Nutrition & metabolism

Question 1

Nutrients

Answer 1

Used for growth repair and maintenance eg. carbohydrates, proteins, fats, minerals and vitamins, water

Question 2

Examples of macronutrients

Answer 2

Water, carbohydrates, proteins and fats

Question 3

Examples of micronutrients

Answer 3

Minerals and vitamins

Question 4

Carbs

Answer 4

Monosaccharides:
- glucose
- galactose 
- fructose
Disaccharides:
- sucrose
- maltose
- lactose
Polysaccharides:
- starch
- glycogen
- cellulose
ALL carbs generate glucose - converted to energy
Required daily amount = 230g/day

Question 5

Fibre

Answer 5

Absorbs water into the intestine = softens stool
Provides bulk so speeds up transmit time
Daily requirements = 24g/day

Question 6

Protein

Answer 6

Broken down into amino acids in digestive tract then synthesised into new proteins
20 amino acids eg. glutamine, tyrosine
Daily requirements = 45-60g/day depending on age and sex

Question 7

Lipids

Answer 7

Energy store
Absorption of fat-soluble vitamins
Plasma membranes & myelin
Precursor of steroid and prostaglandins
Daily requirements = 70g/day of which 20g saturated
Lipids are not water soluble so transported in blood as lipoprotein droplets
Low-density lipoproteins = bad as transport cholesterol to tissues
High-density lipoproteins = good as transport cholesterol to liver for elimination

Question 8

What are chylomicrons?

Answer 8

Protein coated lipid droplets

Transport triglycerides and cholesterol from S intestine to liver

Question 9

Vitamins

Answer 9

Fat soluble = A,D,E,K
Water soluble B, C
some synthesised by the body

Question 10

Minerals

Answer 10

calcium, phosphorous, iron, magnesium, folate etc..

Question 11

Nutrition during pregnancy

Answer 11

Increase fibre and protein

Increase calcium, folate, zinc, iodine, iron

Question 12

Anabolism

Answer 12

Small molecules joined together to form complex structures

- uses energy

Question 13

Catabolism

Answer 13

Large molecules broken down into smaller ones

- releases ATP

Question 14

Basal metabolic rate

Answer 14

Energy released requires to support vital organs at rest

Question 15

Carbohydrate metabolism

Answer 15

Anabolism - glucose converted to glycogen/triglycerides for storage
Catabolism - glucose used to form ATP by glycolysis
Total ATP = 38

Question 16

Protein metabolism

Answer 16

Anabolism - amino acids used to form new proteins
Catabolism - amino acids enter Krebs cycle, deaminated by removal of NH2, NH2 becomes NH3 (ammonia) - converted to urea by liver and excreted in urine

Question 17

Lipid metabolism

Answer 17

Anabolism - fatty acids + glycerol = triglyceride, lipogenesis = triglycerides formed from amino acids and glucose
Catabolism - lipolysis, breaking down fats for fuel

Question 18

Metabolic states

Answer 18

Absorptive - up to 4 hours after a meal, mainly anabolic

Postabsorptive - from 4 hours after next to next meal, catabolic

Question 19

Normal blood glucose

Answer 19

3.5-8

Question 20

Glycogenesis

Answer 20

Synthesis of glycogen from glucose

Question 21

Glycogenolysis

Answer 21

Breakdown of glycogen to glucose

Question 22

Gluconeogenesis

Answer 22

Synthesis of glucose from amino acids

Question 23

Blood glucose homeostasis

Answer 23

During absorptive state = blood glucose is high
- insulin secreted from B cells in islets of Langerhans
- this lowers blood glucose levels by increasing entry of glucose into cells, stimulating glycogenesis, inhibiting gluconeogenesis
During post absorptive state - blood glucose is low
- glucagon is secreted from alpha cells in islets of Langerhans
- stimulates glycogenolysis and gluconeogenesis

Question 24

Ketones

Answer 24

When liver breaks down fats and proteins:
- too much acetyl-coA to enter krebs cycle - acetyl-coA converted into ketones
too many ketones = ketoacidosis
Diabetes mellitus = lack of insulin leads to increased breakdown of fats and amino acids = ketoacidosis