Difference between bolus and chyme | Difference Between | Difference between bolus vs chyme
Each bolus of food is propelled through the esophagus by gravity, and by the is absorbed to gradually convert the chyme into semisolid material called feces. The bolus is broken down into acid chyme in the lower third of the stomach, allowing Tight junctions link the epithelial stomach-lining cells together, further . The virus causing Hepatitis A is primarilly transmitted by fecal contamination, C is presently the leading cause of the need for liver transplants in the United States. Transplantation and Cancer Immunology . Mixes chyme with digestive juices; Propels food at a rate slow enough for digestion area of the food and allows an appropriately sized bolus to be produced. the final step in digestion, undigested materials are removed from the body as feces. Interactive Link Questions.
Problems in the large intestine include hemorrhoids, diverticular disease, and constipation. Conditions that affect the function of accessory organs—and their abilities to deliver pancreatic enzymes and bile to the small intestine—include jaundice, acute pancreatitis, cirrhosis, and gallstones. In some cases, a single organ is in charge of a digestive process. For example, ingestion occurs only in the mouth and defecation only in the anus.
However, most digestive processes involve the interaction of several organs and occur gradually as food moves through the alimentary canal Figure 2. The digestive processes are ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and defecation. Some chemical digestion occurs in the mouth. Some absorption can occur in the mouth and stomach, for example, alcohol and aspirin. Regulatory Mechanisms Neural and endocrine regulatory mechanisms work to maintain the optimal conditions in the lumen needed for digestion and absorption.
These regulatory mechanisms, which stimulate digestive activity through mechanical and chemical activity, are controlled both extrinsically and intrinsically. Neural Controls The walls of the alimentary canal contain a variety of sensors that help regulate digestive functions. These include mechanoreceptors, chemoreceptors, and osmoreceptors, which are capable of detecting mechanical, chemical, and osmotic stimuli, respectively. Stimulation of these receptors provokes an appropriate reflex that furthers the process of digestion.
This may entail sending a message that activates the glands that secrete digestive juices into the lumen, or it may mean the stimulation of muscles within the alimentary canal, thereby activating peristalsis and segmentation that move food along the intestinal tract.
The walls of the entire alimentary canal are embedded with nerve plexuses that interact with the central nervous system and other nerve plexuses—either within the same digestive organ or in different ones. These interactions prompt several types of reflexes. Extrinsic nerve plexuses orchestrate long reflexes, which involve the central and autonomic nervous systems and work in response to stimuli from outside the digestive system.
Short reflexes, on the other hand, are orchestrated by intrinsic nerve plexuses within the alimentary canal wall. These two plexuses and their connections were introduced earlier as the enteric nervous system. Short reflexes regulate activities in one area of the digestive tract and may coordinate local peristaltic movements and stimulate digestive secretions. For example, the sight, smell, and taste of food initiate long reflexes that begin with a sensory neuron delivering a signal to the medulla oblongata.
The response to the signal is to stimulate cells in the stomach to begin secreting digestive juices in preparation for incoming food. In contrast, food that distends the stomach initiates short reflexes that cause cells in the stomach wall to increase their secretion of digestive juices. Hormonal Controls A variety of hormones are involved in the digestive process. So I'm no more - although I talk about it constantly, I'm not immune to that very unique embarrassment.
Now I can easily imagine you going well, there's a funny and interesting story about this. Let me tell you how you collect You might be wondering about the science behind this. Let me tell you how you collect that stuff. So now that you can visualize what's going on in your colon, do you feel your digestion more powerfully? Like do you visualize the food going down? Do you visualize the twist and turns in your intestines? I'm one of those fortunate people that goes around largely ignorant of their intestinal goings-on.
I don't really pay much attention to it. But what happened, I did, as I was working on the mouth side of it, I became unpleasantly aware of things happening in my mouth. Things I had never really given any thought to when you chew food what is going on in there. And really, you're taking something apart by, grinding it up and then you're reassembling it for the swallow and you're creating this thing called a bolus, which is a cylindrical moistened cohesive mass.
