Digestion And Nutrition Study Guide Answers
Protein Proteins are important nutrients that your body uses to build cellular structures that carry out vital functions. In fact, the basic building blocks of proteins are so important to your cells that if you did not consume protein, it would be like trying to build a house without tools or nails. In this lesson, you will learn how proteins are broken down into their basic units, called amino acids. You will then see how amino acids are absorbed through the small intestine wall and used by your body to build cellular structures and components. When we talk about digestion, we look at protein as a large molecule composed of one or more chains of amino acids. Proteins are large molecules made up of one or more chains of amino acids. Amino Acids When you feel hungry, you typically think of protein as a food, such as eggs, milk, meat, nuts, or beans.
Regardless of which way you want to look at protein, one fact remains, and that is that are the basic building blocks of protein. The term 'building block' is a good way to describe amino acids because they are literally used by your body for building biological substances. In fact, many of these biological substances are actually specialized proteins. So, you might eat an egg for breakfast, and once you swallow it, enzymes break down the protein in the egg into amino acids. Then, those free amino acids recombine in different ways to form specialized proteins. These specialized proteins become different things, such as enzymes, or, or hormones. Or, they might become structural proteins, such as muscle proteins or collagen found in connective tissue.
Protein Digestion It's good to keep in mind that protein digestion is not as simple as eating an egg and magically getting amino acids. A large protein molecule breaks down via a few intermediate steps, in the stomach and in the small intestine, before it becomes the tiny amino acids. So, let's take a look at how proteins are broken down by your digestive system. Protein digestion begins in the stomach with the action of an enzyme that we previously learned about called pepsin. Pepsin is the active protein-digesting enzyme of the stomach.
When pepsin acts on the protein molecule, it breaks the bonds that hold the protein molecule together, called. So, you can think of pepsin as the enzyme that breaks peptide bonds. When these bonds are broken, you get chains of amino acids linked together called polypeptides. Since we know that the prefix 'poly' means 'many,' we can easily recall that a polypeptide is many amino acid units joined together. These polypeptides then move into your small intestine, where digestion will be completed by additional enzymes. Pepsin is an enzyme in the stomach that breaks down the peptide bonds in protein.
In the small intestine, pancreatic enzymes that we previously learned about, called trypsin, chymotrypsin, and carboxypeptidase, really go to work breaking down the polypeptides. These enzymes enter the duodenum via the pancreatic duct.
These pancreatic enzymes are helped by the brush border enzymes. We previously learned that the brush border enzymes are special enzymes found on the microvilli of the small intestine that complete digestion. The peptide bonds holding the polypeptides together continue to be hydrolyzed, or broken down, and result in smaller units called peptides. Peptides are simply defined as two or more amino acids linked together. Enzymes continue to break down polypeptides and peptides into amino acids. Because amino acids are very small, they are able to be absorbed through the small intestine lining and into your bloodstream. Hepatic Portal System It's important to note that digested nutrients that leave the digestive tract take a detour to the liver before entering the general bloodstream.
Your liver is an important organ, and this detour allows your liver to have first claim at nutrients coming from the digestive tract. It's almost like the liver is king and it gets first dibs at the good nutrients; then, when it takes its fill, the rest of the body has the leftovers.
So, we see that capillaries in the wall of the digestive tract pick up the amino acids. These amino acids, along with other digested nutrients, then move to the liver through a unique system of veins called the hepatic portal system. This is the system of veins that are responsible for directing blood from the digestive tract to the liver.
We see that the word 'hepatic' means 'liver' and the word 'portal' means 'gateway,' so you can think of the hepatic portal system as the gateway to the liver. The liver is like a king and gets the first claim at nutrients coming from the digestive tract.
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This nutrient-rich blood that drains out of your digestive tract travels to the liver via the hepatic portal vein. This vein is defined as a vein that transports blood from the digestive tract to the liver.
