Jennifer Ellison Brown: The digestive and absorptive system

first_img Digestion Digestion and absorption requires a large volume of blood in the capillaries in the walls of the intestine. If exercise is done too soon after eating, blood is moved from the digestive process to working muscles and the food is left undigested. It is important to keep physical activity to a minimum after eating. Generally, it is best to avoid exercising until at least three hours after a meal. By that time, the food would have entered the small intestine, where it passes quickly into the bloodstream and is stored around the body, ready to be converted to energy during physical activity. Digestion and exercise Digestion is the breakdown of food into simpler molecules (nutrients), which can be absorbed into the bloodstream and used by the cells of the body. The process begins in the mouth, where the food is chewed into smaller pieces and mixes with saliva that contains the digestive enzyme amylase. Amylase digests starch (e.g. bread, rice, pasta, yam, etc.). After chewing, the food is swallowed into the oesophagus, which leads to the stomach. Food moves through the oesophagus by a process called peristalsis, whereby muscles automatically contract, producing rhythmic waves. When food reaches the stomach, it is mixed with a number of acidic substances, collectively called gastric juices. This gastric juice kills any harmful bacteria that may have been ingested with the food. Some nutrients and water contained in the food are absorbed into the bloodstream. The enzyme pepsin starts the breakdown of protein. Food stays in the stomach for about two and a half hours, where it is churned into a liquefied state to form chyme. The chyme is released in small amounts into the first part of the small intestine, the duodenum. In the duodenum, a number of enzymes produced by the gall bladder, the liver and the pancreas are mixed with the food. The gall bladder stores bile, which neutralises the acid leaving the stomach. Bile also helps to break down fats in the small intestine. The liver produces bile, which also helps with the breakdown of carbohydrates and protein. It also acts as a filter, maintaining the balance of nutrients in the blood. The pancreas produces insulin and other enzymes, which help with the digestion of carbohydrates, fats and proteins. The end products of digestion (glucose, amino acids and fatty acids), along with minerals, vitamins and water are absorbed into the blood stream by hair-like projections (villi) on the inner surface. All the nutrients absorbed from the small intestine is carried to the liver first. The level of nutrients in the blood is adjusted to the best levels for the body to function. Excess glucose is converted to glycogen and fat. Glycogen is stored in the liver and muscles and fat is stored all over the body, but particularly beneath the skin. Excess fatty acid is also converted to fat, while excess amino acid is converted to glucose and the toxic waste urea. Urea is eventually excreted by the kidney. If glucose and fatty acids are in short supply, the liver reverses the processes described above and releases glucose from the glycogen stores and fatty acids from the fat stores. The body cannot store protein. Therefore, if amino acids are in short supply, the liver cannot produce more. After the liver has adjusted the amount of nutrients to the correct level in the blood, they pass on around the body. Glucose and fatty acids are used as energy sources. Amino acids are used to make the proteins necessary for growth and the repair of tissues; e.g. muscle tissue or as a source of energy, if necessary. The remaining undigested food passes into the large intestine (colon), where water is reabsorbed and the undigested food moves to the rectum and eventually passed out the anus as faeces. The digestive and absorptive system consists of the alimentary canal (mouth, oesophagus, stomach, small intestine, large intestine, rectum and anus), salivary glands, the pancreas, the liver and the associated blood vessels.last_img read more

