chapter 38 digestive & excretory system
DESCRIPTION
CHAPTER 38 DIGESTIVE & EXCRETORY SYSTEM. Chapter 38.1 Food & Nutrition. HW: P. 977 #1-4. FOOD AND ENERGY. Why do we need to eat? 1 calories = heat needed to raise 1 gram of water by 1ºC Calories in food are actually kilocalories (1000 calories) - PowerPoint PPT PresentationTRANSCRIPT
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CHAPTER 38 DIGESTIVE & EXCRETORY SYSTEM
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Chapter 38.1Food & NutritionHW: P. 977 #1-4
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FOOD AND ENERGY
• Why do we need to eat? • 1 calories = 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.
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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)
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NUTRIENTS
• Your body needs:• Carbohydrates• Main source of energy• Simple (mono/disaccharides)• Complex (polysaccharides)
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NUTRIENTS
• Your body needs:•Fats• Important building block of many cellular organelles• Vitamin absorption• Saturated (single bonds) BAD• Unsaturated (double bonds) GOOD
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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…)
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CHAPTER 38.2THE DIGESTIVE SYSTEMHW: P. 984 (1-4)
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DIGESTION• Function: breakdown food for absorption•Mechanical: physical breakdown of food• Chemical: chemical breakdown of food• Voluntary and involuntary
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THE MOUTH•Mechanical: teeth chew food into smaller pieces• Chemical: saliva contains amylase, enzyme converts carbohydrates to sugar• Tongue pushes food down pharynx
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THE ESOPHAGUS• Epiglottis covers trachea; food travels down esophagus•Muscle contractions (peristalsis) push bolus through cardiac sphincter to stomach.
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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
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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
• Liver: secretes bile for digestion of fats; stored in gallbladder
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THE LARGE INTESTINE• Also called the colon• Remaining chyme: water, cellulose,
undigested material• Main function: water absorption• Storage of feces until defacation
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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
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CHAPTER 38.3THE EXCRETORY SYSTEMHW: P. 989 (1-4)P. 993 (1-10, 15, 19, 20)
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FUNCTIONS OF THE EXCRETORY SYSTEM
• Remove waste•Carbon dioxide•Excess water and salts•Urea
• Liver: excess amino acids nitrogen compounds urea
What happens to all of the urea in the bloodstream?
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THE KIDNEYS (FIG. 38.17)• Function: maintain
homeostasis• Remove waste•Maintain blood pH•Maintain blood volume
• Structure:• Renal Cortex (outer layer)• Renal Medulla (inner layer)• Nephron• Glomerulus in Bowman’s
capsule filters blood
• Impure blood (renal artery) nephron ( impurities filtered out into collecting duct) purified blood (renal vein)
• Waste ureter urinary bladder urethra