Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
116 Cards in this Set
- Front
- Back
Ingestion
|
consumption/act of taking food into the body/stomach
|
|
Mastiation
|
process of chewing
|
|
Digestion
|
Material subjected to chemicals/enzymes with resultant change/decomposition of physical/chemical nature of that substance
|
|
Absorption
|
passage of nutrients and other materials to blood, lymph, and cells of allimentary tract (digestive tract)
|
|
Metabolism
|
all chemical processes of the body involved in the miantenence of life
|
|
Excretion
|
removal of waste porducts in the body, mainly in the form of feces/urine
|
|
Why study nurtrition?
|
1. Feed costs- comprise 40-70% of total production costs
2. Nutrition affects health and performance- many diseases nutrition related 3. Feed industry is a major employer- 20-30% animal sci/ag. graduates get jobs as nutritional/management consultants 4. Better informed consumers- interpritation of food/feed labels, terminology is important, evaluation of fad diets |
|
Disciplines involved in nurtition
|
1. Chemistry- Antioine Lavoisier: "father of nutrition"- developed theory of combustion and related it to how the body actually burns nutrients through cellular oxidation. Inventions: metric system, analytical balance, thermometer, bomb calorimeter
2. Biochemistry 3. Physiology 4. Microbiology- microbes that live in digestive tract and aid in digestion and silage making process. Some microbes live on feedstuffs and produce toxins. |
|
Other disciplines in nutrition
|
Immunology- nutrition relationship to immune function
Genetics- certain nutritional disorders genetically inherited Math- algebra needed for ration balancing Stats- interpritation of research data Physics- radioactively tagged nurtients for research and their fate following digestion Economics- least cost ration balancing |
|
Nutrient
|
Any chemical/compound in diet that supports normal reproduction, growth, lactation, or maintenance of life processes
|
|
Ration
|
Amount of feed consumed by an animal in 24 hours (daily amount)
|
|
Diet
|
Feed ingredient or mix of ingredients (including water) consumed by animals
|
|
Balanced Diet
|
diet that supplies required nutrients in correct amounts and proportions to nourish target animal for specific purpose of production
|
|
Food/Feed
|
Edible material that provides nutrients. Can be natural or artificial. used for purpose of sustaining animals.
(Feed-animal food, Food- human food) |
|
Foodstuff/Feedstuff
|
Any material made into or used as food/feed
|
|
Water
|
Cheapest and most abundant nutrient:
65-85% of animal body weight at birth and 45-65% of body weight at maturity. Percentage of body weight decreases with age- inverse relationship with body fat 90-95% blood, 70-90% tissues Various Functions: transport nutrients and aid in excretion medium that allows chemical reactions regulate body temp. lubricate joints and organs in body cavities |
|
Carbohydrates
|
By % molecular weight: C (77%), H (12%), O (11%)
Includes sugar, starch, cellulose, and gum serve as structrual components in plants very little occurs as carbs in animal body source of energy and bulk to keep digestive tract working smoothly *Glucose* |
|
Lipids
|
By % molecular weight: C (77%), H (12%), O (11%)
Insoluble in water, soluble in organic solvents (ex. ether) most energy dense nutrient produce ~2.25 times more energy than carbs |
|
Proteins
|
By % molecular weight: C (55%), H (72%), O (23%), N (16%), S&P (<1%)
Principle constituent of organs and soft tissue Complex molecules containing various amino acids. (22 comonly found in proteins) Essential Amino Acids (10)- body can't sythesize fast enough to meet its requirements |
|
Minerals
|
Inorganic, solid, crystalline chemical eliments. total mineral content= ASH
Comprise 3-5% of animal's dry body weight. (Ca- 1/2 total body minerals, P- 1/4 total body minerals) Macrominerals: essential, required in large amounts (Ca, P, Na, Cl, Mg, K) Microminerals: trace elements required in small amounts (Ca, Cu, F, I) |
|
Vitamins
|
Organic components of natural food, but distinct from carbs, fat, protein, and water.
