10.2 The Human Digestive System (textbook p )

Transcription

1 10.2 The Human Digestive System (textbook p ) Learning Goal: Label and explain the anatomy of the Digestive System See text p411 Fig.10.6: Label "Organs of Digestive System": See text p411 Fig.10.6: "Organs that Contain Food" vs "Assist in Breakdown of Food": Accessory Organs (structures that aid digestion) Digestive Tract (organs that contain food) Fact: The digestive tract and associated organs take up a significant portion of the space in the human body. The small intestine is. The large intestine is. 1

2 A) Parts of the Human Digestive System 1. Mouth: See text p411 Fig.10.7: Label "Salivary Glands of Mouth": Read text p411: Describe "Chemical Digestion" vs "Mechanical Digestion" by Explaining Function of Each Part: Part Function/Definition 3 Salivary Glands Teeth 2

3 Video 1: Explanation of Swallowing of the throat and esophagus.html **textbook never mentions 2. Pharynx:? The mouth is equipped with teeth arranged along upper & lower jaws and a tongue to push food back to the pharynx Taste buds (4 main) located on the tongue sweet, salty, sour, or bitter enhance flavour of our food The uvula hangs from the back of the soft palate, a flap that guides food to enter the pharynx as we swallow and then down the esophagus Further down, the epiglottis is another flap that prevents food from entering the larynx (voice box) and trachea where air leads to the lungs If you swallow correctly, solids or liquids will go down your esophagus into your stomach. This is because, when your tongue propels the food into your throat, your voice box elevates to close off your trachea, or breathing pipe. At the same time, the opening of your esophagus opens up (it is usually closed to protect the contents of your stomach from pouring out each time you bend over). Your food really can go down the wrong pipe since your mouth has to do double duty, breathing air in and out and swallowing food, things don t always run smoothly. When somebody feels like something went down the wrong pipe, it usually means that it went into his or her trachea, a process known as aspiration. 3

4 3. Esophagus: Read text p412: Complete Table: Part Function/Definition Bolus Esophagus Esophageal sphincter Q: What does this diagram represent? Q: Briefly explain what happens when you "vomit"? 4

5 4. Stomach: Read text p413: Complete Table: Part Function/Definition Stomach Gastric juices Chyme Pyloric sphincter Stomach's 3 methods of protection See text p413 Fig. 10.9: Label Stomach Diagram Parts of the Stomach 5

6 5. Small Intestine: Read text p : Complete Table: Fact: the intestines contain more than 100 different species of "good" bacteria, with numbers in the billions these bacteria aid in digestion and absorption and also help keep out the "bad" bacteria that make us sick Fact: the small intestine is approximately 6m or 20 ft long Part Function/Definition Small intestine Duodenum Jejunum Ileum See text p413 Fig. 10.9: Label "Lining of Duodenum Diagram": Layers of small intestine 6

7 6. Accessory Organs: Read text p415: Complete Table: Part Function/Definition Pancreas Liver Gall Bladder Q: What is the size and mass of the liver? See text p413 Fig. 10.9: Label Accessory Organs Diagram 7

8 7. Large Intestine (Colon): Read text p418: Complete Table: Part Function/Definition large intestine (ascending colon, transverse colon, descending colon, sigmoid colon) rectum anus Q: Briefly explain why feces is typically a "brown" colour, and briefly explain why feces has an odour? 8

9 ** textbook never mentions all parts of the Large Intestine! (see diagram below) Actual real life pictures text p418 text p426 appendix: an organ that plays no role in digestion, but may help fight infections "Dr. William Parker, (USA) and his team were trying to find out how the immune system interacts with normal bacteria found in the intestines. They found evidence of large populations of good bacteria around the appendix. They think that this little pouch is ideally situated out of the way of intestinal clean outs to provide a place for good bacteria to stay until the bad bacteria have been cleaned out." ** textbook never mentions the cecum (caecum): a short, pouch like region of the large intestine between the ascending colon and appendix "In herbivores, the cecum is used to digest cellulose. This adaptation no longer exists in humans, who cannot digest insoluble plant fibers. Birds and some herbivorous mammals have two cecums, and there is scientific debate as to whether or not the appendix is a remnant of this second cecum. Fish, amphibians and some carnivorous mammals completely lack a cecum." 9

10 You will be expected to label a Digestive System Diagram like this one! mouth (submandibular) common with cystic duct sigmoid colon anus 10

11 Most of us are guilty of eating too fast (inhaling our food) let's try and slow down and enjoy the flavour first! text p418 Gross things you do not want to happen to you! 11

12 B) Chemical Digestion and Absorption Learning Goal: Explain enzymatic digestion of macromolecules text p416 Q: What do bile and pancreatic fluid do? Enzyme Digests what? carbohydrases lipases proteases nucleases p416 Fig Q: What enzymes are where? "Flowchart of Chemical Digestion": complex carbohydrates proteins fats nucleic acids Mouth Stomach Small Intestine 12

13 text p417 Q: Briefly explain the "2 factors" that affect the rate at which enzymes function: Q: Briefly summarize "Absorption in the Small Intestine": 1. monosaccharides: 2. amino acids: 3. glycerol & fatty acids: 13

14 Nerves and hormones regulate secretion of digestive enzymes There are three major hormones involved in digestion: gastrin stimulates the release of digestive juices from the stomach Q: Find the 3 hormones (gastrin, secretin, CCK) in the diagram below and highlight them! secretin stimulates the release of pancreatic juice from the pancreas cholecystokinin (CCK) stimulates the release of bile from the gall bladder, into the duodenum Video 1: Hank overviews Digestive System Video 2: Hank tells Alexis St Martin Story "whole in stomach" and Digestive System to the Stomach Video 3: Hank finishes Digestive System YOU ARE FINISHED! 14