3. Periodontal/Gum Disease
Periodontal/gum diseases are serious infections that, left untreated, can lead to tooth loss
The word periodontal literally means "around the tooth“
Periodontal disease is a chronic bacterial infection that affects the gums and bones supporting the teeth
Periodontal disease can affect one tooth or many teeth. It begins when the bacteria in plaque causes the gums to become inflamed

7. Do you have gum disease??? Do you ever have pain in your mouth?
Do your gums ever bleed when you brush your teeth or when you eat hard food?
Have you noticed any spaces developing between your teeth?
Do your gums ever feel swollen or tender?
Have you noticed that your gums are receding (pulling back from your teeth) or your teeth appear longer than before?
Do you have persistent bad breath?
Have you noticed pus between your teeth and gums?
Have you noticed any change in the way your teeth fit together when you bite?
Do you ever develop sores in your mouth?

8. How to look after your teeth

9. How to Brush
Place your toothbrush next to the teeth so that it rests on the gums forming a 45-degree angle against the gums.
Move the toothbrush from the gums towards the edge of teeth to move the dental plaque away from the gum line.
After brushing, one by one tooth, all the outer teeth surfaces do the same for the inner surfaces. 
Brush the chewing surfaces of the teeth with horizontal moves.

10. How to Floss

11. Human Torso Model
*Please refer to your handout of the human digestive system

12. Human Digestive System
Alimentary Canal + Associated Glands

13. Alimentary Canal and Associated Glands
Mouth
Pharynx
Oesophagus
Stomach
Small Intestine
Large Intestine
Anus
Salivary Glands
Gastric Glands
Pancreas
Liver
Intestinal Glands

14. Digestion

15. Digestion
Digestion is the process of breaking down large, complex substances into smaller, simpler molecules for absorption
Carbohydrates -> glucose/fructose/galactose
Proteins -> amino acids
Fats -> fatty acids and glycerol
Vitamins, minerals and water can be absorbed directly without digestion

16. Mechanical Digestion vs. Chemical Digestion
Mechanical process
Chewing of teeth
Churning of stomach
Food is changed physically but not chemically
Increase surface area of food substances
Chemical process
Involves action of digestive enzymes secreted from glands
Different types of enzymes break down different food types

17. Protease Breaks down protein molecules
A protein molecule is made of many different amino acids
Amino acids

18. Breaks down carbohydrate molecules
Carbohydrase
Breaks down carbohydrate molecules
A starch molecule is made of many glucose molecules
Glucose

19. Lipase Breaks down fat molecules Fatty acids
Glycerol
A fat molecule is made up of fatty acids and glycerol molecules

20. Example of Carbohydrase: Amylase
In saliva and pancreatic juice
Helps break down starch into simple sugars in mouth and in small intestine

21. Example of Protease: Pepsin
In gastric juice
Helps break down proteins into amino acids in stomach

22. Example: Lipase In pancreatic juice
Helps break down oil droplets into fatty acids and glycerol in small intestine

23. Saliva
The taste, smell and sight of food can stimulate salivary glands to secrete saliva into the mouth via salivary ducts
Saliva – contains water, mucus and salivary amylase. Slightly alkaline
Water – moistens and softens food
Mucus – lubricate food for swallowing
Salivary amylase – starch -> maltose

25. Swallowing Food is chewed and mixed with saliva
Tongue rolls the food into a bolus
Food is swallowed down the oesophagus through the pharynx
Tongue moves upwards and backwards to prevent food from entering the trachea/nasal cavity
The soft palate moves up to block the nasal cavity
The larynx moves upwards to so that the glottis (the opening to the larynx) is covered by the epiglottis to prevent food from entering the trachea

27. Movement of Food Along the Alimentary Canal
Inner surface of alimentary canal is lined with one to several layers of cells – epithelium
Some epithelial cells produce mucus, which acts as a lubricant

28. Peristalsis
The small intestine has two muscle layers that work together in peristalsis and segmentation

29. Peristalsis
The inner circular muscles contract, tightening the tube and pushing the food forward in the intestine

30. Peristalsis
When the circular muscles relax, the outer longitudinal muscles contract, and the intestinal tube is shortened

31. Peristalsis
As the circular and longitudinal muscles tighten and relax, the food moves forward

32. Stomach
a muscular, elastic, pear-shaped bag, lying crosswise in the abdominal cavity
food enters the stomach from the esophagus. The connection between the stomach and the esophagus is called the cardiac sphincter
The other end of the stomach empties into the duodenum, the first section of the small intestine. The pyloric sphincter separates the stomach from the duodenum

