Nutrition Unit 2 Digestion, Absorption and Metabolism

process of digestion for fats

** they don't usually begin digesting at all until they hit the small intestine.

functions of all organs

-The MOUTH is the beginning of the digestive system, and, in fact, digestion starts here before you even take the first bite of a meal. The smell of food triggers the salivary glands in your mouth to secrete saliva, causing your mouth to water. When you actually taste the food, saliva increases. -the PHARYNX also called the throat, is the portion of the digestive tract that receives the food from your mouth. Branching off the pharynx is the esophagus, which carries food to the stomach -The ESOPHAGUS is a muscular tube extending from the pharynx and behind the trachea to the stomach. Food is pushed through the esophagus and into the stomach by means of a series of contractions called peristalsis. -Just before the opening to the stomach is an important ring-shaped muscle called the lower ESOPHAGEAL SPHINCTER (LES). This sphincter opens to let food pass into the stomach and closes to keep it there. -The STOMACH is a sac-like organ with strong muscular walls. In addition to holding food, it serves as the mixer and grinder of food. The stomach secretes acid and powerful enzymes that continue the process of breaking the food down and changing it to a consistency of liquid or paste -SMALL INTESTINES is made up of 3 parts the duodenum, jejunum, and ileum. SMALL INTESTINE also breaks down food using enzymes released by the pancreas and bile from the liver. The small intestine is the 'work horse' of digestion, as this is where most nutrients are absorbed. Peristalsis is also at work in this organ, moving food through and mixing it up with the digestive secretions from the pancreas and liver, including bile. -The DUODENUM (10in) is largely responsible for the continuing breakdown process, with the JEJUNUM(8ft) and ILEUM(12ft) being mainly responsible for absorption of nutrients into the bloodstream. **A more technical name for this part of the process is "motility," because it involves moving or emptying food particles from one part to the next. While food is in the small intestine, nutrients are absorbed through the walls and into the bloodstream. What's leftover (the waste) moves into the large intestine (large bowel or colon). The colon (large intestine) is a five- to seven -foot -long muscular tube that connects the small intestine to the rectum. As stool passes through the colon, any remaining water is absorbed. The rectum is an eight-inch chamber that connects the colon to the anus. -The LARGE INTESTINE is a highly specialized organ that is responsible for processing waste so that defecation (excretion of waste) is easy and convenient.

1 gm carbohydrates

4 Kcal

1 gm protein

4 Kcal

1 gm fat

9 Kcal

step 3 fats

ABSORPTION AND DISTRIBUTION Fatty acids, cholesterol, and other products of fat digestion are typically absorbed into the bloodstream through the walls of the small intestine. This organ determines how much of the substances to distribute to the body and how much to send out as waste.. In general, though, about half of the cholesterol that enters the small intestine never makes it into the bloodstream, and the ratio is only slightly higher for most fatty acids. Once fat hits the bloodstream, it can go almost anywhere in the body, and has a profound impact on blood sugar as a whole.

step 3 proteins

CONTROL Your body regulates protein digestion through hormones and nerve signals. Gastrin stimulates your stomach cells to produce acid, while secretin tells your pancreas to secrete both bicarbonate and digestive enzymes. Cholecystokinin is a third hormone involved in protein digestion, which also directs your pancreas to release digestive enzymes. Your nervous system assists in protein digestion by responding to the physical presence of food in your digestive tract. Stimulation of nerves in this area helps move food through the different organs of your gut.

process of digestion for carbohydrates

Carbohydrate digestion begins in the mouth. The salivary glands in the mouth secrete saliva, which helps to moisten the food. The food is then chewed while the salivary glands also release the enzyme salivary amylase, which begins the process of breaking down the polysaccharides in the carbohydrate food.