This is a unique vein; in fact, some would argue that it's not a true vein because it conducts blood to the capillary beds of the liver. We know that 'true veins' carry blood back to the heart, and arteries are typically the blood vessels that travel toward the capillary beds. So, the hepatic portal system has many unique circulatory facts to consider.
After the liver takes its share of the nutrients, the blood enters the general circulation through the hepatic veins, which drain the liver. The remaining amino acids can now circulate to your body cells. Your cells remove amino acids from the blood and use them to build the specialized proteins that we talked about at the beginning of this lesson, such as enzymes, antibodies, hormones, muscle proteins, or collagen. Lesson Summary Let's review. Proteins are defined as large molecules composed of one or more chains of amino acids. So, we see that amino acids are the basic building blocks of protein. Amino acids can be used by your body to form important cellular structures, such as enzymes, antibodies, hormones, muscle proteins, and collagen.
Protein digestion begins with the action of an enzyme called pepsin. Pepsin is the active protein-digesting enzyme of the stomach.
Pepsin acts on protein molecules by breaking the peptide bonds that hold the molecules together. Digestion of protein is completed in the small intestine by the pancreatic enzymes trypsin, chymotrypsin, and carboxypeptidase. These enzymes also get some help from the brush border enzymes found in the small intestine. When proteins are broken down, they create polypeptides, which are chains of amino acids linked together, and peptides, which are two or more amino acids linked together. Before entering the general circulation, digested nutrients that leave the digestive tract take a detour to the liver. The hepatic portal system is the system of veins that are responsible for directing blood from the digestive tract to the liver. The hepatic portal vein is the vein that transports blood from the digestive tract to the liver.
After the liver takes its share of the nutrients, the blood enters the general circulation through the hepatic veins that drain the liver. Learning Outcomes After this video, you'll be able to:. Describe the structure of protein. Explain the importance of amino acids. Summarize the process of protein digestion.
Describe the function of pepsin. List the pancreatic enzymes and enzymes from the small intestine that aid in protein digestion. Understand the importance of the hepatic portal system in the process of protein digestion.
Animal Nutrition and Digestion Terms. Get down with the lingo Active TransportA rapid transport of nutrients that comes with a cost: the need to burn energy in the form of adenosine 5'-triphosphate (ATP, the energy transport molecule). Active transport occurs independently of the concentration gradient, and is a mechanism to build up the nutrient concentration. AldosteroneStimulated by angiotensin II and released by the adrenal glands, aldosterone causes the nephron's distal tubule to reabsorb more NaCl and water to increase blood volume and pressure. Think of it as the hormone that tells the kidney it was born to be a sponge.
Alimentary CanalMost animals have this digestive tube that flows from the oral cavity to the anus, including people. No gondolas in this canal though; just keeping things simple. Food goes in one end and comes out the other.
Flatworms are an exceptionway to be unique, guys. Antidiuretic Hormone (ADH)Hormone secreted from the pituitary gland in response to hyperosmotic blood. ADH will increase water solubility in the nephron's collecting duct and lower blood osmolarity. If things are bad enough, it'll make you thirsty too. Atrial Natriuretic Peptide (ANP)Released by the heart atria in response to high blood pressure and/or volume.
ANP is renin's worst nightmare, since it blocks its release and reduces aldosterone release to effectively lower blood pressure and volume. Too much blood means the body will try to dry things out a bit. BileProduced by the liver, stored in the gallbladder, and secreted in the small intestine, this green goo breaks down fats into fatty acids. Its release is stimulated by the hormone cholecystokinin.
Bowman's CapsuleThe filtered stuff (the proteins, ions, nutrients) from the blood enters Bowman's capsule, a hollowed out space where pee starts to look like pee. CarnivoreAn animal that just relies on eating other animals for its nutrition. If you offer one a salad, even if it's drenched in Ranch dressing and bacon bits, it will be more interested in munching on you instead. ChemotrophsOrganisms, including bacteria, which get all their energy through biological reactions, like moving electrons around.
