Biology 140 Nutrition WSU- Online Exam 2 Angela Brown

Digestion of Lipids

-Mouth *Lingual lipase -Stomach *Gastric lipase -Small intestine *Bile (emulsifier) *Pancreatic lipase READ OFF SLIDES To begin lipid digestion in the mouth and stomach is most important for infants whose nutrition consists solely of high fat milk. Lipids generally take much longer to digest than other macromolecules so beginning the process early on is beneficial. Adults have a varied diet so most lipid digestion takes place in the small intestine. The pancreas produces many substances to facilitate chemical digestion of food, including pancreatic lipases. In addition, bile produced in the liver and stored in the gallbladder functions as an emulsifier in the duodenum, keeping micelles suspended in the watery environment of the small intestine. The presence of partially digested fat and the protein in the duodenum starts off a series of events. First of all the hormone cholecystokinin, or CCK, is produced by endocrine cells in the mucosa of the small intestine. This hormone circulates in the blood and on reaching the gallbladder causes it to contract and release bile into the duodenum. Bile functions like a detergent, breaking apart large fat globules into smaller ones, creating an emulsion in the aqueous environment. This produces a larger surface area which is exposed to lipase enzymes, allowing them to make contact with the chemical bonds. At the same time, CCK stimulates the pancreas to produce and release lipase enzymes to digest the fat which is present in chyme. Secretin is another hormone produced by endocrine cells of the duodenal mucosa. This hormone causes the pancreas to release sodium bicarbonate and neutralize the acid chyme. This is an important step since most enzymes are unstable in acidic conditions. Chemical digestion is taking place in the small intestine. During this process, triglycerides and phospholipids are disassembled into free fatty acids, glycerol and monoglycerides, by the lipase enzymes. Cholesterol may be present in the chyme but it does not undergo any chemical digestion and is absorbed as an intact molecule.

According to AMDRs, what percentage of your daily nutrition should be from carbohydrates?

45%-65%

Cholecystokinin (CCK)

A HORMONE, produced by the small intestine, that stimulates the release of enzymes from the pancreas and contraction of the gallbladder. Released from the intestinal cells (enterocytes) particularly in response to high fat and protein foods, signaling the brain to decrease food intake. Plays a roe in short-term satiety.

Chylomicron

A LIPOPROTEIN (largest and least dense), which the body makes to transport dietary lipids. made in the enterocyte, that transports large lipids away from the small intestine in the lymph. When in the blood they deliver fatty acids to cells via the enzlme liporportein lipase. Chylomicrons are large structures and leave the cell via exocytosis. They are lipoproteins that function to transport hydrophobic substances around the body in the blood stream. Because they enter the lymphatic system, they bypass the initial trip to the liver, taken by amino acids and simple sugars. About 90% of a chylomicron is fat, but as they circulate in the blood stream they give up their triglycerides.

One diference between dietary fiber and amylose is that

amylose has alpha glycosidic bonds whereas dietary fiber has beta glycosidic bonds

Amylases

an ENZYME in saliva and pancreatic fluid that digests carbohydrates and converts starch and glycogen into simple sugars

Maltose

formed during starch digestion. Used in the brewing process.

Which monosaccharide is present in all three disaccharides (maltose, sucrose and lactose)

glucose

Which carbhoydrate consists of highly branched arrangement of glucose molecules?

glycogen

The hormone released from the pancreas that helps decrease blood glucose

insulin

Blood glucose levels are regulated by the hormones __________ and ____________.

insulin;glucagon

Digestion of carbohydrates such as sucrose takes place in the

small intestine

Cells with insulin responsive glucose transporters include..

(beta cells for insulin, alpha cells for glucagon) tissues that have insulin reponsive glucose transporters are skeletal muscle and adipose tissue

Diglyceride

(diglycerol) A LIPID made of glycerol molecule bonded to two fatty acids.

Simple Carbohydrate

(simple sugar) Category of carbohydrates consisting of MONOSACCHARIDES and DISACCHARIDES because they are small in size.

Cholesterol

A STEROL (most abundant) found in animal foods and made in the body; required for bile acid and steroid hormone synthesis. some free cholesterol is found in the body but most is bonded to a fatty acid (cholesteryl ester, an example of a sterol ester and is more hydrophobic because they contain fatty acids than free cholesterol bwhich is weakly polar). Needed to syntehsize bile acids, which are important for the digestion and absorption of lipids. Similar to phospholipids, cholesterol and esters are components of membranes where they help maintain fluidity. It is needed for the synthesis of the steroid hormoens which are important for reproduction, energy metabolism, calcium homeostasis, and elextrolyte balance. Esters serve as crucial carrier molecules for fatty acids in the blood. ALmost every tissue in the body, especially liver can make choelsterol from glucose and fatty acids. Obtained from animal derived foods. Plants are very low in cholesterol. Cholesterol has many functions in the body. It is an integral part of the cell membrane, helping to keep it intact so it functions properly. Cell membranes of nerve and brain tissue have an especially high concentration of cholesterol. Cholesterol is also a precursor to many important molecules in the body. The liver uses cholesterol molecules to make bile acids used in fat digestion. It is also a precursor to vitamin D, an important vitamin associate with bone health. Sex hormones such as estrogen, progesterone and testosterone are all produced from cholesterol molecules. These hormones are involved in sexual development, sex drive, and reproduction. Two other classes of hormones, the glucocorticoids, for example cortisol, and the mineral corticoids, for example aldosterone, are produced by the adrenal glands adjacent to the kidneys. Cortisol is associated with glucose metabolism where it increases the availability of blood glucose through the breakdown of non-carbohydrate molecules such as protein. On the other hand, aldosterone is involved in maintaining blood pressure and volume by regulating salt and water intake by the kidneys.