Present in food in minute amounts and effective in body in small amounts Essential for developement of normal tissue; necessary for metabolic activity, but don't enter structural portion When absent from diet or not absorbed/ utalized properly disease/syndrome may result |
|
Proximate Analysis
|
1. Heat feed above bp of water to get %DRY MATTER
2. Burn in muffle furnace to get ASH (estimate total meneral content- does not tell about individual minerals) 3. kjeldahl process to find amount of N in sample. Nx6.25= CRUDE PROTEIN (based on protein containing 16% protein. 100/16=6.25) 4. Extract with ether. Loss of weight after drying= FAT 5. Boil extracted sample in dilute acid, then weak alkali to determine CRUDE FIBER. (remove starches, protein, sugar) 6. 100%- water-ash-protein-fiber-fat=NITROGEN FREE EXTRACT. (soluble carbs., sugars, and starches) |
|
Classes and Proximate Analysis
|
Water- dry matter
Carbohydrates- NFE/Crude fiber Fat- Crude fat/ether extract Protein- Crude protein (Nx6.25) Minerals- Ash Vitamins- water soluble (B) and fat soluble (A, D, E, K) |
|
General uses of Nutrients
|
1. Maintain body- energy needed for normal processes, activity, and warmth. Cells must always be replaced
2. Build the body 3.Egg production- protein and calcium 4. Production of young (gestation) 5.Production of milk- sale/nourishment of young 6.Work- pleasure/draft horses |
|
Prehension
|
Taking feed/ water into the mouth
|
|
Deglutition
|
Act of swallowing
|
|
Regurgitation
|
Casting up of undigested material
|
|
Digestion
|
Breakdown of feed particles into suitable products for absorption.
May include: Mechanical forces- chewing Chemical action- acidity of stomach (pH 2-3) Enzymitic Activity- hydrolysis; catalysts for biochemical reactions Microbial Fermentation- pre/post gastric |
|
Absorption
|
Transfer of nutrients from GIT to circulating blood/lymph system
|
|
Anabolism
|
Growth/building process (synthesis)
|
|
Catabolism
|
Breakdown/destructive reactions (degredation)
|
|
Metabolism
|
Combination of anabolic and catabolic reactions occuring in the body with liberation of energy
|
|
Excretion
|
Removal of waste products
|
|
Carnivores
|
Feed almost entirely on flesh of other animals
Short, simple GIT- rapid passage Rich diet, easily digested except for hairs, feathers and other types of resistant proteins Must have strong protein digesting enzyme systems |
|
Herbavores
|
Depend entirely on plants for food (cows, horses)
long, complex GIT, slower passage, many compartments, some large for long term storage and fermentation of fiber aided by microbes |
|
Ominivores
|
Consume plants and flesh (dog, hog, poultry, humans)
Medium length and complexity of GIT |
|
Monogastrics (Nonruminents)
|
Pig/horse/cat/avian- Single compartment stomach
Make poor use of fibrous feeds Microbial fermentation in cecum and large intestine allows horse to utalize fibrous feeds effectively. |
|
Ruminants
|
Cow/sheep/goats/deer- multicompartmental stomach
By means of microbial fermentation processes of the rumen these animals can: make effective use of high fiber feed utalize nonprotein N to make microbial protein (ex. urea) synthesize B-vitamins in ruman reducing requirement for these vitamins |
|
Digestive Tract of a Pig
|
Oe- eshophagus
S-stomach D-duodenum I-intestine Ca- caecum Co-colon Re- rectum An- anus |
|
Tounge (pig)
|
Prehension, mixing, and deglutition
|
|
Mouth (pig)
|
proximal organ of the gastrointestinal tract that contains three accessory organs: Tounge, teeth, salivary glands
|
|
Teeth (pig)
|
Paired glands that secrete saliva
|
|
Components of Saliva (pig)
|
Water- moistens consumed feed and aids in taste mechanisms
Mucin- lubrication/ aid in deglutition Inorganic salts- in form of bicarbonate which acts as buffer to regulate pH of the stomach Amylase- initiates carbohydrate breakdown *not found in all species |
|
Esophagus (pig)
|
Hallow muscular tube that transports ingesta from the mouth to the stomach.
Material moved by waves of contractions of muscles that encircle esophagus and referred to as PERISTALTIC WAVES or PERISTALISIS Valve exists (cardiac sphincter) at the junction of stomach and esophagus (allows ingesta to enter stomach) |
|
Stomach (pig)
|
Hallow, pear-shaped muscular digestive organ.
