Class:
6
6.1
(
Name:
)
Date:
Nutrition in humans
The human digestive system
(Book 1A, p. 6-3)
(1) _______________ (營養) in humans consists of five main processes:
(2) _______________ (攝食):
Food is taken in through the
(3) _______________.
(4) _______________ (消化):
Food is broken down into
(5) _______________ and simple
molecules.
(6) _______________ (吸收):
The soluble and simple food molecules
enter the (7) _______________ system.
digested
food
(8) _______________ (同化):
The absorbed food molecules are taken
up by cells for (9) _______________.
undigested
food
(10) _______________ (排遺):
The undigested and unabsorbed
materials are removed from the body as
(11) _______________ (糞便).
Nutrition in humans takes place in the (12) _______________ system (消化系統), which
consists of the (13) _______________ _______________ (消化道) and its associated
(14) _______________ _______________ (消化腺).
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The human digestive system:
mouth cavity (口腔)
tongue
tooth
(20) _______________ (咽)
(15) _______________
_______________ (唾腺)
(21) _____________ (食道)
liver (肝)
(16) _______________
(22) _______________ (胃)
_______________ (膽囊)
(23) _______________ (胰)
bile duct (膽管)
pancreatic duct (胰管)
small intestine (小腸)
large intestine (大腸)
(17) _______________
(24) _______________
(十二指腸)
(結腸)
(18) _______________
caecum (盲腸)
(迴腸)
appendix (闌尾)
(19) _______________
(25) _______________
(肛門)
(直腸)
The alimentary canal receives (26) _______________ _______________ (消化液) secreted
from a number of digestive glands, e.g. the salivary glands, the pancreas and the liver.
Go to
Practical 6.1
Examination of the mammalian digestive system
(Book 1A, p. 6-5; Practical Workbook for SBA 1A, p. 6-1)
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6.2
Ingestion
(Book 1A, p. 6-6)
In the mouth cavity, food is cut up into small pieces by the (1) _______________. The process
of chewing food into small pieces is called (2) _______________ (咀嚼).
A
What types of teeth do we have?
Type of tooth
(3) _______________
(門齒)
(Book 1A, p. 6-6)
Shape
(4) _______________-shaped
Biting and
(鑿形的),
(5) _______________
with flat sharp edges
food
Has one root
(6) _______________
(7) _______________ and
curved
(犬齒)
Function
(8) _______________
flesh
Has one root
(9) _______________
(前臼齒)
Broad top with
(10) _______________ (尖突)
Has one or two roots
Similar to premolars but
(11) _______________
(12) _______________
(臼齒)
(larger / smaller)
(13) ______________ and
(14) ______________
food
Has two or three roots
B
What is the dentition of humans?
(Book 1A, p. 6-7)
(15) _______________ (齒系) refers to the numbers and arrangement of different types of teeth
in a mammal. It can be represented by a (16) _______________ _______________ (齒式).
Humans have two sets of teeth:
(17) ______________ ______________ (乳齒)
(19) ______________ ______________ (恆齒)
Appear during the first two years of life
Replace the milk teeth between the ages of
6 and 12
Dentition: (18) _______________
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Dentition: (20) _______________
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C
What is the structure of a tooth?
(Book 1A, p. 6-8)
(24) _______________ (琺瑯質)
(25) _______________ (牙本質)
(21) _______________
(26) _______________
(齒冠)
_______________ (髓腔)
(22) _______________
gum (齒齦)
(齒頸)
jawbone (顎骨)
(23) _______________
(27) _______________
(齒根)
_______________ (牙周膜)
(28) _______________ (牙骨質)
▲ Structure of a canine
Each tooth consists of three layers:
Layer
Feature
The outermost, hardest part of the crown
Non-living, made mainly of (29) _______________ salts
Enamel
Protects the tooth from wearing down
Replaced by (30) _______________ around the roots. The cement and the
(31) _______________ _______________ fix the tooth to the jawbone
The middle region of the tooth
Dentine
A (32) _______________-like substance; not as hard as the enamel
With strands of living (33) _______________ running through
Contains (34) _______________ (living / non-living) cells
Contains (35) _______________ _______________ to supply oxygen and
Pulp cavity
nutrients to the tooth, and remove wastes from it
Contains (36) _______________ _______________ which detect
temperature and pressure
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6.3
A
Digestion
(Book 1A, p. 6-11)
Why is digestion necessary?
(Book 1A, p. 6-11)
The wall of the alimentary canal is (1) _______________ permeable. Large, complex food
molecules must be broken down into small, (2) _______________ molecules so that they can
pass through the wall and enter the blood.
