why is the pineal gland considered the biological clock of the body?
484390
Pinealocytes, neuron-like cells in the Pineal Gland, produce melatonin which is derived from serotonin. They induce rhythmic changes in the body in response to light. Melatonin levels rise at night and make us sleepy. Melatonin plays a role in our light-dark cycles and its secretion (or lack thereof) is one basis for our feelings associated with jet lag. \n\nThe responses generated by the Pineal Gland and its secretions make it the biological clock of the body.
196749
no, it's because of the rotation of the earth.  Clocks in the southern hemisphere go around the other direction, like your toilet ;-).\n\nIt's because the shadow on a sun dial in England goes around that direction.
777530
I dont believe it has anything to do with the spring season.Children grow when they sleep....no sleep.no growth.With setting the clocks ahead 1 hour in the spring they are actually getting more sleep, which means more growth
469294
Hair is an interesting biological structure. What we usually think of as 'hair' is really just the part we see... that's the hair shaft, which contains pigment (a chemical that gives color to things). There is also a hair follicle, which is a multi-cellular structure inside the skin of our scalp that creates the hair strand (making it grow), and also is responsible for the pigmentation. Some of the cells in the follicle make the chemical melanin, which is a skin and hair pigment in many species on our planet. \n\nHair turns grey when the pigment cells in the hair follicle stop making melanin. When this happens due to aging, it's mostly under the control of the genes we inherit. Long periods of constant stress may also contribute, but a big shock won't turn hair grey overnight.
344727
The influence of maternal circadian rhythms on fetal circadian oscillations during pregnancy was examined. Circadian rhythms of spontaneous locomotor activity and plasma corticosterone level in pregnant rats were eliminated by bilateral lesions of the suprachiasmatic nuclei (SCN) at different stages of gestation and the postnatal manifestation of the circadian corticosterone rhythm was examined in individual pups. Effective lesions of SCN at day 3 of gestation resulted in an abortion in all rats examined. Rats whose SCN were lesioned at day 10 or 17 of gestation maintained their pregnancies. At term, pups were removed by Cesarean operation and immediately blinded by bilateral ocular enucleation; they were reared by unoperated foster mother afterwards. All pups from SCN lesioned mothers showed a clear free running circadian rhythm of plasma corticosterone levels after the 4th week of postnatal life. Furthermore, the circadian rhythm that developed in pups from SCN- lesioned mother at day 10 of gestation (G10 pups) was always phase- delayed about 4 h as compared with that in pups from mothers whose SCN were lesioned at day 17 of gestation (G17 pups) and in pups from sham- operated mothers (S pups). It is concluded that the circadian hormone rhythmicity develops in normal fashion postnatally when the maternal SCN are effectively lesioned after day 10 of gestation. The phase-angle difference in the circadian rhythm between G10 pups and G17 or S pups suggests that fetal circadian oscillation is entrainable at least after day 10 of gestation.
805486
3pm is when the sprit of the Trinity is stronger so it wards off demons\n3am is Satan's way of mocking God.\n\nI don't beleive it has anything to do with the time, just got that off of Exorcism of Emily Rose...
525194
Body odors come from many parts of the body, not just the sweat glands. Hygiene, diet, laundry, perfumes-colognes-aromatic oils and health-ill-health are also known to affect the odors we give off, sweet or not so sweet.  \n\nBut there are 2 basic types of sweat glands, apocrine and eccrine.  Both types produce sweat, but the sweat is different chemistry and for different purposes.  Mammals have sweat glands covering their skin all over.  Sweat glands are important for evaporative cooling and are especially activated when body is overheated.  But the sweat glands associated with the hairy parts of the body that we get a puberty are different, and the odors associated with these parts (axilla and pubic hair) of the body give distinct odors associated with stress and or mating-pairing-breeding-sex and the conscious-unconscious communications by "pheromones" and are activated by the sympathetic nervous system when we are in a "stimualted-fight or flight emergency." Diabetics who are not in good blood sugar health or people losing weight rather rapidly can also have the smell of KETONES coming from them breath or skin.
