The Digestive and Excretory Systems

1. The Digestive and Excretory Systems

2. Objectives • To list the organs of the digestive and excretory systems • To describe the function of the organs of the digestive and excretory system • To compare and contrast the digestive and excretory systems • To explain how the digestive and excretory systems relate to each other as well as in relation to other body systms

3. Components • Esophagus • Stomach • Small Intestine • Large Intestine • Gall bladder • Liver • Pancreas

4. Digestive System • This system is responsible for breaking down food into a useable form of energy for the body

5. Alimentary Canal • Path food travels through the body (your digestive tract) • From mouth to the anus

6. Organs of the Digestive system • Mouth • Digestion starts here • Mechanically breaks down food by the chewing mechanism • Chewing is called mastication • Here there are enzymes (present in saliva) that also aid in the break down of food • Enzymes are chemicals that simply break up particles/bacteria/viruses… etc • Words ending in –ase are usually enzymes

7. Esophagus Stomach

8. Esophagus • the tube that connects your mouth and your stomach

9. You have a trap door called the epiglottis to cover your windpipe when you swallow.

10. Organs of the Digestive System • Esophagus- muscular tube through which food travels to the stomach • Food moves along the digestive system by means of a muscular movement called peristalsis • Peristalsis is an involuntary contraction (and relaxation) of muscles in the digestive system that moves food along the alimentary canal • At the beginning of the esophagus is a small flap (or gate-like structure) called the epiglottis that closes off the entrance to the trachea when you swallow

11. Peristalsis

12. Stomach • A stretchy bag that holds your food after you eat • Helps to break food into smaller pieces so your body can use it for energy and nutrition

13. Organs • Stomach- muscular organ responsible for the further breakdown of nutrients • Mixing chamber and storage chamber • Chemical break down through stomach acid • Mechanical break down through churning/mixing • No food is absorbed through the stomach wall (which is coated with mucus to prevent the stomach acid from “eating through” itself)

14. Small Intestine

15. Small Intestine • Tube that is 20 feet long. • Continues to digest food • Food stays in your small intestine for 4 to 8 hours

16. Organs • Small intestine- chemical digestion continues here; in fact, most of the chemical digestion occurs here along with NUTRIENT ABSORPTION! • From ~15 to 32 feet • Average 17 feet • Has 3 sections • Duodenum- • ~10 inches • digestive juice are secreted from intestine, pancreas and liver are mixed with the food to further break it down

17. Small intestine cont • Pt 2 • Jejunum- ~4 to 7 ft long • Food nutrients are absorbed here • Pt 3 • Ileum- ~5 to 7 feet long • More food absorption occurs here

18. Small intestine • Food absorption • Villi- small tube structures that cover the wall of the small intestine • Used for food/nutrient absorption • Food absorbed in the small intestine enters the blood stream in the capillaries and is transported throughout the body (to where needed)

19. Liver

20. Liver • Factory for antibodies and bile • Stores vitamins and sugars until your body needs them

21. Food Processors • Liver- the largest internal organ • Functions as an aid to the digestive system in 2 ways • 1 through production of bile- yellowish-greenish fluid used for digestion of fats in the small intestine • 2 to filter toxic substances from the body and it stores excess glucose

22. Gall Bladder

23. Gall Bladder • Storage tank for bile (a greenish-yellow liquid) that helps your body break down and use fats • Located under your liver • Shaped like a pear

24. Pancreas • Helps you digest food by breaking down sugars

25. Large Intestine

26. Large Intestine • Tube that is 5 feet long • Gets waste from small intestine • Waste stays for 10 to 12 hours

27. Garbage Disposal • Large Intestine/Colon • Measures about 5 feet long • This organ absorbs most of the water and some of the remaining nutrients left from the food you ate • After food has finished its trip through the colon it moves to the rectum and then anus to be excreted as fecal matter

28. Large Intestine/Colon • Also aids the immune system in that it contains healthy bacteria to fight off harmful bacteria (or microorganisms) • These bacteria also provide vitamins for the body

