Unit 10 The Human Body

1. Unit 10 The Human Body Ch. 38 Digestive & Excretory Systems

2. Food & Energy • The energy available in food can be measured by burning the food • When food is burned, the energy content of the food is converted to heat, which is measured in calories

3. Food & Energy • The average energy needed for a teenager is 2200 Calories per day

4. Nutrients • The nutrients that the body needs are water, carbohydrates, fats, proteins, vitamins, & minerals • Every cell in the body needs water because many body processes, including chemical reactions, take place in water

5. Nutrients • Carbohydrates – main source of energy for the body • Sugars & starches are main source of carbs • Starches are broken down by digestive system into simple sugars & carried to cells through blood

6. Nutrients • Sugars not immediately used for energy are converted into complex carbs & stored in the liver & in skeletal muscles

7. Nutrients • Fats – lipids – important to the body to produce cell membranes, myelin sheaths, & certain hormones

8. Nutrients • Proteins – supply raw materials for growth & repair of structures like skin & muscle • Also have regulatory & transport functions

9. Nutrients • Vitamins – organic molecules that help regulate body processes, often working with enzymes

10. Vitamins

11. Nutrients • Minerals – inorganic nutrients the body needs • Includes: calcium, iron, & magnesium

12. Important Minerals

13. Nutrition & a Balanced Diet • The Food Guide Pyramid classifies foods into 6 groups & indicates how many servings from each group should be eaten every day

14. The Process of Digestion • The digestive system includes: the mouth, pharynx, esophagus, stomach, small intestine, & large intestine • Several major accessory structures, including the salivary glands, the pancreas, & the liver, add secretions to the digestive system

15. The Digestive System

16. The Mouth • The function of the digestive system is to help convert foods into simpler molecules that can be absorbed & used by the cells of the body • Teeth cut & grind the food, while the salivary glands secrete saliva, which helps to moisten the food & make it easier to chew

17. The Mouth • Amylase – enzyme found in saliva, that breaks the chemical bonds in starches & releases sugars

18. The Esophagus • Esophagus – food tube, connects to the stomach • Food travels through esophagus by process of peristalsis – contractions of the smooth muscle tissue in the esophagus

19. The Stomach • Stomach – large muscular sac, continues the mechanical & chemical digestion of food

20. The Small Intestine • Small intestine – where almost all of the digestive enzymes enter the intestine • Most chemical digestion & absorption of food occurs in the small intestine

21. Accessory Structures of Digestion • Pancreas – gland that serves 3 important functions: • 1. Produce hormones that regulate blood sugar levels • 2. Produces enzymes that break down carbs, proteins, lipids, & nucleic acids • 3. Produces sodium bicarbonate, a base that neutralizes stomach acid so enzymes can be effective

22. Accessory Structures of Digestion • Liver – large organ just above & to the right of the stomach • Produce bile, a fluid loaded with lipids & salts • It acts like detergent, dissolving & dispersing the droplets of fat found in fatty foods • Bile is stored in the gallbladder

23. Accessory Structures

24. The Large Intestine • Large intestine – primary function is to remove water from undigested material that is left

25. Digestive System Disorders • Peptic ulcer – when powerful acids released into the stomach damage the organ’s own lining, producing a hole in the wall • Diarrhea occurs when not enough water is absorbed • Constipation occurs when too much water is absorbed

26. The Excretory System • The kidneys play an important role in maintaining homeostasis • They remove waste products from the blood; maintain blood pH; & regulate the water content of the blood &, therefore, blood volume

27. The Kidneys • Kidneys – located on either side of the spinal column near the lower back • Ureter – tube that leaves each kidney, carrying urine to the urinary bladder • Urinary bladder – saclike organ where urine is stored before being excreted

28. Kidney Structure • Nephron – the functional units of the kidney • As blood enters a nephron through the arteriole, impurities are filtered out & emptied into the collecting duct • The purified blood exits the nephron through the venule

29. Filtration • Filtration – passing a liquid or gas through a filter • Glomerulus – where the filtration of blood takes place

30. Reabsorption • Reabsorption – process where liquid is taken back into a vessel • Material that remains, called urine, is emptied into a collecting duct • Urine contains urea, excess salts, & water • Urine is stored in the urinary bladder until released from the body through the urethra

31. Structure Of The Kidneys

32. Kidney Stones • Sometimes, calcium, magnesium, or uric acid salts in the urine, crystallize & form kidney stones