Animal rhythms {biological rhythm}| depend on year, lunar month, tides, and day.
brain clock
Brain can time intervals {brain clock} using striato-cortical loops and frontal-cortex, caudate-putamen, and thalamus dopamine neurons. Clocks can be neuron circuits for each time interval, or neuron populations can code all intervals. Somatosensory lemniscal system can backdate events.
millisecond rhythm
Biochemical reactions have millisecond intervals. Coupled reaction systems can have cycles up to 100 seconds.
second rhythm
Heartbeat has ultradian rhythm regulated by pacemaker-neuron membrane-potential changes by voltage-sensitive K-channels.
minute rhythm
Cycles can repeat every few seconds or minutes for sessile, burrowing, and boring animals. Protein regulates cell 12-minute growth cycles. Inositol-trisphosphate receptor regulates calcium release in C. elegans in fifty-second intervals.
day rhythm
People can live on 23-hour and 25-hour cycles.
development rhythm
Reaction-cycle superpositions cause development cycles, which have intervals from minutes to hours to days.
month rhythm
Biological rhythms can be monthly, for hormones and temperature. Sex-hormone levels vary over lunar month. Marine organisms feed or rest with lunar tides. Shore-living invertebrates typically have tidal cycles and long-term rhythms related to Moon cycles.
year rhythm
Biological rhythms can be yearly, for migrations and moods. Yearly rhythms include hibernation and estivation. Breeding seasons typically are yearly. In autumn, plants can die or start low-metabolism state {dormancy, plant}.
In mammals, Mop3 gene product is main component of 24-hour biological clocks {biological clock}|, in hypothalamus, eye, testis, ovary, liver, heart, lung, and kidney, which work by positive and negative feedback among proteins. Mammals can rest themselves according to environment. Mutant Mop3 requires homozygosity. Clock-gene product acts as a pacemaker in hypothalamus suprachiasmatic nucleus (SCN), which synchronizes other organ clocks. CLOCK, PER, and MOP3 proteins have PAS domains. Circadian rhythm affects albumin D-element-binding protein {mDbp}, which does not regulate circadian rhythm.
Neuron networks {central pattern generator} control breathing, walking, and swimming.
Body has daily activity patterns {circadian rhythm}|. Internal mechanisms for daily cycles have 24-hour cycles.
functions
Body temperature, activity, blood pressure, blood pulse rate, blood volume, hormone levels, eosinophil levels, ACTH concentration, cortisol concentration, magnesium concentration, calcium concentration, 17-hydroxycorticosteroid concentration, sodium concentration, potassium concentration, catecholamine concentration, and phosphate concentration vary over day.
functions: time of day
Labor is most frequent and T lymphocytes are most at 1 AM. Growth hormone and deep sleep are greatest at 2 AM. Asthma attacks are most frequent at 4 AM. Body temperature is lowest at 4:30 AM. Menstruation starts most frequently at 6 AM. Insulin, blood pressure, heart rate, and cortisol are lowest at 6 AM, but melatonin is highest. Blood pressure starts to rise at 6:45 AM. Hay fever is worst at 7 AM. Melatonin production stops at 7:30 AM. Heart attack and stroke are most frequent at 8 AM. Rheumatoid arthritis is worst at 8 AM. T lymphocytes are fewest at 8 AM. Bowel movements are most likely at 8:30 AM. Alertness is highest at 10 AM. Blood hemoglobin concentration is highest at 12 PM. Coordination is best at 2:30 PM. Respiration is fastest, reflexes are quickest, and hand grip is strongest at 3 PM to 3:30 PM. Body temperature, heart rate, and blood pressure are highest at 4 PM. Muscle strength is greatest at 5 PM. Urination is most frequent at 6 PM. Blood pressure is highest at 6:30 PM. Body temperature is highest at 6:30 PM. Sensitivity to pain is greatest at 9 PM. Melatonin production starts at 9 PM, induces sleep at night, and maximizes just before morning. Bowel movements stop at 10:30 PM. Allergic reaction is most frequent at 11 PM.
cycle
Light affects retinal ganglion-cell melanopsin receptors, which catabolize PERIOD (PER) and TIMELESS (TIM) protein complexes in cytoplasm. Six hours later, catabolism is complete and CYCLE and CLOCK proteins bind. Then combined proteins bind to PER and TIM genes in cell nucleus, to start transcription. Six hours later, PER and TIM proteins bind in cytoplasm to form complex that blocks binding of CYCLE and CLOCK in cell nucleus.
After several days {jet lag}|, travelers can adjust to new local time. Travel across time zones can cause disturbances in sleep, digestion, and daily activity rhythms, and disturbances are unpleasant, impair performance, and last several days.
People have 90-minute to 100-minute cycles {ultradian rhythm}|. Desire to eat, desire for sex, sleep phases, daydreams, dreams, alertness, stomach contractions, and instinctual drives in general have ultradian rhythms. Infants have 60-minute movement and inactivity cycles.
Animals can have twilight activity {crepuscular}|.
Animals can have daytime activity {diurnal}|.
Animals can have nighttime activity {nocturnal}|.
Yearly rhythm is deep suspended animation, with low temperature, slow heartbeat, and slow breathing, for summer {estivation}|.
Yearly rhythm is deep suspended animation, with low temperature, slow heartbeat, and slow breathing, for winter {hibernation}|.
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Date Modified: 2022.0225