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Chapter 17 – Part I. Alimentary canal Mouth Pharynx Esophagus. Carbohydrates, proteins and fats are all made up of carbon, hydrogen, nitrogen and oxygen. Fats are made up of smaller units called amino acids. Starch is a large carbohydrate molecule.
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Chapter 17 – Part I Alimentary canal Mouth Pharynx Esophagus
Carbohydrates, proteins and fats are all made up of carbon, hydrogen, nitrogen and oxygen. Fats are made up of smaller units called amino acids Starch is a large carbohydrate molecule Proteins are made up of one or more glucose molecules Starch molecules can be broken down by amylase. Can you sort out the statements into True and False? Proteins are important for the growth and repair of cells
How do we break down the food we eat? 1. Mastication/Mechanical • teeth 2. Chemical Digestion • enzymes • stomach acid • bile
The Alimentary Canal • The alimentary canal (or gut) is the tube within the body through which food passes and is processed in various ways
Layers of the Alimentary Canal 1. Mucosa - protects tissues and carries absorption 2. Submucosa - glands, blood vessels, nerves 3. Muscular Layer - smooth muscle tissue, circular & longitudinal fibers, pushes food (PERISTALSIS) 4. Serosa (serous layer) - visceral perineum, outer covering of the tube, lubricates surfaces (serous fluid)
Incisors –cutting and chopping food Cuspid (canine) – sharp and pointed for cutting and tearing food Bicuspids – cutting and chopping Premolars – crushing and grinding food Molars - grinding and mashing food
Get a mirror and look at a partner’s teeth. Identify each type of tooth – count them • A dentist would write your dental records as: • I: 2/2 C:1/1 PM: 2/2 M: 3/3. • What do you think this means?
Saliva is slightly alkaline – it’s not that! When we eat, bacteria in your mouth feeds on the sugar and turns it to acid. The acids wear away the enamel. What causes tooth decay? Decay has spread down to the nerve root Decay has started in the enamel Decay reaches the pulp Decay has reached the dentine SEVERE TOOTHACHE EXCRUCIATING PAIN!! SLIGHT TOOTHACHE NO PAIN
Dry mouth –xerostomia (no neutralization of acids) • Shrinking blood vessels • Erosive chemical • Compulsive grinding • Desire for sugar Meth Mouth
‘the breakdown of large insoluble molecules into soluble molecules’ Digestion
TASK: Copy and complete this diagram into your notes: AFTER ABSORPTION BEFORE ABSORPTION INSIDE THE BODY (BLOOD) INSIDE THE BODY (BLOOD) GUT GUT starch starch G G starch G G Absorption – only small particles can pass through cells, but large molecules can be broken down into smaller ones G starch G
There are 3 main types of digestive enzymes: • Amylase breaks starch down into glucose. • Protease breaks protein down into amino acids. • Lipase breaks fats down into fatty acids and glycerol Digestive Enzymes
Teeth assist the mechanical breakdown of food Saliva is mixed with food during chewing Saliva contains the enzyme amylase which starts the digestion of food Salivary Glands Saliva contains mucus that keeps the mouth moist and lubricates food for easier swallowing
Amylase Protease Glucose Starch Digestive Enzymes Amino Acids Protein
Lipase Fatty Acid Glycerol Fatty Acid Glycerol Fatty Acid Fatty Acid Fatty Acid Fatty Acids and Glycerol Fat
SALIVA • Salivary amylase LIVER • bile GASTRIC JUICE • Hydrochloric acid • Pepsin (protease) Digestive Juices PANCREATIC JUICE • Pancreatic lipase • Proteases (trypsin) INTESTINAL JUICE • Mucus, various enzymes
Peristalsis http://nutrition.jbpub.com/resources/animations.cfm?id=1&debug=0
nasopharynx oropharynx laryngopharynx Pharynx
esophageal hiatus is where it penetrates the diaphragm cardiac sphincter at entrance to stomach Esophagus