Biological rhythms are linked to an internal clock in the brain called the suprachiasmatic nucleus (SCN). It is located in the hypothalamus. This is the area of the brain that manages the autonomic nervous system and the pituitary gland. The SCN sends signals during the day to regulate the body's activity.
Catecholamines, norepinephrine, and renin are natural hormones made by the kidneys and adrenal glands (small glands located near the top of both kidneys). These hormones cause narrowing of the body's blood vessels (vasoconstriction). Vasoconstriction causes resistance to blood flow and raises blood pressure. Another type of pseudoscience, called biorhythms, originated in the 19th century and became popular in the 60s, 70s and 80s.
Biorhythms are based on the idea that a person's life is in a cycle, with peaks and valleys. Using mathematical formulas, people can calculate and graph their cycles, thus determining the good days (peaks) and the bad days (valleys). Among the many varieties of biological rhythm, the best known are those related to sleep and wakefulness, which are part of the circadian rhythm that we will discuss later in this essay. Circadian or daily cycles are just one type of biological rhythm.
Some rhythms take place in a cycle shorter than the duration of a day, while others are based on a monthly or even annual pattern. The biological rhythms of daily, tidal, lunar and annual periodicity, which are an inherent characteristic of organic organization, are recognized as adaptations to our periodically changing environment. Schwassmann, in Fish Physiology, 1971 The biological rhythms of daily, tidal, lunar and annual periodicity, which are an inherent characteristic of organic organization, are recognized as adaptations to our periodically changing environment. Considering experimental evidence, it is obvious that rhythmic phenomena in many fish species are in no way different from those known in other organisms with respect to endogenous nature and phase and period control by periodic environmental variables.
Therefore, certain established generalities resulting from studies in different organisms should also be valid for biological rhythms in fish. Experimental evidence is available for circadian rhythms in several fish species; most, however, merely demonstrate a persistence of manifest periodic functions under constant conditions. Regarding annual rhythms, several studies mainly investigated the change in day length and temperature due to their effect on the time of annual reproductive cycles in approximately 10 teleost species. The rhythms of tidal, semilunar and lunar periodicity in intertidal fish are known from some rather spectacular examples, but with one exception, they have not been investigated in the laboratory.
Most progress has been made recently in the field of functional analysis of circadian rhymicity. The circadian organization appears to be the oldest phylogenetically characteristic and could well be of common origin, while the many diverse manifest functions could be considered secondary consequences of the circadian system. An important role of the circadian organization seems to be in its participation in the mechanism of photoperiodic control as an adjustment to the temporal order of annual environmental cycles. In photojournalism, the circadian oscillation makes possible sensitivity to the length of the daily light period.
The ecologically significant effect of photoperiodic control, especially evident from studies on annual fish farming, appears to be in adjusting the temporal sequence of a physiological rhythm of gonadal maturation rather than triggering certain specific physiological events. Photoperiodic control cannot explain the timing of reproduction and the previous migratory movements of species living in the tropics, where the coincidence of spawning activity with the onset of the rainy season seems to be a fairly common phenomenon. Most experimental studies involved animals from temperate zones, which may have led to the current emphasis on photoperiodic control mechanisms. Experimental work on the possible timing mechanisms of breeding cycles in tropical fish seems to be hampered by the scarcity of information on their natural behavior and reproductive activity times in natural habitats of different weather conditions.
Despite the great progress made by laboratory studies of rhythmic phenomena in various organisms, including fish, essentially in terms of analysis of functional systems, this writer believes that subsequent achievements will depend on field studies that not only provide the basis for any analysis experimental tests in the laboratory, but also evidence of current generalizations and theories. The mean of a rhythm is the average value of a continuous variable in a single cycle. When rhythm is described by fitting a cosine curve, the intermediate point between peaks and valleys is known as MESOR. Only when the data is measured equidistantly, over an integer number of cycles, will the MESOR be equal to the arithmetic mean.