Functions: 1. Storage- ingested feed stored temporarily in form of CHYME (thick semi-fluid material) or partially digested contents 2.Muscular Contractions- causes movement and mixing of the chyme 3. Secretions- various digestive juices are secreted including: HCl: strong acid that lowers pH of digesta to ~2.0. Ideal pH for enzymes in stomach to function. MUCUS- covers the entire stomach to protect it from the acidic environment PEPSIN- a protease enzyme that hydrolizes/digests protein *pepsinogen (zymogen)--HCl--->pepsin *protein--pepsin-->polypeptides and peptides RENNIN- protease enzyme that converts: Milk casein to curdled /coagulated casein *slow rate of passage to prevent diarrhea No carbohydrate digestion in stomach. Fat moves slowly through stomach. Fat presence in stomach slows action of pyloric sphincter to hold fatty food in stomach longer for m ore effiicient digestion. |
|
Why is the Stomach Acidic? (pig)
|
Acidity:
-bacterial effect ( kills bacteria) -breakdown/digest food components and makes protein more suseptable to enzymatic digestion -activates pepsinogen conversion to pepsin -provides proper environment for pepsin to work -chyme that leaves stomach and enters small intestine stimulates various secretions from the small intestine |
|
Cardiac Shincter of Pig Stomach
|
muscle that opens and closes to allow food in
|
|
Esophageal Region of Pig Stomach
|
nonglandular area surrounding cardia
|
|
Fundic gland region of pig stomach
|
contains cells that provide gastric secretions needed for initial stages of digestion
*parietal cells- produce HCl *chief cells- produce enzymes/precursers of enzymes |
|
Pyloric gland region of pic stomach
|
contains cells that produce mucus and some proteolytic enzymes
|
|
Pylorus of pig stomach
|
beginning of small intestine (duodenum)
|
|
Pyloric sphincter of pig stomach
|
located in pyloris- controls passage of chyme out of stomach
|
|
Small Intestine (pig)
|
long, narrow tibe that is the most active digestion and nutrient absorption site.
*in market pig: >50ft long! |
|
Duodenum (first section of pig stomach)
|
site of active enzyme secretions from duodenum lining and pancreas.
bile secreted from liver into gall bladder, then secreted into stomach |
|
Jejunum (middle section of pig stomach)
|
active in nutrient absorption
|
|
Ileum (last section of pig stomach)
|
active in nutrient absorption
pH of small intestine ~6-7 (much more BASIC than the stomach) |
|
Pig liver secretions
|
BILE produced by liver and stored in gall bladder and is comprised mostly of water and alkaline salts that help neutralize acidic chyme (From 2-->7).
Bile secreted into small intestine when needed- important in fat digestion: include bile acids that activate pancreatic lipase and emulsifies fat. |
|
Pig pancreas secretions
|
pancreatic juice is secreted by the pancreas into the duodenum through the pancreatic duct:
1.WATER 2.ALKALINE- strongly alkaline; raises pH from 2 to 7 3. PROTEOLYTIC ENZYMES- trypsin, chymotrypsin, carboxypeptidases; all aid in digestion. *Zymogen- Trypsinogen--enterokinase-->trypsin 4.AMYLASE- breakdown starch- attacks 1,4 glucan links in starch and glycogen 5.LIPASE- digest fat: tryglycerol converted to monoglycerol |
|
Pig intestinal wall
|
1.WATER
2. ALKALINE- neutralize strong stomach acidity 3. CARBOHYDRATES- catalyze final steps of carbohydrate digestion. Disaccharidases are produced by villi that line the intestinal wall: sucrase digests sucrose ---> glucose+fructose lactase digests lactose--->glucose+galactose maltase digests maltose--->glucose+glucose 4. AMINOPEPTIDES AND DIPEPTIDES- catalyze final steps of protein digestion and work on intermediates from protein digestion. 5.ENTEROKINASE- Converts trypsinogen (zymogen) to trypsin |
|
Movement of digesta in pig GIT
|
Peristalisis- contractions of smooth intestinal muscles, stimulated by presence of ingesta, especially fiber.
|
|
Absorption in pig GIT
|
transfer of material from lumen (inside) of GIT to the cells
|
|
Active absorption
|
requires energy and can occure against concentration gradient.
|
|
Passive absorption
|
movement of materials across cell membrane by simple diffusion; automatically by physical principles.
|
|
Effect of suface area on absorption
|
smooth lining for fixed area absorption
VILLI- small projections extending from wall of lumen to increase surface area for more efficient absorption *each villus has microvilli (brush border) and arteriole and venule, together with drainage tube of lymphatic system, a lacetal. Venules ultimately drain into protal blood system, which goes directly to the liver. |
|
Blood vs lymph absorption
|
most nutrients are absorbed into the blood.