Cis-fatty acid

A fatty acid containing a least one carbon-carbon double bond in which the hydrogen atoms are positioned on the SAME side of the double bond. Bend

Bile

A fluid, made by the liver and stored in and released from the gallbladder, that contains bile salts, cholesterol, water, and bile pigments. A mixture of bile acids, cholesterol and phospholipids. The bile is recycled in the duodenum where it forms more micelles. Further down the small intestine, bile is absorbed and returned to the liver for recycling.

Gestational Diabetes

A form of diabetes, characterized by insulin resistance, that devolps in response to hormone-related changes during PREGNANCY

Glucose

A six-carbon MONOSACCHARIDE produced by photosynthesis in plants. The most abundand monosaccharide in the body. Green plants absorb light energy using chlorophyll in their leaves. They use it to react carbon dioxide with water to make a sugar called glucose. The glucose is used in respiration, or converted into starch and stored. The liver both stores and manufactures glucose depending upon the body's need. The need to store or release glucose is primarily signaled by the hormones insulin and glucagon. During a meal, your liver will store sugar, or glucose, as glycogen for a later time when your body needs it. When plant foods are consumed the body breaks down (digests) these large carbohydrates into glucose. which is subsequently used by cells as a source of energy. Primary function of glucose is to provide cells with a source of energy (ATP). While most cells use a combination of energy sources, glucose is the preferred energy source for the NERVOUS system and the sole source of energy for RED BLOOD cells. Used to sythesize other compounds in the body. It can be converted to some amino acids and fat for long term energy storage. Can store small amounts of this as a compound called glycogen. Glucose is the primary fuel for your body. Therefore on arrival at the liver, galactose and fructose is each converted to glucose. Some glucose will be released into the blood stream to fuel cells in the body. Some glucose molecules will be converted into glycogen, ready for temporary storage in the liver or skeletal muscle. Liver cells also need energy so some glucose molecules will be used to fuel different reaction that take place in the liver. Once the immediate energy needs of the body are met, and sufficient glycogen is in storage, any remaining glucose molecules are converted to fatty acids and stored in fat cells.

Amylopectin

A starch consisting of glucose molecules bonded together in a highly branched arrangement

Amylose

A starch that is a linear chain of glucose molecules bonded together

Emulsifier

A substance that helps (used as a food additive to stabalize processed foods, can be done by stirring or shaking a substance) in the emulsification process. Lethicin and Bile Acids

Adipose Tissue

ANIMALS make triglycerides and store them here.

2 forms of starch

Amylose (linear), and Amlopectin (highly branched). They both consist of entirely glucose molecules. Used to store energy from photosynthesis. Plants typically contain a mix of both types of starch.

Type 1 Diabetes

An autoimmune disorder where the antibodies attack and destroy the insulin producing (beta cells) of the pancreas. This is a disorder of the immune system where antibodies do not recognize the insulin, resulting in little or no insulin production. Insulin dependent diabetes mellitus, this form of diabetes results when the pancreas is no longer able to produce insulin due to a loss of insulin-producing (b)-cells. Without insulin most cells cannot take up glucose, causing blood glucose levels to become dangerously high. This is caused by complex interactions among genetic, environmental factors, and the immune system that leads to an inability of the pancreas to produce insulin, genetics play a big role. Triggered by something in the environment. The cell membrane has insulin receptors, glucose receptors are present in the cell however they still need to be activated, glucose is circulating in the blood stream but the cell cannot use it. This type of disorder is sometimes referred to as starvation of amid times of plenty; the individual has lots of glucose but cannot utilize it. And individual with Type 1 diabetes has a pancreas; it just does not produce any insulin, the key to unlocking this whole process. The symptoms of Type 1 diabetes usually become apparent over a period of a few weeks. An individual begins to lose weight for no obvious reason. They eat plenty of food but the body cannot use the glucose, therefore it begins to break down fat and protein to provide energy. They are unable to satisfy their thirst so they drink more fluids. This in turn results in an increased frequency of urination. The individual is also tired all the time since cells are not receiving the glucose they need to produce energy. This type of diabetes usually appears during childhood and adolescent. Diabetes increases the risk of heart attacks and strokes, can lead to blindness, limb amputation, impaired kidney function, and a loss of feeling in the feet and hands.

So how does insulin enable cells to remove glucose from the blood stream?

As blood glucose levels approach the upper set point, the pancreas switches most effort to INSULIN production. Cells that recognize insulin or are sensitive to insulin begin to remove glucose molecules from the blood stream. The liver also converts some of that glucose to glycogen to be stored in the liver for the next time blood glucose levels fall. We can describe the two hormones, insulin and glucagon, as antagonistic, i.e. they oppose each other. It is the balance between these two hormones that determines the outcome. The movement of glucose into the cell requires transport proteins to be present in the cell membrane. Insulin is a hormone and therefore functions as a signal molecule. It is this signal received at the cell membrane which activates the glucose transport molecules, enabling the movement of glucose into a cell. Think about this situation which we can use as an analogy: You walk into a dark room. There is a switch on the wall and a light bulb in a lamp, but the room remains dark until the light it switched onto the on position allowing the flow of electrons or electricity to the light bulb which then lights up the room. In this analogy, the light switch is the receptor protein on the cell membrane, you are the signal, insulin, to activate the switch, and the movement of electrons is the activation of the transport proteins, and the visible light is the response that is the uptake of glucose by the cell.

RDA for carbs 130g a day is based on the amount of glucose needed by the ..

BRAIN

Fiber is a carbohydrate but we are unable to digest it, i.e. extract energy from it. Why?

