Water is virtually everywhere, from soil moisture and ice caps, to the cells inside our own bodies. Depending on factors like location, fat index, age, and sex, the average human is between 55-60% water. At birth, human babies are even wetter. Being 75% water, they are swimmingly similar to fish. But their water composition drops to 65% by their first birthday. So what role does water play in our bodies, and how much do we actually need to drink to stay healthy? The H20 in our bodies works to cushion and lubricate joints, regulate temperature, and to nourish the brain and spinal cord. Water isn't only in our blood. An adult's brain and heart are almost three quarters water. That's roughly equivalent to the amount of moisture in a banana. Lungs are more similar to an apple at 83%. And even seemingly dry human bones are 31% water. If we are essentially made of water, and surrounded by water, why do we still need to drink so much? Well, each day we lose two to three liters through our sweat, urine, and bowel movements, and even just from breathing. While these functions are essential to our survival, we need to compensate for the fluid loss. Maintaining a balanced water level is essential to avoid dehydration or over-hydration, both of which can have devastating effects on overall health. At first detection of low water levels, sensory receptors in the brain's hypothalamus signal the release of antidiuretic hormone. When it reached the kidneys, it creates aquaporins, special channels that enable blood to absorb and retain more water, leading to concentrated, dark urine. Increased dehydration can cause notable drops in energy, mood, skin moisture, and blood pressure, as well as signs of cognitive impairment. A dehydrated brain works harder to accomplish the same amount as a normal brain, and it even temporarily shrinks because of its lack of water. Over-hydration, or hyponatremia, is usually caused by overconsumption of water in a short amount of time. Athletes are often the victims of over-hydration because of complications in regulating water levels in extreme physical conditions. Whereas the dehydrated brain amps up the production of antidiuretic hormone, the over-hydrated brain slows, or even stops, releasing it into the blood. Sodium electrolytes in the body become diluted, causing cells to swell. In severe cases, the kidneys can't keep up with the resulting volumes of dilute urine. Water intoxication then occurs, possibly causing headache, vomiting, and, in rare instances, seizures or death. But that's a pretty extreme situation. On a normal, day-to-day basis, maintaining a well-hydrated system is easy to manage for those of us fortunate enough to have access to clean drinking water. For a long time, conventional wisdom said that we should drink eight glasses a day. That estimate has since been fine-tuned. Now, the consensus is that the amount of water we need to imbibe depends largely on our weight and environment. The recommended daily intake varies from between 2.5-3.7 liters of water for men, and about 2-2.7 liters for women, a range that is pushed up or down if we are healthy, active, old, or overheating. While water is the healthiest hydrator, other beverages, even those with caffeine like coffee or tea, replenish fluids as well. And water within food makes up about a fifth of our daily H20 intake. Fruits and vegetables like strawberries, cucumbers, and even broccoli are over 90% water, and can supplement liquid intake while providing valuable nutrients and fiber. Drinking well might also have various long-term benefits. Studies have shown that optimal hydration can lower the chance of stroke, help manage diabetes, and potentially reduce the risk of certain types of cancer. No matter what, getting the right amount of liquid makes a world of difference in how you'll feel, think, and function day to day.
Air ada di mana-mana sahaja, dari kelembapan tanah hingga litupan ais, dan juga sel di dalam badan kita. Bergantung kepada faktor seperti lokasi indeks lemak, umur dan jantina, secara purata badan manusia mengandungi 55-60% air. Bayi mengandungi lebih banyak air. Dengan 75% air, bayi hampir sama dengan ikan. Tetapi komposisi air mereka turun kepada 65% menjelang usia satu tahun. Jadi apa peranan air dalam badan kita, dan berapa banyak air yang kita perlu minum untuk kekal sihat ? H20 dalam badan kita berfungsi sebagai kusyen dan pelincir sendi, mengawal suhu, dan menyuburkan otak dan saraf tunjang. Air bukan sahaja terdapat dalam darah kita. Otak dan jantung dewasa terdiri daripada 3/4 air. Lebih kurang sama dengan kandungan air sebiji pisang. Paru-paru hampir sama dengan epal dengan 83% air. Dan tulang yang nampak kering mengandungi 31% air. Jika kita terdiri daripada air, dan dikelilingi air, kenapa kita masih perlu minum dengan banyak ? Setiap hari kita kehilangan dua ke tiga liter air melalui peluh, air kencing dan pembuangan air besar, malahan melalui pernafasan. Kesemua fungsi penting untuk kelangsungan, maka kita perlu mengganti kehilangan air. Mengekalkan tahap air yang seimbang penting untuk mengelak penyahhidratan atau terlebih hidrasi, kedua-duanya boleh mendatangkan kesan buruk ke atas kesihatan. Apabila kandungan air rendah dikesan, reseptor deria di dalam hipotalamus otak menghantar isyarat kepada hormon antidiuertik. Apabila ia sampai di buah pinggang, ia mencipta akuaporins, saluran khas yang membolehkan darah menyerap dan menyimpan lebih banyak air, menghasilkan air kencing gelap dan pekat. Penyahhidratan boleh menyebabkan penurunan tenaga yang ketara, emosi, kelembapan kulit, dan tekanan darah, serta tanda-tanda gangguan kognitif. Otak yang mengalami penyahhidratan perlu bekerja lebih keras berbanding otak biasa, dan ia juga mengecut buat sementara waktu disebabkan kekurangan air. Terlebih hidrasi, atau hyponatremia, selalunya disebabkan meminum air terlalu banyak dalam tempoh masa yang pendek. Atlit selalu mengalami terlebih hidrasi disebabkan komplikasi mengawal selia kandungan air dalam keadaan fizikal yang melampau. Jika otak yang mengalami penyahhidratan menghasilkan lebih hormon antidiuretik, otak terlebih hidrasi perlahankan atau berhenti melepaskannya ke dalam darah. Elektrolit natrium di dalam badan menjadi lebih cair, menyebabkan sel membengkak. Dalam kes yang teruk, buah pinggang tidak dapat menampung jumlah air kencing yang meningkat. Mabuk air akan berlaku, menyebabkan sakit kepala, muntah, kadangkala sawan atau kematian. Tetapi itu situasi melampau. Secara normal setiap hari, mengekalkan sistem hidrasi yang baik mudah untuk diuruskan bagi kita yang cukup bernasib baik mempunyai akses kepada air minuman bersih. Selama ini, kita telah diberitahu perlu minum lapan gelas sehari. Anggaran itu telah diperhalusi. Sekarang, pakar mengatakan jumlah air yang perlu kita minum sangat bergantung kepada berat badan dan persekitaran kita. Pengambilan harian yang disyorkan untuk lelaki antara 2.5-3.7 liter dan 2-2.7 liter untuk wanita, jumlah yang turun naik bergantung kepada keadaan kesihatan kita, aktif, usia, atau kepanasan. Walaupun air adalah sumber terbaik, minuman lain, malah yang mengandungi kafein seperi kopi atau teh, menggantikan bendalir juga. Air di dalam makanan membentuk kira-kira satu perlima pengambilan H20 harian kita. Buah dan sayuran seperti strawberi, timun dan juga brokoli mengandungi lebih 90% air, boleh membantu pengambilan air di samping membekalkan nutrisi dan serat. Minum air secukupnya juga memberi kesan jangka panjang yang baik. Kajian menunjukkan hidrasi optimum boleh mengurangkan risiko strok, bantu mengawal kencing manis, dan berpotensi mengurangkan risiko beberapa jenis kanser. Apapun, mengambil jumlah air yang betul membawa perbezaan besar terhadap bagaimana anda rasa, berfikir, dan berfungsi setiap hari.