Tuesday, November 10, 2009


Electricity is a general term that encompasses a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning and static electricity, but in addition, less familiar concepts, such as the electromagnetic field and electromagnetic induction.

In general usage, the word "electricity" is adequate to refer to a number of physical effects. In scientific usage, however, the term is vague, and these related, but distinct, concepts are better identified by more precise terms:

* Electric charge – a property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields.
* Electric current – a movement or flow of electrically charged particles, typically measured in amperes.
* Electric field – an influence produced by an electric charge on other charges in its vicinity.
* Electric potential – the capacity of an electric field to do work on an electric charge, typically measured in volts.
* Electromagnetism – a fundamental interaction between the magnetic field and the presence and motion of an electric charge.

Electrical phenomena have been studied since antiquity, though advances in the science were not made until the seventeenth and eighteenth centuries. Practical applications for electricity however remained few, and it would not be until the late nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry and society. Electricity's extraordinary versatility as a source of energy means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. The backbone of modern industrial society is, and for the foreseeable future can be expected to remain, the use of electrical power.

Blood Circulation

Living things must be capable of transporting nutrients, wastes and gases to and from cells. Single-celled organisms use their cell surface as a point of exchange with the outside environment. Multicellular organisms have developed transport and circulatory systems to deliver oxygen and food to cells and remove carbon dioxide and metabolic wastes. Sponges are the simplest animals, yet even they have a transport system. Seawater is the medium of transport and is propelled in and out of the sponge by ciliary action. Simple animals, such as the hydra and planaria, lack specialized organs such as hearts and blood vessels, instead using their skin as an exchange point for materials. This, however, limits the size an animal can attain. To become larger, they need specialized organs and organ systems.
I found this picture at the American Medical Association home page.

Monday, November 9, 2009

Bintang dan Galaksi

Bintang merupakan benda langit yang memancarkan cahayanya sendiri. Terdapat bintang semu dan bintang nyata. Bintang semu adalah bintang yang tidak menghasilkan cahaya sendiri, tetapi memantulkan cahaya yang diterima dari bintang lain. Bintang nyata adalah bintang yang menghasilkan cahaya sendiri. Secara umum sebutan bintang adalah objek luar angkasa yang menghasilkan cahaya sendiri (bintang nyata).

Galaksi pula merupakan kumpulan bintang-bintang yang terdapat dalam Alam Semesta. Galaksi dalam mana sistem suria, iaitu bumi dan matahari berada di dalamnya dikenali sebagai Bima Sakti.

Bintang-bintang sentiasa wujud secara berkelompok yang dikenali sebagai galaksi, bersama-sama dengan gas, debu interstellar, dan "jisim gelap"; sekitar 10-20% dari galaksi terdiri daripada bintang, gas, dan debu. Galaksi dikekalkan bersama oleh tarikan graviti dan komponen galaksi mengorbit satu pusat. Terdapat bukti bahawa lubang gelap mungkin wujud di pusat sebahagian, atau kebanyakan, galaksi. Galaksi terbentuk dari protogalaksi.

Perkataan galaksi dalam bahasa Inggeris galaxy diambil dari nama galaksi kita , Bima Sakti ( Milky Way ), menggunakan perkataan Yunani gala (umumnya galaktos) bererti susu.


The respiratory system's function is to allow gas exchange to all parts of the body. The space between the alveoli and the capillaries, the anatomy or structure of the exchange system, and the precise physiological uses of the exchanged gases vary depending on the organism. In humans and other mammals, for example, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles. Molecules of oxygen and carbon dioxide are passively exchanged, by diffusion, between the gaseous external environment and the blood. This exchange process occurs in the alveolar region of the lungs.

Sumber - Sumber Maklumat

Saya telah mendapat beberapa maklumat melalui perkhidmatan jalur lebar ini dan beberapa alamat yang boleh saya kongsikan dengan anda semua berada dalam link yang disediakan.

Friday, October 30, 2009

Sistem Tubuh Badan Manusia

Sistem tubuh badan manusia pada dasarnya mempunyai ciri-ciri yang prinsipnya sama pada setiap individu. Dari prinsip karakteristik sama ini sistem tubuh manusia dapat dipelajari. Misalnya cara oksigen masuk ke dalam tubuh, cara zat-zat makanan diserap dari saluran pencernaan, cara sel mendapatkan makanan dan sebagainya.

Tubuh manusia sebagai organisme hidup terdiri dari berbagai sistem fungsional misalnya sistem pernafasan, pencernaan, sistem saraf dan sebagainya. Sistem-sistem tersebut terdiri dari beberapa organ pendukungnya. Misalnya sistem pencernaan terdiri dari mulut, esophagus, lambung, usus halus, usus besar dan anus. Organ-organ tubuh yang mempunyai fungsinya masing-masing tersebut terdiri dari jaringan-jaringan. Jaringan tersebut dibentuk dari sel-sel yang sama.