Because fiber contains beta glycosidic bonds that are resistant to digestive enzymes. Undigested fiber passes from the small to the large intestine relatively intact. Intestinal bacteria then begin to break down the fiber, producing gas, lipids, and other substances.

Briefly describe how blood glucose levels are maintained through the use of the hormones insulin and glucagon.

Because our cells need energy 24 hrs a day, the pancreatic hormones insulin and glucagon work viligantly to maintain blood glucose levels within an acceptable range at all times. Pancreas plays a major role in glucose homeostasis. These endocrine cells, known as the islets of Langerhans, consist mainly of beta cells that produce the hormone insulin, and alpha cells that produce the hormone glucagon. The pancreas which has a rich blood supply, releases these hormones directly into the circulation in response to fluctuations in blood glucose. Insulin and glucagon assist in blood glucose regulation and energy storage. After a meal, blood glucose levels increase which stimulates the release of the hormone insulin from the pancreas, insulin enables insulin dependent glucose transporters to take up glucose from the blood into tissue cells such as muscles and adipose. THIS LOWERS BLOOD GLUCOSE. In the liver, insulin promotes the formatioon of glycogen, THIS LOWERS BLOOD GLUCOSE. Low blood glucose levels stimulate the release of the hormone glucagon from the pancreas, glucagon stimulate the breakdown of glycogen in the liver and release of glucose into the blood, THIS RAISES BLOOD GLUCOSE.

Enzyme

Biological catalysts that facilitate chemical reactions

Lactase

Brush border ENZYME that hydrolyzes lactose into glucose and galactose. Needed for digestion of lactose

Sucrase

Brush border ENZYME that hydrolyzes sucrose into glucose and fructose

How are fatty acids named?

By their number of double bonds, the different ends (omega and alpha)

Disaccharide

CARBOHYDRATE consiting of two monosaccharides bonded together. Lactose (galactose and glucose), Maltose (glucose and glucose), and Sucrose (fructose and glucose). In all these, at least one of the monosaccharides in the pair is glucose. A CONDENSATION reaction joins monosaccharides together by a glycosidic bond (which disaccharides can have dif types of these bonds).

Plants make the first sugars from _______________ and _______________ during the process of photosynthesis.

CO2 and H2O

Polysaccharide

COMPLEX CARBOHYDRATE made of more than 10 monosaccharides. Most are made of hundreds of monsaccharides bonded together by glycosidic bonds. Some have an orderly appearance while some branch off like a tree. The three most common are Starch, Glycogen, and Dietary Fiber. These are mostly structural or storage carbohydrates.

Complex Carbohydrate

Category of CARBOHYDRATE that includes OLIGOSACCHARIDES and POLYSACCHARIDES. consists of many carbohydrates bonded together in a varitey of arrangements.

Insoluble dietary fibers

Cellulose, that makes up the cell wall associated with the plant cells, it the most abundant insoluble dietary fiber in food. Cellulose is made up of individual glucose units chemically bound together. However our bodies do not have the necessary enzymes to break apart this particular type of chemical bond, therefore the material is indigestible to us. Whole grain flour, wheat bran, whole grain breakfast cereals, seeds, many vegetables including carrots, broccoli, celery, peppers and cabbage. hemicellulose and lignin which are found in wheat and some green, leafy vegetables. They do not form viscous gels. Bacteria in the colon do not readily ferment them. It passes through the GI tract, which helps to increase fecal weight and volume. Large amounts of fecal mass move through the colon quickly by stimulating the peristaltic contractions in the colon, propelling the material forward. When consumed with sufficient amounts of fluid it can help prevent and alleviate constipation.

Oligosaccharide

Complex carbohydrate made of 3-10 monosaccharides. Components of cell membranes, allow cells to interact with one another, made in the breasts and are incorporated into human milk. Protect infants from disease-causing pathogens, and this is why mothers are encouraged to breast feed. Common oligosaccharides are raffinoses which is compose of one glucose plus one fructose plus one galactase molecule. And stachyose. Both of these oligosaccharides are found in legumes, that is beans, peas and lentils. Many people do not have the enzymes to digest these oligosaccharides. This results in the bloating, and extreme flatulence often associated with eating beans as bacteria in the large intestine begin to digest these complex carbohydrates. The pancreatic amylases disassemble polysaccharides and oligosaccharides into simple carbohydrates

What types of food supply Carbohydrates?

Compounds produced primarily by plants. The sugars in fruit, the fibers in celery, and the starch in potatoes are examples. Wheat, rice, potatoes, corn, sweet potato and cassava are six foods high in carbohydrates that literally feed the world

Simple sugars are joined together to make larger molecules during a __________________ reaction.

Condensation. The hydroxyl group of one molecule forms a covalent bond with the hydrogen atom of the other molecule. Conversely they can be broken apart in a hydrolysis reaction. Recall that these reactions are made possible by the function of enzymes. The name of an enzyme associated with a specific substrate usually ends with the letters -ase. Hence the enzyme involved in breaking apart sucrose into single sugars is called sucrase. The enzyme associate with lactose is lactase. The enzyme associated with maltose is maltase, and so on.

Insulin Resistance

Condition characterized by the inability of insulin receptors to respond to the hormone insulin

Sucrose

DISACCHARIDE consisting of glucose and fructose; found primarily in fruits and vegetables. Found in many plants, abundant in sugar cane and sugar beets. These plants are crushed to produce molasses. Most added to processed foods. Table sugar

Lactose

DISACCHARIDE consisting of glucose and galactose; produced by mammary glands. the most abundant carbohydrate in milk, and the only Disaccharide that has a beta glycosidic bond between the monosaccharides. During lactation enzymes in the mammary glands (breasts) combine glucose and galactose to produce lactose. Milk sugar

Which types of food provide fiber in the diet?