The process of breaking down food into small molecules is called (3) _______________.
B
1
Physical digestion and chemical digestion
(Book 1A, p. 6-11)
Physical digestion (機械消化)
It is the breaking down of food into smaller pieces by physical actions.
It increases the (4) _______________ _______________ of food in contact with the digestive
juices.
It is brought about by:
2
-
Chewing in the mouth cavity, i.e. (5) _______________
-
(6) _______________ (劇烈攪動) in the stomach
-
(7) _______________ along the alimentary canal
-
(8) _______________ (乳化) of lipids by bile salts (膽鹽) in the small intestine.
Chemical digestion (化學消化)
It involves (9) _______________ reactions in which large, complex food molecules are
broken down into small, simpler forms. The reactions are catalysed by (10) _______________
_______________ (消化酶).
Three main types of digestive enzymes in our digestive system:
Type of enzyme
I
Carbohydrases (碳水化合物酶)
Function
a
Break down proteins into polypeptides,
peptides and amino acids
II
Proteases (蛋白酶)
b
Break down lipids into fatty acids and
glycerol
III Lipases (脂肪酶)
c
Break down complex carbohydrates into
simpler sugars
I: (11) _____________
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II: (12) ____________
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III: (13) ____________
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C
Digestion in the mouth cavity
(Book 1A, p. 6-12)
In the mouth cavity, food is chewed into smaller pieces by the teeth and mixed with
(14) _____________ (唾液), which contains:
Component
Function
(15) _______________
_______________
Catalyses the breakdown of starch into (16) ____________
(唾液澱粉酶)
(17) _______________
Helps bind food particles together
(黏液)
Moistens and (18) _______________ the food
Water
(19) _______________ soluble substances in the food
After chewing, the tongue rolls the food into a (20) _______________ (食團), which is then
swallowed down the oesophagus through the pharynx.
1 The tongue rises to push the bolus towards the pharynx.
2 The soft palate (軟腭) moves up to prevent the bolus from
entering the (21) ______________
nasal
cavity
______________.
3 The larynx rises so that the epiglottis (會厭) covers the
opening to the trachea. This prevents the bolus from entering
the (22) _______________.
trachea
▲ The swallowing process
4 The bolus enters the oesophagus.
When the bolus enters the oesophagus, it is pushed down the oesophagus to the stomach by
(23) _______________, which is produced by the alternate contraction and relaxation of
the (24) _______________ muscles (縱肌) and (25) _______________ muscles (環肌) in the
wall of the alimentary canal.
Peristalsis has the following importance:
-
It pushes food along the oesophagus and other parts of the alimentary canal.
-
It helps (26) _______________ the food with the digestive juices.
-
It increases the (27) _______________ between the wall of the alimentary canal and
digested food to facilitate (28) _______________.
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D
Digestion in the stomach
(Book 1A, p. 6-13)
The entrance of the stomach is guarded by the (29) _______________ _______________
(賁門括約肌). The exit
is guarded by the (30) _______________ ______________ (幽門括約肌).
Gastric glands (胃腺) on the stomach wall produce (31) ____________ _____________ (胃液),
which contains:
Component
Function
Catalyses the breakdown of proteins into (33) ______________
(32) _______________
(胃蛋白酶)
Works best in an (34) _______________ (acidic / alkaline)
medium
(35) _______________
Provides an acidic medium for the action of pepsin
_____________ (氫氯酸)
Kills most (36) _______________ in food
Protects the stomach wall from being digested by the
Mucus
(37) _______________ and being damaged by the
(38) _______________ _______________
Muscles in the stomach lining contract to churn the food into (39) _______________ (食糜),
which is then released into the duodenum.
E
1
Digestion in the small intestine
(Book 1A, p. 6-16)
Bile
(40) _______________ (膽汁) is produced by the (41) _______________. It is temporarily
stored in the (42) _______________ _______________ and is released through the bile duct
into the (43) _______________. Bile contains:
Component
Bile salts
Function
(44) _______________ lipids into small droplets to
facilitate the chemical digestion of lipids
(45) _______________
_______________ (膽色素)
(46) _______________
_______________ (碳酸氫鈉)
Do not take part in digestion
(47) _______________ the acidic chyme
Provides an (48) _______________ (acidic / alkaline)
medium for the action of enzymes in the small intestine
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2
Pancreatic juice
Pancreatic juice is produced by the (49) _______________. It is carried along the
(50) _______________ _______________ to the duodenum. Pancreatic juice contains:
Component
Function
Pancreatic amylase
Catalyses the breakdown of the remaining starch into maltose
Catalyse the breakdown of some proteins into peptides, and
(51) _______________
some peptides into amino acids
Catalyses the breakdown of the emulsified lipids into
Pancreatic lipase
(52) _____________ _______________ and glycerol
Neutralizes the acidic chyme
Sodium
Provides an (53) _______________ (acidic / alkaline) medium
hydrogencarbonate
for the action of the enzymes in the small intestine
3
Intestinal juice
Intestinal juice is produced by some glands in the wall of the small intestine. It is slightly
(54) _______________ (acidic / alkaline).