And every time you take a bite of something and chew it up you're building a bolus in your mouth. And I didn't, I just. I don't want to know about my bolus building. I don't want to think about it. And I think because the food has just been in front of you as this wonderful, sensuous, delicious thing and now it's in your mouth and it's becoming this unpleasant, not sensuous, revolting thing.
Does that clear things up? And speaking of revolting, so as we make our way down the digestive system, again, I want to say to our listeners this is subject matter you might find very unappetizing. My apologies if you're eating at the moment. But again, I just want to mention this is what's going to happen in your system after you're done eating. So, let's go down toward the end of the digestive process.
In Digestion: Mary Roach Explains What Happens To The Food We Eat : NPR
And I learned from your book that - something that should've been obvious, so I can't say I ever thought about it at all, is that the rectum has a lot of nerve endings in it because? Well, the anus, specifically, is the champion here. The human anus is this ring of muscle and it's highly enervate. It's got tons of nerves. And the reason is that it needs to be able to discriminate, by feel, between solid, liquid and gas and be able to selectively release one or maybe all of those.
And thank heavens for the anus because, you know, really a lot of gratitude, ladies and gentlemen, to the human anus. It's kind of an amazing thing that it does.
If you joining us, my guest is Mary Roach. She's the author of the new book called "Adventures on the Alimentary Canal. Let's take a short break here, then we'll talk some more. She's written several books about the human body. And her new book called "Gulp: So one of the things you did as research for your book is to swallow a pill cam - like a little pill-size camera - to see your digestive tract.
You did it in your own body? Actually, I watched footage from an unknown person's pill cam. I watched my own - I had a colonoscopy done without drugs so that I could see my insides, so I did an even more heroic thing, Terry. I didn't swallow a pill cam, but I did do that. So why don't we start with the colonoscopy. Why did you do that? I know that there was sedation standing by should you need it - which you didn't - but why did you want to endure a sedation-free colonoscopy in order to bear witness to what you're insides looked like?
Well, that is precisely why. Well, I don't know that I would have done it were I not writing this book. But this was an opportunity - probably the only opportunity - hopefully, the only opportunity - I'll ever get to witness to see the inside of my large intestine. And, OK, my rectum, also interesting. And it's your guts and I don't know how people can kind of be curious about what their own insides look like.
So I had this curiosity and also I had come across this wonderful, it was then maybe the "Lancet," one of the major medical journals, it was someone who had put two photographs side-by-side. One of them was the interior of Guadi's "La Pradera" - I believe this is how you pronounce it. It was this wonderful archways that looked very much like the connections between segments of the colon.
And he had made this comparison between these, you know, this work of art and the human colon. And I thought I want to see my own internal Gaudi; I want to see that. What did it look like? What did you learn from seeing it? I failed to see the Gaudi in there.
For me it was just kind of surprisingly pink and glistening - a kind of a bubblegum pink and pretty. I mean that sounds - because it's been cleaned out very, very, very, very thoroughly, it's a surprisingly - it looks like, you know, the interior of a very clean spaceship or something, not at all what you would expect.
And it was healthy. And it was healthy, thankfully. No strange growths, yeah. So let's get back to the pill cam. And you watched an ominous person's inside through this pill-size camera. But you compare what happens to the stomach - what you saw happening to the stomach - with the Titanic. It was this dark, murky kind of watery scene with little bits kind of floating around, and that's immediately what came to mind. And what was striking is as soon as you pass through that sphincter into the small intestine, everything changes and now it's a pale pink, kind of the color of that white tuna sushi, that lovely pale pink, that's the color and it's got these little sort of Dr.
Seuss projections, little fingers. It looks like velvet or terrycloth. And that's what it is essentially, by terrycloth, it's increasing the surface area for absorption.
Obviously, with a towel you are absorbing more water and with the small intestine you're absorbing nutrients. But it really is this kind of velvety undulating surface, it's like that, what is that film where people take a trip down the Elementary Canal and they see these sites?
