YOU WILL ACHIEVE….YOU WILL ACHIEVE…. To identify the parts of the digestive To identify the parts of the digestive system involved in the absorption of system involved in the absorption of digested food;digested food;

To explain the adaptive characteristic of To explain the adaptive characteristic of the digestive system related to the digestive system related to absorption;absorption;

To draw & label the structure of a To draw & label the structure of a villus;villus;

To explain the process of absorption in To explain the process of absorption in the villus;the villus;

To make an analogy on the process of To make an analogy on the process of absorption in the small intestineabsorption in the small intestine

2 process occur which are 2 process occur which are digestion & digestion & absorptionabsorption

The The process of digestionprocess of digestion is is completedcompleted in the in the ileumileum to produce simple sugars, amino acids, to produce simple sugars, amino acids, glycerol & fatty acids.glycerol & fatty acids.

The The process of absorptionprocess of absorption also occurs in the also occurs in the ileum to absorb the products of digestion ileum to absorb the products of digestion into the blood capillaries & to be used by into the blood capillaries & to be used by the cells in the body.the cells in the body.

Absorb by Absorb by villivilli ( (singular : villussingular : villus) in the ) in the walls of the small intestine. Each villus walls of the small intestine. Each villus contains a network of blood capillaries & a contains a network of blood capillaries & a lymph capillary in the centre of the villuslymph capillary in the centre of the villus

Absorption of Digested Food in Small Absorption of Digested Food in Small IntestineIntestine

Adaptation of the Adaptation of the small intestine to small intestine to

aid absorptionaid absorption

LEARNING OUTCOMESLEARNING OUTCOMES

Explain the adaptive Explain the adaptive characteristic of the digestive characteristic of the digestive system related to absorption.system related to absorption.

It is It is long & coiledlong & coiled to increase to increase the surface area for absorptionthe surface area for absorption

The lining of the intestine is The lining of the intestine is greatly foldedgreatly folded to increase the to increase the surface area for absorptionsurface area for absorption

The The epithelial cellsepithelial cells lining the lining the villus is villus is very thinvery thin to to facilitate diffusion of facilitate diffusion of digested food.digested food.

There are There are many villus & many villus & microvillusmicrovillus to increase to increase surface area for absorptionsurface area for absorption

Each villus has Each villus has a network of a network of blood capillariesblood capillaries to transport to transport the digested food that has the digested food that has been absorbedbeen absorbed

Each villus also has Each villus also has lacteal lacteal (lymph vessel(lymph vessel) to transport ) to transport glycerol & fatty acids.glycerol & fatty acids.

Structure of villiStructure of villi

LEARNING OUTCOMESLEARNING OUTCOMES

Explain the process of Explain the process of absorption in the villus.absorption in the villus.

Blood capillariesBlood capillaries at the villus absorb at the villus absorb glucose glucose (simple sugar), amino acids, minerals, (simple sugar), amino acids, minerals, vitamins B & Cvitamins B & C by simple diffusion through by simple diffusion through the epithelium of the villusthe epithelium of the villus

These substances are carried by the These substances are carried by the hepatic hepatic portal veinportal vein to the liver & then distributed to to the liver & then distributed to the body cells by the circulatory systemthe body cells by the circulatory system

The products of fats digestion such as The products of fats digestion such as glycerol & fatty acidsglycerol & fatty acids as well as as well as vitamins A, vitamins A, D, E & KD, E & K are absorbed into the are absorbed into the lacteallacteal of of villusvillus

Across the thin epithelium into the Across the thin epithelium into the lacteal. Once inside the lacteal, lacteal. Once inside the lacteal, they recombine to they recombine to form fat droplets.form fat droplets.

The fat droplets & vitamins ADEK in The fat droplets & vitamins ADEK in the lacteals are carried out of the the lacteals are carried out of the ileum by a lymph vessel called ileum by a lymph vessel called thoracic ductthoracic duct..

Ileum Ileum thoracic duct thoracic duct left left shoulder vein (left subclavian vein) shoulder vein (left subclavian vein) bloodstream bloodstream body cells body cells

The absorptive surface area of the small The absorptive surface area of the small intestine is roughly intestine is roughly 250 square 250 square metersmeters - the size of a tennis court!!! - the size of a tennis court!!!

ABSORPTIONABSORPTIONOFOF

WATERWATER&&

MINERALS IN MINERALS IN COLONCOLON

Large intestine :Large intestine :–CaecumCaecum : the part where the : the part where the small intestine joins with small intestine joins with the large intestinethe large intestine

–ColonColon : the longer part of : the longer part of the large intestinethe large intestine

–RectumRectum : the last part of : the last part of the large intestinethe large intestine

Fluid material from ileum (not Fluid material from ileum (not absorbed) absorbed) caecum caecum colon colon

Colon Colon absorbsabsorbs much of the much of the waterwater from from the indigestible food residue which becomes more solid as it passes along.

Colon also Colon also absorbs mineralsabsorbs minerals from from the indigestible residue passing the indigestible residue passing from the small intestinefrom the small intestine

TRANSPORTTRANSPORTOF OF

NUTRIENTS BY NUTRIENTS BY CIRCULATORY CIRCULATORY

SYSTEMSYSTEM

LEARNING OUTCOMESLEARNING OUTCOMES

Describe the transport of Describe the transport of nutrients by the circulatory nutrients by the circulatory

system for assimilation.system for assimilation.