It mainly contains water, mucus and sodium hydrogencarbonate.
The (55) _______________ of the small intestine has specialized cells that have various
enzymes on their cell membranes. These enzymes include:
Enzyme
Function
(56) _______________
Catalyse the breakdown of disaccharides into monosaccharides
(57) _______________
Catalyse the breakdown of some peptides into amino acids
Go to
Practical 6.2
Investigation of the action of pepsin
(Book 1A, p. 6-14; Practical Workbook for SBA 1A, p. 6-4)
Practical 6.3
Demonstration of the effect of bile salts on oil
(Book 1A, p. 6-17; Practical Workbook for SBA 1A, p. 6-8)
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6.4
Absorption
(Book 1A, p. 6-20)
Absorption of food molecules mainly takes place in the (1) ______________.
A
How is the small intestine adapted for absorption?
mitochondria
small intestine
villi (絨毛)
(Book 1A, p. 6-20)
a villus
mircovilli
(微絨毛)
epithelial cell of villus
lacteal (乳糜管)
capillaries
▲ Structure of the small intestine showing the villi
Feature
Adaptation for absorption
Being very long
Inner wall highly-(2) ______________
with numerous (3) ______________
Increase the (5) _____________ _____________
for absorption
Numerous (4) ______________ on the
epithelial cells of villi
Thin (6) ______________
Reduces the (7) ______________ for diffusion
of food molecules into the blood
Allow the absorbed food molecules to be carried
Presence of lacteals and a network of
(8) ______________
away rapidly, thus keeping a steep
(9) ______________ ______________ of food
molecules across the wall of the small intestine to
increase the rate of (10) ______________
Movement of the villi caused by
Keeps a steep concentration gradient of food
(11) ______________
molecules across the wall of the small intestine
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B
1
How is digested food absorbed?
(Book 1A, p. 6-21)
Absorption into the blood
Water-soluble food molecules, e.g. monosaccharides, amino acids, minerals and watersoluble vitamins, can be absorbed into the capillaries by (12) ______________ and
(13) ______________ ______________.
As the absorption of digest food into the blood (14) ______________ (increases / decreases)
the water potential of the content in the small intestine, water is drawn into the blood by
(15) ______________.
2
Absorption into the lymph
Fatty acids and glycerol enter the epithelium of the villi by (16) ______________. In the
epithelial cells, they recombine into fine (17) ______________ ______________, which then
enter the lacteals of the lymphatic system. (18) ______________-______________ vitamins
are also absorbed into the lacteals.
amino acids
monosaccharides
minerals,
water-soluble
vitamins
epithelial cell
capillary
lacteal
fine lipid droplets
glycerol
lipid-soluble
vitamins
fatty acids
The lipids and lipid-soluble vitamins in the lacteals are transported to the main
(19) ______________ ______________ (淋巴管), and eventually to the bloodstream near the
neck region.
Go to
Practical 6.4
Simulation of digestion and absorption in the small intestine using dialysis tubing
(Book 1A, p. 6-23; Practical Workbook for SBA 1A, p. 6-10)
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6.5
Assimilation of the absorbed food
(Book 1A, p. 6-26)
Assimilation is the uptake and use of absorbed food molecules by cells for (1) ______________.
A
How is the absorbed food transported to other parts of the body?
(Book 1A, p. 6-26)
Transport of absorbed food from the villus to other parts of the body through different vessels:
(4)
(5)
(3)
heart
liver
(6)
(2)
lipids and
lipid-soluble
vitamins
monosaccharides,
amino acids, minerals and
water-soluble vitamins
all parts
of the body
villus
a
aorta (大動脈)
b
hepatic portal vein (肝門靜脈)
d
lymph vessel
e
vena cava (腔靜脈)
(2): ________
B
(3): ________
(4): ________
Glucose
hepatic vein (肝靜脈)
(5): ________
What are the fates of the absorbed food?