When they get a little low on energy, they're not looking to call the local pizza place. Chief CellPresent in the stomach, chief cells secrete pepsinogen, which is converted into pepsin once it joins the acid pool party in your tummy. CholecystokininHormone secreted when fats and amino acids hit the small intestine. It stimulates the release of bile so the fats can finally get digested.
Breaking down fats, it might as well be the body's personal trainer—complete with neon stretch pants and some Cyndi Lauper on the Walkman. ChylomicronsWater-soluble groups of triglycerides (groups of three fatty acids), formed within the epithelial cells of the small intestine. They are too large to pass into the blood stream directly, so they sneak in through the back door via the lymphatic system before making their way back to the blood. ChymeEssentially 'food goo.' Chyme is what kicks around in your tummy early on in the digestion process. It's a joyous mixture of gastric juices and partially digested food.
Don't be embarrassed; everyone has partially digested goop in his or her stomach at some point. Collecting DuctAt the collecting duct, the filtrate's trip is almost complete. This is the nephron's last-ditch-effort to conserve water and salt before the filtrate leaves the body as urine. Antidiuretic hormone increases water permeability here.
CortexWhether we are talking about the kidney or the brain, the cortex is the outer part of the organ. But here we're all about the kidneys, and the outer cortex for that pink pair of organs is where the majority of the nephron is located. Countercurrent Multiplier SystemThe teamwork of salt, water, and both the up-and-down portions of the Loop of Henle causes hyperosmotic medullary (see medulla) interstitial fluid.
Its ultimate goal is to create concentrated urine. Some folks want to be astronauts; others want to create concentrated urine. Either way, it's good to have goals.
Digestion And Nutrition Study Guide Answers
DigestionThe process by which food is broken down into simple compounds that can be taken up by the blood stream or used by cells. Primarily takes place in the small intestine where carbohydrates, proteins, and fats are broken down into sugar, amino acids, and fatty acids so they can be sucked up by the body and put to good use. It's the reason we're all able to do what we do, and it's the reason you get to enjoy a greasy slice of pizza whenever your stomach starts growling. Distal TubuleAfter the ascending Loop of Henle, filtrate flows into the distal tubule where K+ and NaCl concentrations are regulated. Essential Amino AcidsSmall nitrogen-containing compounds that are an essential component in forming protein, but like essential nutrients, they need to be obtained via the diet.
There's no magic button hidden deep in your small intestine to make the amino acid valine, so listen to your mom the next time she orders you to eat those beans. She's not just a great cook; she's got your back. FiltrateFluid that ultimately becomes urine. Consider it 'pre-pee.' The filtrate flows through the tubules of the nephron (part of the kidney) until it gets to the ureter, the tube that connects the kidney to the bladder where it awaits excretion. GastrinHormone secreted when peptides reach the stomach.
Gastrin stimulates the stomach's parietal cells to produce HCl (that's hydrochloric acid) and aid in digestion. GhrelinWhen this stomach-released peptide reaches the brain, it stimulates hunger, making high calorie foods extremely appealing. We may be dating ourselves here at the Shmoop mothership, but one way to remember what ghrelin does is to think back to. Don't worry; you can still eat after midnight with only heart burn to show. Just don't feed the gremlins.
GlomerulusThese are blood vessels at the beginning of the nephron that are surrounded by Bowman's capsule. Blood is filtered through these blood vessels in the first step in making urine. HerbivoreAn animal that strictly receives its nutrition only from plants or algae. Meats are strictly off the menu. If you call yourself a vegan, you're also an herbivore. HeterotrophsAn organism that relies on ingesting food and carbon compounds to provide essential energy.
