F4 Biology teaching notes Ch 6: NE 26

E  Digestion in the small intestine (Book 1A, p. 6-16)

http://trc.ucdavis.edu/biosci10v/bis10v/media/ch24/small_intestine.html (動畫: 小腸結構)

Ø   Small intestine:

n  (51) Duodenum (十二指腸) (~20cm)

n  Ileum (迴腸) (~5m)

Ø   Digestive juices in the small intestine:

1      Bile (膽汁)                                                                    

n   is produced by the (52) liver

n   is temporarily stored in the (53) gall bladder and is released through the (54) bile duct into the duodenum

n   contains:

Component	Function / Feature
(55) Bile salt (膽鹽)	l  For physical digestion: ²  (56) emulsify lipids into small droplets微滴 ²  to increase the (57) surface area in contact with the lipase ²  to facilitate the chemical digestion of lipids
(58) Bile pigment (膽色素)	l  Do not take part in digestion l  Green pigment formed from the (59) haemoglobin of the worn-out red blood cells
(60) Sodium hydrogencarbonate (碳酸氫鈉)	l  (61) Neutralizes the acidic chyme l  Provides an (62) alkaline medium for the action of enzymes in the small intestine
Does not contain any (63) enzymes

http://bcs.whfreeman.com/thelifewire/content/chp50/5002001.html (網上教室: 脂肪消化與吸收)

http://digestive.niddk.nih.gov/ddiseases/pubs/gallstones/ (網頁: 膽石)

2      Pancreatic juice (胰液)                                    èFig 8: Liver, gall bladder and pancreas

n   is produced by the (63) pancreas.

n   is carried along the (64) pancreatic duct to the duodenum

n   contains:

Component		Function
Enzymes	(65) Pancreatic amylase (胰澱粉酶	l   Catalyses the breakdown of the remaining starch into (66) maltose
	(67) Proteases (蛋白酶)	l   Catalyse the breakdown of some proteins into (68) peptides
	Peptidase	l  Catalyses the breakdown of some peptides into amino acids
	(69) Pancreatic lipase            (胰脂肪酶)	l  Catalyses the breakdown of the emulsified lipids into (70) fatty acids and glycerol
	Nuclease (核酸酶)	l   Catalyses the breadown of nucleic acid
Sodium hydrogencarbonate (碳酸氫鈉)		l  Neutralizes the acidic chyme l  Provides an (71) alkaline medium for the action of the enzymes in the small intestine

http://www.yteach.com/page.php/resources/view_all?id=pepsin_pepsin_proteins_pepsinogen_peptide_bond_peptide_bond_breakdown_polypeptide_chain_pro_rennin_protein_protein_digestion_rennin_salivary_amylase_short_chain_polypeptide_small_intestine_stomach_tripeptide_trypsin_villi_t_page_8&from=search (動畫: 小腸蛋白消化)

http://www.mayoclinic.com/health/pancreatitis/DS00371 (網: 胰臟炎)

3      Intestinal juice (腸液)

n   is produced by some (72) glands in the wall of the small intestine.

n   is slightly (73) acidic / alkaline

n   mainly contains:

Component	Function
Water
(74)  Mucus	l   Lubricates the intestinal wall l   Prevents self-digestion (自我消化)
(75) Sodium hydrogencarbonate	l  (76) Neutralizes the acidic chyme l   Provides an alkaline medium for the action of the enzymes in the small intestine

n   The (77) epithelium of the small intestine has specialized cells that have various enzymes on their cell membranes. These enzymes include:

Enzyme		Function
(78)     Carbohydrases		Catalyse the breakdown of disaccharides into (79) monosaccharides (單糖)
e.g.	Maltase (麥芽糖酶)	Maltose à Glucose
	Sucrase (蔗糖酶)	Sucrose à Glucose + Fructose (果糖)
	Lactase (乳糖酶)	Lactose à Glucose + Galactose (半乳糖)
(80)             (protease/肽酶peptidase)		Catalyse the breakdown of some peptides into (81)amino acid
Lipase		Catalyses the breakdown of lipide into Glycerol and(82) fatty acids

Misconception Bile is not produced in gall bladder. Instead, it is produced in liver but is temporarily stored in gall bladder