Lion heart

first_imgTwisting and turning, it was as if Matt Leinart was carrying the football under one arm and the Heisman Trophy in the other. Slung over his back were the expectations of winning a third consecutive national championship, something nobody else has done, and the demands of his growing celebrity, which he was learning are inseparable from the perks that come with jumping to the other side of the velvet rope. It’s one thing to bear that burden when you’ve spent your whole life preparing for it, but who could have seen this coming? If Leinart can lead No. 1-ranked USC past No. 2-ranked Texas on Wednesday at the Rose Bowl, he’ll have concluded each of his three years with at least a share of a national championship, and he’ll leave school with just as many Heisman Trophies as losses. Even if he can’t, some will still make the argument that he’s the best quarterback in college football history. As the accolades and attention have been laid at Leinart’s feet, it’s something he’s still coming to terms with. If he’s grown to be tall, handsome, athletic and immensely popular, he can’t help but wonder why? This is because Leinart never has forgotten who he used to be. “The fat, cross-eyed kid with glasses,” he said. Leinart was born with his left eye out of alignment with his right, something he underwent surgery for when he was 3 years old. But he wore glasses growing up and that, with his chubby build, made him an easy target on the playground. “I know what it’s like to be on both sides,” Leinart said. “There’s all the glory, all the attention, living on top of the world. Growing up – it’s not a super sob story – but it was tough. “When you’re a kid and you have the problems I had, it’s one of those things where I never thought this would happen. My life has completely changed. How people treat me has completely changed. The attention is fun, it’s a great opportunity, but sometimes I look at it like that’s not who I am.” Leinart given ‘nothing’ When Hue Jackson, the offensive coordinator under Paul Hackett, recruited Carson Palmer, he put together a glossy brochure that listed his future accomplishments should he become a Trojan: Heisman Trophy winner, national championship, No. 1 pick in the draft. Asked what Jackson gave him, Leinart said: “Nothing.” Leinart was a Parade All-American at Mater Dei High in Orange County, but he wasn’t the type of prospect they actually threw a parade for, like Palmer before him or John David Booty and Mark Sanchez after him. Leinart came to USC mainly because the Trojans would have him, something UCLA, the school he grew up rooting for, wouldn’t. When Hackett was fired and Carroll hired, Leinart signed a letter of intent, even if he wasn’t sure what he was signing on for. “I just wanted to play,” Leinart said of his expectations. “I don’t think any of us imagined what was going to happen. Coach Carroll was preaching when he came in, but we didn’t know if he was going to follow up or really change the program.” Leinart redshirted his first year, hoping to back up Palmer the next season. Instead, he was stuck behind sophomore Matt Cassel. His father asked for a conference with offensive coordinator Norm Chow, concerned that his son wasn’t getting enough work in practice to improve. When Leinart returned to Mater Dei to work out and visit with friends and coaches, it wasn’t hard to tell he was down. “Matt thrives on confidence,” said Bruce Rollinson, his coach at Mater Dei. “By no means did we coddle him when he was here, but we kept it light and airy, which is difficult for me to do. If he came off after throwing a bad pass, I’d say, `That was a real beauty.’ ” USC was headed in the right direction after a 10-2 season, but with Palmer departing the big question facing the team was who would be his replacement? Just before the start of spring practice, Carroll told Leinart the job was his to lose. Suddenly, everything started to click. “He looked like a different guy,” offensive tackle Winston Justice said. “He was confident. It was like it was his team.” Still, Leinart had yet to throw a pass in a game, and if the demanding Chow wasn’t enamored of Cassel, Brandon Hance or Billy Hart, there was the possibility he could turn to Booty, who had enrolled after graduating high school a year early. In his first start, a 23-0 win at Auburn, which was ranked third and had been picked by Sports Illustrated to win the national championship, Leinart was flawless. But late in September, he threw three interceptions in an overtime loss at Cal and suffered a knee injury the next week at Arizona State that sent him to the sidelines for much of the second quarter. With the score tied at 10-10, Cassel ineffective and Hance warming up to start the second half, Leinart asked back in the game. He passed for two touchdowns in the second half and earned the name “Lion Heart” from his teammates. USC hasn’t lost since. “When you’re named the starter and you grow and get experience, that builds your confidence game-by-game,” Leinart said. “That first year, about halfway through is when I really started gaining the confidence I needed to start playing and it’s just grown from there.” Indeed, in the ensuing 34-game winning streak, the Trojans have failed to score at least 37 points just eight times. As it turns out, winning isn’t Leinart’s only habit. Each Wednesday he must have lunch with his dad and each Friday he must have lunch with his brother, though that has called for some recalibration of the calendar this week since game day is Wednesday. Then there are the boxers. He has worn the same pair for each start of his career, except one: the loss to Cal. “They’re my lucky boxers,” he said. “They’ve got holes in them. I clean them every week, but they’re gross.” Too much information, you say? Perhaps, but Leinart’s profile in Hollywood has been raised enough that inquiring minds want to know. When Nick Lachey and Jessica Simpson were splitting up, tabloids offered USC beat reporters $400 if they could get a comment from Leinart, who is a friend of Lachey. Since last season, USC has limited Leinart’s availability to the media to once a week, not that it has kept his appearances at Hollywood parties out of the papers or prevented news that his only class this semester was ballroom dancing from becoming a national story. To ensure he isn’t bothered by autograph seekers, Leinart is whisked from practice to the locker room in a motorized cart. When he isn’t in uniform, Leinart usually wears a baseball cap pulled down tight or a hooded sweatshirt over his head. Leinart joked after the NCAA banned him from speaking to the media for one week after he improperly filmed a promotional spot for ESPN that he was disappointed it wasn’t longer. If it’s distasteful, all the attention might be good medicine. “It’s helped him understand the amount of scrutiny you’re under to be an NFL quarterback,” said Sarkisian, who spent last year as an assistant with the Oakland Raiders between stints at USC. “That’s what he was playing for us this year. The media, the questions, the time management, the notoriety, girls trying to throw themselves at him – they’re all different issues to deal with.” Leinart also has made other good uses of his decision to return, which was influenced by his need for elbow surgery after last season. He has improved his mobility and his arm strength, Sarkisian said. Leinart is so proud of his work ethic and aptitude that he fights the perception that, with his class schedule and club-hopping, he has a case of senioritis. “Matt knows how hard he worked to get to this point and he never takes it for granted,” said his roommate, receiver Dwayne Jarrett. In fact, Sarkisian calls Leinart his toughest critic, saying he’ll dwell on his mistakes and have to be built up the rest of the week. After USC fell behind by 13 points at Oregon and 18 points at Arizona State before kicking it into gear and winning, and didn’t put away woeful Arizona until the fourth quarter, Leinart went into a funk. Then came Notre Dame. “We kind of faced the monster a little bit and he has not been the same since,” Carroll said. “He stopped projecting about what should happen and what he should be and just got back to being a kid playing football and having fun with it.” Sometimes it’s that simple. The difference between carrying the world on your back – or holding it in your hands. Billy Witz, (818) 713-3621 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! AD Quality Auto 360p 720p 1080p Top articles1/5READ MORECoach Doc Rivers a “fan” from way back of Jazz’s Jordan Clarkson Yet instead of exhilaration, Leinart felt exhaustion. Lying in the turf, he began to cry. When his teammates mobbed him as he staggered to the sidelines, he looked stunned, his eyes glazed over. The emptiness didn’t stop then. The next day he met with quarterbacks coach Steve Sarkisian. Leinart vented. Then he listened. “I took a deep breath and said, ‘You know, this is what I came back to do, to have fun and be a part of this,’ ” Leinart said. “I’m not a guy that gets tense or nervous or anything like that. I think everything was kind of building up. I think I’ve been doing a pretty good job of kind of handling everything the past couple of years. (It) was just like, oh, man, I felt like there was so much weight on my shoulders.” center_img No wonder he needed a push. When Leinart, with his all-or-nothing lunge, crossed the goal line at Notre Dame, it was the signature moment of his career. last_img