Amplitude refers to the magnitude of the response variable between its mean value and the valley or peak (estimated). Such mathematical use, however, is limited to rhythms that oscillate symmetrically around the mean value. The phase refers to the value of a biological variable at a fixed time. The word phasing is often used to describe the shape of a curve that represents the relationship of a biological function to time.
Acrophase is a narrower term that refers to a specific reference pattern or zero time and indicates the delay in the crest of the function used to describe the rhythm. Haus and Halberg (1980) have categorized rhythms (by time frame) as infradian, circadian and ultradian. Circadian rhythms are the rhythms that have been studied most extensively and have periods in the range of 20 to 28 hours (hence the frequencies are approximately 0.04 cycles per hour). There are many examples that can be cited, including rhythms in mitotic activity, metabolic processes and drug susceptibility.
The infradian rhythms have periods of more than 28 hours and, therefore, their frequencies are correspondingly lower than the circadian ones. Some of the well-known infradian rhythms are the human menstrual cycle and the annual reproductive cycle of salmon. Infradian rhythms in nutrient intake and food metabolism have been identified (Reinberg, 1988.A more specific type of infradian rhythm is circasemiseptan (period of approximately 3.5 days) found by Schweiger et al. Ultradian rhythms have periods of less than 20 hours.
Examples of these rhythms are electrocardiogram, breathing, peristalsis in the intestine, etc. TSH, thyroid-stimulating hormone; ALT, alanine aminotransferase. Signals from synapses reaching the nucleus could alter gene expression, which plays a key role in long-term memory, biological rhythm, neuronal and behavioral plasticity, neuronal survival and death, etc. The mechanisms behind altering gene expression include structural change in chromatin, transcription (DNA to RNA), splicing (RNA to mRNA), covalent modification of mRNA, translation (mRNA to protein), and protein modification.
The collective factors that regulate these processes are protein activators, transcription factors (CREB, AP-1 activator protein, signal transducer and transcription activator STAT, c-Fos, NF-B), dimerization or multimerization of transcription factors, phosphorylation, availability of adaptor protein (protein binding), translocation of the transcription factor from the cytoplasm to the nucleus, chaperone proteins (Hsp90, Hsp5, binding of transcription factors to the promoter or enhancer region of the gene, histone, modification of histone by acetylation, methylation, phosphorylation, ubiquitylation, etc. The malfunction of these factors disrupts gene expression that affects learning and memory. In addition to directly influencing neurotransmitter levels by acting on transporters and enzymes, recent research focuses on drugs or nutraceuticals that target transcription factors and related proteins involved in gene expression to act as cognition enhancers and to treat diseases neurological. Evolution shapes the temporal functioning of all living organisms, favoring organisms that adapt their behavior to a changing world (Hochachka and Somero, 200.
Photoperiod, temperature, tides) are driven by the rotation of the earth on its axis and relative to its position with respect to the sun and the moon. In response, species developed a complex system to synchronize their biological activity within the framework of deterministic changes in habitat. This adjustment is necessary to anticipate the emergence of unfavorable conditions (reviewed by Naylor, 20. As a result, all species show marked daytime, night, twilight or tidal adaptations to their respective ecological niches (Kronfeld-Schor and Dayan, 200.
The nature and location of the pacemaker is a current topic of research in many marine species. This structure is neuronal in nature and in vertebrates it is located in the suprachiasmatic nucleus of the brain (Stephan and Zucher, 197.The fruit fly, Drosophila melanogaster), is located in the cerebral hemispheres. In crustaceans, no master clock has yet been identified, but a model of distributed clockwork made by different oscillators has been proposed (eg,. Retinular cells, neurosecretory systems in the optic lobes; Aréchiga and Rodriguez-Sosa, 2002; Strauss and Dircksen, 20.