*lipids absorbed into lymphatic system, then into the blood. *lymph- clear, water, liquid, white and red blood cells; remove protein from tissues |
|
Absorption location
|
most absorption takes place in the small intestine
very little absorption in stomach some absorption in large intestine |
|
Pig large intestine
|
larger diameter and volume than small intestine, but shorter.
nearly all amino acids and monosaccharides absorbed prior to this point and only fiber remains |
|
Sections of pig's large intestine
|
1. Caecum- first section, little functional significance
2.Colon- middle section, largest part 3.Rectum- last section |
|
Functions of pig's large intestine
|
Site of water reabsorption- recycling water is critical funcion to avoid dehydration
secretion of some mineral elements such as calcium storage resevoir of undigested GIT contents (feces) Bacterial fermentation- synthesis of some water soluble vitamins and vitamin K; some breakdown of fiber that reamins in GIT (acetate, buterate, propionate-->volitlie fatty acids) No villi- limited absorption from large intestine of nutrients from feedstuffs or from microbial origin peristalic movements in large intestine cause slow movement- need time for water removal defication- expulsion of waste material through anus |
|
Differences in horse digestive system (compared to the pig)
|
1. saliva contains no enzymes
2. never vomits 3. no gall bladder 4. greatly enlarged large intestine -both caecum and colon greatly enlarged. -bacteria turns fiber into volitile fatty acids (acetate, propionate, butyrate) that are absorbed and used as energy. *less fiber digestion in the pig |
|
Horse mouth
|
prehensive agents include:teeth, upper lip, and tounge
upper jaw is wider than lower jaw- mastication occurs on only one side of the mouth at a time saliva-contains no enzymes; mature horse may secrete up to 10gallons/day |
|
Horse esophagus
|
50-60 inch long tube from mouth to stomach on left side of neck.
ONE WAY peristalic movements TOWARD STOMACH- horse doesn not regurgitate |
|
Horse stomach
|
smaller stomach than other animal species (3-4gallons)
the stomach does not have extensive muscular moement activity as other species like the pig-ingesta tend to arrange themselves in layers *causes the horse to be more prone to disorders |
|
Hosre small intestine
|
similar anatomy and function to the pig but no gall bladder
*bile secreted directly from liver to duodenum |
|
Horse large intestine
|
Accounts for large part of GIT capacity (over 60%)
divided into caecum, large colon, small colon, and rectum |
|
Caecum and colon of the Horse
|
contain active microbial population similar to that of a rumen. The bacteria can:
-breakdown cellulose and other carbohydrates to produce volitile fatty acids -synthesize water soluble vitamins (not many reabsorbed into system) -synthesize protein- N+carbohydrate (structural unit of protein/energy) *some absorption of VFA occurs from caecum because protein and other large molecules originating in caecum and colon are not subjected to digestive juices- of limited use to the horse |
|
Small Colon of horse
|
primary area of water reabsorption from intestinal contents
*because large intestine usually expanded with ingesta material, impaction can easily occur. |
|
Order of AVIAN digestive tract
|
esophagus
crop proventriculous gizzard pacrease liver small intestine ceca colon cloaca vent/anus |
|
Avian mouth
|
no teeth- rigid and attached tounge, poorly developed salivary glands
has a beak- adapted to rapidly pick up small particles (reduce particle size) saliva- contains salivary amylase |
|
Avian crop
|
enlarged area in esophagus; functions include:
-ingesta holding/moistening reservoir (cotrol flow rate through GIT) -allows breakdown reactions of salivary amylase -some microbial activity so fermentation ocurs in some species |
|
Avian proventriculus
|
site of gastric juice production (HCl and pepsin)
pH = ~4 ingesta passage rapid ~14 sec |
|
Avian gizzard
|
Thick muscular walled area- physically reduce particle size of ingesta by mixing and grinding (similar to mastication)
Contains grit (small stones or hard particles)- aids in grinding ingested seed and grain no secretions of enzymes-HCl and pepsin work from proventriculus in gizzard |
|
Avian small intestine
|
pH slightly acidic
absorption similar to mammals most enzymes found in mammalian species ARE present in avian small intestine |
