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Metabolism represents the nexus of fundamental physical forces, which while present in all structure and function require new explanatory emergent principles, which, so far, cannot be predicted or derived solely from description of chemistry and physics. Metabolism is essentially concerned with the transduction of energy flows with respect to time, space, and matter. Language models and metaphors contribute to construction of scientific explanation within biology. The concept of a metabolic field yields a deeper, broader, more quantitative integrated theoretical framework leading to novel predictive models of systems biology.

Organisms maintaining circadian rhythmicity are responding to physical constraint of a 24-hour cycle. Time-cue sensing is fundamental to the clock existence, and entrainment of circadian rhythm is indeed accessible to a wide variety of geophysical stimuli. Light-dark and temperature changes are the main time-cues. Additional physical forces such as barometric pressure, electrostatic and electromagnetic fields and gravity force, display a daily cyclic behavior and can function as secondary time-cues. A conceptual framework that contains explanations to all circadian properties including cell autonomous, environmental responsiveness and self-sustained character, is still lacking. It is argued that clock responsiveness to external cues is central to the cellular clock mechanism, and therefore, the nature of the time-cues and the pathways that enable the cell to respond to physical stimuli are of central importance. A role for cytoskeleton in clock entrainment mechanism is suggested in light of cytoskeleton's major involvement in cellular mechanotransduction.

The concept that the mitral valve of the heart is a passive flap that opens and closes like a barn door has been emphasized for decades by medical and biology professors to their students. But experimental findings, which are outlined in this report, support the theory of an active valve. We hypothesize that the two leaflets of the mitral valve are actively contractile; that physical forces generated in the valve itself may stabilize and add precision to the sum of forces that regulate valve movement. This precision could be of critical significance both in the moments preceding, and during, valve opening and closing. Evidence supporting our active valve hypothesis includes the profuse innervation of motor and sensory nerves that are present in the mitral valves of all animals studied. In addition, multiple contractile cell types have been found in the mitral valve, including cardiac muscle cells, smooth muscle cells, and cardiac valvular interstitial cells. In vitro work in our laboratories using the rat mitral valve shows that not only are the valves capable of contraction and relaxation, but that the contractions and relaxations are nerve-mediated. We theorize that the rich innervation and contractile cells in the mitral valve work together to modulate fine-tuning of valve movements and tone, thereby ensuring the integrity of the valve seal. Other investigators have reported that the mitral valve demonstrates contractile activity and that denervation localized to the mitral valve affects valve competence. The evidence for an active mitral valve presented by these and other experimental studies warrant a reexamination of the validity of the passive valve concept. An accurate and full understanding of the precise movements of the valve leaflets and the mechanisms that regulate these movements is likely to provide the information needed to understand and develop treatments for many different cardiac valve problems, including mitral valve diseases such as prolapse and myxomatous degeneration. In view of the available experimental evidence, the concept that the mitral valve functions only as a passive structure is challenged by numerous anomalies. A reinterpretation of the concept of valve function that incorporates active as well as passive roles for the valve leaflets and other components of the valve apparatus would have significant implications both for the directions taken in research involving the cardiac valves and for the approaches to treatment.

A theoretical design for a non-invasive, continuous, applanation, contact lens tonometer is proposed based on physical forces which cause a contact lens to adhere to the eye and the principles of applanation to measure pressure within a sphere. This instrument has potentially wide applications in the continuous measurement of intraocular pressure in patients with glaucoma, a blinding disease characterized by elevated intraocular pressure.

The hypothesis considers organisms' ambivalence towards physical forces as a crucial point of difference between living and non-living objects:-while the latter are fully dependent on physical forces, the essential characteristics of organisms displayed in the course of their interactions manifest their relative independence of the forces that postulate the objects' interactions. According to the presented model the organisms configuration holds a borderline position in three-dimensional space and it is assumed that this particular position exactly accounts for the ambivalent behaviour of living objects. The model outlines a globule-shaped chain of components with different levels of organization. The similarities of the model and the living cell are discussed.