F4 Biology teaching notes Ch 6: NE 29

C  What are the roles of the liver? (Book 1A, p. 6-27)

Ø  Metabolism of carbohydrates

n  Regulation of the blood (17) glucose level by converting:

l excess glucose to (18) glycogen, which is stored in the liver è ¯ blood glucose level

l the stored glycogen to glucose, which is released into the (19) blood

è ­ blood glucose level

http://bcs.whfreeman.com/thelifewire/content/chp50/5002002.html (動畫: 胰島素與高血糖素的影響)

http://www.wiley.com/college/fob/quiz/quiz15/15-21.html (動畫: 糖原代謝的激素調節)

Ø  Metabolism of lipids

n  conversion of excess carbohydrates to (20) lipids for energy storage

n  release energy by breaking down the stored lipids according to body needs

Ø   Metabolism of proteins                                                                   èFig15: Transamination

n  (21) Deamination (脫氨作用): breakdown of excess amino acids:

l amino groups are converted into (22) urea (尿素) for excretion through kidney

l remaining carbon skeletons are broken down to release energy in respiratory pathway

n  (23) Transamination (轉氨): synthesis of different (24) non-essential amino acid

Ø   Production                                        

n  bile (contains metabolic wastes of haemoblobin)     

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter21/animation__hemoglobin_breakdown.html (動畫: 血紅蛋白的分解)                                                           

n  vitamin A from (25) carotene (胡蘿蔔素)

n  (26) Heat which is distributed throughout body through bloodstream

Ø  Storage

n  glycogen and lipids

n  iron (where is it from?)

n  (27) Lipid-soluble vitamins (e.g. vitamins A and D)

Ø   (28) Detoxification (解毒)

6.6 Egestion (Book 1A, p. 6-30)

Ø  (1) Faeces is formed in the large intestine from:

n  the undigested and unabsorbed materials like (2) dietary fibres

n  secretions (分泌物) from the alimentary canal

n  bacteria

n  dead cells from the intestinal wall

n  a small amount of water

n  (3) bile pigment which gives the faeces a brown colour

Ø   Faeces are temporarily stored in the (3) rectum (直腸), and are pushed out through the anus

Ø   Egestion or (5) defecation (排糞) is the process of expelling faeces from the body:

n   the (4) anal sphincter (肛門括約肌) relaxes                

n   the muscles of the rectum contract

http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter16/animation__reflexes_in_the_colon.html (動畫: 結腸反射)

F4 Biology teaching notes Ch 6: NE 28

B  What are the fates of the absorbed food? (Book 1A, p. 6-27)

Absorbed food	Fate
Glucose	n used by body cells for releasing energy by (8) respiration n excess glucose are converted to: l (9) glycogen and stored in liver and muscles l lipids in the liver for storage
Amino acid	n used by cells to make different (10) proteins: l structural molecules for growth and repair l functional molecules, e.g. (11) enzymes, antibody and hormones n excess amino acids are (12) deaminated in the liver: l amino group is converted to (13) urea (尿素) à blood    à kidney à excreted (排泄) in urine l remained part à respiratory pathway (呼吸作用途徑) à release energy
Lipids	n  As energy (14) reserves n  Used to make cell (15) membrane and some hormones n  stored in (16) adipose tissue if in excess: l Deposited around the internal organs l build up under skin

http://www.wiley.com/college/fob/quiz/quiz15/15-1.html (動畫: 葡萄糖代謝)

http://nutrition.jbpub.com/resources/animations.cfm?id=18&debug=0 (動畫: 脫氨)

http://www.wiley.com/college/fob/quiz/quiz20/20-8.html (動畫: 尿素週期)

http://www.wiley.com/college/boyer/0470003790/animations/fatty_acid_metabolism/fatty_acid_metabolism.htm (動畫: 脂肪消化, 吸收與代謝)

F4 Biology teaching notes Ch 6: NE 27

6.4  Absorption (Book 1A, p. 6-20)

Ø   Absorption of food molecules mainly takes place in

the (1) small intestine, only small amounts

take place in the stomach and the large intestine.                                  

A  How is the small intestine adapted for absorption? (Book 1A, p. 6-20)

Feature	Adaptation for absorption
Ileum is very long	n Increase the surface area for absorption n Increase the time for absorption
n Inner wall is highly-(2)folded (摺疊) n with numerous (3) villi (絨毛) n Numerous (4) microvilli on the epithelial cells of villi) (brush border刷狀緣)	Increase the (5) surface area for absorption èFig10: Inner wall of ileum, villi and epithelium èFig11: Photomicrograph of villus and its epithelium èFig12: Villi, epithelium and microvilli
Thin (6) epithelium (上皮) (one-cell think)	Reduces the (7) diffusion distance for diffusion of food molecules into the blood
Present of associated transport system: n a network of (8) blood capillaries n (9) lacteal (乳縻管)	n Rapidly carry away the absorbed food molecules, thus n keeping a steep concentration gradient of food molecules across the wall of the small intestine to increase the rate of (10) ____________________________
Movement of the villi caused by (11) peristalsis	n Keep villi contact with newly digested food molecules n Keeps a steep (12) concentration gradient of food molecules across the wall of the small intestine to increase the rate of diffusion

http://www.youtube.com/watch?v=XSUalboGM0A&feature=related (youtube: 小腸)

http://www.youtube.com/watch?v=iK8MOA32vAY&feature=related

B  How is digested food absorbed? (Book 1A, p. 6-21)

http://bcs.whfreeman.com/thelifewire/content/chp50/5002001.html (動畫: 脂肪的吸收)              

1      Absorption into the blood

n  Water-soluble food molecules, e.g. monosaccharides, amino acids, minerals and water- soluble

vitamins, can be absorbed into the capillaries by (13) diffusion and (14) active transport.

n  As the absorption of digest food into the blood (15) increases / decreases the water potential of the content in the small intestine, water is drawn into the blood by (16) osmosis.

2      Absorption into the lymph (淋巴)

n  Fatty acids and glycerol enter the epithelium of the villi by (17) diffusion.

n  In the epithelial cells, they recombine into fine (18) lipid droplet, which then enter the (19) lacteal of the lymphatic system (淋巴系統).

n  (20) Lipid-soluble vitamins are also absorbed into the lacteals.

n  The lipids and lipid-soluble vitamins in the lacteals are transported to the main (21) lymph vessel (淋巴管), and eventually to the bloodstream near the neck region.

	Water-soluble substances	Lipid-soluble substances
Example	l monosaccharides, amino acid l minerals and water soluble vitamins	l Fatty acid and glycerol l Lipid-soluble vitamins
Ways of absorption	l  Food substances are absorbed by diffusion and active transport l  Water is absorbed by osmosis	Diffusion
Transport	microvilli à epithelium à capillary network in villi à hepatic portal vein (肝門靜脈) à Liver à hepatic vein (肝靜脈) à heart à different parts of body	epithelium à reform lipid à lacteals (乳糜管)   à lymph vessels (淋巴管) à heart à different parts of body

Ø  Over 90% of water are absorbed in stomach and small intestine by (22) osmosis.

Ø  Only small amounts water and minerals are absorbed in (23) large intestine.