6.1: Digestion & absorptionWhy digest?

Define these terms

Ingestion Eat the foodDigestion Chemical reactions

breaking down the food

Absorption Small molecules passing into blood/lymphatic vessels

Transport Circulatory system delivering absorbed molecules

What are molecules made of?

Protein

LIPIDS

Carbohydrates

Nucleic acids

Poly, di or monosaccharides monosaccharides

Triglycerides glycerol & fatty acids

Protein amino acids

DNA, RNA nucleotides

What is this?

Amino acid!

Mono, Di or Poly?

Maltose

Disaccharide

What is this?

Saturated fatty acid

Mono, Di or Poly?

Glycogen

Polysaccharide

What is this?

Ribose

What is this? Unsaturated

fatty acid

Mono, Di or Poly?

Fructose

Monosaccharide

Glucose

What is this?

How are molecules broken down?

Salivary enzymes

Pepsin (protease)

Pancreatic lipase

Source Salivary glands Stomach cells Pancreas cellsSubstrate Amylose

(starch)Proteins (polypeptides)

lipids

Products Maltose, glucose

Amino acids Glycerol & fatty acids

Optimum pH 7 3 7

Digestive System aka alimentary canal

Page 280 (154 in the old book) – draw and annotate a diagram of

the human digestive system.

You will be expected to draw this from memory!

Pancreas- Secretes enzymes into the S.I- Contains two gland tissues types

- Hormone secretions- Enzyme secretions

- Digestive enzymes synthesized in pancreatic gland cells on ribosomes (rER) then processed by the Golgi apparatus and excreted by exocytosis.

- Pancreatic juice contains:- Amylase- Lipases- Proteases

Small intestine- Duodenum is the first part. Food stuff mixed

with bile (from liver/gall bladder) and trypsin (protease), lipase, amylase and bicarbonate (from pancreas)

- Most molecules absorbed through capillary bed expect fatty acids (absorbed into lacteal)

Tissue layers in transverse section of the small intestines, as seen with an electron microscope. (also on pg. 281 fig. 2)

It would be a good idea to be able to draw and label this diagram.

Enzymes in the small intestines

Enzyme Substrate ProductAmylase Starch MaltoseLipase Triglycerides Fatty acids &

glycerol or fatty acids & monoglycerides

Phospholipase Phospholipids Fatty acids, glycerol & phosphate

Protease Proteins & polypeptides

Shorter peptides

Immobilized enzymes

Enzyme Substrate ProductNucleases DNA, RNA NucleotidesMaltase Maltose GlucoseLactase Lactose Glucose &

galactose

Sucrase Sucrose Glucose & fructoseExopeptidases Peptides Remove single

amino acid at a time until a dipeptide remains

Dipeptidases Dipeptides Amino acids

In summary….

Small intestine is able to absorb a wide range of substances including:

Glucose, fructose, galactose, the twenty amino acids, fatty acids, monoglycerides, glycerol, nucleotides, mineral ions (Ca, K, Na) and vitamins (vitamin C aka ascorbic acid)

6. 1: Methods of absorption HWK sheet