35. Sphincter Opened
Sphincter Closed

36. Functions of Stomach Storage
Mechanical digestion – turns food into chyme
Chemical digestion

38. The lining of the stomach contains deep collections of cells organized into gastric glands
The openings of the gastric glands into the surface of the stomach are called gastric pits
The mucous cells in the gastric pits secrete mucus
In the deeper part of the gland, the parietal cells secrete hydrochloric acid
The chief cells secrete pepsinogen (an inactive form of the protein-digesting enzyme pepsin)

39. Rennin
In young children, the gastric juice also contains a type of protease called rennin
Rennin coagulates milk – allow the proteins to stay in stomach longer for digestion
* Rennin can be used to curdle milk to make cheese!

40. Ulcer/Peptic Ulcer A small erosion in the gastrointestinal tract
A weakening of the mucus coating – acid erodes the wall of the GI tract
Stomach – gastric ulcer
Small intestine – duodenal ulcer
Main cause – bacterial infection
Can be treated with antibiotics

41. Small Intestine The small intestine is divided into 3 sections:
Duodenum
Jejunum
Ileum
* In the small intestine, both digestion and absorption occur

43. Bile Bile is a dark green fluid containing: 1) bile salts
2) sodium hydrogen carbonate
3) bile pigments
Bile does NOT contain digestive enzymes
Made by the liver
Stored in the gall bladder

45. The gall bladder contracts to release bile into the duodenum via the bile duct
Stimulated by the arrival of chyme in the duodenum

46. Bile 1) Bile salts – EMULSIFICATION
Bile salts break up (emulsify) lipids into small oil droplets
This allows enzymes to have a larger surface area to break down the fat molecules
Lipids Small oil droplets
Bile salts (emulsification)

47. Bile 2) Sodium Hydrogen Carbonate – NEUTRALIZATION
It neutralizes stomach acid to provide the necessary alkaline condition (pH 8) for the pancreatic and intestinal enzymes to work

48. The pH Scale Acidic Alkaline Neutral More acidic More basic
Acidic
Alkaline
Neutral
More acidic
More basic

49. The Need for Different pH Levels
The stomach releases hydrochloric acid to provide an acidic condition (pH1 - 2) for stomach proteases (e.g. pepsin) to work. Acid also kills germs
The activity of salivary amylase is stopped in the stomach since it cannot work in acidic conditions. Pancreatic amylase also requires an alkaline condition to work

50. The Need for Different pH Levels
3) The gall bladder releases bile into the small intestine to provide an alkaline condition (pH 8) for the pancreatic and intestinal enzymes to work

51. Bile
3) Bile pigments
Waste products formed from the breakdown of old red blood cells in the liver

52. Investigation #1: Investigating the effect of bile salts on oil

54. Pancreas
A yellowish organ found beneath the stomach and is connected to the small intestine at the duodenum
Produces pancreatic juice that flows into the duodenum through the pancreatic duct

57. Pancreas Pancreatic juice contains 3 types of digestive enzymes:
Tryptase
Amylase
Lipase
*Pancreas also produces the hormones glucagon
and insulin to regulate the level of blood glucose

58. Intestinal Juice
Alkaline solution containing digestive enzymes, hormones, mucus, neutralizing substances, etc.
Secreted by intestinal glands in the wall of the duodenum
e.g. carbohydrases catalyze the breakdown of double sugars into simple sugars

59. Carbohydrase Maltase: Maltose -> Glucose + Glucose
2) Sucrase: Sucrose -> Glucose + Fructose
3) Lactase: Lactose -> Glucose + Galactose

60. Lactose Intolerance
Inability to digest significant amount of lactose, the predominant sugar of milk, due to a shortage of the enzyme lactase
Common symptoms include nausea, cramps, bloating, gas, and diarrhoea
The undigested lactose will serve as food for bacteria found in the large intestine

61. Digestion in Ileum Completion of digestion
Food is churned by peristaltic movement and is mixed with digestive juices
Food becomes watery fluid called chyle
Food is now present in simplest form

62. Absorption

63. Absorption
Absorption is the uptake of simple and small food molecules from the alimentary canal into the blood stream
Food molecules can be absorbed into blood by diffusion or active transport
Absorption occurs in the stomach, the small intestine and the large intestine

64. Absorption in Stomach Food substances that are absorbed in the
Water
Minerals
Alcohol
Simple sugars
Water-soluble vitamins