waste products

Co2-lungs nitrogen- kidneys

DIGESTION

Digestion. 1. Carbohydrates: principally starches, lactose, and sucrose. Starches are acted on by the enzyme ptyalin (alpha-amylase) secreted in saliva, by hydrochloric acid (HCl) in the stomach, and by pancreatic amylase and intestinal amylase in the small intestine, which split the starches into maltose and isomaltose. These, in turn, are acted on by maltase and isomaltase and split into two molecules of glucose. Lactose is split by the enzyme lactase into a molecule of galactose and a molecule of glucose. The monosaccharides glucose, galactose, and fructose are absorbed from the small intestine into the blood. 2. Fats: emulsified by bile salts and agitation. The emulsified fats are acted upon by pancreatic and enteric lipase to form fatty acids, glycerol, and monoglycerides, which are absorbed through the intestinal walls. Small quantities of diglycerides and triglycerides are also absorbed. 3. Proteins: acted on chiefly in the stomach by pepsin, which splits proteins into proteoses, peptones, and polypeptides. In the small intestine they are acted on by the pancreatic enzymes trypsin, chymotrypsin, and carboxypeptidase to form polypeptides and amino acids. In the small intestine the peptidases complete the breakdown of the peptides into dipeptides and amino acids. Almost all proteins are eventually digested and absorbed either as amino acids or as dipeptides or tripeptides.

role of enzymes in digestion

Digestive enzymes are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body. are found in the digestive tract where they are secreted by digestive organs to aid digestion. Digestive enzymes are classified by their substrates ***Proteases and peptidases breakdown proteins into amino acids ***Lipases split fat into fatty acids and glycerol ***Carbohydrases break carbohydrates into starch and sugars ***Nucleases split nucleic acids into nucleotides

step 1 in fats

EMULSIFICATION There are two organs in the body that secrete substances essential to the digestion of fats: the liver and the pancreas. The pancreas secretes lipase, a substance that breaks down nearly all foods, including fat, and the liver secretes bile, a substance that emulsifies fat in particular. When food enters the small intestine, lipase is secreted into the area via the main pancreatic duct through the hepatopancreatic ampulla. It then breaks down food into simpler particles. the lipase is only able to attack and break down the outer layer of most fatty particles. This is where bile comes into the equation. Though bile is secreted by the liver, it is stored in the gallbladder. When fat hits the small intestine, bile is released through the bile duct and joins lipase in the hepatopancreatic ampulla. It is this substance that allows the fat to be broken down into smaller particles so the lipase can attack it more thoroughly.

step 2 fats

ENZYME BREAK- DOWN Once the fat is suspended like this, the lipase can get to work breaking it down. Lipase is a digestive enzyme that works in many of the same ways as enzymes elsewhere along the digestive tract, particularly in the saliva and the stomach. Fat that has been emulsified is usually a lot easier for lipase to break down and in most cases the decomposition is complete, meaning that all parts of the fat molecules are exposed and deconstructed into particles that can be easily absorbed by the bloodstream.

role of villi in the process of absorption

Finger-like protrusions on the surface of the intestinal lining called villi make this massive surface area possible. Because the proteins, carbohydrates, lipids as well as many vitamins and minerals are absorbed through the small intestine, nutrient uptake would be greatly inhibited without villi The villi create a folded, wavy texture on the intestinal lining, which is how the body fits area into the small space of your abdomen. A single villus consists of one vein, one artery and a central lacteal, which is a type of capillary that transports lymphatic fluid. The villus is structurally supported by one strand of muscle and connective tissue. Two types of cells coat the villi -- goblet cells that secrete mucus and epithelial (surface) cells that are responsible for absorption. The epithelial cells are coated with even smaller projections called microvilli which further increase the absorptive capacity of the intestines. Microvilli are covered with digestive enzymes that break down carbohydrates and protein. ***When food is broken down in the stomach, it forms a substance called chyme, which is a slurry of nutrients. When that slurry passes into the small intestine, it comes into contact with the villi. The carbohydrates and proteins in the chyme enter the bloodstream passively via the vein and artery. The fat is absorbed by the lacteal into the lymphatic system, which eventually empties into the bloodstream. In a process called active transport, specialized intestinal cells of the villi allow the passage of B-12, iron and calcium into the bloodstream.