Norvegicus seems to fit within this scattered model (Aréchiga et al. Biorhythm theory is the pseudoscientific idea that our daily life is significantly affected by rhythmic cycles with periods of exactly 23, 28 and 33 days, typically a 23-day physical cycle, a 28-day emotional cycle and a 33-day intellectual cycle. The idea was developed by Wilhelm Fliess in the late 19th century and became popular in the United States in the late 1970s. The proposal has been independently tested and, consistently, no validity has been found for it.
JOSEPH S. TAKAHASHI, PHD,. Professor of Glass in the Department of Neurobiology and Physiology and Researcher at the Howard Hughes Medical Institute, Northwestern University, Evanston, Illinois. The synchronicity of an organism with its external and internal environments is critical to the well-being and survival of the organism; a lack of synchrony between the organism and the external environment can lead to the immediate death of the individual.
For example, if a nocturnal rodent ventured out of its burrow in broad daylight, the rodent would be an exceptionally easy prey for other animals. Similarly, a lack of synchrony within the internal environment could lead to health problems in the individual, such as those associated with jet lag, shift work and accompanying loss of sleep (for example,. Researchers began studying biological rhythms approximately 50 years ago. Although there is not a single experiment that serves as the defining event from which to date the beginning of modern research in chronobiology, studies carried out in the 1950s on circadian rhythmicity in fruit flies by Colin Pittendrigh and in humans by Jurgen Aschoff can be considered its foundation.
The area of sleep research, which is also included in the field of chronobiology, evolved somewhat independently, with the identification of several stages of sleep by Nathaniel Kleitman at approximately the same time (Dement 2000). The legacy of these pioneers continues today with the advancement of the fields they founded. Since the discovery of the Clock gene in mice, the list of circadian clock genes identified in mammals has grown in a remarkably short period of time (see table. For example, researchers have identified not one, but three mammalian genes that correspond to the gene per tanto in its structure (ie,.
Some of the proposed circadian clock genes have been identified solely on the basis of their sequence similarity to the Drosophila clock genes and have not been confirmed to have clock function based on an examination of the behavior of the corresponding mutants. However, the findings to date clearly indicate the scheme of a pacemaker that is based on a feedback loop of gene expression (see figure. Howard Hughes Medical Institute Christmas Conference Website. Skeptical evaluations of the various biorhythm proposals led to a series of criticisms that criticized the issue published in the 1970s and 1980s.
Articles on biorhythms are found in scientific journals, but most studies (99 out of 13) indicate that biorhythms are not valid and that they are not better at predicting than chance. In the early 1900s, a professor named Hermann Swoboda claimed to have independently devised biorhythms, and then another professor named Alfred Teltscher noticed that students' academic success was executed in 33-day cycles. The 23-day and 28-day rhythms used by biorhythmists were first devised in the late 19th century by Wilhelm Fliess, a Berlin doctor and friend of Sigmund Freud. Since body cycles are related to birth dates, the biorhythm system is analogous to medical astrology.
Biorhythms are based on the idea that cycles, which can be calculated and graphed, can be used to make predictions about your life. The idea of biorhythms first appeared in the late 19th century when a doctor named Wilhelm Fliess came up with the idea that women ran on a 28-day cycle and men on a 23-day cycle. In the early 1900s, a professor named Hermann Swoboda claimed to have created cycles of biorhythms independently. Biorhythms are similar to astrology in their emphasis on the time of a person's birth, and although biorhythms have a slightly more scientific basis than astrology, that in itself doesn't say much.
Creating biorhythm charts for personal use was popular in the United States during the 1970s; many places (especially video rooms and entertainment areas) had a biorhythm machine that provided graphics upon entering the date of birth. A 1978 study on the incidence of industrial accidents found no empirical or theoretical support for the biorhythm model. According to the theory of biorhythms, a person's life is influenced by rhythmic biological cycles that affect his ability in various domains, such as mental, physical and emotional activity. Some doctors tried to use biorhythm for diagnosis, and others used biorhythms to predict football matches.
However, unlike biorhythms, which are claimed to have precise and unalterable periods, circadian rhythms are found observing the cycle itself and periods are found to vary in length depending on biological and environmental factors. . .