It really, you do have this sense of being able to fly over this bizarre alien landscape. I thought it was absolutely fascinating and not at all disgusting. So one of odder things that you learned for your book is about hooping. And this relates to stashing things in your body Say a little bit more about like what hooping is and what are some of the things you learn have been stored at the bottom end of the digestive tract?
Well, this is the rectum chapter and I wanted to provide a narrative that would be appropriate and interesting setting for the reader. And I thought well, what is the rectum? Well, it's a storage facility. The rectum enables us to hold on to waste and that means we don't need to stop what we're doing and find a bathroom. We can hold it. I mean we have a little closet, we have a little suitcase - if you will - and we can hold it there.
And that, you know, it's a force for civilized behavior and again, thank you to the rectum well. OK, so I thought all right, well, who would be someone who'll would be interesting to talk to. And people who smuggle contraband. For people who smuggle contraband, the human body, the human alimentary system, is a handy pocket - if you will - particularly the rectum.
In prisons, there's a, I was at Avenel State Prison where they have a problem with cell phone smuggling, people smuggling cell phones in and conducting drug deals and hits and things like that that they shouldn't be doing. And so I spent some time with a man who is - it's called hooping - as in through the hoop.
And hooping is a way of life in prison. It's not - 'cause I thought well, this would be a little strange to sit down with the man and talk about the things that he puts in his rectum.
Digestive System Processes and Regulation | Anatomy & Physiology
But, in fact, he was just like yeah, well, what do you want to know? So it was an interesting afternoon. So what are some of the things that he's put there? The most common thing is bindles of tobacco, because you're not supposed to have tobacco. And so people put these plugs of tobacco wrapped in a condom or a piece of latex and that's often - he said if you're going into solitary confinement, you're going into the hole, the other hole, you want to bring in your smoking material.
So they'll put up the tobacco and the lighter and so they'll smuggle it into solitary because you're not allowed to have it there. And this shed light on something I had come upon when I was writing "Bonk," which was a collection of things that people had put in rectums, they showed up in the emergency room, and here was this one that just made no sense to me at the time.
It was a magazine, tobacco pouch and spectacles. And I thought who puts that in their rectum?
And now I realize this was probably a guy going into solitary, and here was his reading material and his smoking material and his glasses. So was the person who you interviewed in prison there because he had smuggled things this way? Like how did you know to talk with him? He was there for murder. When I spoke to the public relations people at the California Department of Corrections and Rehabilitation, they said well, we can let you speak to the staff who deal with this, but we can also put you in touch with somebody who is known for his talents in this area.
So he was famous for having, on a bet, I was told, hooped something quite large. And so they thought that he would be the most appropriate person for me to speak with. That's so interesting that the prison itself recommended him. I guess, you know It's legitimate - it's like legitimate research. I sent an email to the public relations guy explaining what I was doing, and I wanted to write about the alimentary canal as a criminal accomplice, essentially, and I wanted to speak to someone.
And, you know, I expected to get no reply and I got this reply back that said well, absolutely. We have a big problem with cell phone smuggling and would four hours be enough for you? I'm like to speak to a stranger about his rectum? Have you ever had a kind of growth or rash or something that your body has produced or done that is so incorrect looking and just so, like, fascinating and revolting at the same time that you just, it just kind of stopped you?
I had a bike accident a few years ago and I went to the emergency room and I had to have a gash sewn up. And I am the kind of person that I was sitting up fascinated watching to the extent that the doctor said, do you want to do a couple of stitches?
You seem to be very interested. I'm really, I've been in operating rooms at UCSF here, I've for a couple of my books where I've been in the operating room and they've really had to stop and say Ms. Roach, could you step back? Your head is actually inside the body cavity. I'm like - but I don't think that I'm strange.
