5th Class Part 4 PDF - Nutrition and Digestion

Chapter One: Nutrition and Digestion Digestive tract Animals have different digestive system. General functions of digestive tract are; A. Swallowing the food. B. Breaking down the food into monomers. C. Absorption of digested food. D. Excretion of wastes. There are two kinds of digestive systems...

Chapter One: Nutrition and Digestion Digestive tract Animals have different digestive system. General functions of digestive tract are; A. Swallowing the food. B. Breaking down the food into monomers. C. Absorption of digested food. D. Excretion of wastes. There are two kinds of digestive systems they are;  complete digestive tract  incomplete digestive tract. 1- Incomplete digestive tract: This kind of digestive system has;  only one opening called as mouth and it used for ingestion of food and excretion of wastes.  Digestive system  starts by mouth  muscular digestive tract  extend as branched gastrointestinal cavity.  Planaria has this kind of digestive system. Planaria are tiny aquatic organisms and they feed on organic remains. During ingestion digestive tract extend out of body to take food and extracellular digestion is performed in digestive tract. Q/How do planarians ingest food? Which type of digestion takes place? A/ During ingestion digestive tract extend out of body to take food and extracellular digestion is performed in digestive tract. 2- Complete digestive tract: This system;  starts by mouth and end by anus.  These animals;  absorb nutrients by muscular pharynx  then it passes to the crop where food is stored  Then food pass to the gizzard where food broken down by help of small stones in it.  Extracellular digestion happens in digestive tract digested food absorbed and wastes are removed through anus.  Earthworms have this system and feed on organic materials in soil. Q/ Which type of digestion takes place in earthworms? A/ Extracellular digestion. Q/ Mention the importance of gizzard? A/ where food broken down by help of small stones in it. 18  Chapter One: Nutrition and Digestion Q/compare between complete and incomplete digestive tract? complete digestive tract incomplete digestive tract 1 starts by mouth and end by anus Has only one opening called as mouth and it used for ingestion of food and excretion of wastes 2 Earthworm has this kind of digestive Planaria has this kind of digestive system, also system hydra 3 extracellular digestion is performed in this extracellular digestion is performed in digestive type of digestive tract. tract. Q/ How do parasites which cause the anemia and meningitis infect the human body? A/ Mosquito is carrier of these parasites, It secretes a kind of substance on human body to prevent blood coagulation and absorb blood. Only female mosquito absorb the blood. And parasites pass the human body in this way. Define Appendix: It is a finger like small extension at the beginning of large intestine. It is site of cellulose digestion in herbivores. It causes dangerous medical problems in human when it is inflamed and can be removed by surgery. Q/ What was the function of appendix? A/ It is site of cellulose digestion in herbivores. Movement in digestive tract Food transport by:  movement of muscles in wall of digestive tract. In other animals food transport by contraction and relaxation of muscles in wall of digestive tract. These wave like movement of muscles is called as peristaltic movement.  fimbriae (cilia). Movement of food by fimbriae performs in animals which have pseudo- coelom. Anatomical and physiological structure of digestive system There are different types of digestive systems in animals depend on the nutrients that they ingest. 19  Chapter One: Nutrition and Digestion Parts of digestive system according to their function as follows: A. Food reception zone B. Transport and storage zone C. Digestion zone D. Last digestion zone and absorption E. Water absorption zone A. Food reception zone  It is front part of digestive tract  consist of mouth, mouth components and muscular pharynx.  Digestion start in this zone by secretion of Ptyalin enzyme which involved in digestion of complex carbohydrates like starch. This enzyme found in snail, some insects, mammals and human.  Tongue is a distinctive feature of vertebrates that help chewing and swallowing of food. Epiglottis closes the trachea during swallowing and food pass into esophagus then by peristaltic movement transport to the stomach. Q/ Where does Ptyalin enzyme lose its function? A/ Ptyalin enzyme lose its function when it reaches the stomach with semi digested food. Digestion of starch complete in small intestine. Q/ Where is starch (complex carbohydrates) digested in the digestive tract?  Digestion of starch (complex carbohydrates) starts in food reception zone by secretion of Ptyalin enzyme  Digestion of starch complete in small intestine by Amylase enzyme secreted from pancreas. Q/ Mention the functions of tongue? A/ Tongue is a distinctive feature of vertebrates that help chewing and swallowing of food. B. Transport and storage zone  Pharynx involved in transmission of nutrients to the digestive tract of invertebrates and some vertebrates.  