Absorption 20/4/09 Prepared by Miss Izzati Apr 09

Previously…

3 GROUP ACTIVITY You are provided with: 1.Organs Cards (O) 2.Physical Digestion Cards (P) 3.Chemical Digestion Cards (C) 4.Mahjong Paper with body outline. 5.Markers (to draw arrows).

4 Instructions 1.Label all the organs in the digestive system. Use all the Organs (O) cards. 2.Label all the physical digestion processes that you have learnt. Stick the Physical Digestion (P) cards near the correct body part where the process occurs. 3.Label all the chemical digestion processes that you have learnt. Stick the Chemical Digestion (C) cards near the correct body part where the process occurs. 4.Fastest group wins!

5 Example (O) oesophagus (P) chewing Starch  maltose amylase

6 INGESTION DIGESTION ABSORPTION EGESTION ASSIMILATION Food is taken into body Carbohydrates, proteins and fats are broken down into soluble glucose, amino acids, fatty acids and glycerol. Glucose, amino acids, fatty acids and glycerol are absorbed into body cells Removal of undigested food e.g. dietary fibre Absorbed nutrients are transported and utilized by the body

7 ABSORPTION Monosaccharides (glucose, fructose and galactose), amino acids, fatty acids, glycerol and water are absorbed in the small intestine. The absorbed nutrients passes from the lumen of the small intestine into the bloodstream. lumen

How to ensure that nutrients are quickly absorbed?

9 Adaptations of the Small Intestine 1.Large surface area: volume ratio 1.1The inner walls of the small intestine have numerous folds

10 Adaptations of the Small Intestine 1.Large surface area: volume ratio 1.2Folded inner walls are lined with numerous minute finger-like projections called villi Intestinal%20villi%20Jejunum-A.jpg

11 1.Large surface area: volume ratio 1.3The epithelial cells of the villi have numerous microvilli. Adaptations of the Small Intestine

12

13 Adaptations of the Small Intestine 2.The villi wall (epithelial cell layer) is only one cell thick.

14 Adaptations of the Small Intestine 3.Presence of numerous capillaries to carry away the absorbed nutrients. blood capillaries Lacteal/lymphatic capillary Digested food enters villus lumen epithelial cell layer

15 Adaptations of the Small Intestine Blood capillaries: transport monosaccharides and amino acids. Lymphatic capillaries (lacteals): transport fats The continual removal of nutrients maintains a concentration gradient for diffusion. liver

16 Adaptations of the Small Intestine 4.Small intestine is long to provide sufficient time for absorption. The small intestine is about 6m long!

How are the nutrients absorbed? Recall what you have learnt in the topic Movement of Substances! (Diffusion, osmosis, active transport….) glucose amino acids Fatty Acids glycerol

18 What type of movement occurs through the epithelium in these situations? High concentration of glucose and amino acids in the lumen of the small intestine. Low concentration of glucose and amino acids in the lumen of the small intestine. High concentration of fatty acids and glycerol in the lumen of the small intestine High water potential in the lumen of the small intestine. High concentration of minerals salts in the lumen of the small intestine.

19 How does absorption take place in the villi? Soluble substanceType of movement into the epithelium Note: Monosaccharides (e.g: glucose) Diffusion Active Transport High conc. in lumen low conc. in lumen Amino AcidsDiffusion Active transport High conc. In lumen low conc. In lumen Fatty acids and glycerolDiffusionGlycerol and fatty combine to form small fat droplets that enter the lacteals. WaterOsmosisEnter the blood capillaries Mineral SaltsDiffusionEnter the blood capillaries Water soluble vitamins (B and C) DiffusionEnter the blood capillaries Fat –Soluble Vitamins (A, D, E and K) DiffusionEnter the lacteals

20 SUMMARY Adaptations of the small intestine: 1.Large SA: Vol.  folds, villi and microvilli. 2.Villi epithelial wall is one cell thick  rapid diffusion. 3.Blood capillaries and lacteals  maintain concentration gradient. 4.Long  allows sufficient time for absorption Movement into villi: Glucose and amino acids absorbed by diffusion or active transport into blood capillaries of the villi. Glycerol and fatty acids diffuse into the epithelium  combine to form minute fat globules which enter lacteals. Water and mineral salts are also absorbed by the small intestine.

21 Egestion In the colon, water and mineral salts are absorbed from the undigested food material. Bacterial Activity Presence of dietary fibre/roughage helps in peristalsis. Unabsorbed matter is stored temporarily in the rectum. Faeces is discharged through the anus. colon rectum anus

22 INGESTION DIGESTION ABSORPTION EGESTION ASSIMILATION Food is taken into body Carbohydrates, proteins and fats are broken down into soluble glucose, amino acids, fatty acids and glycerol. Glucose, amino acids, fatty acids and glycerol are absorbed into body cells Removal of undigested matter e.g. dietary fibre Absorbed nutrients are transported and utilized by the body

23 QUICK CHECK 1.Which one of the following features of the small intestine does not help in its function of absorption? a)The constant production of mucus b)The folding of its inner surface c)One cell thick villi wall d)Presence of villi and microvilli.

24 QUICK CHECK 2.Which of the following statements correctly describe the labelled diagram? IIIIII ABlood capillary LactealEpithelial cell B LactealBlood capillary C Epithelial cell Lacteal DEpithelial cell Blood capillary Lacteal I III II

25 QUICK CHECK 3.Which of the following statements correctly describe the functions of II and III? IIIII ATransports monosaccharides and amino acids Transports fats BTransports proteinsTransports glycogen CTransports monosaccharides and amino acids Transports fatty acids and glycerol DTransports fatsTransports monosaccharides and amino acids. I III II

26 QUICK CHECK 4.How are glucose and amino acids absorbed into the blood capillaries of the villi? a)Diffusion only. b)Diffusion and active transport c)Active transport only d)Osmosis and diffusion.

27 QUICK CHECK 5.How are water and mineral salts absorbed into the blood capillaries of the villi? a)Active transport only. b)Diffusion and active transport c)Osmosis and active transport d)Osmosis and diffusion.