step 4 carbohydrates

LARGE INTESTINE (Colon) Carbohydrates that were not digested and absorbed by the small intestine reach the colon where they are partly broken down by intestinal bacteria. Fiber, which cannot be digested like other carbohydrates, is excreted with feces or partly digested by the intestinal bacteria.

step 1 carbohydrates

MOUTH Carbohydrate digestion begins in the mouth. The salivary glands in the mouth secrete saliva, which helps to moisten the food. The food is then chewed while the salivary glands also release the enzyme salivary amylase, which begins the process of breaking down the polysaccharides in the carbohydrate food

step 1 proteins

MOUTH TO STOMACH Once the food reaches your stomach, it encounters a harshly acidic environment. Your stomach acid serves several purposes. It denatures, or unfolds, the proteins in your food so digestive enzymes can act on it, it activates a protein-specific enzyme that clips the protein into smaller molecules called peptides and it inactivates any potentially harmful microorganisms you may have ingested along with your food. The peptides in your stomach now move to your small intestine.

process of metabolism

Metabolism is the set of life-sustaining chemical transformations within the cells . The three main purposes of metabolism are the conversion of food/fuel to energy to run cellular processes, the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates, and the elimination of nitrogenous wastes.

process of absorption

NUTRIENTS TAKEN INTO THE CELLS THAT LINE THE G.I TRACT a. normal assimilation by the tissues of the products of digestion b. the passage of a gas, fluid, drug, etc, through the mucous membranes or skin 1. Uptake of substances, such as digested food and oxygen, into cells. 2. The transfer of digested nutrients from the alimentary canal into blood or lymph.

step 3 carbohydrates

PANCREAS AND SMALL INTESTINE After being in the stomach, the chyme enters the beginning portion of the small intestine, or the duodenum. In response to chyme being in the duodenum, the pancreas releases the enzyme pancreatic amylase, which breaks the polysaccharide down into a disaccharide, a chain of only two sugars linked together. The small intestine then produces enzymes called lactase, sucrase and maltase, which break down the disaccharides into monosaccharides. The monosaccharides are single sugars that are then absorbed in the small intestine.

step 2 carbohydrates

STOMACH After the carbohydrate food is chewed into smaller pieces and mixed with salivary amylase and other salivary juices, it is swallowed and passed through the esophagus. The mixture enters the stomach where it is known as chyme. There is no further digestion of chyme, as the stomach produces acid which destroys bacteria in the food and stops the action of the salivary amylase.

step 2 proteins

STOMACH TO SMALL INTESTINE To neutralize the acidic food particles coming from your stomach, your pancreas secretes a bicarbonate buffer into your small intestine. The neutral environment of this portion of your gut encourages the activity of more protein-digesting enzymes originating from both your pancreas and the cells lining your small intestine. These enzymes work on the food peptides, systematically breaking them down into even smaller peptides and then snipping off the amino acids one by one. At this point, the absorptive cells of your small intestine carry the single amino acids to your bloodstream and then on to the cells throughout your body.

organs in the digestive system

The digestive system is made up of the gastrointestinal (GI) tract-also called the digestive tract-and the liver, pancreas, and gallbladder. The GI tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus.

identify the common bile duct

The duct that carries bile from the gallbladder and liver into the duodenum (upper part of the small intestine). The common bile duct is formed by the junction of the cystic duct, from the gallbladder, and the common hepatic duct, from the liver.

process of digestion for proteins

The proteins you eat are large, globular molecules made up of smaller molecules called amino acids. Protein digestion works by reducing each dietary protein to a pool of amino acids within your gastrointestinal tract. The amino acids, once they are absorbed and transported to your cells, can then mix and match in a variety of ways to create the different proteins your body needs at any given point in time. The process begins in your mouth and ends in your small intestine, with the help of digestive juices and enzymes.

