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Metabolism, Endocrinology and Haematology > Session 1 > Flashcards

Session 1 Flashcards

1
Q

What is metabolism?

A

Set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body to sustain life

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2
Q

How does biological chemistry occur?

A

By making small chemical changes

Lots of reactions are occurring but only a few reaction types

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3
Q

How are reactions organised into metabolic pathways?

A
  • some metabolic pathways occur in all cells
  • others are restricted to certain cell types
  • some may be further restricted to compartments within cells
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4
Q

What are catabolic pathways?

A

Breakdown of larger molecules into smaller ones or intermediary metabolites
Releases large amounts of free energy
Oxidative - release H atoms - “reducing power”

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5
Q

What are anabolic pathways?

A

Synthesis larger important cellular components from intermediary metabolites
Use energy released from catabolism (ATP)
Reductive - use H atoms released from catabolism

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6
Q

What are the products of catabolic metabolism?

A
  • Building block materials (e.g. amino acids, sugars and fatty acids)
  • > used for turnover, cell growth and division and repair
  • Organic precursors (e.g. Acetyl-CoA)
  • > interconversion of building block materials
  • Biosynthetic reducing power (NADH, NADPH)
  • Energy for cell function (ATP)
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7
Q

What is energy defined as?

A

Capacity to do work

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8
Q

What is biosynthetic work also known as?

A

Anabolism - synthesis of cellular components

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9
Q

What is transport work done by?

A

Membranes

  • maintenance of ion gradients (Na+/K+/Ca2+)
  • nutrient uptake
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10
Q

What are the specialised functions that work can do?

A

Mechanical work - muscle contraction
Electrical work - nervous impulse conduction
Osmotic work - kidney

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11
Q

How can energy balance be explained in terms of average daily energy intake and expenditure?

A

Intake = expenditure

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12
Q

What are the different energy requirements for the whole body?

A

Basal metabolic rate
Activity (muscular work)
Specific dynamic action of food

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13
Q

What is the basal metabolic rate?

A

Energy required by an awake individual during physical digestive and emotional rest at 18C - sum off all tissues in the body

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14
Q

What is activity (muscular work)?

A

Amount of energy required depends on type, intensity and duration of activity (skeletal and heart muscle)

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15
Q

What is the specific dynamic activity of food?

A

Energy cost of ingestion, digestion and absorption of food

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16
Q

What happens when energy intake is greater than the energy required?

A

Excess energy is stored

  • growth - synthesis of new tissue -> repair, children, pregnancy
  • production of adipose tissue
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17
Q

Energy can exist in?

A

Many different forms - all of which are interconvertible

Heat, light, mechanical, electrical, osmotic and chemical bond energy

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18
Q

Biology uses what form of energy?

A

Chemical bond energy -> used directly without prior conversion to heat

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19
Q

What is chemical bond energy used for?

A

All cellular reactions are expressions of chemical reactions in which chemical bonds are broken or formed
A characteristic energy change accompanies each chemical reaction

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20
Q

What is the difference between exergonic and endergonic reactions?

A

Exergonic - release energy - SPONTANEOUS - free energy change = +ve
Endergonic - requires energy - not spontaneous - free energy change = -ve

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21
Q

What is important to remember about redox reactions?

A

Chemical bond energy of fuel molecules is released by oxidation reactions (removal of electrons/H+)
All oxidation reactions are accompanied by reduction reactions
OIL RIG

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22
Q

What is the significance of H carrier molecules?

A

Protons are transferred to carrier molecules e.g. NAD, NADP, FAD etc -> oxidised and reduced forms
These act as carriers of reducing power (ATP production and biosynthesis)
There is a cycle between oxidative processes and reductive processes

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23
Q

How are complex molecules converted to reduced form?

A

Adding two H atoms

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24
Q

How can energy released from food be used in coupling systems?

A

Directly - use of NADPH in biosynthesis

Indirectly - use of NADH coupling in the mitochondrial system to produce an intermediate ‘energy currency’ molecule

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25
Q

When energy is released, what reaction does it drive?

A

ADP + Pi = ATP

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26
Q

What is important to remember about ADP and ATP?

A

ADP is a carrier of energy not a source

ATP is stable in the absence of certain catalysts - allows the flow of energy to be controlled

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27
Q

Name some of the high energy signals?

A

ATP, NADH, NADPH, FADH2

Activate anabolic pathways

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28
Q

Name some of the low energy signals?

