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Digestive > Macronutrients > Flashcards

Macronutrients Flashcards

1
Q

3 types of lipid

A

Triglycerides
Sterols
Phospholipids

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2
Q

Triglyceride structure

A

3 fatty acid chains bonded to a glycerol backbone

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3
Q

Key features of saturated fats

A

Solid at room temperature
Saturated carbon structure
Resistant to oxidation due to stabile nature

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4
Q

Key features of polyunsaturated fats

A

Liquid at room temperature
Susceptible to spoilage
Can be hydrogenated to trans fats to protect against oxidation, causing them to behave like saturated fats

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5
Q

Sterols

A

Starting material for bile acids, sex hormones, adrenal hormones and vitamin D
Structural component of cell membranes

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6
Q

Endogenous cholesterol

A

The liver produces 800 - 1500 mg of cholesterol a day

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7
Q

Exogenous cholesterol

A

Cholesterol we take in from dietary animal products

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8
Q

Plant sterols importance

A

Can interfere with cholesterol absorption

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9
Q

Fat digestion - mouth

A

Salivary glands release lingual lipase

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10
Q

Fat digestion - stomach

A

Lingual lipase initiates lipid digestion. Muscle contractions disperse fat into smaller droplets which are then exposed to gastric lipase causing some digestion.

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11
Q

Fat digestion - small intestine

A

Acidic chyme neutralised in duodenum by bicarbonate from pancreatic juice and bile. Bile salts emulsify fat, turning it into small droplets with a large surface area.

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12
Q

3 major emulsifying agents

A

Bile salts
Lecithin
2-monoacylglycerol

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13
Q

Lipid digestion in small intestine enzymes

A

Pancreatic lipase
Pancreatic non-specific esterase
Phospholipase A2

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14
Q

Pancreatic lipase

A

Digests triglycerides to glycerol and free fatty acids

Requires colipase from pancreas to become active

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15
Q

Pancreatic non-specific esterase

A

Removes fatty acids from a variety of non-triglycerides and non-phospholipids

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16
Q

Phospholipase A2

A

Removes fatty acid from 2-position on phospholipid

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17
Q

Milk lipase

A

Important in breast fed human neonate nutrition. Only becomes active in small intestine because it is bile-dependent

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18
Q

Lecithin

A

Phospholipid present in bile and food membranes

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19
Q

2-monoacylglycerol

A

Breakdown product from triglyceride

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20
Q

Bile salts are stored in the:

A

Gallbladder

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21
Q

Bile salt movement

A

Made by liver, stored in gallbladder
CCK stimulates bile release
Reabsorbed in terminal ileum of small intestine
Reused via enterohepatic circulation

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22
Q

4 major roles of bile salts in fat digestion

A

Emulsification
Removal of lipid digestion products from emulsified fat droplets
Cofactors required by lipases for activity
Aids absorption of fat products across enterocyte membrane

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23
Q

Chylomicron

A

Package of lipid digestion, cholesterol, fat soluble vitamins and apolipoproteins. Transport system pass from lacteal in intestinal epithelium to the lymph and eventually the bloodstream.

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24
Q

Chylomicron components are removed:

A

During circulation as a result of TG hydrolysis

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25
Q

Chylomicron repackaging

A

As components are removed from the chylomicron they become smaller and denser
Remnants endocytosed by liver
Remaining lipid repackaged into lipoprotein complexes to leave liver

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26
Q

Types of lipoproteins

A 
Chylomicron
VLDL
IDL
LDL
HDL
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27
Q

VLDLs are composed primarily of:

A

Triglycerides

28
Q

LDLs are composed primarily of:

A

Cholesterol

29
Q

HDLs are composed primarily of:

A

Protein

30
Q

Foam cells

A

Residual fractions of LDL bind low affinity scavenger receptors on macrophages. Macrophages phagocytose LDL forming a fatty aggregate called a foam cell which deposit themselves in atherosclerotic plaques

31
Q

Key roles of proteins

A 
Building material
Hormones
Enzymes
Immune function
Fluid balance
Transporters
Antibodies
Energy
32
Q

9 essential amino acids

A 
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
33
Q

11 non-essential amino acids

A 
Alanine
Arginine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine
Proline
Serine
Tyrosine
34
Q

2 semi-essential amino acids

A

Histidine and arginine

35
Q

AMDR

A

Acceptable macronutrient distribution rate

36
Q

24 specific organic compounds we require for health

A

9 essential amino acids
2 fatty acids
13 vitamins

37
Q

Two factors that influence protein quality

A

Protein digestibility

Amino acid composition

38
Q

Protein digestibility

A

High in animal protein, lower in plant protein
Higher digestibility means we can gain more amino acids from it through digestion
Can depend on source and also what we eat with the protein

39
Q

Amino acid composition

A

Essential amino acids are vital for energy and synthesis of other amino acids. A lack of just 1 EAA limits the action of other EAAs even if they are in abundance - it becomes the limiting factor.

