पुढील उतारा वाचून त्यापुढील प्रश्नांची उत्तरे लिहा :
जीवनसत्त्वे
जीवनसत्त्वे ही सेंद्रिय घटके बऱ्याच अन्नपदार्थांमध्ये अतिशय कमी प्रमाणात असतात. शरीरातील बऱ्याच महत्त्वपूर्ण कार्यांमध्ये त्यांची गरज असते; त्याचप्रमाणे बरीचशी जीवनसत्त्वे ही काही प्रमुख पोषकांच्या वापरासाठी जसे की प्रथिने, चरबी, कार्बोहाइड्रेट वगैरे कामात येतात. जरी जीवनसत्त्वे ही अतिशय कमी प्रमाणात वापरात येतात; तरी ती आरोग्य आणि शरीराच्या स्वास्थ्यासाठी अत्यंत जरूरी असतात. ह्या जीवनसत्त्वांचा जेव्हा त्यांच्या कार्यानुरूप शोध लागला परंतु त्यांची रासायनिक घडण पूर्ण माहित नव्हती तेव्हा त्यांना जीवनसत्त्व A, जीवनसत्त्व B, जीवनसत्त्व C, जीवनसत्त्व D अथवा त्यांच्या प्रमुख उपयोगासाठी जसे की; अँटिझेरोथैलेमिक, अँटिन्युरीटीक, अँटिस्कॉरब्युटिक आणि प्रतिजैविक जीवनसत्त्वे असे संबोधण्यात येत होते. ह्या जीवनसत्त्वांची रासायनिक घडण पूर्ण समजल्यानंतर त्यांना आता रेटिनॉल, थायमिन, रिबोफ्लेविन, एस्कॉर्बिक आम्ल आणि कोल-कॅल्सीफेरॉल ह्या नावाने ओळखले जाते.
जीवनसत्त्वांचे सर्वसाधारणपणे वर्गीकरण हे पाण्यात विरघळणारी जीवनसत्त्वे अथवा चरबीमध्ये विरघळणारी जीवनसत्त्वे असे केले जाते. B कॉम्लेक्स जीवनसत्त्वे आणि एस्कॉरबिक आम्ल हे आधीच्या वर्गात येतात तर जीवनसत्त्वे A, D, E आणि K हे चरबीमध्ये विरघळणारी असतात. पाण्यात विरघळणारी जीवनसत्त्वे शरीरात साठून न रहाता; ती उत्सर्जित केली जातात तर चरबीमध्ये विरघळणारी जीवनसत्त्वे ही शरीरात साठवली जातात. ह्याच कारणामुळे चरबीमध्ये विरघळणाऱ्या जीवनसत्त्वांचा जीवनसत्त्व A आणि D ह्यांचा अतिरेक हा घातक होवू शकतो.
रेटिनॉल अथवा जीवनसत्त्व A हे अंधुक प्रकाशातही स्पष्ट दिसण्यासाठी जरूरी असते, त्यामुळेच A जीवनसत्त्वाची कमतरता ही रातांधळेपणा आणते. जीवनसत्त्व A चे आणखी एक कार्य म्हणजे एपिथेलीअल् उतकाला स्वस्थ्य राखणे. रेटिनॉल अथवा जीवनसत्त्व A हे काही पदार्थांमध्ये जसे की लोणी, तूप, दूध, अंड्यातील बलक, प्राण्यांचे काळीज इत्यादी मध्ये असते. वनस्पतीजन्य अन्नपदार्थांमध्ये जीवनसत्त्व A हे रेटिनॉल ह्या प्रकारात नसते. ह्या अन्नपदार्थांमध्ये पिवळ्या रंगाचे-कॅरोटिन-नावाचे रंग द्रव्य असते जे शरीरात गेल्यावर जीवनसत्त्व A मध्ये बदलते म्हणून त्यांना "प्रोव्हिटॅमीन A" असे संबोधले जाते.
जीवनसत्त्व D हे हाडांच्या वाढीसाठी आणि कॅल्शियमच्या चयापचयासाठी जरूरी असते. खाद्यपदार्थांमधून आलेले कॅल्शियम आतड्यात आल्यानंतर शोषून घेऊन ते हाडांमध्ये जमवण्याचे महत्त्वाचे काम जीवनसत्त्व D करते.
सूर्यप्रकाशातील अतिनील किरणे ही त्वचेमध्ये असलेल्या कोलेस्टेरॉल डेरीव्हेटिवचे जीवनसत्त्वे D मध्ये रूपांतर करतात. जीवनसत्त्व D ची कमतरता ही रिकेटस् आणि ऑस्टिओमॅलेशियाला कारणीभूत ठरते. लहान मुलांमध्ये जीवनसत्त्व D चे प्रमाण 200 - 400 IU एव्हढे असावयास हवे; जे उष्णकटिबंधीय देशांमध्ये सूर्यप्रकाशात सहज उपलब्ध असते.