Fruits and vegetables, whole grains. Grain should have all three components (bran, germ, and endosperm). Bran provides the most fiber, germ supplies much of the vitamins and minerals, and endosperm is mostly starch. A food considered and excellent source of fiber msut contain 20 percent of more of the Daily Value of fiber or at least 5 grams of fiber per serving. "good" sources must have 2.5 to 4.9 grams of fiber per serving.

Triglycerides in Lipid digestion are hydrolyzed to ..

Glycerol Fatty acids Monoglycerides

Insulin

HORMONE secreted by the pancreatic (b)-cells in response to increased blood glucose. Promotes energy storage (in the form of glycogen and body fat), LOWERS blood glucose. Stimulates protein synthesis and inhibits the breakdown of muscle.

What are the consequences of poorly managed diabetes?

If the body cannot utilize sufficient amount of glucose, then it uses fat and protein as alternative sources of fuel. Still it needs a small amount of glucose to completely break down those fatty acids. If no usable glucose is available, ketone bodies that form as a result of fat breakdown can be used as energy and allow most cells to function. However, ketone bodies usually form at a faster rate than the body can use them, so they are excreted in urine and when you exhale it causes an odor similar to acetone on the breath. Too many ketone bodies in the blood cause it to become acidic; a condition called ketosis. In uncontrolled type 1 diabetes this can result in a diabetic coma, brain damage, or even death. In poorly managed diabetes, damage to blood vessels can occur resulting in poor circulation and therefore slow healing of any injured tissues. Extremities such as hands and feet are especially vulnerable and many elderly individuals with diabetes have amputations of the feet and lower limbs. When nerve damage occurs, injuries may go undetected and become gangrenous, resulting in the loss of a limb or death. Damage to small blood vessels can result in poor vision and reduced kidney function. Increased glucose in the urine also leaves the individual susceptible to bladder and urinary tract infections. The main damage in larger blood vessels is atherosclerosis; the thickening of arteries leading to high blood pressure and heart disease.

Starch

It is a POLYSACCHARIDE that functions as a carbohydrate store and is an important constituent of the human diet. Seen in plant tissue. (cereals and potatoes). Amylose and Amlopectin. Foods include grains such as corn, rice, and wheat. Products made from them are pasta and bread and legumes such as lentils and split peas. Potatoes and hard winter squashes. It is added to food to enhance it texture and stability. Modified food starch is used in food production. Converted to sugars during the ripening process. Starch is the stored carbohydrates found in plants. From the plants perspective, starch is a stored form of energy for cellular function and growth when light is unavailable or for the embryo during seedling germination. From a humans perspective it is a welcomed source of energy for growth, development and reproduction.

Which enzyme is required to digest lactose? Which simple sugars result from digestion of lactose?

Lactase is required to digest lactose. Lactase breaks down lactose into GLUCOSE and GALACTOSE, and the body absorbs these simple sugars into the blood stream.

Monosaccharide

MOST IMPORTANT role is the ability to transform the energy contained in glucose into ATP. Carbohydrate consisting of a single sugar. Made up of carbon, hydrogen, and oxygen atoms in the ratio 1:2:1. The number of carbon atoms and the arrangement of atoms can vary, so they typically have different shapes and sizes. There are hundreds of diffirent naturally occuring ones, but the three most plentiful are: glucose, fructose, and galactose. p. The covalent bonds within these simple sugars can be broken in such a way as to release the energy they contain and fuel functions within cells and hence the body. They all contain 6 carbon atoms, theyre molecular formulas are the same but the arrangements are different. (HEXOSE sugars)

Type 2 Diabetes

Most common. Genetic and lifestyle factors increase the risk. OBESITY. At risk for heart diesease, blindness, impaired kidney function. Skeletal muscle and adipose tissue develop insulin resistance, resulting in blood glucose levels that are abnormal. Genetics, obesity, and physical inactivity play major roles in insulin resistance, Can often be managed by diet, weight loss, and excercise. may require glucose lowering medications or insulin injections. Body develops insulin resistance. Non-insulin dependent mellitus, this form of diabetes results when insulin-requiring cells have difficulty responding to insulin. When an individual has Type 2 diabetes, the pancreas produces insulin but the insulin receptor proteins at the cell membrane are overworked and do not recognize the presence of insulin. And so the cellular pathway to take insulin into the cell becomes inefficient and glucose continues to circulate at higher than normal levels in the blood stream. In this case we describe the cells as being insulin resistant. The pancreas produces insulin, insulin receptors are at the cell membrane but very few are functional and therefore limit the uptake of glucose into the cell. This means that blood glucose levels remain higher than normal. This type of diabetes is closely associated with obesity and physical inactivity. Obese individuals require more insulin than those with a healthy weight and the pancreas simply cannot keep up with the demand for insulin to remove the excessive amount of glucose from the blood stream. This in conjunction with worn out insulin receptor proteins results in Type 2 diabetes. Type 2 diabetes is the most common type of diabetes. It can often be managed by a change in eating habits, increasing physical activity, and weight loss. Many individuals with this type of diabetes fail to recognize that they have the disorder and so it remains undiagnosed. the pancreas produces insulin but the insulin receptor proteins at the cell membrane are overworked and do not recognize the presence of insulin. And so the cellular pathway to take insulin into the cell becomes inefficient and glucose continues to circulate at higher than normal levels in the blood stream.

the following foods provide dietary carbohydrate EXCEPT

OILS

Carbohydrate

ORGANIC compound made up of varying numbers of MONOSACCHARIDES. Sugars, Starches, and Fiber. Compounds produced by plants. Made of one or more sugar molecules. As the number of sugar molecules in a carbohydrate increases, so does its size and complexity, Provide cells with a vital source of energy and are components of ribonucleic and deoxyribonucleic acids (RNA and DNA). Not an essentail nutrient, they provide energy and dietary fiber. Best sources are nutrient dense. All carbohydrates contain carbon, hydrogen, and oxygen that come from CO2 in the air and water, plants combine these 2 inorganic molecules and produce simple sugars during the process of photosynthesis.