I could be very, very wrong about that, but I think people underestimate their ability to cope with kind of gross and upsetting things because a lot of it is fear of the unknown. Do you have a favorite place that you've visited for research for your book that you haven't told us about yet? Oh, that place is so great. Mutter is - yes. Yes, you write about the mega colon there. So you can talk about that.
That's probably the most relevant thing for your book. The mega-colon is on display and it's this big glass vitrine with kind of perfectly placed museum lighting.
And it's this colon that is as big around as my waist, literally. And it's a sad thing. The man who had it was a very unhappy man who had a lot of problem, you know, emptying his colon and eventually died from it.
But it is a very - it's a strange place because a lot of the exhibits are upsetting. But it's beautiful, like any well-curated museum. And you go in and there's the beautiful lighting and the professional people who - I just - the Mutter Museum is - I got to go into the basement where they have all kinds of weird goodies. And I should explain it was a teaching museum for medical oddities like conjoined twins and the mega-colon that you mentioned.
So it's just - it's a fascinating collection of things that can go wrong with the body, unusual things. For example, a bracelet made of hemorrhoids, I think it was.
Or maybe it was a necklace. Anyway, sometimes doctors come upon these things or they make them - I don't know - and they just drop them off at the Mutter Museum. So if you work at the Mutter Museum every day brings a new and strange surprise. Mary Roach, it's been a pleasure. Other factors, including stress and aspirin, can also produce ulcers.
The Small Intestine The small intestineshown in Figure 6, is where final digestion and absorption occur. The small intestine is a coiled tube over 3 meters long. Coils and folding plus villi give this 3m tube the surface area of a m long tube. Final digestion of proteins and carbohydrates must occur, and fats have not yet been digested. Villi have cells that produce intestinal enzymes which complete the digestion of peptides and sugars. The absorption process also occurs in the small intestine.
Food has been broken down into particles small enough to pass into the small intestine. Sugars and amino acids go into the bloodstream via capillaries in each villus. Glycerol and fatty acids go into the lymphatic system.
Absorption is an active transport, requiring cellular energy. Structure and details of the small intestine. Food is mixed in the lower part of the stomach by peristaltic waves that also propel the acid-chyme mixture against the pyloric sphincter.
Increased contractions of the stomach push the food through the sphincter and into the small intestine as the stomach eempties over a 1 to 2 hour period.
High fat diets significantly increase this time period. The small intestine is the major site for digestion and absorption of nutrients. The small intestine is up to 6 meters long and is centimeters wide.
The upper part, the duodenumis the most active in digestion. Secretions from the liver and pancreas are used for digestion in the duodenum. Epithelial cells of the duodenum secrete a watery mucus. The pancreas secretes digestive enzymes and stomach acid-neutralizing bicarbonate. The liver produces bile, which is stored in the gall bladder before entering the bile duct into the duodenum.
Digestion of carbohydrates, proteins, and fats continues in the small intestine. Starch and glycogen are broken down into maltose by small intestine enzymes. Proteases are enzymes secreted by the pancreas that continue the breakdown of protein into small peptide fragments and amino acids. Bile emulsifies fats, facilitating their breakdown into progressively smaller fat globules until they can be acted upon by lipases.
Bile contains cholesterol, phospholipids, bilirubin, and a mix of salts. Fats are completely digested in the small intestine, unlike carbohydrates and proteins. Most absorption occurs in the duodenum and jejeunum second third of the small intestine. The inner surface of the intestine has circular folds that more than triple the surface area for absorption. Villi covered with epithelial cells increase the surface area by another factor of The epithelial cells are lined with microvilli that further increase the surface area; a 6 meter long tube has a surface area of square meters.
Each villus has a surface that is adjacent to the inside of the small intestinal opening covered in microvilli that form on top of an epithelial cell known as a brush border. Each villus has a capillary network supplied by a small arteriole. Absorbed substances pass through the brush border into the capillary, usually by passive transport.
Maltose, sucrose, and lactose are the main carbohydrates present in the small intestine; they are absorbed by the microvilli. Starch is broken down into two-glucose units maltose elsewhere. Enzymes in the cells convert these disaccharides into monosaccharides that then leave the cell and enter the capillary.