वनस्पतीजन्य अन्नपदार्थांमध्ये रेटिनॉलच्या ऐवजी खालील रासायनिक घटक असतो :
EN
Read the following passage and answer the questions:
Vitamins Vitamins are organic substances present in small amount in many foods. They are required for carrying out many vital functions of the body and many of them are involved in the utilization of the major nutrients like proteins, fat and carbohydrates. Although they are needed in small amounts, they are essential for health and well-being of the body. When these vitamins are discovered on the basis of their function and before their chemical nature fully elucidated, they used to be designated by affixing the letter A, B, C, D or in terms of their major functions, viz Antixerophthalmic, Antineuritic, Antiscorbutic and Antirachatic Vitamins. After establishing the chemical nature of these Vitamins, they are now referred to by their chemical names such as Retinol, Thiamin, Riboflavin, Ascorbic Acid and Chole-calciferol. Vitamins can be broadly classify as water soluble and fat soluble vitamins. B-complex Vitamins and Ascorbic Acid belong to the former group while Vitamin A, D, E, K are the fat soluble Vitamins. Water soluble Vitamins are not accumulated in the body, but are readily excreted while fat soluble Vitamins are stored in the body. For this reason, excessive intake of fat soluble Vitamins, Vitamin A and D can prove toxic. Retinol or Vitamin A is necessary for clear vision in dim light. Lack of Vitamin A thus leads to night blindness. Another function of vitamin A is to maintain the integrity of epithelial tissue. Retinol or vitamin A is present in some foods like butter and ghee, whole milk, curd, egg yolk, liver etc. In vegetables food Vitamin A is not present as Retinol. These food contain yellow pigment called Carotene which is converted into Vitamin A in the body. So they are termed as Provitamin A. Vitamin D is required for bone growth and calcium metabolism. It plays an important role in the absorption of dietary calcium from the intestine and its deposition in bone. Vitamin D is formed in the skin by Ultraviolet rays present in sunlight which convert a cholesterol derivative present in the skin to Vit. D. Lack of Vitamin D leads to rickets and osteomalacia. The Vitamin D requirement of child is placed between 200 - 400 IU; which may be obtained in great measures in tropical countries through exposure to sunlight. In vegetable foods, instead of Retinol following chemical is present :
Vitamins Vitamins are organic substances present in small amount in many foods. They are required for carrying out many vital functions of the body and many of them are involved in the utilization of the major nutrients like proteins, fat and carbohydrates. Although they are needed in small amounts, they are essential for health and well-being of the body. When these vitamins are discovered on the basis of their function and before their chemical nature fully elucidated, they used to be designated by affixing the letter A, B, C, D or in terms of their major functions, viz Antixerophthalmic, Antineuritic, Antiscorbutic and Antirachatic Vitamins. After establishing the chemical nature of these Vitamins, they are now referred to by their chemical names such as Retinol, Thiamin, Riboflavin, Ascorbic Acid and Chole-calciferol. Vitamins can be broadly classify as water soluble and fat soluble vitamins. B-complex Vitamins and Ascorbic Acid belong to the former group while Vitamin A, D, E, K are the fat soluble Vitamins. Water soluble Vitamins are not accumulated in the body, but are readily excreted while fat soluble Vitamins are stored in the body. For this reason, excessive intake of fat soluble Vitamins, Vitamin A and D can prove toxic. Retinol or Vitamin A is necessary for clear vision in dim light. Lack of Vitamin A thus leads to night blindness. Another function of vitamin A is to maintain the integrity of epithelial tissue. Retinol or vitamin A is present in some foods like butter and ghee, whole milk, curd, egg yolk, liver etc. In vegetables food Vitamin A is not present as Retinol. These food contain yellow pigment called Carotene which is converted into Vitamin A in the body. So they are termed as Provitamin A. Vitamin D is required for bone growth and calcium metabolism. It plays an important role in the absorption of dietary calcium from the intestine and its deposition in bone. Vitamin D is formed in the skin by Ultraviolet rays present in sunlight which convert a cholesterol derivative present in the skin to Vit. D. Lack of Vitamin D leads to rickets and osteomalacia. The Vitamin D requirement of child is placed between 200 - 400 IU; which may be obtained in great measures in tropical countries through exposure to sunlight. In vegetable foods, instead of Retinol following chemical is present :