A

ADP, AMP, NAD+, NADP+, FAD

Activate catabolic pathways

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29
Q

What is the role of adenylate kinase?

A

It is an enzyme that catalyses:

2ADP => ATP + AMP

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30
Q

How is energy stored in cells?

A

Energy is stored as polymer macromolecules of fuel molecules - glycogen/triglyceride

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31
Q

What is creatine phosphate and why is it needed?

A

Some cell types need to increase metabolic activity quickly - skeletal muscle - need a reserve of high energy stores that can be accessed immediately
When ATP levels are high, creatine is converted to phosphocreatine (catalysed by creatine kinase)

32
Q

What is creatine kinase?

A

Marker of myocardial infarction
Different isoforms - one specific to heart muscle
CK is released from cardiac myocytes when damaged, in MI
Appears in blood after a few hours
Diagnostic of MI

33
Q

What is the breakdown product of creatine (and creatine phosphate)?

A

Excreted via kidneys

Creatinine excretion is proportional to muscle mass of individual

34
Q

What is metabolism?

A

Chemical processes that occur within a living organism in order to maintain life

35
Q

Energy is produced by the oxidation of?

A

Lipids, carbohydrates, proteins, alcohol

36
Q

How is energy used?

A 
Ion transport
Muscle contraction
Biosynthesis
Thermogenesis
Detoxification
37
Q

What are the 7 food groups required?

A 
Carbohydrate
Protein
Fat
Minerals
Vitamins
Water
Fibre
38
Q

What are carbohydrates?

A

General formula: (CH2O)n
Mono -> Di -> Oligo -> Polysaccharides
Dietary carbohydrates: starch, sucrose, lactose, fructose, glucose, maltose and glycogen

39
Q

What is protein?

A

Composed of amino acids joined to form linear chains

Digestion breaks down proteins to constituent amino acids which enter blood

40
Q

What are the 9 essential amino acids?

A 
Isoleucine
Lysine
Threonine
Histidine
Leucine
Methionine
Phenylalanine
Tryptophan
Valine
41
Q

What is fat?

A

Lipid composed of triglycerides - produces more energy than carbohydrates when oxidised
Required for absorption of fat-soluble vitamins (ADEK) from the gut
Essential fatty acids = linoleic/linolenic acid

42
Q

What are minerals?

A

Electrolytes establish ion gradients across membranes and maintain water balance
Calcium and phosphorus are both important signalling molecules
Enzyme cofactors
Iron -> used for haemoglobin

43
Q

What are vitamins?

A

Essential for life
Fat or water soluble
Deficiency can cause disease

44
Q

What is dietary fibre?

A

Cereal foods - cellulose, lignin, pectin etc
Cannot be broken down but required for normal functioning of the GI tract
Low fibre -> constipation and bowel cancer
High fibre -> reduce cholesterol and risk of diabetes

45
Q

What is the daily energy expenditure?

A

Energy requirements vary between individuals depending on age, sex, body composition and physical activity

46
Q

Energy expenditure is the sum of what?

A

Basal metabolic rate
Diet induced thermogenesis
Physical activity level

47
Q

Describe what the basal metabolic rate describes?

A

Maintains the resting activities of the body, cells, function of organs, body temperature etc

48
Q

What affects basal metabolic rate

A 
Body size
Males v females
Environmental temp
Endocrine status
Body temp
49
Q

What is voluntary physical activity and how does this impact energy usage?

A

Energy required depends on intensity and duration of activity - skeletal muscle, heart muscle and respiratory muscles

50
Q

What types of energy stores are there in the body?

A

Muscle - v short term supply
Carbohydrates - immediate use
Adipose - long term store
Muscle proteins - extreme condition

51
Q

What is obesity?

A

Excessive fat accumulation in adipose tissue which impairs health
BMI > 30

52
Q

How do you calculate BMI?

A

weight (kg) / height2 (m2)

53
Q

What are the difference classes of BMI?

A 
<18.5 = underweight
18.5 - 24.9 = desirable weight
25 - 29.9 = overweight
30 - 34.9 =  obese
>35 = severely obese
54
Q

What is an alternative to BMI?

A

Waist-hip ratio

55
Q

How does body fat distribution affect people?

A

More fat found in abdomen indicates an increased risk of insulin resistance (diabetes)

56
Q

What is malnutrition?