Galactose

Our body uses galactose to make certain components of cell membranes and to synthesize lactose, an important sugar in breast milk. The majority of galactose in the body is convertes to glucose and used as a source of energy (ATP). MONOSACCHARIDE. gluctose and galactose look similar, however, the Hydroxyl (-OH) groups on Carbon 4 are facing the opposite directions, this minor structural variation results in important differences in phsyiological functions of galactose and glucose. A 6-carbon monosaccharide found mainly bonded with glucose to form the milk sugar LACTOSE. Few foods contain galactose in its natural form, most comes from the DISACCHARIDE lactose (comprised of galactose and glucose).

Glycogen

POLYSACCHARIDE consisting of a highly branched arrangement of glucose molecules; found primarily in liver and skeletal muscle. Small amounts of glucose are stored as this. Although many tissues store small amounts of this, the majority is found in the LIVER and SKELETAL MUSCLES. Highly branched, this provides a physiological advantage because enzymes can hydrolyze multiple glycosidic bonds simultaenously. This means it can be broken down quickly when energy is needed. The body turns to this when glucose availability is low, such as during fasting and prolonged exercise. When liver __ is broken down, the glucose can be released directly into the blood. Liver __ plays an important role in blood glucose regulation. Glucose that results from the breakdown of muscle __ is used to fuel physical activity. Unlike the liver, muscle lacks the enzyme needed to release glucose into the blood. Some athletes try to incrase their muscle __ stores by Carbohydrate loading. Glycogen stores are usually depleted within 24 hours if no food is consumed in this time period. Glycogen stored in skeletal muscle is also made entirely of glucose molecules. Glycogen stored in the liver is broken down to glucose and released into the blood stream. This is useful during fasting and periods of reduced food intake

Emulsification

Phase 1 in Lipid digestion in small intestine. Bile; no lipase. Emulsified triglycerides, diglycerides, and fatty acid micelles. It is the process whereby large lipid globules are broken down and stabilized into smaller lipid droplets. When lipids arrive in the small inestine the hormone CCK is released which signals the gallbladder to contract and release bile. When bile acids and phosphilipids are released into the duodenum their hydrophobic portions are drawn toward the lipid globules, while their hydrophilic portions pull in the opposite direction toward the surrounding water, these opposing forces disperce the large lipid globuls into smaller droplets (emulsification), Makes the ester linkages more accessible to the digestive enzymes in the small intestine. Bile also disperces phospholipids and cholesteryl esters in the same way. Bile acis and phospholipids then stay with the newly formed droplets which are now referred to as micelles.

Enzymatic Digestion

Phase 2. Digestion of Triglycerides by Pancreatic Lipase. In response to lipid containing chyme entering the dudoenum the small intestine releases the hormones secretin and CCK. They signal the pancreas to release pancreatic juices containing the enzyme pancreatic lipase which completes trighlycerid digestion by hydrolyzing additional fatty acids from glycerol molecules in the micelles. In general 2 of the three fatty acids are reomved from the triglyceride molecules resulting in the release of a monoglyceride and two free fatty acids.

Photosynthesis

Process whereby plants trap energy from the sun to produce glucose from CO2 and H20. Plants produce oxygen and glucose, and energy from the sun is transferred to chemical bonds of glucose. CO2 and H20 in sunlight yield Glucose and Oxygen. Provides an important energy source for plants. This is how plants synthesize glucose. To store this important source of energy, plants convert glucose to starch.

Small Intestine in Digestion of Carbs

Recall that the inner surface of the small intestine is covered with finger like projections called villi which in turn are covered with microvilli that collectively are called the brush border. These villi create a vast surface area for the absorption of nutrients. Notice that each villus contains a network of blood capillaries. These transport nutrients to other parts of the body. Figure 5.12B presents a diagrammatic representation of disaccharides into their basic components before they can be absorbed into the epithelial cells of the small intestine. The small intestine is subject to friction as chyme is moved along it and nutrients are digested. Epithelial cells are sloughed off and replaced every few days

Number and Positions of double Bonds

SFA, MUFA, PUFA, USFA. For each carbon-carbon double bond, two hydrogen atoms are lost from the fatty acid backbone. This is because carbon atoms can only have 4 chemical bonds. A double bond counts as two chemical bonds so one must be given up. The number of double bonds can influence the physical nature of the fatty acid. SFA (butter or coconut oil) is surrounded by hydrogen atoms which prevents the fatty acid from bending. USFA can easily bend and can cause them to be disorganized, preventing them from becoming densely packed. SFA (like uncooked spaghetti), PUFA (cooked spaghetti). MUFA is a thick oil.

