chemosensors can be incorporated into LOAC devices as a selective sensor, which enables the sensor to be contained within the protective internal environment. Figure 5... 

The pharmacopeias have worked with the ICH process to facilitate the international environment of pharmaceutical research and product registration. On the other hand, the additional situation for compendia is that the standards which they have published now apply to all of the already marketed products. In that case a company has testing history and product history in their quality control departments. These are the most conservative elements within the pharmaceutical industry as is necessary to their task. Quality control departments are reluctant to change methods when they feel that their products are properly represented by the current of tests. Therefore, a tension is ereated between trying to develop harmonized standards, which facilitate one area of activity in the world of pharmaeeutieals, and not disturbing a satisfactory marketplace. A vast amount of progress has been made in the harmonization of phar-maeopeial methods. 

This concordance rests on the probable presumption of Good Manufacturing Practices environments in production and control, now a reasonable presumption in today s international environment. 

There are two classes of movements in the human body voluntary and involuntary. Voluntary movements are pretty clear they are the movements that we can control. Reaching for the French fries, swinging a baseball bat, turning on the TV, and typing at a computer keyboard provide obvious examples. Involuntary movements include those movements that we cannot readily control such as heart beats, vascular contraction, and movement of the gut muscles, and they basically control the internal environment of the body. Voluntary movements are controlled by the somatic nervous system. Involuntary movements are controlled by the autonomic nervous system, to which we now turn. 

In higher organisms, metabolic and other processes (growth, differentiation, control of the internal environment) are controlled by hormones (see pp. 370ff)... 

---