how does bile function in digestion

There are two fundamentally important functions of bile Bile contains bile acids, which are critical for digestion and absorption of fats and fat-soluble vitamins in the small intestine. Many waste products are eliminated from the body by secretion into bile and elimination in feces.

pepsin

activated in the presence of hydrochloric acid starts to breakdown proteins

gastric lipase

acts on emulsified( breaks down to smaller) fats

ATP

adenosinc triphosphate energy mitochondria >nutrients+O2

weight control

amount of kilocalories in equal to kilocalories out

mechanical digestion

breaking down foods by physical means teeth, peristalis

hydrochloric acid

breaks down food, so enzymes can work on it destroys bacteria on food makes iron and calcium more soluble

chemical digestion

chemical alteration of food salivary glands secrete ptyalin (salivary amylase)

large intestine

consist of cecum( meets the ileum), colon, rectum and responsible for absorbing water synthesizing some B vitamins and vitamin K and to collect food residue (undigestables, roughage, fiber)

how to calculate your basal metabolic rate

convert lbs into kg multiply kg by 24 (hours) multiply by 0.9 for women 1.0 for men energy requirement multiply by 1.5

brush border enzymes

enzymes that are secreted in the small intestine lactase maltase sucrose peptidases- final breakdown of proteins to amino acids mona seceria ?

Vitamins A.D.E.K

fat soluble vitamin need bile/ fat for absorption

digestive system

hollow tube extending from mouth to anus mouth pharynx esophagus stomach small intestine large intestine rectum anus *accessory organs salivary glands teeth liver gallbladder pancreas ****ingest food digest it absorbs the end products eliminates waste

process of digestion

is the breakdown of food into smaller particles or individual nutrients. It is accomplished through six basic processes, with the help of several body fluids—particularly digestive juices that are made up of compounds such as saliva, mucus, enzymes, hydrochloric acid, bicarbonate, and bile. (1) the movement of food and liquids; (2) the lubrication of food with bodily secretions; (3) the mechanical breakdown of carbohydrates, fats, and proteins; (4) the reabsorption of nutrients—especially water; (5) the production of nutrients such as vitamin K and biotin by friendly bacteria; and (6) the excretion of waste products.

factors effecting BMR

lean body mass-greatest factor due to metabolic activity that larger people body size sex- men faster age- drops as we get older heredity physical condition climate- cold works harder fever-^ pregnancy-^ lactation

cardiac spinchter

located between esophagus and stomach when not working-gerd

energy

maintenance of body tissue body temp growth physical and mental activity

kilocalories

measurements of heat measure the energy value of food

stomach

mixes food with gastric juices to form chyme temporarily stores food provides a slow emptying into small intestine

transportation

movement through circulatory system

chyme

moves through the pyloric sphincter(bottom of stomach) into the duodenum

bile

necessary to emulsify fat

iodine

needed for thyroid hormones to transfer from T3 to T4

metabolism

oxygen is necessary for metabolism metabolism is governed by the hormones secreted from the thyroid= T3&T4 too much- hyperthyroidism, too little-hypothyroidism

liver

produces bile which is stored in the gallbladder (bile salt)

BMR

rate of energy needed to keep a body going at rest and doing involuntary functions (BP, HR, RR)

pancreas

sodium biocarbonate(NaHCO3) secretes insulin from the islets of langerhans pancreatic proteases- protein pancreatic lipase- reduces fats to fatty acids and glycerol pancreatic amylase (maltose)- starch

glucose

sugars simplest form

calorie

the amount of heat needed to raise the temp of 1kg of water 1 degree C*

absorption

the passage of nutrients into the blood or lymphatic system

pyloric cyanosis

vomiting due to inability to pass food

catabolism

when the energy is used to break down substances

anabolism

when the energy is used to build new tissues