Gluconeogenesis

SYNTHESIS of glucose from NON-carbohydrate sources. If not a sufficient amount of carbohydrates are consumed. During this process the body can synthesize glucose from amino acids, lactic acid or glycerol. Gluconeogenesis primarily takes place in the liver and glucose is then released into the blood stream. Some non-carbohydrate molecules are not converted to glucose but rather enter the Krebs cycle as other molecules and produce ATP for energy. When you reduce the amount of carbohydrate consumed, for example when you consume a low carbohydrate diet such as the Aitkin diet you force your body to use alternative fuels for energy and gluconeogenesis takes place. The burning of fatty acids produces ketone bodies which are used to provide energy in place of glucose. Over time ketone bodies build up in the blood stream making it more acidic and possibly leading to ketosis. If you run a marathon or partake in other endurance sports and the body uses up all of the available glucose and glycogen stores then the body reverts to protein and fat as alternative fuels for energy. Note that glucose can be converted to fatty acids but fatty acids cannot be converted back to glucose.

List two glands that produce amylases.

Salivary (Salivary amylase begins carbohydrate digestion in the mouth starting the process of breaking down the starch into smaller sugar molecules) and Pancreatic glands (The pancreatic amylases disassemble polysaccharides and oligosaccharides into simple carbohydrates.)

Atherosclerosis

The hardening and narrowing of blood vessels caused by fatty build-up of fatty deposits and inflammation in the vessel walls

Dextrins are fromed during the digestion of

Starch Digestion; Amlose and Amlopectin

Hormone

Substances released from glands or cells in response to various stimuli that exert their effect by binding to receptors on specific tissues

Brush Border

The absorptive surface of the small intestine made up of thousands of microvilli that cover the luminal surface of the enterocytes

Ketones

The body's alternative energy source. To minimize the loss of muscle when gluconeogensis breaksdown muscle protein to provide a source of glucose. To minimize the loss of muscle, the body reduces its dependency on glucose and uses an alternative energy source. These organic compounds form when fatty acids are broken down in a relative absence of glucose. Ketone sytnesis has consequences, KETOSIS. KETOSIS occurs when production exceeds the rate of ketone use, resulting in the accumulation of ketones in the blood, this happesn when energy intake is very low or when the diet is low in carbs. It causes a varitey of complications including loss of appetite.

Endoplasmic Reticulum

The endoplasmic reticulum serves many general functions, including the folding of protein molecules in sacs called cisternae and the transport of synthesized proteins in vesicles to the Golgi apparatus. It usually has ribosomes attached and is involved in protein and lipid synthesis.???

Duodenum

The first segment of the small intestine. t receives partially digested food (known as chyme) from the stomach and plays a vital role in the chemical digestion of chyme in preparation for absorption in the small intestine.

Once in the bloodstream, what is the first organ that monosaccharides encounter?

The liver. The majority of galactose and fructose is converted into other compounds- most notably glucose, however some monosaccharides are converted to ribose a constituent of many vital compounds including ATP, RNA, and DNA.

Where in the digestive tract, does most carbohydrate digestion take place?

The majority of carbohydrate digestion occurs in the small intestine. It is here that disaccharides (sugars composed of two monosaccharides) like sucrose, maltose, and lactose are broken down into monosaccharides, which are then absorbed directly into the cells that form the intestinal lining (brush border). The absorption of most digested food occurs in the small intestine through the brush border of the epithelium covering the villi

Fatty Acid

The most common type of lipid, most abundant in your body and the foods you eat. Made entirely of carbon, hydrogen, and oxygen atoms. One end of the carbon chain (alpha end contains a carboxylic group; the other the omega end contains a methyl group (CH3)). Most fatty acids do not exist by themselves, they are components in large molecules such as triglycerides, and phospholipids. They are bound to cholesterol forming cholesteryl esters, A LIPID consisting of a chain of carbons with a methyl (-CH3) group on one end and a carboxylic acid (-COOH) group on the other end. Named for their structures, based on the number of carbonds, they number and types of double bonds, and the positions of the double bonds. Some fatty acids have "common names".. Either starting at the alpha or the omega (does not identify where bonds are) end. Linoleic and Linolenic acid are 2 fatty acids that are essential. nuts, seeds, and certain oils, are abundant in linoleic and linolenic acid, soybean oil and walnuts are good sources of both essentail fatty acids. Higher intakes of long chain fatty acids are related to lower risk for heart disease and stroke (eat, poultry and eggs). Omega 6 fatty acids are more plentiful in our diets. Can be converted into energy yielding ketones. Fatty acids are the building blocks for triglycerides and phospholipids. They also determine some of the properties of the final molecule. 4-24 carbons. The terminal end of the chain where 3 hydrogen atoms are bonded to the carbon atom, called the methyl group, is also called the omega end of the fatty acid. Some lipids refer to this term in their name, for example, Omega-3 fatty acid. The opposite end of the carbon chain forms a carboxylic acid group. This end of the chain is referred to as the alpha end of the molecule and it too may be found in common names, for example, alpha-linoleic acid.

What is the stored form of carbohydrate in plants? In animals?

The storage form of glucose in plants is STARCH, the storage form of glucose in animals is GLYCOGEN.

How do monosaccharides get from the small intestine to the bloodstream?

They are absorbed from the small intestine into the blood directly to the liver via the hepatic portal system. Glucose and galactose are absorbed across the lumenal membrane of the enterocytes via a carrier mediated active transport (active transport mechanisms; move from lower to higher concentration with the assistance of trasnport protein.), and fructose is absorbed through facilitated difussion (moving from a higher to lower concenration with the assistance of transport proteins), after crossing the basolateral membrane via facilated difusion they then circulate in the bloodstream. Notice that each glucose molecule or galactose molecule is co-transported across the membrane with a sodium ion in exchange for a potassium ion. Monosaccharides enter the capillary network of blood vessels and are transported directly to the liver via the hepatic portal vein.

When are blood glucose levels at the lowest point? When are they at the highest point?