29. Functions of the Digestive System • Digest the food we eat • Take the nutrients out of your foodso your body can use it

30. Human Excretory System

31. Excretory System • The kidneys regulate the amount of water, salts and other substances in the blood. • The kidneys are fist-sized, bean shaped structures that remove nitrogenous wastes (urine) and excess salts from the blood. • The ureters are tubes that carry urine from the pelvis of the kidneys to the urinary bladder. • The urinary bladder temporarily stores urine until it is released from the body. • The urethra is the tube that carries urine from the urinary bladder to the outside of the body. • The outer end of the urethra is controlled by a circular muscle called a sphincter.

32. Kidneys Two reddish organs just above the waist behind the stomach Filter the blood and removes waste

33. Food Processors • Gallbladder- located beneath the liver and stores the bile produced in the liver • Pancreas- located behind the stomach and produces pancreatic juices • Pancreatic juices are sent to the small intestine to aid in digestion of carbohydrates, proteins and fats

34. The Job of the Kidneys • They are responsible for cleaning the blood by removing metabolic wastes, excess solutes, and excess water and excreting them as urine • Besides removing urea, it also removes excess salts or glucose, the remnants of drugs (reason for urine tests), and excess water.

35. Function of the Kidney • The principal function of the kidney is to filter blood in order to remove cellular waste products from the body. • At any given time, 20 % of blood is in the kidneys. Humans can function with one kidney. • If one ceases to work, the other increases in size to handle the workload.

36. NOTE • Since the kidneys control what leaves and what remains in the nephrons, they maintain the levels of water, ions and other materials nearly constant and within the limits to maintain homeostasis.

38. Urinary Bladder Smooth muscle bag Stores waste solution - urine

40. Urethra Connects bladder to outside of the body Allows urine to pass out of the body

41. Ureter Connects the kidneys to the urinary bladder

42. Nephron Filtering unit of the kidney Blood enters full of waste and leaves filtered Blood enters under high pressure and flows into the capillary beds

43. Regulation of Water Levels • If the blood becomes too dilute or too concentrated with solutes, then it can interfere with normal cellular activity. • The kidneys are able to regulate water concentration in the blood by removing excess water if the blood is too dilute or conserving water in the blood if it is not dilute enough

44. Waste Products • Carbon dioxide – a waste product of cellular respiration is dumped into the blood stream and eventually removed by the lungs • Ammonia (NH3) is removed through water • This waste comes from the cells breakdown of old proteins • It is also what makes bleach smell so in high concentrations it is poisonous to the cells and must be removed

45. Formation of Urine • If there is too much water in the blood, then it is removed and put in urine. • If there is not enough water in the blood, the kidneys will not remove it. • If there is too much urea or other solutes in the blood, the kidneys will remove these excess solutes. • By regulating solute numbers and water volume, the kidneys normally maintain homeostasis in blood solute concentration.

46. Why is excretion necessary? • In order for cells to stay alive, they must continually intake water and other molecules. • The cells would continue to get bigger and bigger if they only took in molecules • They must also export molecules • These molecules may be important signaling molecules such as hormones, or they may be molecules of glucose on their way to other cells, or they may be waste products of cellular metabolism that cells need to dispose.

47. Removal of Ammonia • Once excreted into the blood stream by cells, it is carried to the liver where it is converted from ammonia into urea which is much less toxic • It is then carried from the liver to the kidneys where it is removed

48. Excretory System Problems • Kidney stones – crystalized mineral salts and uric acid salts in the urine. Stones block flow of urine and cause excrutiating pain. • Kidney failure - can be caused by long-term diabetes, infections, physical injuries, chemical poisoning. Causes toxic materials to build up to lethal levels. Dialysis or kidney transplant is the treatment.

49. Describe the functions of a person's urinary system Rids the body of wastes, control blood volume, balances salts & water

50. Explain how the kidneys remove wastes and keep fluids and salts in balance Kidneys filter the blood to remove extra wastes, sugar, water, and salt. Sugar, water, and salt still needed by the body is returned to the blood.