40
Q

Process of protein digestion

A

1) Mastication - involves moistening protein rich foods into a bolus
2) HCl denatures food proteins and stimulates pepsinogen —> pepsin cleavage
3) Pepsin catalyses hydrolysis of proteins into smaller polypeptides and amino acids
4) Pancreatic endopeptidases secreted as inactive precursors in small intestine. When activated by enteropeptidase they break polypeptides down into tripeptides, dipeptides and amino acids
5) Remaining peptides break down further into amino acids

41
Q

Enzyme mediated protein digestion in small intestine

A

Pancreatic endopeptidases secreted as inactive precursors which are activated by enteropeptidase (which activates trypsinogen first, followed by the other proteases)
Activated endopeptidases cleave polypeptides into peptides and amino acids which are further cleaved into single amino acids by tripeptidases, dipeptidases and aminopeptidases
Pancreatic juice contains procarboxypeptidases which are activated into carboxypeptidases (A and B) which break down the carbon ends of peptides once activated in the lumen of the small intestine

42
Q

3 pancreatic endopeptidases and their inactive precursors

A

Trypsin - trypsinogen
Chymotrypsin - chymotrypsinogen
Elastase - pancreatic elastase

43
Q

Protein absorption

A

Sodium linked amino acid transporters and sodium linked peptide transporters on enterocyte in the small intestine which are pulled across by the diffusion of Na+. At the same time, Na+/K+ antiporters are moving ions across the enterocyte/blood border to power the Na+ linked symporters

44
Q

3 key hormones in the protein digestion process

A

Gastrin (regulates acid secretion in stomach)

Secretin and CCK (regulate pancreatic secretions)

45
Q

Nitrogen balance

A

A state of equilibrium where the rate of nitrogen intake is equal to the rate of nitrogen expenditure

46
Q

Factors causing negative nitrogen balance (degradation > synthesis)

A 
Decreased short term protein intake
Starvation
Injury, trauma and surgery
Illness, infection and burns
Cancers
Lactation
47
Q

Factors causing positive nitrogen balance (synthesis > degradation)

A

Increased short term protein intake
Growth
Pregnancy
Recovery from illness or trauma

48
Q

Protein Energy Malnutrition

A

A condition often seen in poor communities characterised by wasted limbs but protruding bellies due to fluid retention around the liver as a result of low protein

49
Q

3 types of nitrogen excretion

A

Urea
Uric acid
Creatinine

50
Q

Types of carbohydrate

A

Complex (starch and dietary fibre)

Simple (sugars)

51
Q

Energy that we use most readily

A

Carbohydrate

52
Q

Energy that we store the most

A

Fat

53
Q

Carbohydrate that makes up plant cell walls

A

Cellulose

54
Q

2 basic compounds that make up a carbohydrate

A

Ketone and aldehyde

55
Q

3 key monosaccharides

A

Glucose
Galactose
Fructose

56
Q

3 key disaccharides

A

Lactose
Maltose
Sucrose

57
Q

Sucrose is made of:

A

Glucose and fructose

58
Q

Lactose is made of:

A

Glucose and galactose

59
Q

Maltose is made of:

A

Glucose and glucose

60
Q

Storage polysaccharide in plants

A

Starch (amylose and amylopectin)

61
Q

Non-starch polysaccharides

A

Glucose links can’t be broken so they aren’t digested

Dietary fibre - can be soluble or insoluble

62
Q

Glycogen

A

Storage carbohydrate in animals. Stored in liver and muscles, broken down when energy required for rapid glucose release

63
Q

Soluble fibre

A

Dissolves in water to form a gel like substance and is easily digested by bacteria in the colon
Commonly found in legumes, psyllium and fruits and vegetables

64
Q

Insoluble fibre

A

Not dissolvable in water and is not broken down as easily by bacteria
Responsible for bulking feces for easy passage
Commonly found in whole grains and vegetables

65
Q

Carbohydrate digestion

A

1) Salivary alpha amylase hydrolyses starch
2) Breakdown of oligosaccharides to monosaccharides at brush border
3) Monosaccharides absorbed at enterocyte brush border. Non-degraded disaccharides continue into colon where bacteria feed and can cause inflammation
4) Glucose and galactose absorbed by active transport
5) Fructose and galactose isomerised to glucose

66
Q

High glycaemic index

A

Blood sugar peaks when lots of simple sugars are consumed. Insulin also peaks to force blood sugar down. Feel hungry due to low blood sugar, eat more sugar causing another spike and so on.

67
Q

Low glycaemic index

A

Lower insulin response means you feel full for longer and don’t need to eat as often so less blood sugar and insulin spikes. Increased exercise increase glucose utilisation so not as much insulin needed to push sugar spikes down.

Digestive (9 decks)

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