Alimentary Canal

1. Alimentary Canal • Aka the gastrointestinal tract (G.I. tract) • The order is: • Mouth • Pharynx • Esophagus • Stomach • Small intestine • Large intestine • Rectum • Anus

3. Ingestion and mastication

4. Mouth (aka Oral cavity) • Both physical (chewing food) and chemical digestion occur (salivary amylase) • It contains multiple structures for breaking down food: • Teeth • Tongue • Salivary glands • Hard Palate • Soft Palate

7. Teeth • Primary teeth vs. secondary teeth

8. Anatomy of a Tooth

9. Tooth • Enamel – White outer part of the tooth. Is mostly made of calcium phosphate, a rock-hard mineral. • Dentin – has living cells, is porous, and is like bone (softer than enamel) • Pulp – the softer, living inner structure of teeth. Blood vessels and nerves run through the pulp.

10. Dental Caries (aka Cavities) • 500 species of bacteria inhabit the mouth. • Certain bacteria thrive on sugar, and produce lactic acid which destroys tooth enamel. • Streptococcus mutans

11. Teeth Questions • What are three types of teeth? What are they used for? • Why do Cavities Hurt? • Analyzing the teeth of animals is a good indication of their diet. Explain why. SciShow Videos • Why do we have baby teeth? • Why is flouride good for our teeth? • Why do we have to brush our teeth? List the two main reasons.

12. 3 Types of teeth • Incisors: These teeth are excellent for bitingand cutting food. • Canines (cuspids): Being pointed in shape they are used to tear or shred food. • Premolars and Molars: Both are flattened on the upper surfaces and are used for grinding and chewing food.

13. Root Canal • https://www.youtube.com/watch?v=jHHn52KhBkQ • https://www.youtube.com/watch?v=YDs-848-u-U

14. Tongue • Made up of groups of muscles that run in different directions. This gives the tongue its flexibility. • Mixes food with saliva to form a mass of wet food called a bolus. • Initiates swallowing by pushing bolus towards the pharynx

16. Tongue continued • The top layer of the tongue is covered with a layer of bumps called papillae • Papillae helps grip food and contains taste buds • People are born with ~10 000 taste buds, which decline as we age

18. Taste buds Can detect the following tastes: • Sweet • Salty • Sour • Bitter • Umami

19. Why is the tongue important in choosing the kinds of food you eat? Tastes has a homeostatic function • Promotes the intake of nutritious foods that your body needs • Protects you body from possible dangers • Example: Natural poisons and spoiled foods tastes bitter

20. Do you taste different components of taste with different parts of your tongue? The “Taste Map”: All Wrong

21. Tongue Papillae Circumvallate papillae

22. Taste Test! • You will be tasting flavoured candies. Yummy  • Catch! – You have to PLUG YOUR NOSE! • One student = facilitator, other = taster • Facilitator chooses 1 candy (don’t show the taster!), unwrap it while the taster has their eyes closed and put it in their hands. • 60 seconds (keep your nose plugged!) – describe sensations and try to determine the flavour of the candy. Guess again after the min is up. THEN unplug your nose... Switch roles and repeat. **Remember keep the flavour a secret until the end**

23. Taste • What is the difference between taste and flavour? • Does smell affect taste? • If your sense of taste is impaired, it is possible your appetite might decrease. • What things might decrease your sense of taste? • Cigarettes, illness, medications, vitamin deficiencies

24. Babies response to sour taste • http://www.dailymail.co.uk/news/article-2392574/Photographers-April-Maciborka-David-Wile-capture-toddlers-reactions-trying-lemon-time.html

25. Check Your Understanding! • What is the tongue? What function does it perform? • How many different tastes can the tongue detect? What are the tastes? • What kind of homeostatic function does your tongue serve? Explain.

26. Salivary Glands • There are three types of salivary glands: 1. Parotid Glands2. Submandibular Glands3. Sublingual Glands

27. Salivary Glands continued • Serous cells produce amylase – splits starch and glycogen into disaccharides

28. Salivary Glands continued • Mucous cells produce mucus – lubrication during swallowing • Saliva is 99% water, the rest is mucus, salts, and enzymes • The water in saliva moistens and dissolves particles of food, aiding chemical digestion, the ability to taste, and the chewing process

29. Exocrine glands • Are glands that produce and secrete substances onto an epithelial surface by way of a duct • For example: Salivary Glands

30. Swollen parotid gland in child with viral mumps. This virus can also infect the testes.

31. Parasympathetic innervationstimulates salivary gland secretion (anticipation of tasty food). Sympathetic stimulationinhibits normal secretion, which is why people who are frightened experience the sensation of a dry mouth.

32. Check Your Understanding! • Describe the chemical digestion that occurs in the mouth • Mucus is found in saliva. What might its function be?

33. Movement!!

34. Swallowing • Voluntary • Tongue pushes bolus to back of throat (Pharynx) • Soft palate closes off nasal passage • Epiglottis closes off the trachea and food travels down esophagus

35. Pharynx • The junction between nasal and oral cavity, part of the throat

36. Can you drink upside down?

37. Can you drink upside down? Questions: • Is gravity needed to make fluids come down the esophagus? • Can we drink while we stand on our head? • How does food go down the esophagus into the stomach? • Why did the fluid not flow out of the mouth when drinking upside down? • What is the muscle action called, which pushes food into the stomach?

38. Esophagus • Esophagus is made of smooth muscle that becomes stretched to help food bolus move along. • Inside is covered in a thick lining of mucus • Causes a wavelike contraction called PERISTALSIS. • Reverse peristalsis = Vomiting

39. The wall of the esophagus contains both circular and longitudinal muscle.

44. Movement cont. • Smooth muscle contractions also move food through the rest of the digestive tract.

45. Digestion / Absorption

46. Sphincter • A sphincter is a ring of muscle that controls the passage of material. Relaxed = open, Contracted = closed • At the junction of esophagus and stomach is the cardiac sphincter (AKA Lower Esophageal Sphincter). Stops stomach contents from going into esophagus

47. At the junction of stomach and duodenum is the pyloric sphincter. Regulates movement of stomach contents from stomach  small intestine.

49. Draw This!

50. Heart Burn • Caused by a cardiac sphincter that doesn’t tighten as it should  stomach acid into esophagus • Often happens when too much food in the stomach (overeating) or to much pressure on the stomach (obesity, pregnancy) • Certain foods act as a trigger (relaxes the sphincter or causes more acid production  smoking causes both!)