Digestion

Digestion

Digestion Grade 9 Video Demo http://videos.howstuffworks.com/hsw/ 5822-digestive-system-stomach-video .htm

Bill Nye Jelly Bean Digestion What biochemical compound makes up this jelly bean? Eg. lipids, carbohydrates, proteins or nucleic acids

What happens when you put the jelly bean into your mouth? Than what happens? Teeth Tear, rip and chew food to physically break it into smaller pieces. (Mechanical Digestion).

Lets look at the internal structure of teeth. Teeth The crown is the part of the tooth above the gum line The root is

the part of the tooth below the gum line The enamel is the white part you can see covering the crown. Enamel is the hardest substance in the human body It covers the dentine

and stops bacteria getting inside the tooth Teeth The crown is the part of the tooth above the gum line The root is the part of

the tooth below the gum line The dentine is the major component within the tooth. It is made from softer material than enamel so is easier to decay. Teeth

The crown is the part of the tooth above the gum line The root is the part of the tooth below the gum line

The pulp contains the nerves and blood vessels of the tooth. It is underneath the dentine. This is the part that hurts when you have a toothache! Teeth The crown is the part

of the tooth above the gum line The root is the part of the tooth below the gum line The cementum is found outside the dentine in

the root. It cements (holds) the tooth into the jaw bone. Bacteria Our mouths are busy places, full of friendly bacteria that coat our teeth

Sometimes unfriendly bacteria, including one called Porphymonas gingivalis, will overgrow the friendly bacteria and cause damage to the gums and the jawbone. This bacterium is one of the main causes of gum disease. Porphymonas gingivalis To fend off the attack, the body will send immune cells to kill the bacteria.

The bacteria are difficult to kill so the immune cells can cause even more damage to your gums. Mouth: What happens Food is crushed and ground up by teeth The salivary glands secrete saliva which makes the food moist and easy to swallow (Semi-solid lump now called Bolus).

Amylase enzyme (in saliva) breaks the carbohydrate starch down into glucose. Enzymes Remember : Large particles cannot be absorbed in the small intestine INSIDE THE BODY (BLOOD)

GUT starch starch G starch G G G

Large particles (e.g. starch) are left in the gut and small particles (e.g. glucose) pass into the bloodstream. G G starch

BUT large particles can be broken down into small particles. This is called DIGESTION Enzymes Large particles need to be broken down chemically by ENZYMES. Enzymes are biological catalysts. They speed up chemical reactions in the body. Digestive enzymes cleave (cut) the larger

molecules into smaller ones. Digestive Enzymes Mouth: Amylase breaks starch down into glucose. Stomach:

Protease (Pepsin) breaks protein down into peptides. Digestive Enzymes Amylase Glucose Starch Protease Peptides

Protein Enzymes and pH Enzymes work best at one pH. This pH is different for each different enzyme. If the pH goes too low (more acidic) or too high (more alkaline), the enzyme will not work as effectively. However, changes to pH will NOT denature enzymes.

Epiglottis Is the flap of cartilage lying behind the tongue and in front of the entrance to the larynx (voice box). At rest, the epiglottis is upright, allowing air to pass into the trachea (for breathing).

At Rest During Swallowing The tongue pushes the bolus toward the pharynx (throat). The epiglottis folds back to cover the entrance to the trachea, protecting the larynx. This allows food to enter into the esophagus. *The epiglottis acts as a lid*

Swallowing Esophagus A muscular tube that leads from the throat to the stomach. The smooth muscle of the esophagus pushes the bolus toward the stomach using wave-like contractions. This is called Peristalsis.

Peristalsis Entering the Stomach From the esophagus, the bolus enters the stomach through the Cardiac sphincter (muscular ring). -Sphincters help move digested material in one direction.

Entering the Stomach The Stomach A hollow, sac-like organ that stores, mixes, sterilizes and continues the digestive process.

Storage: walls have folds called Rugae which allow the stomach to expand. Food spends 3-4 hours in here! The Stomach Mixes: The

stomach walls contain three layers of smooth muscle arranged in longitudinal, circular, and oblique (diagonal) rows. These muscles allow the stomach to squeeze and churn the food (mechanical digestion). Muscles and Rugae

The Stomach Sterilizes and Chemically Digests: Secretes gastric juice & hydrochloric acid The acid kills germs in the food (pH 2) The gastric juice contains the protease enzyme PEPSIN to digest protein into peptides Protease

Peptides Protein Mucus A thick mucus layer lines the stomach walls to prevent the stomach from digesting itself. Mucus

Mucus What do you think may happen when mucus is limited? Ulcer Peptic ulcer disease occurs when the protective mucus layer wears away in certain areas, allowing

damage to occur from the natural acids of the stomach. Ulcer- 60% to 80% of gastric ulcers caused by bacteria Helicobacter pylori is a spiral shaped bacterium that lives in the stomach and duodenum (section of intestine just below stomach) The stomach is protected from its own gastric juice by a thick layer of mucus that covers the stomach lining. Helicobacter

pylori takes advantage of this protection by living in the mucus lining. Helicobacter pylori Once H. pylori is safely ensconced in the mucus, it is able to fight the stomach acid that does reach it with an enzyme it possesses called urease However, the immune system will respond to an H. pylori infection It may not be H. pylori itself which causes

peptic ulcer, but the inflammation of the stomach lining; i.e. the immune response to H. pylori. Continuation of Digestion The chyme is slowly transported from the stomach through the pyloric sphincter and into the small intestine where further digestion and nutrient absorption occurs.