Glucose + amino acids + minerals + vits. Glucose + amino acids + minerals + vits. B & CB & C blood capillariesblood capillaries of the villus of the villus out of the small intestine out of the small intestine liver liver (by the (by the hepatic portal vein) hepatic portal vein) the food molecules the food molecules are transported away to all the cells in the are transported away to all the cells in the body by the blood circulatorybody by the blood circulatory

Glycerol + fatty acid + vits. A, D, E & KGlycerol + fatty acid + vits. A, D, E & K the the lacteallacteal of the villus of the villus transport out of transport out of the small intestine by the thoracic duct the small intestine by the thoracic duct (lymph vessel) (lymph vessel) lymphatic systemlymphatic system at at the left shoulder, the thoracic duct joins the left shoulder, the thoracic duct joins the left subclavian vein the left subclavian vein bloodstream bloodstream

ASSIMILATION BY BODY ASSIMILATION BY BODY CELLCELL

AssimilationAssimilation : : the process where the process where the products of digestion are the products of digestion are absorbed & utilised in the body cellsabsorbed & utilised in the body cells

Used Used to synthesis complex moleculesto synthesis complex molecules required for growth, reproduction or required for growth, reproduction or repair. (amino acids are used to repair. (amino acids are used to synthesis protoplasm of cells)synthesis protoplasm of cells)

ExcessExcess absorbed foodabsorbed food molecules are molecules are stored in the bodystored in the body

GlucoseGlucose = = oxidised oxidised to produce energyto produce energy in cell respiration, excess in cell respiration, excess glycogen glycogen

Amino acidAmino acid = = to synthesis enzymes, to synthesis enzymes, antibody, plasma membrane & antibody, plasma membrane & protoplasmprotoplasm, excess , excess urea urea urine urine (deamination)(deamination)

LipidsLipids = = to build plasma membrane & to build plasma membrane & cholesterol,cholesterol, excess excess stored as adipose stored as adipose tissue (under the skin, abdomen & tissue (under the skin, abdomen & internal organs as kidneys, hearts)internal organs as kidneys, hearts)

Minerals & vitaminsMinerals & vitamins = = assimilatedassimilated by the body cellsby the body cells

Minerals (Minerals (calcium & phosphoruscalcium & phosphorus) ) build strong bone & teeth build strong bone & teeth

IronIron to synthesis haemoglobin to synthesis haemoglobin in the RBC, excess in the RBC, excess stored in stored in liverliver

Vitamins A & DVitamins A & D also stored in the also stored in the liver.liver.

LEARNING OUTCOMESLEARNING OUTCOMES

Explain the main Explain the main function of the function of the liver and describe liver and describe the process of the process of assimilation.assimilation.

FUNCTIONS OF THE FUNCTIONS OF THE LIVERLIVER

The The largest gland in the body largest gland in the body & & carries out many metabolic carries out many metabolic processesprocesses

Carries out assimilation Carries out assimilation & also & also act as a storage organact as a storage organ

Receives the products of Receives the products of digestion dissolved in the digestion dissolved in the blood via the hepatic portal blood via the hepatic portal veinvein

MAIN FUNCTIONS OF THE MAIN FUNCTIONS OF THE LIVERLIVER

•Storage of nutrientsStorage of nutrients•Processing the products of digestionProcessing the products of digestion•Detoxification Detoxification •Breakdowns of lipids in storage to Breakdowns of lipids in storage to provide energyprovide energy•Production of bileProduction of bile•Removal of damaged red blood cellsRemoval of damaged red blood cells•Synthesis of vitamin A & blood Synthesis of vitamin A & blood clotting substancesclotting substances•Synthesis of plasma protein (fibrinogen, prothrombin).

REGULATION OF BLOOD REGULATION OF BLOOD GLUCOSE LEVELSGLUCOSE LEVELS

Excess glucose Excess glucose glycogen (present of glycogen (present of hormone insulin) hormone insulin) stores in the liver. stores in the liver.

Lack of glucoseLack of glucose; glycogen ; glycogen glucose by glucose by hormone glucagons.hormone glucagons.

DEAMINATIONDEAMINATION

Excess amino acids Excess amino acids liver liver amino group amino group is removed (-NHis removed (-NH22) ) ammonia (toxic) ammonia (toxic) urea urea urine urine

Remaining amino acids Remaining amino acids carbohydrate or carbohydrate or fat.fat.

STORAGE FUNCTIONSTORAGE FUNCTION Stores vitamins Stores vitamins A & D and B12.A & D and B12.

Some minerals Some minerals : irons, potassium, cobalt, : irons, potassium, cobalt, zinc & copper.zinc & copper.

DETOXIFICATIONDETOXIFICATION BacteriaBacteria engulfed & destroyed by engulfed & destroyed by

phagocytic cells in the liver.phagocytic cells in the liver.

ToxinToxin chemically modified chemically modified non-toxic non-toxic eliminated.eliminated.

CirrhosisCirrhosis long time intake of large quantities long time intake of large quantities of alcohol @ viral diseases (hepatitis)of alcohol @ viral diseases (hepatitis)