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ACTIVITY. Can you identify these organs?. Large Intestine. Oesophagus. Small Intestine. Stomach. Can you guess the length of the above organs?. 5 Processes of Nutrition. Ingestion Digestion Absorption Assimilation Egestion. Ingestion. The taking-in of food. Digestion.
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5 Processes of Nutrition • Ingestion • Digestion • Absorption • Assimilation • Egestion
Ingestion • The taking-in of food
Digestion • The breaking down of large molecules into smaller molecules • Rely on action of digestive enzymes
Absorption • The entrance of digested food molecules into blood streams by diffusion or active transport
Assimilation • The transportation of food particles to various parts of the body via blood streams
Egestion • The removal of undigested or unabsorbed food from the body in the form of faeces
Can you match each process to different parts of the alimentary canal?
Ingestion: mouth Digestion: mouth, stomach and small intestine Absorption: mainly in small intestine; some in stomach and large intestine Assimilation: all over body Egestion: anus
Incisors • Located at front of jaws • Sharp and chisel-like edge • For cutting food into pieces • Single root embedded in jaw bone
Canines • Located next to the incisors • Sharp and pointed • For piercing and tearing food • Single root embedded in jaw bone
Premolars • Located on the sides of jaws • Large with a flattened top • Cusps for crushing and grinding food
Molars • Located at the back of the jaws, behind the premolars • Larger than the premolars • For crushing and grinding food
enamel crown dentine capillary nerve endings gum neck pulp cavity cement root periodontal membrane jaw bone
External Structure of a Tooth • Crown – the part above the gum • Neck – the region between the root and the crown that is bounded by the gum • Root – the part embedded in the jaw bone
Internal Structure of a Tooth 1) Enamel • Outermost region • Hardest region of the tooth • 97% of it is made of calcium and magnesium salts • Contains no living cells • Protects the tooth from mechanical damage
Internal Structure of a Tooth 2) Dentine (Ivory) • Middle region of a tooth • Bone-like substance • 73% is inorganic matter (mainly calcium and phosphate crystals) • Make up the bulk of a tooth • Contains odontoblasts, the dentine-forming cells
Internal Structure of a Tooth 3) Pulp cavity • Innermost region of a tooth • Filled with living cells • Contains blood capillaries (to supply nutrients and oxygen to the dentine) and nerve endings (to produce sensations of pressure, pain and temperature) • Blood vessels and nerves enter the tooth through an aperture at the base of the root
Internal Structure of a Tooth 4) Cement • Thin layer of substance covering the dentine in the root • Similar to bone • Attached to a fibrous membrane called periodontal membrane – periodontal fibres connect the cement to the jaw bone • These fibres anchor the tooth firmly in place but still permit slight movement which helps to protect the tooth from mechanical damage
What is the difference between their teeth? I have milk teeth We have permanent teeth
Milk Teeth vs. Permanent Teeth • Milk teeth start to develop after birth • Begin to show when child is about 5 months old • Begin to shed when child is between 7 and 11 years old • Permanent teeth are fully developed by age 17 • Permanent teeth stop growing once they are fully developed, and cannot be replaced if damaged
Dentition and Dental Formula • Dentition – represents the number and arrangement of different types of teeth • Dental formula – a formula that shows the number of different types of teeth on the upper and the lower jaws • i = incisorsc = canines pm = premolarsm = molars
Dentition of Herbivores • Herbivores – feed on plants only • Their dentition is adapted for cutting and grinding grasses and plant tissues • Diastema – a space in front of the premolars to allow grass to be moved freely inside the mouth
Dentition of Carnivores • Carnivores – feed on animals only • Their dentition is adapted for killing preys and eating animal tissues (e.g. gripping, cutting and tearing flesh, etc.) • Carnassial teeth – the last upper premolar and the first lower molar on each side of the jaws. Can cut through flesh and crush bones when the jaws move up and down