Macronutrients

Question 1

Influx of TAG into adipose tissue mediated by

Answer 1

Adipose tissue lipoprotein lipase

Upregulated by insulin presence

Question 2

Fat digestion

• Mouth
• Stomach

Answer 2

Mouth: Lingual lipase (serous gland)

Stomach: Gastric lipase (gastric cells in fundic mucosa) -> doesn’t require bile acid or colipase (pancreas)

Question 3

Enzymes in neonates

Answer 3

in neonates contributing to up to 50% of lipid hydrolysis

in adults up to 30% of lipid hydrolysis

Question 4

Bile acids from liver

Answer 4

Cholic and chenodeoxycholic acid

Amphipathic - solubilise lipids to form mixed micelles

Question 5

Pancreatic lipase

Answer 5

Small intestine

Secreted from pancreas alongside pro-colipase

Question 6

Procolipase

Answer 6

Activated in intestinal lumen by trypsin to form collapse

Colipase stabilise pancreatic lipase = increase efficiency
Pancreatic lipase hydrolyse

TG to form monoglycerol, FA and glycerol

Question 7

Fat absorption - small intestine

Answer 7

Water soluble mixed micelle pass through overlying microvillus
Monoglycerol and FA cross apical membrane of microvillus and pass through
- passive diffusion
- lipid transporter mechanism

Question 8

CHO digestion

Answer 8

Starches digested by alpha amylase in saliva and pancreatic secretions -> maltose, maltotriose and α–dextrins

Further digestion by brush border enzymes - gluco-amylase, α-dextrinase, sucrase, and maltase to form monosaccharides – glucose and fructose

Question 9

CHO absorption

Answer 9

Absorption of CHO is limited to the monosaccharides - glucose, galactose and fructose.
It occurs in the 
    small intestine
Capacity to absorb 
    fructose is limited

Question 10

Non-starch polysaccharide

Answer 10

NSP (Fibre) resistant starch and most oligosaccharides are not digested and absorbed in the small intestine
Soluble fibres (pectin/gum) are fermented by bacteria in the colon
Insoluble fibres make up the cellulose ‘roughage’ in the diet

Question 11

Express protein requirement

Answer 11

Protein percent of the diet 
Amino acid percent of the diet
Amino acid percent of total protein
Digestible protein percent of the diet
Ideal Protein ratios (relationships among amino acids) 20 amino acids of which 9 must be consumed in the diet

Question 12

Protein requirements

Answer 12

Maintenance = nutritional requirements to stay alive (does not require positive BW gain)

Growth = positive tissue accretion

Reproduction = tissue specific growth related to reproduction, reproductive function (milk, eggs, reproductive tissue)

Question 13

Protein digestion

Answer 13

Pepsinogen from chief cells
HCL from parietal cells
Response to gastrin and vagus nerve
pH 2-3

Only protease to break down collagen
Neutralised by bicarbonate

Question 14

Pancreatic proteases

Answer 14

The two primary pancreatic proteases are trypsin and chymotrypsin.

They are synthesized and packaged within secretory vesicles as inactive pro enzymes:
trypsinogen chymotrypsinogen

The pro enzymes are activated by an enteropeptidase - enterokinase secreted by the mucosal membrane of duodenum

The secretory vesicles also contain a trypsin inhibitor to serve as a safeguard against trypsinogen converting to trypsin within the pancreas or pancreatic ducts

Question 15

Trypsinogen
Chymotrypsinogen
Proelastase
Procarboxypeptidase

Answer 15

Trypsin
Chymotrypsin
Elastase
Carboxypeptidase

Question 16

AA absorption

Answer 16

Dependent on electrochemical gradient of Na+ across epithelium
Transporters bind AA after sodium
Fully loaded transporter undergoes conformational change -> dump Na+ and AA into cytoplasm

Basolateral enterocyte contains additional transporters (cell -> blood)