Absorbed food
c
(6): ________
(Book 1A, p. 6-27)
Fate
Used by body cells for releasing (7) ______________
Converted to (8) ______________ or lipids for storage if in excess
Amino acids
Used by cells to make (9) ______________
(10) ______________ in the liver if in excess
Used by cells to make cell membranes and some hormones
Lipids
As energy (11) ______________
Deposited around the internal organs or build up in (12) _____________
tissue if in excess
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C
What are the roles of the liver?
(Book 1A, p. 6-27)
The liver has the following functions:
Regulation of the blood (13) ______________ level by converting excess glucose to
(14) ______________, which is stored in the liver, and converting the stored glycogen to
glucose, which is released into the (15) ______________
Storage of glycogen, iron and (16) ______________-______________ vitamins
Production of bile
Production of vitamin A from (17) ______________
(18) ______________ (脫氨作用): breaking down excess amino acids and converting the amino
groups into (19) ______________ (尿素)
(20) ______________ (解毒)
6.6
Egestion
(Book 1A, p. 6-30)
In the large intestine, the undigested and unabsorbed materials form the (1) ______________.
Faeces contain dietary fibre, bacteria, secretions from the alimentary canal, dead cells from
the intestinal wall and a small amount of water. They are brown in colour because of the
presence of (2) ______________ ______________.
Faeces are temporarily stored in the (3) ______________.
When the (4) ______________ ______________ (肛門括約肌) relaxes and the muscles of the
rectum contract, faeces are pushed out through the anus. The process of expelling faeces from
the body is called egestion or (5) ______________ (排糞).
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Answers
Ch 6
Nutrition in humans
6.1
1
Nutrition
2
Ingestion
3
mouth
4
Digestion
5
soluble
6
Absorption
7
circulatory
8
Assimilation
9
metabolism
10
Egestion
11
faeces
12
digestive
13
alimentary canal
14
digestive glands
15
salivary glands
16
gall bladder
17
duodenum
18
ileum
19
anus
20
pharynx
21
oesophagus
22
stomach
23
pancreas
24
colon
25
rectum
26
digestive juices
6.2
1
teeth
2
mastication
3
Incisor
4
Chisel
5
cutting
6
Canine
7
Pointed
8
Tearing
9
Premolar
10
cusps
11
Molar
12
larger
13
Grinding / Crushing
14
crushing / grinding
15
Dentition
16
dental formula
17
Milk teeth
18
2102/2102
19
Permanent teeth
20
2123/2123
21
crown
22
neck
23
root
24
enamel
25
dentine
26
pulp cavity
27
periodontal membrane
28
cement
29
calcium
30
cement
31
periodontal membrane
32
bone
33
cytoplasm
34
living
35
blood vessels
36
nerve fibres
1
differentially
2
soluble
3
digestion
4
surface area
5
mastication
6
Churning
7
Peristalsis
8
Emulsification
9
chemical
10
digestive enzymes
11
c
12
a
13
b
14
saliva
15
Salivary amylase
16
maltose
17
Mucus
18
lubricates
19
Dissolves
20
bolus
21
nasal cavity
22
trachea
23
peristalsis
24
longitudinal / circular
25
circular / longitudinal
26
mix
27
contact
28
absorption
29
cardiac sphincter
30
pyloric sphincter
31
gastric juice
32
Pepsin
33
peptides
34
acidic
35
Hydrochloric acid 36
bacteria
37
pepsin
38
hydrochloric acid
39
chyme
40
Bile
41
liver
42
gall bladder
43
duodenum
44
Emulsify
45
Bile pigments
46
Sodium hydrogencarbonate
47
Neutralizes
48
alkaline
49
pancreas
50
pancreatic duct
51
Proteases
52
fatty acids
53
alkaline
54
alkaline
55
epithelium
56
Carbohydrases
57
Proteases
6.3
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6.4
1
ileum
2
folded
3
villi
4
microvilli
5
6
epithelium
7
distance
8
capillaries
9
concentration gradient
10
diffusion
11
peristalsis
12
diffusion
13
active transport
14
increases
15
osmosis
16
diffusion
17
lipid droplets
18
Lipid-soluble
19
lymph vessels
1
metabolism
2
b
3
c
4
e
5
a
6
d
7
energy
8
glycogen
9
proteins
10
Deaminated
11
reserves
12
adipose
13
glucose
14
glycogen
15
blood
16
lipid-soluble
17
carotene
18
Deamination
19
urea
20
Detoxification
faeces
2
bile pigments
3
rectum
4
anal sphincter
5
defaecation
surface area
6.5
6.6
1
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