|
Differences in avian small intestine from the pig
|
1.Bile and pancreatic ducts enter the small intestine near the end of the duodenum
2.no lactase-milk not part of avian diet; lactase not necessary 3.villi contain no lacetals- not lymphatic drainage-fat absorbed directly into blood 4.hormone enterogastrone-not present in birds, which affects fat absorption |
|
Differences in avian ceca and colon from pig
|
1. two ceca- "blind pouches" mammals and some birds only have 1
2.Colon is very short- 2-4in. and empties into cloaca where fecel material excreted through vent/anus 3.feces and urine excreted together- birds produce uric acid and mammals produce urea. Bird urine dumped into lower large intestine, moves back to ceca for water reabsorption, then emptied through vent |
|
Functions of avian ceca and colon
|
water reabsorption
some fiber digestion and water soluble vitamin synthesis in ceca because of bacterial fermentation, but much lower levels than in most mammals |
|
Cow mouth
|
no upper incisors- only upper dental pad
molar teeth (upper and lower)- shaped so animal can chew on one side of jaw at a time saliva production relatively continous- can produce 25 gallons/day in adult cows and 2gallons/day in adult sheep no enzymes in saliva- provides N (urea), P, and Na to microbes saliva highly buffered to buffer pH in rumen so microbes can exist |
|
Cow stomach
|
esophagus openeing is common to both reticulum and rumen compartments
|
|
Reticulum (honeycomb)
|
walls lined with mucus membrane containing many intersecting ridges that subdivides the surface into honeycomb like compartments.
wall arrangement traps hardware (nails, wire) so it won't pass to lower GIT and cause problems walls secrete NO ENZYMES functions in moving ingested feed into rumen or omasum and in regurgitation of ingesta during rumination |
|
Rumen
|
large muscular compartment that almost entirely fills the left side of the abdominal cavity.
walls contain projections called papillae NO enzymes functions: storage soaking physical mixing and breakdown fermentation chamber: moist, warm (~38C), anaerobic, desireable pH, and continual infusion of substrate and removal of end products of digestion. *ideal environment for microbes |
|
Pregastric fermentation in cows
|
bacterial synthesis of water soluble vitimins and vitamin K
bacterial synthesis of amino acid and protein (N+carb--->microbial protein) breakdown of fibrous feeds (high in cellulose)- rumanents produce CELLULASE fibrous feeds--->VFAs (energy) |
|
Omasum
|
spherical organ filled with muscular laminae (leaf structure)
walls secrete NO ENZYMES Functions: reduce particle size of ingesta before it enters the abomasum absorbs water |
|
Abomasum
|
"true/glandular stomach"
first glandular protion of the ruminant GIT **WALLS SECRETE ENZYMES** In general, corresponds to gland regions in simple stomach of nonruminents |
|
Cow small and large intestine
|
similar in structure and function to those of the pig.
|
|
Esophegeal (or reticular groove)
|
passageway that extends from the cardia to the omasum, which can close to direct ingesta from the esophagus into the omasum directly, or open and permit ingesta to enter rumen/reticulum
Functions: allow milk consumed to bypass reticulorumen and excape bacterial fermentation *groove not functional in adult animals |
|
Rumination
|
process that allows an animal to ingest feed rapidly, the complete the chewing at a later time.
Steps: 1. Regurgitation 2. Remastication 3. Resalivation 4. Reswallowing |
|
Eructation
|
belching of gas
microbial fermentation in rumen results in large amounts of carbon dioxide and methane which must be eliminated. BLOAT: common problem in which gas can't escape. Froth/foam produced in rumen which interferes with normal belching and gas accumulates. Control measures must prevent foam or break it rapidly after it has formed. |
|
Carb fermentation in horse vs cow
|
starch-advantage to horse, rumen less efficient
fiber-advanage to ruminent, total fermentation greater in ruminent compared with hindgut of horse |
|
Protein fermentation in horse vs. cow
|
dietary protein quality more important to the horse
microbes in rumen alter dietary protein (make it higher quality) |
|
Vitamin fermentation in horse vs. cow
|
vitamins produced by microbes in rumen are available for absorption in small intestine, and in horse they are not.