DIGESTION Definitions Gland: an organ or group of cells which secretes enzymes or hormones Peristalsis:

muscle contractions that push food through a tube Bolus: chewed food Definitions continued Chyme: nutrients in semi-liquid

form Uvula: component that stops food from entering nasal cavity Epiglottis: component that stops food from entering the trachea Digestive Tract and Functions 1) 2)

3) 4) 5) 6) 7) 8) Mouth Pharynx Esophagus Stomach Small intestine

Large intestine Rectum Anus Decomposition of food Absorption of nutrients Elimination of waste

Digestive Glands and Functions Salivary glands In mouth Gastric glands

In walls of stomach Pancreas Liver Intestinal glands In

small intestine Secretion of: saliva Gastric enzymes Digestive juices Bile Physical/Mechanical Breakdown

Food DOES NOT change its molecular makeup, just its shape and size, looks different 1. 2. 3. 4. 5. Mouth- chewing and swallowing Esophagus- peristalsis

Stomach- churning, grinding and peristalsis Small intestine- peristalsis and churning Large intestine- peristalsis and churning Chemical Breakdown Food changes its molecular makeup, looks and is different See handout* Absorption

Through folds called villi by diffusion Small intestine amino acids, glucose, glycerol and fatty acids Large intestine vitamins, minerals and water

Recently Viewed Presentations

  • Chapter 52

    Chapter 52

    Birds nesting on small islands, such as these king penguins on South Georgia Island in the South Atlantic Ocean, often exhibit uniform spacing, maintained by aggressive interactions between neighbors. LE 52-3c. Random. Dandelions grow from windblown seeds that land at...
  • Unit 3 Part 1 Resistance to Slavery Divides the Nation

    Unit 3 Part 1 Resistance to Slavery Divides the Nation

    Pre-Beard Lincoln. John Brown and His Failed Raid on Harper's Ferry. John Brown, a white abolitionist, planned to end slavery by force. ... Unit 3 Part 1 Resistance to Slavery Divides the Nation Last modified by: Gay, Jonathan
  • Derivatives of the ectodermal germ layer Development of

    Derivatives of the ectodermal germ layer Development of

    neuropore. closes at. day . 27. Parts of the neural tube. 1-neural crest. 2-alar plate. 3-basal plate. alar plate. basal plate. The nervous system is formed from the ectoderm (the neural tube) The . neural crest . gives rise to...
  • Current Advanced Teleconferencing Solutions Dan Sandin EVL Feb

    Current Advanced Teleconferencing Solutions Dan Sandin EVL Feb

    Bandwidth 100 Mbit each way with sound DVCPRO HD Teleconferencing Development Need to test latency and quality Need to develop software decode I meet with Panasonic feb 8 06 HDSDI Teleconferencing No compression 4-2-2 Use widely deployed HD format 1920...
  • Data Mining in Resource-constrained Environments: Techniques ...

    Data Mining in Resource-constrained Environments: Techniques ...

    Symbolic Approximation of ECG Symbolic ApproXimation (SAX) has been invented by Prof. Eamonn Keogh and his colleagues at UCR. SAX representation of time series is considered the state-of-the-art. SAX has been successfully used with notable efficiency in: Discord discovery Motif...
  • Caste System Worksheet - Socorro Independent School District

    Caste System Worksheet - Socorro Independent School District

    CASTE SYSTEM India's Caste System What is a Caste? social group that someone is born into and cannot change How many of you have felt excluded from a group of people at one time or another?
  • 2012 Plumbing Codes International Plumbing Code Uniform Plumbing

    2012 Plumbing Codes International Plumbing Code Uniform Plumbing

    The International Plumbing Code (IPC) and the Uniform Plumbing Code (UPC) cover the initial design of plumbing systems through the installation and construction phases, and into the maintenance of operating systems. Fuel-gas appliances and systems are addressed in the 2012...
  • Research Questions and Projects

    Research Questions and Projects

    Arial Default Design Research Questions and Projects Veronica Renee Boehmer: Source of Fatigue and Love Research Process Origin of Research Questions Beginning Empirical Research: Reasoning Deductive and Inductive Logic Social research strategies Subjectivity and Ideas Slide 9 Slide 10 Slide...