F4 Biology teaching notes Ch 6: NE 23

6.2  Ingestion (攝食) (Book 1A, p. 6-6)

Ø  In the mouth cavity, food is cut up into small pieces

by the (1) teeth.

Ø  (2) Mastication (咀嚼) is the process of chewing food into small pieces.

A  What types of teeth do we have? (Book 1A, p. 6-6)

	Type of tooth	Shape and feature	Function
A	(3) incisors (門齒)	n (4) chisel-shaped (鑿形的) with flat sharp edges n  Has one root (齒根)	Biting and (5) cutting food
B	(6) canines (犬齒)	n (7) pointed and curved n Has one (8) root	(9) Tearing flesh
C	(10) premolars (前臼齒)	n Broad top with (11) cusps (尖突) n Has one or two roots	(14) Crushing and (15) grinding food
D	(12) molars (臼齒)	n Similar to (13) premolars but larger n Has two or three roots

B  What is the dentition of humans? (Book 1A, p. 6-7)

Ø   (16) Dentition (齒系):

n   refers to the numbers and (17) arrangement of different types of teeth in a mammal

n   can be represented by a (18) detal formula (齒式):

Ø   Humans have two sets of teeth:

(19) Milk teeth (乳齒)	(20) Permanent teeth (恆齒)
n Appear during the first two years of life n are replaced by another set of teeth n Dentition: (21) 2012 2102	n Replace the milk teeth between the ages of 6 and 12 n no further replacedment n Dentition: (22) 2123                            2123