They are at your lowest when you have gone severl hours without eating. They are at their highest when we eat carbohydrate rich foods. However not all carbs have the same effect on blood glucose levels. The change in blood glucose following the ingestion of a specific food is called the glycemic response. Simple carbs have higher responses than complex carbs. However, this is not always the case. The factors of the presence of fat or protein, viscosity, processing, ripeness, and food additives are important.

How are simple and complex carbohydrates a) the same? b) different?

They are both categories of carbohydrates consisting of monosaccharides. Simple only consists of mono and di, and complex (more than 3 sugars) consist of poly and oligo ??

Hypoglycemia

abnormal LOW level of glucose in the blood, brain is very sensitive to low levels of glucose. Can make you feel anxious, dizzy, lethargic, and irritable. Reactive and Fasting Hypoglycemia.

Why is there a minimum recommendation of 130g of carbohydrate per day for individuals 1 year and older? If an individual consumes less than this amount how does the body obtain the much needed carbohydrate?

This is because the brain must have glucose as fuel, otherwise some regions of the brain shut down. Also if the body is required to burn fat as an alternative fuel source a small amount of glucose is required to completely disassemble fatty acids and reduce the risk of ketosis.

Exocytosis

This is how the large chlyomicron structures exit the cells. A form of VESCILAR ACTIVE TRANSPORT whereby intracellular cell products are enclosed in a vesicle and the contents of the vesicle are released to the outside of the cell

An individual is unable to make insulin. This is known as_____________diabetes.

Type 1 Diabetes

Fats and Oils

Type of lipids, water-insoluble, organic molecules consisting mostly of carbon, hydrogen, and oxygen atoms. They are hydrophobic "water fearing" . At room temp.

Glucagon

USED WHEN THERE IS A DECREASE OF BLOOD GLUCOSE. HORMONE secreted by the pancreatic alpha (a)-cells in response to decreased blood glucose. Helps increase blood glucose with a signal. Because the brain and other components of the nervous system cannot store glucose, they are dependent on the circulating of glucose for energy, which is why glucagon is important. When you first wake up in the morning your blood glucose levels are lower since you have not eaten in a while. Once the blood glucose level falls below a certain set point, your pancreas releases the hormone glucagon. This hormone stimulates the breakdown of glycogen previously stored in the liver, resulting in the release of glucose molecules into the blood stream. This in turn raises the blood glucose level. In addition to the breakdown of glycogen, you have probably eaten food since you woke up. Glucagon plus digestion of food results in increasing glucose levels.

How does insulin facilitate the uptake of glucose from the bloodstream?

When blood glucose levels increase, the pancreas releases more insulin which lowers blood glucose by facilitating the uptake of glucose into many kinds of cells. Cells that recognize insulin or are sensitive to insulin begin to remove glucose molecules from the blood stream. The liver also converts some of that glucose to glycogen to be stored in the liver for the next time blood glucose levels fall. When meals provide more glucose than we require, insulin stimulate its storage as glycogen. Once muscles and the liver reach their glycogen storage capacity, excess glucose is converted to fat, which is primarily store in adipose tissue. The hormonal balance shifts toward glucagon when blood levels DECREASE, to increase glucose availability, glucagon stimulates the breakdown of glycogen stores in the liver.

What is the difference between the contents of a bag of white flour and a bag of whole wheat flour?

When you consume white flour or other refined grain products you basically eat the endosperm (starch) which is enriched with vitamins and minerals that were lost during processing. When you consume whole wheat flour or whole grain products you have all of three components making whole grain products nutritionally superior food. The trend to consume white flour products began with the affluent portion of the population. Thinking it was a better product, those who could afford it switched to white flour products which later became main stream. Slide five - a grain of wheat, rice, corn or other grain is composed of three basic components. The bran is a protective covering on the outside of the seed, the germ is the embryo which would grow into a new plant and the endosperm is the food store for the embryo during germination. The bran is almost 100 percent fiber; the germ is rich in protein, vitamins and minerals; the endosperm is rich in starch and contains some protein.

Which of the following elements are found in all carbohydrate molecules

carbon, hydrogen & oxygen

Foods eliciting a high glycemic response..

cause a rapid and large surge in blood glucose levels

Bile Acid

consists of a colesterol molecule attached to a very hydrophobic subunit making it amphipathic much like a phospholipid. The production of micelles in the small intestine is also facilitated by bile acids that are released from the gallbladder. Bile acids function as an emulsifier keeping micelles apart and suspended in the watery environment of the intestine.

Fiber

diverse group of PLANT POLYSACCHARIDE that unlike starch, can NOT be digested or absorbed in the human small intestine. This is because they contain beta bonds that are resistant to digestive enzymes. Intestinal bacteria break down the fiber producing gas, lipids, and other substances. Although gas production (Flatulence) by intestinal bacteria may be an annoyance, other substances made by these microorganisms serve useful purposes such as nourishing cells that line the colon. Dietary fiber promotes the selective growth of beneficial intestinal bacteria which in turn help inhibit the growth of other, disease-causing (pathogenic) bacteria. Dietary fiber occurs naturally in plants (whole grains, legumes, vegetables, and fruits), functional fiber is fiber added to food as an ingredient (must have demonstrated beneficial physiological effects to be considered functional) and it can increase the total fiber in certain foods. Total fiber refers to the combination of dietary that exists naturally in a food plus any functional fiber that is added during manufacturing. Fiber is categorized by its solubility in water. Fiber is not a required dietary component, but when coming from whole foods it protects against cardiovascular disease, obesity, and type 2 diabetes. A fiber rich diet is essential for digestive health. helps control weight. reduces "spikes" in blood glucose. reduce risk heart disease. healthy GI tract. Foods that are high in fiber are generally low in fat and calories. This means you can consume a greater volume of food for fewer calories and you feel full for longer. Reducing overall calorie intake helps to control weight. Also, having fiber mixed with chyme delays stomach emptying and helps to keep blood glucose levels stable. Studies have shown a relationship between diets high in fiber and reduced risk of heart disease. High fiber foods also contain antioxidants and other nutrients that help to prevent cell damage which is a component of heart disease. Increasing fiber in your diet also maintains a healthy gastrointestinal (GI) tract. It makes the muscles of the GI tract work out and keeps them strong. This helps to avoid constipation and complications such as diverticular disease in later life