Pharynx is followed by esophagus. It`s front part enlarged to form crop in some animals. Crop stores the food, moistens it before digestion in birds. This stored food became semi digested before coming back for offspring’s. Q/ Mention the origin of crop? A/ enlargement of the front part of esophagus Q/ Mention the importance of crop? 1) stores the food 2) moistens it before digestion in birds. This stored food became semi digested before coming back for offspring’s Q/ Mention the importance of Glands which found in mouth? a) Secretion of digestive enzymes. b) They sometimes involved in calmness of prey c) prevent pain during biting prey d) prevent blood coagulation in some insects 20  Chapter One: Nutrition and Digestion Q/ Explain why do plant hopper species exude waxy secretions from the abdomen? A/To form long waxy strands that may provide protection from predators it could be that they fool a predator into attacking the wrong part of the insect, and the wax breaks off while the insect jumps safety. Organ Differentiated Parts Functions Mouth Teeth, salivary glands and Chewing food and digestion of tongue starch Digestive tract ---------------------------------------- Peristaltic movement Stomach Gastric glands Food storage, destroy bacteria and digest the proteins Small intestine Villi Digestion and absorption Large intestine ---------------------------------------- Water absorption and storage of wastes Anus ---------------------------------------- Defecation process Table 1.2 Parts of digestive tract and their function C. Digestion zone  Stomach used in *digestion and *storage of food in most of vertebrates and some invertebrates.  There are gastric glands that secrete the pepsin enzyme and HCl.  Food is mixed with HCl acid in stomach and expose to the mechanical digestion by peristalsis.  Pepsin enzyme involved in digestion of proteins.  This digestion takes place in arthropods and birds. Stomach consist of thick muscular wall in herbivores and carnivores.  The semi-digested food known as (chyme) pass from the stomach into the small intestine through pyloric sphincter Q/ Where is Protein digested in the digestive tract? 1) In Stomach there are gastric glands that secrete the pepsin enzyme and HCl. 2) Digestion of protein is completed in small intestine by Trypsin and Chymotrypsin enzymes secreted from pancreas. D. Last digestion zone and absorption  It known as intestinal zone.  Intestines are long and bended in herbivores while shorter in carnivores.  There are finger like structures called villi (and microvilli on villi surface) in inner surface of intestine to increase the surface area for digestion and absorption.  First part of small intestine is called as duodenum and it receives the secretions from the 1. Liver: Liver produces bile 2. pancreas. pancreas produces the digestive enzymes.  Food mass digestion complete in this part and transformed into [(chyle )‫])(غير مطلوب من الطالب‬ Q/ What is the difference between the intestine of herbivores and carnivores? A/ Intestines are long and bended in herbivores while shorter in carnivores 21  Chapter One: Nutrition and Digestion Q/ What is the importance of villi? A/ They are finger like structures in inner surface of intestine to increase the surface area for digestion and absorption. Figure 1.15 Inner structure of small intestine Pancreas contains different kinds of enzymes they are: A. Trypsin and chymotrypsin involved in digestion of proteins. B. Lipase digests lipids into fatty acids and glycerol. C. Nuclease digests the nucleic acids. D. Amylase digests the starch molecules. Functions of liver: A. Detoxification of blood.. B. Stores the iron, vitamin A, B12, E and D. C. Produces albumin and fibrinogen proteins. D. Stores the excess amount of glucose as glycogen. E. Convert ammonia to urea. F. Produces bile from partition of old red blood cells. involved in digestion of lipids in duodenum. G. Regulate the amount of cholesterol in blood 22  Chapter One: Nutrition and Digestion Figure 1.16 Liver and pancreas in human Functions of small intestine: A. Completes the digestion of food and absorbs the nutrients. B. Carbohydrates are digested into glucose, galactose or fructose and pass to the blood. C. Proteins are digested into amino acids and pass to the blood. D. Fatty acid and glycerol are pass to the lymphatic system. Q/ Mention the subunits for each of the following? 