新東方新托福聽力特訓(xùn)Biology: Sunshine

Biology: Sunshine

“Good morning class. Today I thought we would talk about something bright and
cheerful: the sun. I know most of you got to school before the sun came up, but can
anyone tell me how they feel when its sunny compared to when it’s cloudy?”
(Another voice)
“I find it’s a lot easier to get up in the morning if it’s sunny”
(Back to narrator)
“Good. How do you usually feel if it’s cloudy?”
(Another voice)
“Well I don’t mind, because I enjoy staying in on a rainy day curled up in bed with a
good book.”
(Back to narrator)
“Well, what if I told you it would rain for weeks on end with no break?”
(Another voice)
“Ya I can see your point. I don’t think I would like that very much”
(Back to narrator)
“Most of the articles we read lately regarding the sun are discussing the negative
effects of staying in the sun for too long saying that ultra violet radiation from the sun
is a major cause of skin cancer. Although these articles are factual, the sun does have
some positive side effects as well. As a matter of fact some scientists believe that
sunlight may reduce the risk of several types of cancer. “
(Another voice)
“Excuse me but many articles I’ve read blame the sun for causing cancer, stating that
it can take as little as 30min to get a sunburn”
(Back to narrator)
“Yes and those articles are correct. However in small doses the sun can be quite
healthy for you. In fact recent studies have found that sunlight can actually help
protect you from certain types of cancer such as breast colon bladder and stomach.
More importantly the sun provides us with our main source of vitamin D.”
(Another voice)
“Well I don’t need to worry about vitamins because I take multi vitamins everyday”
(Back to narrator)
“That’s great, but wouldn’t it be better if you didn’t have to take them and you were
able to get vitamins in a more natural way such as food and the sun? Most people
understand that nutrients strengthen our bones and muscles and heighten our immune
system to better fight diseases like the common cold. However, many people don’t
realize that the ultra violet or UV rays from the sun actually convert irgasterol which
is found in our skin to vitamin D. Vitamin D is needed for normal growth of teeth and
bones and has also been proven to prevent the development and increase of cancerous
tumors”
(Another voice)
“Does that mean we should spend all the day in the sun without any protection?
(Back to narrator)
“No spending roughly 10min per day in the sun should be enough to supply us with
all the Vitamin D that we need.”
(Another voice)
“What happens if we don’t get enough Vitamin D?”
(Back to narrator)
“Excellent question! I’m glad you asked me that. Low Vitamin D can cause many
diseases such as chronic fatigue, a softening of the bones, osteoporosis and multiple
skilerriosis. Getting back to our mood some researchers have proven that sunshine
can actually cheer you up. When I see the sun I always feel happy energetic and
generally positive. But did you realize that the sun can change your mood chemically
and might even prevent depression. There is a saying called ‘spring fever’ when many
people feel the beginning of spring as a sign of good days ahead. During the winter
many of us are stuck indoors out of the sun. The lack of sun causes for many people a
condition called SAD or Seasonal Affective Disorder. SAD is caused by suppression of
serotonin which keeps our mood, emotions, sleep and appetite in check. When we
don’t get enough we feel depressed and this is usually experienced by people who are
deprived of sunlight during the dull winter months. So class during your break why
don’t you step outside and get a bit of Vitamin D?”