1. Unit 9: Human Body Digestive and Excretory Systems Mrs. Howland Biology 10 Rev. April 2016

2. Lesson Objectives: Learners will be able to… Identify the location of and function of the parts of the digestive system Discuss the structure and function of the esophagus, stomach, small intestine, and large intestine Explain the role of glands, enzymes, and bile in the process of chemical digestion Apply their knowledge of human anatomy and physiology to the dissection of a frog

3. Digestive System MAJOR STRUCTURES: Stomach Intestinal tract Liver Pancreas Esophagus Salivary glands FUNCTION: Processes foods; absorption of nutrients into the body

4. BIG IDEAS Digestive system allows the body to change the food that we eat into small molecules The small molecules are nutrients used by body cells There are FOUR (4) phases of digestion: Ingestion Digestion Absorption Elimination

5. Ingestion In order to ‘eat’ we must put food into our bodies! With ingestion, we put food into our mouths The mouths are the opening to our digestive system

6. Digestion Digestion is the process by which food passes through the structures of the digestive system and is broken down Mechanical digestion = Large pieces of food are physically broken down into smaller pieces, which are swallowed Chemical digestion = Small pieces of food are broken down into small molecules by enzymes

7. Digestion in MOUTH Physical digestion = Chewing Teeth tear and grind Tongue moves food around Chemical digestion = Saliva (secreted by salivary glands) Saliva = Moistens food; released by nervous system; contains enzyme amylase that breaks down starches into sugars

8. Salivary GLANDS REMEMBER: GLAND = Structure that excretes a substance Salivary glands = Glands in head that secrete saliva

9. After CHEWING … Clump of food (bolus) passes down pharynx to the esophagus Epiglottis closes and covers trachea to prevent choking!

10. After CHEWING … Esophagus is tube connecting mouth and stomach Smooth muscles in esophagus push food along (This muscle movement is called peristalsis) Cardiac sphincter closes esophagus to prevent backflow Can you swallow hanging upside down???

11. Peristalsis in ESOPHAGUS

12. Digestion in the STOMACH Stomach = Large, muscular sac lined with millions of gastric glands Mucus lines stomach to prevent damage VIDEO: Endoscopy https://goo.gl/a1iBRo https://goo.gl/a1iBRo

13. Chemical Digestion in the STOMACH Glands produce hydrochloric acid and pepsin Enzyme pepsin breaks down proteins into small polypeptides (chemical digestion!)

14. ULCERS Mucus lines stomach to prevent damage Ulcers are sores that may form as result of acid erosion of stomach wall VIDEO: Endoscopy of Ulcer https://goo.gl/vXjPlthttps://goo.gl/vXjPlt

15. Mechanical Digestion in the STOMACH Mechanical digestion in the stomach occurs with smooth muscle movement churning the food into chyme Chyme = oatmeal-like substance that is made of small food particles, digestive enzymes, and gastric juices After 1-2 hours, food exits stomach through pylorus

16. Chemical Digestion in SMALL INTESTINE BEFORE entering small intestine, food mixes with digestive enzymes from liver and pancreas in the duodenum

17. Small Intestine Rapid absorption of nutrient molecules LARGE surface area allows for MAXIMUM ABSORPTION

18. Absorption The small molecules are absorbed in the small intestine The nutrients (small molecules) are carried to body cells by the circulatory system

19. Small Intestine Folded surface = Villi Microvilli = Tiny finger-like projections filled with capillaries and lymph vessels for absorption Capillaries absorb carbohydrates and protein Lymph vessels absorb fats and fatty acids Chyme leaving small intestine is mostly nutrient-free!

20. Pancreas Pancreas = Gland in the body Releases pancreatic amylase (enzyme that breaks down starch/carbohydrates), trypsin (enzyme that breaks down protein), and lipase (enzyme that breaks down fat)

21. Liver and Gallbladder Liver = Organ that produces bile (lipids & salts) Gallbladder = Sac that stores bile and releases it into small intestine when needed BILE breaks down globs of FAT

22. Gallstones Form if there is too much cholesterol, bilirubin, or not enough bile salts, not emptying properly Can cause pain; blockage

23. Appendix Passing from small intestine to large intestine, food passes by the appendix Humans do not use appendix (if food enters it becomes inflamed) Some animals digest cellulose in appendix

24. Large Intestine Chyme from small intestine Made up of mostly water, cellulose, other indigestible substances Shorter than small intestine, larger diameter Function of large intestine = Remove WATER and undigested material Bacterial population ~ produces Vitamin K

25. Elimination At the end of the digestive system, feces (concentrated waste material after water and nutrients have been removed) exits the body through the anus

26. Digestive System Overview

27. Excretory System MAJOR STRUCTURES: Kidneys Urinary bladder Urethra FUNCTION: Elimination of wastes; regulate pH and volume of blood

28. EXCRETION ~ Maintaining homeostasis Excretion maintains homeostasis Excretion = Elimination of wastes generated by cellular metabolism VIDEO (Crash Course Biology): https://goo.gl/FBMyp0 https://goo.gl/FBMyp0

29. How the body performs EXCRETION SKIN ~ Sweat releases extra water, salt, and tiny bit of urea LUNGS ~ Eliminates carbon dioxide during exhalation LIVER ~ Converts nitrogen wastes into urea (nitrogen is generated during breakdown of proteins) KIDNEYS ~ Filter blood to remove excess water, urea, and metabolic wastes

30. KIDNEY Excretion KIDNEYS ‘clean’ the blood Filter out impurities Collect waste products Return purified blood to circulatory system Occurs in nephrons TWO PARTS: Filtration and reabsorption

31. Nephrons Each kidney contains millions of nephrons Nephrons are the primary site of kidney function RENAL artery and RENAL vein connect kidneys to circulatory system

32. Structure and Function of Kidneys

34. Filtration When liquid or gas is passed through a filter to remove wastes, the process is called filtration Where is blood filtered in the kidneys? At each end of the kidney are structures called the Bowman’s capsule

35. Filtration Bowman’s capsule contains glomerulus (network of capillaries) Blood diffuses into Bowman’s capsule where it is filtered

36. Filtration Filtrate = materials filtered (removed) from blood Blood filtrate contains: water, urea, glucose, salts, amino acids, excess vitamins (NO proteins or blood cells!)

37. Reabsorption WOW! ~ 180 LITERS of filtrate pass through the kidneys every day NOT all filtrate is excreted—just the EXCESS! MAINTAINS HOMEOSTASIS Reabsorption is how water and dissolved materials RETURN to the blood 99% of water in Bowman’s capsule is reabsobed Loop of Henle conserves water 2 liters

38. Loop of Henle ~ part of nephron

39. Where does the EXCESS filtrate go? EXCESS filtrates are removed from the body in urine Urine is the liquid waste product of the kidneys Urine is transported to the urinary bladder through the ureters Urine is stored in bladder until it is released through the urethra

40. Urine Pathway

41. Diagrams for Excretory System

42. VIDEO: Digestive & Excretory Systems LINK to video: https://goo.gl/ivdI7xhttps://goo.gl/ivdI7x