CHAPTER 38 DIGESTIVE & EXCRETORY SYSTEMS **Only responsible for knowing YELLOW and RED terms/concepts* DIGESTIVE & EXCRETORY SYSTEMS **Only responsible for knowing YELLOW and RED terms/concepts*

Chapter 38.1 Food & Nutrition

FOOD AND ENERGY  Why do we need to eat?  1 calorie = heat needed to raise 1 gram of water by 1ºC  Calories in food are actually kilocalories (1000 calories)  Nutrition: study of food and its effects on the body.  Why do we need to eat?  1 calorie = heat needed to raise 1 gram of water by 1ºC  Calories in food are actually kilocalories (1000 calories)  Nutrition: study of food and its effects on the body.

NUTRIENTS  Your body needs:  Water  Important element of many bodily and chemical processes  Need at least 1L of water a day  Water loss in urine, sweat and breathing (homeostasis)  Your body needs:  Water  Important element of many bodily and chemical processes  Need at least 1L of water a day  Water loss in urine, sweat and breathing (homeostasis)

NUTRIENTS  Your body needs:  Carbohydrates  Main source of energy  Simple (mono/disaccharides)  Complex (polysaccharides)  Your body needs:  Carbohydrates  Main source of energy  Simple (mono/disaccharides)  Complex (polysaccharides)

NUTRIENTS  Your body needs:  Fats  Important building block of many cellular organelles  Vitamin absorption  Saturated (single bonds) BAD  Unsaturated (double bonds) GOOD  Your body needs:  Fats  Important building block of many cellular organelles  Vitamin absorption  Saturated (single bonds) BAD  Unsaturated (double bonds) GOOD

NUTRIENTS  Your body needs:  Proteins: found in animal products (meats and dairy); need 8 essential amino acids  Vitamins: organic molecules, work with enzymes (ignition, start reactions)  Fat-soluble (A, D, E, K)  Water-soluble (B, C)  Minerals: inorganic molecules, (calcium, sodium, potassium, etc…)  Your body needs:  Proteins: found in animal products (meats and dairy); need 8 essential amino acids  Vitamins: organic molecules, work with enzymes (ignition, start reactions)  Fat-soluble (A, D, E, K)  Water-soluble (B, C)  Minerals: inorganic molecules, (calcium, sodium, potassium, etc…)

CHAPTER 38.2 THE DIGESTIVE SYSTEM WATCH ME!!! THE DIGESTIVE SYSTEM WATCH ME!!!

DIGESTION  Function: breakdown food for absorption  Mechanical: physical breakdown of food  Chemical: chemical breakdown of food  Voluntary and involuntary  Function: breakdown food for absorption  Mechanical: physical breakdown of food  Chemical: chemical breakdown of food  Voluntary and involuntary

THE MOUTH  Mechanical: teeth chew food into smaller pieces  Chemical: saliva contains amylase, enzyme converts carbohydrates to sugar  Tongue pushes food down pharynx  Mechanical: teeth chew food into smaller pieces  Chemical: saliva contains amylase, enzyme converts carbohydrates to sugar  Tongue pushes food down pharynx

THE ESOPHAGUS  Epiglottis covers trachea; food travels down esophagus  Muscle contractions (peristalsis) push bolus through cardiac sphincter to stomach.  Epiglottis covers trachea; food travels down esophagus  Muscle contractions (peristalsis) push bolus through cardiac sphincter to stomach.

THE STOMACH  Muscles contract and churn (mix) food with gastric juices.  Digested food forms chyme (food and gastic juice)  Pepsin & HCl digest protein  Chyme travels through pyloric sphincter  Muscles contract and churn (mix) food with gastric juices.  Digested food forms chyme (food and gastic juice)  Pepsin & HCl digest protein  Chyme travels through pyloric sphincter

THE SMALL INTESTINE & ACCESSORY ORGANS  Digestive enzymes from accessory organs complete majority of chemical digestion in duodenum.  Inner layer of villi/microvilli increase surface area and absorption of nutrients  Pancreas: secretes hormones that regulate blood sugar & digestive enzymes (insulin & glucagon)  Liver: secretes bile for digestion of fats; stored in gallbladder  Digestive enzymes from accessory organs complete majority of chemical digestion in duodenum.  Inner layer of villi/microvilli increase surface area and absorption of nutrients  Pancreas: secretes hormones that regulate blood sugar & digestive enzymes (insulin & glucagon)  Liver: secretes bile for digestion of fats; stored in gallbladder

THE LARGE INTESTINE  Also called the colon  Stores remaining chyme: water, cellulose, undigested material  Main function: water absorption  Storage of feces until defecation  Also called the colon  Stores remaining chyme: water, cellulose, undigested material  Main function: water absorption  Storage of feces until defecation

DIGESTIVE SYSTEM DISORDERS  Peptic ulcers: holes in stomach due to thin mucus layer, caused by bacteria (H. pylori)  “heartburn”: backflow of acid in esophagus  Diarrhea: excess water in feces  Constipation: lack of water in feces  Colon cancer: development of malignant tumors in colon  Peptic ulcers: holes in stomach due to thin mucus layer, caused by bacteria (H. pylori)  “heartburn”: backflow of acid in esophagus  Diarrhea: excess water in feces  Constipation: lack of water in feces  Colon cancer: development of malignant tumors in colon