65. Absorption in Small Intestine
Most of the digested food is absorbed in the small intestine
The inner lining of the small intestine is folded to provide a large surface area
The inner surface of the small intestine is made up of a large number of finger-like projections called villi (singular: villus)
Peristalsis in the small intestine allows the digested food to come into contact with the villi for absorption

70. Structure of Villi Epithelium lining
Blood capillaries (transportation of simple sugars, amino acids and minerals)
Lacteal (lymph vessel)

72. Lacteal
fatty acids and glycerol recombine in the epithelium of the villus to form fat which then enters the lacteal as fine fat droplets
the lymphatic system converges with the circulatory system at a duct located in the neck area

74. They take up the absorbed food and transport them away
4. Each villus contains a dense network of blood capillaries
This allows the food to cross the membrane rapidly
3. The wall of villi is thin (one-cell thick)
These villi can increase the total surface area for absorption
2. Its inner surface is covered with numerous finger-like projections called villi
Food can stay long enough for absorption to occur
1. It is very long (6 m)
Adaptation
Feature

77. Absorption in Large Intestine
Much of the remaining water and minerals is absorbed in the colon
The appendix, which has no known functions, is joined to the caecum
Appendicitis – food materials trapped in the appendix causing bacterial infection

78. Caecum in Herbivores
Do not have digestive enzymes to break down cellulose
Rely on bacteria residing in the long caecum to provide the enzyme cellulase
Cellulose -> Glucose

79. Investigation #2: A Model Gut

80. What does the content inside the dialysis tubing represent?
What does the dialysis tubing represent?
What does the water in the beaker/boiling tube represent?

81. Assimilation

82. Assimilation
the process by which absorbed food molecules in the blood are transported to cells for the use of growth, tissue repair and other metabolic activities. The actual destiny of each food molecule depends not only on its type but also on the body requirements at that time (e.g. use immediately or put into storage)

85. Liver Largest organ of the body Reddish brown in color
Lies on the right side of the abdominal cavity beneath the diaphragm
Blood is carried to the liver via two large vessels called the hepatic artery and the hepatic portal vein
After processing in the liver, blood leaves the liver through the hepatic vein

88. Functions of Liver
Carbohydrate metabolism - the liver converts excess glucose into glycogen as a temporary way of storing the glucose. Glycogen can also be converted back to glucose when needed
Fat metabolism - the liver converts excess protein and carbohydrate into fat. Excess glycogen is stored as fat for long term storage

89. Functions of Liver
3) Protein metabolism – the liver can synthesize new proteins/ amino acids and deaminate excess amino acids

90. Deamination Amino group (~NH2) removed Ammonia (NH3) produced (toxic)
Ammonia converted to urea – excreted in urine
Carbon skeleton – converted to carbohydrates

92. Functions of Liver
3) Protein metabolism – the liver can synthesize new proteins/amino acids and deaminate excess amino acids
4) Vitamin storage - the liver stores mainly vitamins A, D and B12
5) Iron storage - the liver stores iron which is obtained from the breakdown of red blood cells. The iron salts can be used in the formation of new RBC

93. Functions of Liver
6) Bile production – emulsification and neutralization
7) Drug/Alcohol metabolism – the liver changes the drug into an excretable and harmless form (detoxification)
8) Disposal of bacteria - The liver filters many bacteria, viruses, and other microorganisms from the blood

94. Egestion

95. Egestion
Faeces – semi-solid, greenish brown mass containing undigested and unabsorbed food substances. Also contains bile pigment (hence the color of faeces), dead RBC, cells from intestinal wall, bacteria, etc.
Temporarily stored in rectum
Anal sphincter – relaxes to allow a person to defaecate

96. Constipation and Diarrhoea
Peristalsis too slow
Too much water absorbed
Some common causes include lack of fibre in diet, not enough liquids, lack of exercise, etc.
Lead to dry, hard faeces
Difficulty in defaecation
May damage wall of rectum and cause bleeding or form piles
Peristalsis too fast
Too little water absorbed
Some common causes include bacterial / viral / parasitic infections, food intolerance, etc.
Lead to loose, watery stools
More frequent egestion
May cause dehydration

97. Haemorrhoids Also referred to as piles
Haemorrhoids are enlarged veins just under the surface tissue of the rectum or the anus
Haemorrhoids in the rectum are called internal haemorrhoids; those that occur around the anus are called external haemorrhoids
May cause bleeding, pain, itching and a sense of pressure

98. Haemorrhoids
Increased pressure in the veins around the anus is thought to be the cause of haemorrhoids:
straining to pass a bowel motion because of hard, dry stools (as in constipation)
diarrhoea
heavy lifting
being very overweight
sitting or standing for long periods
pregnancy