A

low energy intake
deficiency diseases of other nutrients
low protein intake - insufficient blood protein synthesis leading to a decrease in plasma oncotic pressure and oedema (kwashiorkor)

57
Q

Why do we measure metabolite concentration?

A

Difficult to examine actual tissues in patients
Blood can be readily obtained - tests relatively inexpensive
Concentrations of substances higher or lower than normal range can help indicate nature of problem

58
Q

What is malabsorption?

A

Failure to digest or absorb ingested contests
Eating disorders - anorexia nervosa/bulimia nervosa
Marasmus
Kwashiorkor

59
Q

What are the four stages of catabolism?

A

Stage 1 - breakdown to building block molecules
Stage 2 - breakdown to metabolic intermediates (release of energy)
Stage 3 - TCA cycle (release of energy)
Stage 4 - oxidative phosphorylation (conversion of energy into ATP)

60
Q

What is stage 1 of catabolism?

A

Occurs extracellularly in the GI tract
Saliva and pancrease enzymes -> amylase
Small intestine also contains lots of different enzymes to break down food
No hydrolysis of cellulose in humans
Absorption of monosaccharides:
- active transport by sodium dependent glucose transporter into intestinal epithelial cells and then into blood supply
- uptake into cells from blood via facilitated diffusion using transport proteins
All tissues require glucose - RBCs, neutrophils, brain etc

61
Q

Stage 2 is also known as?

A

Glycolysis

62
Q

What are the different phases of glycolysis?

A

Phase 1 -> investment

Phase 2 -> payback

63
Q

What is the function of glycolysis?

A
  • oxidation of glucose
  • NADH production
  • synthesis of ATP from ADP
  • produces C6 and C3 intermediates
64
Q

What are the important features of glycolysis?

A
  • central pathway of CHO metabolism
  • occurs in all tissues
  • exergonic/ oxidative
  • C6 -> 2C3 (no CO2 lost)
  • anaerobic
65
Q

What are the key regulatory steps from glycolysis?

A

1) Glucose -> G6P
HEXOKINASE/GLUCOKINASE (LIVER)
ATP -> ADP

3) F6P -> F-1,6-P
PHOSPHOFRUCTOKINASE-1
ATP -> ADP

10) Phosphoenylpyruvate -> pyruvate
PYRUVATE KINASE
ADP -> ATP

66
Q

Why are there so many steps in glycolysis?

A

Chemistry easier in smaller stages
Efficient energy conservation
Allows for fine control

67
Q

What does phase 1 of glycolysis consist of? (1-3)

A

Phosphorylation of glucose to G6P (prevents glucose leaving the cell)
Uses 2 mols of ATP per glucose
Steps 1 and 3 are irreversible
Step 3 is a committing step

68
Q

What does phase 2 of glycolysis consist of? (4-10)

A

Steps 7 and 10 are ATP synthesis

10 - irreversible

69
Q

What is the clinical application of glycolysis?

A

Occurs up to 20 times faster in cancer - can measure the uptake of radioactively modified substrates

70
Q

What is special about phosphofructokinase?

A

It is allosterically regulated - inhibited by high ATP and stimulated by high AMP
Also hormonally regulated - stimulated by insulin and inhibited by glucagon

71
Q

How is glycolysis metabolically regulated?

A

high NADH or low NAD = inhibition

72
Q

How is pyruvate kinase hormone regulated?

A

Increased by low insulin and high glucagon

73
Q

What is glycerol phosphate?

A

Intermediate in glycolysis -> important to triglyceride and phospholipid biosynthesis
Produced in adipose and in liver

74
Q

How does the RBC recycle the NADH produced from the anaerobic stages of glycolysis?

A

Use of lactate dehydrogenase
pyruvate
Carried in blood to heart, liver and kidney
Liver and kidney change lactate to pyruvate and then to glycose

75
Q

What is hyperlactaemia?

A

Lactate is below renal threshold

76
Q

What is lactic acidosis?

A

Above renal threshold - blood pH lowered

77
Q

What is the pentose phosphate pathway?

A

Production of 5C
Required by nucleotides, DNA, RNA and coenzymes
NADPH produced - needed for fatty acid biosynthesis, steroid biosynthesis and etc
No ATP made - CO2 made
Rate limiting enzyme - glucose-6-phosphate dehydrogenase

Metabolism, Endocrinology and Haematology (1 decks)

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