week 2

Question 1

positive energy intake =

Answer 1

energy in is greater than energy out = increase weight

Question 2

negative energy balance =

Answer 2

Energy out is greater than energy in = decrease weight

Question 3

what are the digestive processes converting macromolecules to monomers

Answer 3

• carbohydrate to monosaccharides (glucose, fructose, galactose)
• lipids to fatty acids
• protein to amino acids
• micronutrients are freed from macromolecules

Question 4

where does most absorption take place?

Answer 4

small intestine

Question 5

Why is adequate digestion and absorption processes key for optimal nutrition?

Answer 5

food constituents do not contribute to energy for health until they are “inside” the body

Question 6

steps of ATP production from glucose

Answer 6

1. anaerobic respiration
   one glucose molecule (glycolysis, to from pyruvate) has a net yield of 2 ATP
2. Aerobic respiration
   one glucose molecule has a net yield of 32 ATP

Question 7

describe post - prandial (fed state) energy metabolism

Answer 7

about anabolism
promotes up-regulation of relevant enzymes for:
- glycogen synthesis (glycogenesis)
- fat synthesis (lipogenesis)
- protein synthesis (gene expression -> mRNA translation into functional protein)
- Urea synthesis (from deamination of amino acid carbon skeleton use

inulin is the hormone primarily involved in the post-prandial state

Question 8

mouth and salivary glands function (digestion)

Answer 8

• Prepare food for swallowing: chewing, moistening with saliva
• Detect taste molecules
• Start digestion of starch with amylase enzyme
• Start digestion of fat with lingual lipase

Question 9

oesophagus function (digestion)

Answer 9

Moves food to stomach by peristaltic waves initiated by swallowing

The lower oesophageal sphincter prevents back flow (reflux) of stomach contents into the oesophagus

Question 10

stomach function (digestion)

Answer 10

• Secretes gastric juice containing acid, enzymes, and hormones
• Mixes food with gastric juice, converting it to liquid chyme
• Starts digestion of protein and fat
• Kills microorganisms with acid
• Secretes intrinsic factor, a protein required for vitamin B12 absorption
• The pyloric sphincter controls the flow of stomach contents (chyme) into the small intestine

Question 11

pancreas function (digestion)

Answer 11

Secretes pancreatic juice containing digestive enzymes and bicarbonate into the small intestine

The hepatopancreatic sphincter controls the flow of bile and pancreatic juice from the common bile duct and pancreatic duct into the small intestine.

Question 12

liver function (digestion)

Answer 12

produces bile to aid fat digestion and absorption

Question 13

gallbladder function (digestion)

Answer 13

Stores and concentrates bile and releases it to the small intestine

The hepatopancreatic sphincter controls the flow of bile and pancreatic juice from the common bile duct and pancreatic duct into the small intestine

Question 14

small intestine function (digestion)

Answer 14

• Mixes chyme with bile and pancreatic juice to complete digestion
• Secretes hormones that help regulate digestive processes
• Secretes digestive enzymes
• Absorbs nutrients and other compounds in foods
• Transports remaining residue to large intestine
• The ileocecal valve prevents the contents of the large intestine from reentering the small intestine

Question 15

large intestine function (digestion)

Answer 15

Absorbs water and electrolytes (sodium and potassium)

Forms and stores faeces

Houses most of the gut microbiota

Question 16

what are the digestive secretions and their functions

Answer 16

saliva - Dissolves taste-forming compounds; contains compounds that aid swallowing, digestion, and protection of teeth

HCl - Promotes digestion of protein, destroys microorganisms, increases solubility of minerals

mucus - Protects GI tract cells, lubricate digesting food

Bicarbonate - Neutralises stomach acid when it reaches the small intestine

Bile - Aids in fat digestion (emulsifies fat)

enzymes - Break down carbohydrates, fats, and protein into form small enough for absorption

hormones - Regulate food intake, digestion and absorption

Question 17

what are the gastrointestinal hormones?

Answer 17

Ghrelin, gastrin, CCK, secretin, motilin, GIP, Peptide YY

Question 18

ghrelin function

Answer 18

Increases appetite and food intake. Released by the stomach

Question 19

gastrin function

Answer 19

Triggers the stomach to release HCl and pepsinogen; stimulates gastric and intestinal motility. Released by the stomach and duodenum in response to food reaching the stomach.

Question 20

CCK function

Answer 20

Stimulates release of pancreatic enzymes and bile from the gall bladder. Released by the small intestine in response to dietary fat in chyme

Question 21

secretin function

Answer 21

Stimulates release of pancreatic bicarbonate. Released by the small intestine in response to acidic chyme.

Question 22

motillin function

Answer 22

Regulates motility of the gastrointestinal tract. Released by the small intestine in response to gastric distension and dietary fat.

Question 23

GIP function

Answer 23

Inhibits gastric acid secretion, stimulates insulin release. Released by the small intestine in response to glucose, amino acids and fat.

Question 24

peptide YY function

Answer 24

Inhibits gastric and pancreatic secretions. Released by the ileum and large intestine in response to fat in the large intestine.

Question 25

what are the 4 types of absorption

Answer 25

1. passive - moves down the concentration gradient - substrate concentration dependant 2. facilitated - requires a carrier protein; saturable - moves down the concentration gradient 3. active - requires energy (ATP)+ Na+ - can transport against the concentration gradient 4. endocytosis - cell wall engulfs a substance by surrounding it with the cell membrane

Question 26

define glycogenolysis

Answer 26

the breakdown of glycogen to glucose

Question 27

define glycogenesis

Answer 27

the synthesis of glycogen from glucose

Question 28

define glycolysis

Answer 28

the synthesis of glycogen to pyruvate

Question 29

define gluconeogenesis

Answer 29

the synthesis of glucose from non-glucose sources

Question 30

define lipolysis

Answer 30

the breakdown of triglycerides to glycerol and fatty acids

Question 30

define esterification

Answer 30

the synthesis of triglycerides from fatty acids and glycerol

Question 31

define beta-oxidation

Answer 31

the oxidation of fatty acids to acetyl-CoA

Question 32

define lipogenesis

Answer 32

the synthesis of fatty acids from acetyl-CoA

Question 33

define ketogenesis

Answer 33

the synthesis of ketone bodies from acetyl-CoA

Question 34

define glucogenic amino acid oxidation

Answer 34

the oxidation of glucogenic amino acids to pyruvate

Question 35

define non-glucogenic amino acid oxidation

Answer 35

the oxidation of ketogenic amino acids to acetyl-CoA

Question 36

define protein catabolism

Answer 36

the breakdown of protein to amino acids

Question 37

define protein synthesis

Answer 37

the synthesis of proteins from amino acids

Question 38

in the first few hours of a fast, what is the primary fuel for the body

Answer 38

glycogen stored in the liver