1. Proteins amino acids 2. Carbohydrates glucose, galactose or fructose 3. fats Fatty acid and glycerol Q/ Where does digested food inside the small intestine pass to? 1. Amino acids, glucose, galactose or fructose pass to the blood 2. Fatty acid and glycerol are pass to the lymphatic system Q/ Mention the origin of the golden yellow color of bile? A/ formed by partition of hemoglobin of old red blood cells inside the liver. Q/Mention the importance of bile? A/ involved in digestion of lipids in duodenum. Q/ Where is fat digested in the digestive tract? A/ Digestion of fats complete in small intestine by Lipase enzyme secreted from pancreas E. Water absorption zone  Large intestine: 1) absorb water is important for terrestrial organisms like insects birds and reptiles 2) defecate the undigested food in form of a solid mass. 3) There are many bacteria in human large intestine which convert some organic material into vitamin K and little amount of vitamin B. Q/ What does the length of small intestine depend on? With example? A/nutrition type. Length of small intestine in frog larvae which is herbivore longer than small intestine of adult frog which is carnivore. 23  Chapter One: Nutrition and Digestion Nutritional needs Organisms obtain the energy required for all their 1. metabolic functions 2. growth 3. for the repair of their damaged tissues from food. The energy that food provides is necessary for the continuity of life on earth. Food can be divided into six groups, according to its composition: - Carbohydrates - Vitamins - Lipids - Minerals - Proteins - Water All of the above nutrients are essential for a balanced diet. A deficiency of any of them may give rise to serious metabolic disorders.  Carbohydrates, proteins and lipids are used as source of energy  but others (water, minerals and vitamins) are used in regulation and activation of metabolic activities. A. Carbohydrates  Grains are main sources of carbohydrates.  They change into simple sugars gradually in digestive system and contain amount of fibers. Importance of fibers: 1) These fibers limit adhesion of carcinogenic material on wall of intestine they prevent colon cancer by this way. 2) Dissolved fibers in oat prevent absorption of cholesterol and some harmful acids. Q/What is the harm of excessive fiber in food? A/ large amount of fibers prevent absorption of iron, zinc and calcium from food. 24  Chapter One: Nutrition and Digestion B. Proteins  They are the basic structural elements of the body.  The development of an organism from a zygote and the formation of its organ systems are entirely depend on proteins.  proteins contain 20 different amino acids which are structurally and functionally different subunits.  Some of them are synthesized within the body  some are imported, since they are unable to be synthesized in the body.  There are nine vital amino acids that cannot be synthesized in the body and they have role in development of children. Foods vary in their quantity of vital amino acids. a) The qualified proteins contain adequate amounts of vital amino acids and are easily digested. Generally, animal proteins are qualified b) Nonqualified proteins. plant proteins are nonqualified. C. Fats  These giant molecules yield the most energy in comparison to other molecules.  There are two kinds of fats;  saturated and unsaturated. 1. Saturated fats are generally obtained from animal products with exception of some plants like coconut oil. 2. Unsaturated fats from Plant fats necessary for human body for health. Fish contain omega-3 fatty acids which have a role in prevention of heart attack. Q/What is the harm of Consuming large amount of saturated fats? A/ causes arteriosclerosis Q/What foods are high in omega-3 fatty acids? Mention its importance? A/ Fish contain omega-3 fatty acids which have a role in prevention of heart attack. D. Vitamins  Vitamins ingested in food and plays important role in regulation of body metabolism.  Most of them cannot be produced in the body.  Vitamins have two types according to their solubility; 1. water soluble vitamins 2. lipid soluble vitamins. E. Minerals  Inorganic molecules, or minerals, are as important for body functions as organic molecules. They are required for 1. Health 2. continuity of metabolism 3. the formation of bones and teeth. They are divided into two main groups: a) Essential minerals (calcium, phosphorus, sodium, potassium) b) Non-essential but recommended minerals (magnesium, iron, copper, zinc and other trace elements) 25  Chapter One: Nutrition and Digestion  Mother milk is main source of necessary nutrients for babies. It contains all necessary materials for baby and contents change periodically according to growth of baby. Milk secretion of mother is in three stages: 1) Colostrum secretion stage: from the first day of birth till day 5. 2) Natural milk secretion: After fifth day of secretion colostrum secretion decreases and natural milk secretion start and continues until third or fourth week. 3) Mature milk secretion stage start after fourth week. Q/ Can the human body and most of animals survive without carbohydrates? A/Human and most of animals survive with diet that contain enough energy without carbohydrates, for example Eskimos diet contain large amount of fats and proteins but little amount of carbohydrates. 26