Insufficient Fiber

equals constipation which can lead to diverticular disease. Causing the colon wall to become weak. Diverticulitis occurs when the diverticula become infected of inflamed. Dietary fiber helps prevent the formation of diverticula by increasing fecal mass, making bowel movemebts easier. A high fiber diet with plenty of fluids may protect against diverticular disease.

Beta bond

faces down (glycosidic bonds)

Alpha bond

faces up (glycosidic bonds)

Insulin DOES and DOES NOT

it DOES promote glycogen storage, fat sythesis, and muscle syntheis. DOES NOT promote glycogenolysis

Following absorption, monosaccharides are transported to the ___________ for further processing.

liver

Chain Length

the number of carbon atoms in the backbone of a fatty acid determines its chain length. Most have an even number. Fatty acids with fewer than 8 are short-chain fatty acids, and thsoe with 8 to 12 are medium and those with more than 12 are long. The length affects its chemical properties and physiological functions. Inlfuences the temp at which fatty acids melt, short chain have low melting points and take less heat to liquify. They are predominantly short chain (oils and gases) long chain =solid fat. Chain length also effects the solubility in water short chain are more soluble. Short are easily absorbed and trasnported in the body

Fructose

the sweetest of the MONOSACCHARIDES. Naturally occuring monosaccharide in honey, fruits, and vegetables. High Fructose (equal amount of glucose and fructose) corn syrup is used as a sweetner in beverages, and foods.

Carbohydrate Digestion

the ultimate goal is to break down large, complex molecules such as starches into small, absorbable monosaccharides. This process requries a series of enzymes produce in the salivary glands, pancreas, and small intestine. With the help of the digestive enzymes, the glycosidic bonds that hold disaccharides and starches together are broken. Begins in the MOUTH where the salivary alpha amylase hydrolyzes the alpha glycosidic bonds in both the amylose and amylopectin resulting in shorter polysaccharide chains of varying lengths called dextrins. Very little starch digestion takes place in the mouth. Once the dextrin eneters the stomach, the acidic enviornemt stopes the enzymatic activity of the salivary almylase. Dextrins pass unchanged from the stomach to the small intestine, where they then encounter pancreatic alpha amylase. It then hydrolyzes the alpha glycosidic bonds transofroming dextrines into the disaccharide maltose. Lastly, maltase a brush border enzyme produced by eneterocytes, finishes the job of starch digestion by hydrolyizing the last remaining chemical bond in faltose, resulting in 2 free glucose molecules. An extra step is needed to digest the amlopectin, the enzyme alpha dextrinase also a brush border enzyme accomplishes the hydrolysis of the alpha 1,6 glycosidic bonds, completing the digestion of amylopectin. Amylose and Amlyopectin digestion results in the production of numerous glucose molecules that are now ready to be trasnported into the enterocytes. Disaccharides are digested in the small intestine. The enterocytes provide the enzymes needed, each disaccharide hydolyzes into different monosaccharides. Once they are digested into their component monosccharides, they can be transported into the enterocytes. Monosaccharides are readily absorbed from the small intestine. Once disaccharide and starch digestion is complete, the resulting monosachories are readily absorbed from the small intestine into the blood. Glucose and galactose are bsorbed across the lumenal membrane of the enterocytes via a carrier mediated active transport, and fructose is absorbed through facilitated diffusion. After crossing the basolateral membrane (via diffusion) monosaccharides then circulate in the blood directly to the liver via the hepatic portal system. Once the bolus of food reaches the stomach carbohydrate digestion is stopped in the acidic environment created there. Then once the chyme enters the duodenum, the pancreas secrets a number of enzymes, some of which are amylases. Chyme is mixed with digestive enzymes as it moves along the small intestine. The pancreatic amylases disassemble polysaccharides and oligosaccharides into simple carbohydrates. Digestion of any remaining disaccharides to produce monosaccharides is completed at the brush border prior to absorption.

Soluble Dietary Fiber

viscous that absorb water and swell. Soluble dietary fiber (oats, barley, legumes, rice, bran, psyllium, seeds, soy, and some fruits) (Pectin, Gums, and beta-glucan = soluble fibers) its sponge-like effect can help soften fecal matter, reducing strain and making elimination easier. Can help reduce blood cholesterol levels in some people. Eating foods with soluble, viscous fiber can delay gastric emptying, which can help promote satiety. Delayed gastric emptying may also help lower blood glucose levels. Can promote the growth of friendly bacteria in the colon. Viscous fiber may bind with dietary fat and cholesterol in the GI tract making it less likely to be absorbed. Some plant fiber is soluble and forms a gel-like substance when mixed with water. Both types are found in all plants although the proportion of soluble to insoluble fiber differs. Both types are essential for good health. Diets high in fiber, in particular soluble fiber, have been shown to reduce levels of blood cholesterol. One of the reasons for this is that bile, which is made from cholesterol, binds to fiber in the large intestine and is eliminated from the body. The body then has to remove cholesterol from the blood to make more bile. If not bound to fiber then bile is absorbed and recycled in the body. Oats and Psyllium are good sources of soluble fiber.