We're talking about animals, people, basically anything that has to get its energy by ingesting food. This is opposed to plants, which can whip up their energy straight from the sun. HyperosmoticA solution that has a higher osmolarity than normal body tissue. If the membrane is permeable to water, it will flow into this solution in an effort to dilute it. Water always wants to go where it's needed most. Like Superman. HypoosmoticA solution that has a lower osmolarity than normal body tissue.
When a solution is hypoosmotic, it will lose water to other solutions, making it more concentrated. MedullaThe medulla is the inside part of the kidney, where a journey within the Loop of Henle will take you. Inorganic CompoundsCompounds, like sodium chloride (NaCl), that lack the carbon atom. If it's got a carbon atom, the compound is organic. LeptinHormone released by fatty tissues that acts as an appetite suppressant when it reaches the brain.
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Leptin lowers hunger, and it's the thing that tells you that you really don't need another lap around the buffet. Loop Of HenleThe Loop of Henle is not some hot new indie band. Instead, it's a region of the kidney that makes a 'U' shape. The descending part of the Loop is selectively permeable to water so filtrate osmolarity builds up. After the actual Loop, NaCl is selectively permeable in the ascending Loop, and osmolarity decreases. The Loop of Henle is critical in water conservation. NephronPart of the kidney that is responsible for excretion and urine production.
There are millions of nephrons in each vertebrate kidney, and each nephron contains 6 parts: the glomerulus, Bowman's capsule, the proximal tubule, the Loop of Henle, a distal tubule, and the collecting duct. OmnivoreThese animals will eat both plants and animals to get all of their nutritional requirements. They get their name from the Latin phrase 'omni,' which means 'all.' Despite the fancypants Latin origin, we're pretty sure they aren't eating shoelaces and sunglasses for their high protein content. OsmolarityThe measure of solute concentration. For reference, blood's osmolarity is usually around 300 mOsm/L. It measures those compounds that become dissociated in water (like NaCl) and those that don't (like glucose).
OsmoreceptorCell type within the brain's hypothalamus that sense changes in blood osmolarity. If blood is hyperosmotic, these cells will cause ADH release to decrease blood osmolarity to a set point. OsmoregulationThe process by which solute and water concentrations are regulated to make sure everything stays in just the right ratio. Osmoregulation primarily takes place in the good ol' kidney. Parietal CellThese cells are present in the stomach and secrete HCl, making that acidic environment that's the perfect place for enzymes to break down chyme. Passive TransportA digestive process that allows nutrients to be absorbed without requiring the body to burn energy in the process.
When separated by a permeable membrane, nutrients will flow down their concentration gradient (that is, from high concentration to low concentration) with passive transport. Think of it like a ball rolling down a hill.
PepsinProduced by the stomach's chief cells, these peptide-digesting enzymes break proteins down into smaller amino acids. Pepsin works only in acidic conditions, so it's mighty convenient that those parietal cells are handy to make a nice acidic pool for pepsin to work its magic. PhototrophsOrganisms who obtain their energy from the light, such as plants, trees, and glow-in-the-dark t-shirts. Proximal TubuleA part of the vertebrate nephron, where filtrate flows after the Bowman's capsule. At this stage, nutrients and other substances are reabsorbed from the filtrate back into the interstitial fluid, where they will return to the blood stream. ReninHormone stimulated by high blood volume and/or pressure.
Renin is produced in the juxtaglomerular apparatus (that's a real thing, it's in the beginning of the nephron) and stimulates the synthesis of angiotensin II. It is the first step in the renin-angiotensin II-aldosterone system (RAAS), which tells the blood volume to cool it and settle down. SecretinWhen acidic chyme makes it way to the small intestine, secretin is released to stimulate the release of HCO 3 – to buffer the chyme to a more neutral pH, after it got itself all coated in acid in the stomach. Vasa RectaBlood capillaries that follow the kidney's Loop of Henle, providing it with essential oxygen and nutrients.
These blood vessels also help maintain the countercurrent multiplier system by preventing a washout of the medullary concentration gradient.