B vitamin supplementation in diet is less important for rumenents |
|
Fat fermentation in horse vs. cow
|
become saturated by microbes in rumen
|
|
Saliva digestion in mouth
|
SALIVARY AMYLASE- starch-->maltose
*none in rumenents or horse, of little importance in other species |
|
Gastric digestion in stomach
|
PEPSIN- protein-->polypeptides
RENNIN- milk curdling/ protein denaturation LIPASE- fat splitting, minor activity compare dto pancreatic digestion |
|
Pancreas digestion in duodenum and upper small intestine
|
TRYPSIN- protein-->peptides and amino acids
CHYMOTRYPSIN- protein-->peptides and amino acids CARBOXYPEPTIDASE- protein-->peptides and amino acids AMYLASE- undigested carbs to sugars LIPASE- fat splitting: fats-->fatty acid and glycerol BUFFERS- bicarbonates to neutralize stomach acids |
|
Liver digestion
|
no enzymes produced, but produces BILE SALTS important in lipid metabolism and emulsifies fat, giving enzyme (lipaese) greater access/surface area to react. Bile salts also aid in maintaining pH of small intestine
|
|
Intestine digestion
|
AMINOPEPTIDASES- proteins-->peptides and amino acids
DIPEPTIDASE- dipeptides-->amino acids NUCLEASES- nucleoproteins-->purines and pyrimidines MALTASE- maltose-->glucose+glucose LACTASE- lactose-->glucose+galactose SUCRASE- sucrose-->glucose +fructose |
|
Saliva digestion in mouth
|
SALIVARY AMYLASE- starch-->maltose
*none in rumenents or horse, of little importance in other species |
|
Gastric digestion in stomach
|
PEPSIN- protein-->polypeptides
RENNIN- milk curdling/ protein denaturation LIPASE- fat splitting, minor activity compare dto pancreatic digestion |
|
Pancreas digestion in duodenum and upper small intestine
|
TRYPSIN- protein-->peptides and amino acids
CHYMOTRYPSIN- protein-->peptides and amino acids CARBOXYPEPTIDASE- protein-->peptides and amino acids AMYLASE- undigested carbs to sugars LIPASE- fat splitting: fats-->fatty acid and glycerol BUFFERS- bicarbonates to neutralize stomach acids |
|
Liver digestion
|
no enzymes produced, but produces BILE SALTS important in lipid metabolism and emulsifies fat, giving enzyme (lipaese) greater access/surface area to react. Bile salts also aid in maintaining pH of small intestine
|
|
Intestine digestion
|
AMINOPEPTIDASES- proteins-->peptides and amino acids
DIPEPTIDASE- dipeptides-->amino acids NUCLEASES- nucleoproteins-->purines and pyrimidines MALTASE- maltose-->glucose+glucose LACTASE- lactose-->glucose+galactose SUCRASE- sucrose-->glucose +fructose |
|
Saliva digestion in mouth
|
SALIVARY AMYLASE- starch-->maltose
*none in rumenents or horse, of little importance in other species |
|
Gastric digestion in stomach
|
PEPSIN- protein-->polypeptides
RENNIN- milk curdling/ protein denaturation LIPASE- fat splitting, minor activity compare dto pancreatic digestion |
|
Pancreas digestion in duodenum and upper small intestine
|
TRYPSIN- protein-->peptides and amino acids
CHYMOTRYPSIN- protein-->peptides and amino acids CARBOXYPEPTIDASE- protein-->peptides and amino acids AMYLASE- undigested carbs to sugars LIPASE- fat splitting: fats-->fatty acid and glycerol BUFFERS- bicarbonates to neutralize stomach acids |
|
Liver digestion
|
no enzymes produced, but produces BILE SALTS important in lipid metabolism and emulsifies fat, giving enzyme (lipaese) greater access/surface area to react. Bile salts also aid in maintaining pH of small intestine
|
|
Intestine digestion
|
AMINOPEPTIDASES- proteins-->peptides and amino acids
DIPEPTIDASE- dipeptides-->amino acids NUCLEASES- nucleoproteins-->purines and pyrimidines MALTASE- maltose-->glucose+glucose LACTASE- lactose-->glucose+galactose SUCRASE- sucrose-->glucose +fructose |