Irama Sirkadian (Circadian Rhytms): Kitaran biologikal seharian.

ifzaarnia

ScienceDaily (Dec. 29, 2010) — In a new paper published this week in the Proceedings of the National Academy of Sciences, Aziz Sancar, MD, PhD, the Sarah Graham Kenan Professor of Biochemistry and Biophysics in the UNC School of Medicine, and his colleagues have taken an important step in understanding the underlying molecular signals that influence a broad array of biological processes ranging from the sleep-wake cycle to cancer growth and development.

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Link Between Light Signal and Circadian Rhythms Pinpointed



Scientists who work in this field, known as chronobiology, have identified the genes that direct circadian rhythms in people, mice, fruit flies, fungi and several other organisms. However, the mechanisms by which those genes interact with light in the organism's environment have not been well understood.

Circadian rhythms are the physical, mental and behavioral changes that follow the earth's 24 hour cycle, responding primarily to light and darkness in an organism's environment.

About 15 years ago, Sancar discovered a human protein called cryptochrome which acts as a core component of the molecular clock in mammals. The protein is also found in fruit flies, other insects, and plants.
"Cryptochrome 'resets' the circadian clock, but we were not sure how it worked," said Sancar, who is also a member of UNC Lineberger Comprehensive Cancer Center.

Using fruit flies (Drosophilia melanogaster), the team purified cryptochrome and developed a biochemical test that shows when and how the protein transmits signals.

"We can now detect the protein at work. When we expose cryptochrome to blue light in fruit flies, a millisecond of light exposure has a half-life during which we can examine the mechanism in the laboratory," said Sancar. "We can follow the molecular signals after light exposure and have a reliable model to test various hypotheses about how light interacts with the circadian systems we know are so important to biological processes."

The research may be useful to scientists who study the circadian clock's relationship to sleep disorders, jet lag, cancer, bipolar disorder, depression and other diseases.

Sancar's research collaborators include Nuri Ozturk, PhD, Christopher Selby, PhD, and Yunus Annayev, BSc, of UNC-Chapel Hill's Department of Biochemistry and Biophysics and Donping Zhong, PhD from the Ohio State University.
The research was supported by the US National Institutes of Health.

Reference: http://www.sciencedaily.com/releases/2010/12/101229124252.htm

ifzaarnia

Circadian Rythms (jam biologikal dalam kehidupan seharian):

Maksud:

Perubahan suhu badan manusia dan pengeluaran hormon dan fungsi badan yg lain melalui proses perubahan irama yg boleh mempengaruhi kesan waspada atau berjaga-jaga (alertness) dan kesediaan (readiness) untuk tugasan seharian yg berubah-ubah (back and forth) sepanjang waktu sedar (consciousness) dan tidur (sleep).

Circadian Rythms dikawal oleh suprachiasmatic nuclei (SCN) yg merupakan 'master' jam sirkadian otak (the brain's master circadian clock).

SCN terletak dalam bahagian hypothalamus pada otak.

Neutrons SCN secara automatiknya akan mengenal pasti kitaran genetik yg diprogramkan bagi aktiviti atau tanpa aktiviti seharian yg berfungsi sebagai BIOLOGICAL CLOCK.

Neutron SCN ini berkait rapat dengan PINEAL GLAND yg merembeskan hormon MELATONIN (hormon yg memberi kesan relax atau tenang kepada badan).

Waktu Siang:

1) Neutrons SCN menjadi aktif.

2) Mengurangkan rembesan hormon melatonin pada pineal gland.

3) Seterusnya, meningkatkan suhu badan.

4) Akhirnya, menjadi kita lebih fokus dan waspada(Heightening alertness).

Waktu Malam (terbalik daripada waktu siang):

1) Neurtons SCN menjadi TIDAK aktif.

2) Meningkatkan rembesan hormon melatonin pada pineal gland.

3) Mengurangkan suhu badan.

4) Akhirnya menyebabkan kita berada dalam keadaan relax dan mendorong kita untuk tidur.

Kedudukan SCN, Hypothalamus, dan Pineal Gland dalam otak manusia:

Rujukan: kuliah.

>> Gambar ihsan Encik Google.

dauswq

Reply 2# ifzaarnia

good info

winamp05

benda ni akan boleh jadi konflik bila waktu kerja kita bertukar. contoh masa aku kerja kilang dulu dulu. kerja shift pagi nak switch ke malam. hari pertama memang tak best sebab dah biasa tidur malam. bila masuk hari kedua atau tiga, mengantuk datang pada waktu pagi. walau pon ko curi tidur waktu kerja malam dari jam 3.00Am to 6.00Am.  dah bangun pi makan sarapan, naik motor, buat aktiviti menyegarkan pon still akan datang mengantuk. ape pasal ?