Ø
Functions of stomach:
n
To
store food temporarily
n
To
carry out partial digestion of food (proteins)
Ø
Structure of stomach:
n
a sac-like organ formed by muscles
n
The entrance and the exit is
guarded by sphincter muscles (括約肌)
(35) Cardiac
sphincter
(賁門括約肌)
|
(36) Pyloric sphincter
(幽門括約肌)
|
l
Guard the entrance
l
Prevent the backflow of food to
(37) oesophagus
|
l
Guard the exit to
l
Open periodically (週期性打開) to release
digested food
to (38) duodenum
|
n Gastric glands (胃腺) on the stomach
wall produce (39) gastric juice (胃液), which contains:
Component
|
Function
|
(40)
Pepsin
(胃蛋白酶)
|
l Catalyses the
breakdown of proteins into (41) peptides
l Works best in an (42) acidic /
|
(43)
Hydrochloric acid
(HCl, 氫氯酸)
|
l Provides an (44) acdic medium for:
² the action of
pepsin
² stopping the action of
salivary amylase
l
Kills most (45) bacteria in food
|
(46)
Mucus
(黏液)
|
l Protects the stomach wall from being:
² digested by the
(47) enzymes / pepsin
²
damaged by the (48) hydrochloric acid
|
Ø
Digestion
of stomach:
Mechanical Digestion
|
Chemical Digestion
|
n Peristaltic
movement of muscles:
l To chun (攪動) the food into
small pieces
l To mix the food
with (49) gastric
juice
|
n Enzymes
catalyse the protein digestion
|
Food is digested into (50) chyme (食糜) which is released into the duodenum
(十二指腸)
|
http://hk.health.nextmedia.com/index.php?fuseaction=DiseaseDB.ViewDiseaseDetail&cat_id=503415&dis_id=503850 (web: 胃酸倒流)
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