Digestion And Absorption

Question 1

Define digestion

Answer 1

Hydrolysis of large insoluble molecules into smaller soluble molecules that can be absorbed across cell membrane

Question 2

Mouth

Answer 2

Physical digestion with teeth
Salivary glands release amylase to break down starch chemically

Question 3

Oesophagus

Answer 3

Hollow tube with muscular walls that contract to help move food down to stomach

Question 4

Stomach

Answer 4

Protein digestion
Glandular tissue = enzymes and stomach acid
Muscular tissue churns food to mix

Question 5

Small intestine

Answer 5

Digests proteins carbs and lipids mainly in duodenum
Produces enzymes : dipeptidase and maltase membrane bound
Soluble food molecules absorbed into blood stream across the ileum
Water absorption

Question 6

Ileum

Answer 6

Inner walls folded into villi = Large SA

Question 7

Duodenum

Answer 7

Digestion using enzymes from pancreas

Question 8

Large intestine

Answer 8

Any water remaining in good is absorbed along with minerals
Undigested food material stored in rectum

Question 9

Extra cellular

Answer 9

Digestive enzymes that work outside of cells

Question 10

Digestion of carbs

Answer 10

Takes place in mouth and small intestine
Amylase enzyme used
Hydrolysis of starch into maltose
Maltese is used
Hydrolysis of maltose into 2 glucose molecules

Question 11

Where Carb digesting enzymes are made

Answer 11

Amylase ; salivary glands pancreas and small intestine
Maltase ; lining of ileum

Question 12

Digestion of proteins

Answer 12

Begins in lumen of stomach
Protease enzyme
Proteins to amino acids

Question 13

Endopeptidase

Answer 13

Hydrolysis peptide bonds within proteins to create smaller proteins in stomach
Produced in stomach and pancreas
Pancreatic juice will have endo which hydrolyses peptide bonds within polypeptide chain

Question 14

Exopeptidase

Answer 14

Hydrolyses peptide bonds at the ends of polypeptide chain to produce dipeptides
Produced by pancreas

Question 15

Dipeptidase

Answer 15

Hydrolyses dipeptides into amino acids
Found within cell surface membrane of epithelial cells in small intestine
Produced in small intestine

Question 16

emulsification of lipids

Answer 16

Bile made by liver stored in gallbladder
Bile salts bind to fatty liquid and break them into smaller ones

Question 17

Digestion of lipids

Answer 17

Only in lumen of small intestine
Lipase hydrolyses ester bonds in tri to form fatty acids and mono
Produced in pancreas

Question 18

The products of hydrolysis during digestion

Answer 18

Monosaccharides
Amino acids
Monoglycerides
Fatty acids

Question 19

The ileum and villi

Answer 19

Have thin walls lined with epithelial cells
Have large network of capillaries to maintain diffusion gradient
Increases SA of the ileum so accelerates rate of diffusion
Thin outer layer so shorter diffusion distances

Question 20

Process involved in absorption and transport of digested lipids from ileum into vessels

Answer 20

Micelles contain bile salts and fatty acids
Fatty acids more soluble in water
Fatty acids absorbed by diffusion into epithelial cells
Triglycerides reformed in epithelial cells ER
Packaged into chylomicrons and enter bloodstream via lacteal

Question 21

Function of ATP in cotransport

Answer 21

Releases energy to allow ions to move against the conc gradient
Maintains a conc gradient

Question 22

How does glucose enter by co-transport

Answer 22

Na is actively transported from ileum cells to blood using energy from ATP
This forms and maintains a diffusion gradient for Na to enter cells from the gut by diffusion from high to low
Glucose enters by facilitated diffusion and co transport by sodium

Question 23

When mentioning why amounts of different molecules decreases or increases

Answer 23

Mention the enzyme (lipase) which breaks down triglycerides so they decrease
Mention hydrolysis
Mention bonds broken (ester bonds)

Question 24

Role of Micelles in absorption of fats into cells lining ileum

Answer 24

Micelles contain bile salts and fatty acids
Fatty acids more soluble in water so help
Maintains higher concentration of fatty acids to lining of ileum
Fatty acids are absorbed by diffusion

Question 25

Describe roles of protein enzymes

Answer 25

They hydrolyses peptide bonds Endopeptidase acts in the middle to produce shorter polypeptide chains and increase ends Exopeptidase acts on the end of polypeptides and produces dipeptides Dipeptidase acts between 2 amino acids to produce a single amino acid

Question 26

Advantage of lipid droplets and Micelle formation

Answer 26

Droplets increase SA so faster hydrolysis Micelles carry fatty acids and glycerol through membrane to epithelial cells

Question 27

How Golgi apparatus involved in absorption of lipids

Answer 27

Modifies triglycerides Combines them with proteins So that they can be packed for exocytosis

Question 28

Components of chylomicrons

Answer 28

Cholesterol and phospholipids

Question 29

Why does emulsion of lipids help digestion

Answer 29

Smaller lipid droplets = more SA Lipase action faster so higher rate of digestion

Question 30

How proteins are digested and absorbed

Answer 30

Stomach secretes protease Endopeptidase acts in the middle to produce more end and shorter chains Exopeptidase secreted by pancreas and produces Dipeptides Dipeptidase membrane bound and produce amino acids

Question 31

Absorption of amino acids in ileum

Answer 31

Facilitated diffusion of amino acids if high conc in the ileum Co transport by Na ions Na diffuses down conc gradient As they’re removed from epithelium cell into blood by active transport Facilitated diffusion of amino acids into blood

Question 32

Roles of enzymes in break down if starch

Answer 32

Salivary amylase hydrolyses starch to maltose Maltase hydrolyses maltose to glucose hydrolysis of glycoside if bonds in maltose

Question 33

Glucose absorption

Answer 33

Glucose cotransported by sodium into epithelial cell Via carrier protein Sodium removed by active transport into blood Creates diffusion gradient glucose can move into blood by facilitated diffusion

Question 34

Absorption of products of fat

Answer 34

Bile slats associate with monoglycerides to form micelles Micelles carry monoglycerides to membrane of epithelial cells Monoglycerides and fatty acids recombine to form triglycerides in ER Triglycerides combine w proteins to from chylomicrons at Golgi body Chylomicrons leave epithelial cells by exocytosis to enter lacteal

Question 35

Chylomicrons

Answer 35

Transport lipids absorbed from the intestine to skeletal muscle tissue