1. Ch. 38 Digestive & Excretory Systems
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