64280
The foundations of the endocrine system are the hormones and glands. As the body's chemical messengers, hormones (pronounced: hor-moanz) transfer information and instructions from one set of cells to another. Although many different hormones circulate throughout the bloodstream, each one affects only the cells that are genetically programmed to receive and respond to its message. Hormone levels can be influenced by factors such as stress, infection, and changes in the balance of fluid and minerals in blood.\n\nA gland is a group of cells that produces and secretes, or gives off, chemicals. A gland selects and removes materials from the blood, processes them, and secretes the finished chemical product for use somewhere in the body. Some types of glands release their secretions in specific areas. For instance, exocrine (pronounced: ek-suh-krin) glands, such as the sweat and salivary glands, release secretions in the skin or inside of the mouth. Endocrine glands, on the other hand, release more than 20 major hormones directly into the bloodstream where they can be transported to cells in other parts of the body. \n\nThe major glands that make up the human endocrine system are the hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal body, and the reproductive glands, which include the ovaries and testes. The pancreas is also part of this hormone-secreting system, even though it is also associated with the digestive system because it also produces and secretes digestive enzymes. Although the endocrine glands are the body's main hormone producers, some non-endocrine organs - such as the brain, heart, lungs, kidneys, liver, thymus, skin, and placenta - also produce and release hormones.\n\nThe hypothalamus (pronounced: hi-po-tha-luh-mus), a collection of specialized cells that is located in the lower central part of the brain, is the primary link between the endocrine and nervous systems. Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary. \n\nAlthough it is no bigger than a pea, the pituitary (pronounced: puh-too-uh-ter-ee) gland, located at the base of the brain just beneath the hypothalamus, is considered the most important part of the endocrine system. It's often called the "master gland" because it makes hormones that control several other endocrine glands. The production and secretion of pituitary hormones can be influenced by factors such as emotions and seasonal changes. To accomplish this, the hypothalamus relays information sensed by the brain (such as environmental temperature, light exposure patterns, and feelings) to the pituitary.\n\nThe tiny pituitary is divided into two parts: the anterior lobe and the posterior lobe. The anterior lobe regulates the activity of the thyroid, adrenals, and reproductive glands. Among the hormones it produces are:\n\ngrowth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body's handling of nutrients and minerals \nprolactin (pronounced: pro-lak-tin), which activates milk production in women who are breastfeeding \nthyrotropin (pronounced: thigh-ruh-tro-pin), which stimulates the thyroid gland to produce thyroid hormones \ncorticotropin (pronounced: kor-tih-ko-tro-pin), which stimulates the adrenal gland to produce certain hormones \nThe pituitary also secretes endorphins (pronounced: en-dor-finz), chemicals that act on the nervous system to reduce sensitivity to pain. In addition, the pituitary secretes hormones that signal the ovaries and testes to make sex hormones. The pituitary gland also controls ovulation and the menstrual cycle in women. \n\nThe posterior lobe of the pituitary releases antidiuretic (pronounced: an-ty-dy-uh-reh-tik) hormone, which helps control body water balance through its effect on the kidneys and urine output; and oxytocin (pronounced: ahk-see-toe-sin), which triggers the contrac
980335
Oh, please, I'm grading 7th grade ISTEP (the Indiana standardized test), and this is the exact question I've been preparing to train evaluators on.  I have seen about 400 papers of  answers to this question.  Because the biological clocks of teenagers change, so that they begin to go to sleep later and get up later, some say they should start later.  Others say that it should remain the same for some of the following reasons:\n\n1.  To change it would mess up their after school sports and activities schedules, especially if they changed and other local schools didn't.\n2.  They wouldn't have time to get their homework done.\n3.  Some kids' parents drop them off, which they couldn't do if school was later.\n4.  Getting up earlier prepares them for college and work.\n5.  They wouldn't have time to spend with their parents.
290474
Humans.  The morning is birth, when we crawl as babies.  The afternoon is when we are young and mid-adults, when we walk.  The evening is when we are older and use a cane.  The one voice is always our own.  Ah, the Riddle of the Sphinx.  ;)
424239
Hi.\n   It has to do with biology.  It goes along with the school of thought that kids of your age are more alert late in the morning, and your internal clocks don't wind down until later in the evening.  That is probably why you are a "night  owl".  Most teens, young 20somethings are.  \n  P.S.   You can use this on your parents come Saturday morning when you want to sleep in and they think you are being a bum sleeping until noon...It is GOOD for teens to rechage their batteries by sleepin in late!!!\n\nA Suburban Teacher
638061
Your body metabolizes fat more efficiently. Your propensity to sweat is greater which promotes increased fluid (water) intake. The ability to eliminate toxins is greater. Your heart functions more efficiently. You're able to provide more oxygen to the brain thereby heightening awareness and the production of useful chemicals that stimulate and provide energy. etc etc...basically you are stress free when you wake up.\n\nwith that said, different people are more energetic at different times of day.  so just get out there and exercise...doesn't really matter what time of day.
955965
An astronomical clock is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets.\n\nThe term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the sun and moon in the sky, the age and phase of the moon, the position of the sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the moon's nodes (for indicating eclipses) or a rotating star map.\n\nAstronomical clocks usually represent the solar system using the geocentric model. The center of the dial is often marked with a disc or sphere representing the earth, located at the center of the solar system. The sun is often represented by a golden sphere, shown rotating around the earth once a day around a 24 hour analog dial. This view accords both with daily experience and with the philosophical world view of pre-Copernican Europe.\n\n- From http://en.wikipedia.org/wiki/Astronomical_clock
388789
Personal Biorhythms.  We all have internal clocks that determine sleep need/time, best time to take med, best time to do almost everything.  From person to person, no two are alike.
778671
Well, the human body does have an electrical energy flow.  The average frequency of a healthy human body during the daytime is 62 to 68 Hz.  All electric flows have an associated electric field and magnetic field.  So, yes.
1179944
it is strongest between 10am and 2pm.  this is because as the sun rises from the horision the light (and other radiations) are being filtered through more atmosphere. as the sun climbs higher it is comming more directly at you, peeking at noon(ish). Finally as the sun sets it reverses the process and again becomes filtered through more atmosphere.
670101
There are a lot of considerations, like the amount of 'deep sleep' or REM (rapid eye movement) time.  It turns out that things like blood pressure and melatonin (hormone related to sleep) follow the diuranal cycle.  Yes, the sleep should ideally be at night.  That is how the human animal evolved on the planet earth.