Lactose intolerance results from the genetic lack of the enzyme lactase produced by the intestinal cells. Peptide fragments and amino acids cross the epithelial cell membranes by active transport. Inside the cell they are broken into amino acids that then enter the capillary.
Gluten enteropathy is the inability to absorb gluten, a protein found in wheat. Digested fats are not very soluble. Bile salts surround fats to form micellesas shown in Figure 7, that can pass into the epithelial cells. The bile salts return to the lumen to repeat the process. Fat digestion is usually completed by the time the food reaches the ileum lower third of the small intestine. Bile salts are in turn absorbed in the ileum and are recycled by the liver and gall bladder.
Fats pass from the epithelial cells to the small lymph vessel that also runs through the villus. Absorption of lipids by cells in the small intestine. The Liver and Gall Bladder The liver produces and sends bile to the small intestine via the hepatic duct, as illustrated in Figure 8.
Bile contains bile salts, which emulsify fats, making them susceptible to enzymatic breakdown. In addition to digestive functions, the liver plays several other roles: The liver and associated organs and their connections to the digestive system. The gall bladder stores excess bile for release at a later time. We can live without our gall bladders, in fact many people have had theirs removed.
The drawback, however, is a need to be aware of the amount of fats in the food they eat since the stored bile of the gall bladder is no longer available. Glycogen is a polysaccharide made of chains of glucose molecules, as shown in Figure 9. In plants starch is the storage form of glucose, while animals use glycogen for the same purpose.
Low glucose levels in the blood cause the release of hormones, such as glucagonthat travel to the liver and stimulate the breakdown of glycogen into glucose, which is then released into the blood raising blood glucose levels.
When no glucose or glycogen is available, amino acids are converted into glucose in the liver. The process of deamination removes the amino groups from amino acids.
Urea is formed and passed through the blood to the kidney for export from the body. Conversely, the hormone insulin promotes the take-up of glusose into liver cells and its formation into glycogen. Note the individual glucose molecules that are linked to form glycogen. Liver diseases Jaundice occurs when the characteristic yellow tint to the skin is caused by excess hemoglobin breakdown products in the blood, a sign that the liver is not properly functioning.
Jaundice may occur when liver function has been impaired by obstruction of the bile duct and by damage caused by hepatitis. Hepatitis A, B, and C are all viral diseases that can cause liver damage. Like any viral disease, the major treatment efforts focus on treatment of symptoms, not removal of the viral cause.
Hepatitis A is usually mild malady indicated by a sudden fever, malaise, nausea, anorexia, and abdominal discomfort.
Jaundice follows up for several days. The virus causing Hepatitis A is primarilly transmitted by fecal contamination, although contaminated food and water also can promote transmission. A rare disease in the United States, hepatitis B is endemic in parts of Asia where hundreds of millions of individuals are possibly infected.
Hepatitis B may be transmitted by blood and blood products as well as sexual contact.
The blood supply in developed countries has been screened for the virus that causes this disease for many years and transmission by blood transfusion is rare.
The risk of HBV infection is high among promiscuous homosexual men although it is also transmitted hetereosexually. Correct use of condoms is thought to reduce or eliminate the risk of transmission. Effective vaccines are available for the prevention of Hepatitis B infection. Some individuals with chronic hepatitis B may develop cirrhosis of the liver. Individuals with chronic hepatitis B are at an increased risk of developing primary liver cancer. Although this type of cancer is relatively rare in the United States, it is the leading cause of cancer death in the world, primarily because the virus causing it is endemic in eastern Asia.
- Difference between bolus and chyme
- Digestive Processes
Hepatitis C affects approximately million people worldwide and 4 million in the United States. The virus is transmitted primarily by blood and blood products. Most infected individuals have either received blood transfusions prior to when screening of the blood supply for the Hepatitis C virus began or have used intravenous drugs.