The Digestive System

1. The Digestive System Chapter 7 Section 1 pg. 204 – 210

2. The Digestive System • The organs that break down food so that it can be used by the body • Digestive tract includes • Your mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus • The liver, gallbladder, pancreas, and salivary glands (food does not pass through these)

3. Breaking Down Food • Digestion is the process of breaking down food into a form that can pass from the digestive tract onto the bloodstream • 2 types • Mechanical • Breaking, crushing, and mashing of food • Chemical • Large molecules are broken down into nutrients • Nutrients are substances that the body needs for energy and for growth, maintenance, and repair

4. Breaking Down Food • 3 major types of nutrients • Carbohydrates, proteins, and fats • Enzymes break some nutrients into smaller particles that the body can use • Ex: proteins are chains of smaller molecules called amino acids. Proteins are too big to be absorbed into the bloodstream, so enzymes cut up the chain of amino acids

5. Digestion begins in the mouth

6. Teeth • Very important for mechanical digestion • Break and grind food with help from the jaw • Enamel • Outermost layer of a tooth, the hardest material in the body • Protects nerves and softer material inside the tooth • Teeth have different shapes for different jobs

7. Saliva • As you chew food mixes with a liquid called saliva • Made in the salivary glands located in the mouth • Contains an enzyme that beings the chemical digestion of carbohydrates • Saliva changes complex carbohydrates into simple sugars

8. Leaving the Mouth • Once the food has been reduced to soft mush, the tongue pushes it into the throat • Leads to a long, straight tube called the esophagus • Esophagus squeezes the mass of food with rhythmic muscle contractions called peristalsis • Forces the food into the stomach

9. Harsh environment of the stomach

10. Stomach • A muscular, saclike, digestive organ attached to the lower end of the esophagus • Continues the mechanical digestion of your meal by squeezing the food with muscular contractions • While squeezing is taking place, tiny glands in the stomach produce enzymes and acid • These work together to break down food into nutrients

11. Stomach • Stomach acid also kills most bacteria that you might swallow with your food • After a few hours of combined mechanical and chemical digestion, your PB&J sandwich has been reduced to a soupy mixture called chyme

12. Leaving the Stomach • Stomach slowly releases the chyme into the small intestine through a small ring or muscle that works like a valve • Because the stomach releases chyme slowly, the intestine has more time to mix the chyme with fluids from the liver and pancreas. • These fluids help digest food and stop the harsh acids in chyme from hurting the small intestine

13. The Pancreas • Oval shaped organ located between the stomach and small intestine • When chyme leaves the stomach it is very acidic • The pancreas makes fluids that protect the small intestine from the acid

14. The Pancreas • Chyme never enters the pancreas , instead the pancreatic fluid flows into the small intestine • Fluid contains enzymes that chemically digest chyme and contains bicarbonate, which neutralizes the acid in chyme • Also functions as part of the endocrine system by making hormones that regulate blood sugar

15. Small Intestine • A muscular tube that is about 2.5 cm in diameter • Inside wall of the small intestine is covered with fingerlike projections called villi • This makes that surface area very large • Villi are covered with tiny, nutrient-absorbing cells • Once the nutrients are absorbed, they enter the blood stream

16. The Liver • Liver • Large reddish brown organ that helps with digestion • Can be as large as a football • Located towards the right side, slightly higher than your stomach • Helps with digestion by • Making bile to break up fat • Stores nutrients • Breaks down toxins

17. The Gallbladder (Breaking up Fat) • Bile is temporarily stored in a small, saclike organ called called the gallbladder • Bile is squeezed from the gallbladder into the small intestine, where the bile breaks large fat droplets into very small droplets • This allows more fat molecules to be exposed to digestive enzymes

18. Storing Nutrients and Protecting the Body • Nutrients not used right away are stored in the liver • Nutrients are released as they are needed • Also captures and detoxifies many chemicals in the body • For instance, the liver produces enzymes that break down alcohol and many other drugs

19. End of the line

20. Large Intestine • Material that cannot be absorbed into the blood is pushed into the large intestine • Large intestine • Organ of the digestive system that stores, compacts, and the eliminates indigestible material from the body • Has a larger diameter than the small intestine

21. In the Large Intestine • Undigested material enters the large intestine as a soupy mixture • LI absorbs most of the water in the mixture and changes the liquid into semisolid waste material called, feces, or stool

22. In the Large Intestine • Whole grains, fruits, and vegetables contain a carbohydrate, called cellulose, that humans cannot digest • Commonly referred to as fiber • Keeps the stool soft and keeps material moving through the intestine

23. Leaving the Body • The rectum is the last part of the large intestine • Stores feces until it can be expelled • Feces pass to the outside of the body through an opening called the anus • Takes meals about 24 hours to make the journey through the digestive system

24. The Urinary System Section 2 pg. 212 – 215

25. Get It Out!!! • Excretion is the process of removing waste products from the body • 3 body systems play a role • Urinary System • Contains the organs that remove waste products from your blood

26. Cleaning the Blood • Your body preforms chemical activities that keep your alive, waste products, such as carbon dioxide and ammonia are made • Your body has to get rid of this waste to stay healthy • The urinary system removes these waste products from the blood

27. The Kidneys as Filters • The kidneys are a pair of organs that constantly clean the blood • Filter about 2,000 L (528 gallons) of blood each day • Your body only holds about 5.6 L of blood, so it cycles through your kidney about 350 times per day

28. The Kidneys • Inside each kidney is more than 1 million nephrons • Are microscopic filters in the kidney that remove wastes from the blood • Removes many harmful substances, most importantly is urea • Contains nitrogen and is formed when cells use protein for energy

29. Water In, Water Out • You need to get rid of as much water as you drink, if you don’t your body will swell up • The balance of fluids is controlled by chemical messengers in the body called hormones

30. Sweat and Thirst • When you get hot you sweat to cool down • As water content of the blood drops, the salivary glands produce less saliva • This is one of the reasons you feel thirsty

31. Antidiuretic Hormone • When you get thirsty your body reacts to the water shortage • A hormone, ADH is released • Signals the kidneys to take water from the nephrons • Nephrons return the water to the bloodstream, thus the kidneys make less urine

32. Diuretics • Some beverages contain caffeine, which is a diuretic • Diuretic • Cause the kidneys to make more urine, which decreases the amount of water in the blood • Caffeine increases fluid loss • Your body gets used to less of the water from the caffeinated beverage than from a glass of water

33. Urinary System Problems • Bacterial Infections • Kidney Stones • Kidney Disease