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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
When energy is released, what reaction does it drive?
ADP + Pi = ATP
26
What is important to remember about ADP and ATP?
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
27
Name some of the high energy signals?
ATP, NADH, NADPH, FADH2 | Activate anabolic pathways
28
Name some of the low energy signals?
ADP, AMP, NAD+, NADP+, FAD | Activate catabolic pathways
29
What is the role of adenylate kinase?
It is an enzyme that catalyses: | 2ADP => ATP + AMP
30
How is energy stored in cells?
Energy is stored as polymer macromolecules of fuel molecules - glycogen/triglyceride
31
What is creatine phosphate and why is it needed?
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
What is creatine kinase?
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
What is the breakdown product of creatine (and creatine phosphate)?
Excreted via kidneys | Creatinine excretion is proportional to muscle mass of individual
34
What is metabolism?
Chemical processes that occur within a living organism in order to maintain life
35
Energy is produced by the oxidation of?
Lipids, carbohydrates, proteins, alcohol
36
How is energy used?
``` Ion transport Muscle contraction Biosynthesis Thermogenesis Detoxification ```
37
What are the 7 food groups required?
``` Carbohydrate Protein Fat Minerals Vitamins Water Fibre ```
38
What are carbohydrates?
General formula: (CH2O)n Mono -> Di -> Oligo -> Polysaccharides Dietary carbohydrates: starch, sucrose, lactose, fructose, glucose, maltose and glycogen
39
What is protein?
Composed of amino acids joined to form linear chains | Digestion breaks down proteins to constituent amino acids which enter blood
40
What are the 9 essential amino acids?
``` Isoleucine Lysine Threonine Histidine Leucine Methionine Phenylalanine Tryptophan Valine ```
41
What is fat?
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
What are minerals?
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
What are vitamins?
Essential for life Fat or water soluble Deficiency can cause disease
44
What is dietary fibre?
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
What is the daily energy expenditure?
Energy requirements vary between individuals depending on age, sex, body composition and physical activity
46
Energy expenditure is the sum of what?
Basal metabolic rate Diet induced thermogenesis Physical activity level
47
Describe what the basal metabolic rate describes?
Maintains the resting activities of the body, cells, function of organs, body temperature etc
48
What affects basal metabolic rate
``` Body size Males v females Environmental temp Endocrine status Body temp ```
49
What is voluntary physical activity and how does this impact energy usage?
Energy required depends on intensity and duration of activity - skeletal muscle, heart muscle and respiratory muscles
50
What types of energy stores are there in the body?
Muscle - v short term supply Carbohydrates - immediate use Adipose - long term store Muscle proteins - extreme condition
51
What is obesity?
Excessive fat accumulation in adipose tissue which impairs health BMI > 30
52
How do you calculate BMI?
weight (kg) / height2 (m2)
53
What are the difference classes of BMI?
``` <18.5 = underweight 18.5 - 24.9 = desirable weight 25 - 29.9 = overweight 30 - 34.9 = obese >35 = severely obese ```
54
What is an alternative to BMI?
Waist-hip ratio
55
How does body fat distribution affect people?
More fat found in abdomen indicates an increased risk of insulin resistance (diabetes)
56
What is malnutrition?
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
Why do we measure metabolite concentration?
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
What is malabsorption?
Failure to digest or absorb ingested contests Eating disorders - anorexia nervosa/bulimia nervosa Marasmus Kwashiorkor
59
What are the four stages of catabolism?
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
What is stage 1 of catabolism?
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
Stage 2 is also known as?
Glycolysis
62
What are the different phases of glycolysis?
Phase 1 -> investment | Phase 2 -> payback
63
What is the function of glycolysis?
- oxidation of glucose - NADH production - synthesis of ATP from ADP - produces C6 and C3 intermediates
64
What are the important features of glycolysis?
- central pathway of CHO metabolism - occurs in all tissues - exergonic/ oxidative - C6 -> 2C3 (no CO2 lost) - anaerobic
65
What are the key regulatory steps from glycolysis?
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
Why are there so many steps in glycolysis?
Chemistry easier in smaller stages Efficient energy conservation Allows for fine control
67
What does phase 1 of glycolysis consist of? (1-3)
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
What does phase 2 of glycolysis consist of? (4-10)
Steps 7 and 10 are ATP synthesis | 10 - irreversible
69
What is the clinical application of glycolysis?
Occurs up to 20 times faster in cancer - can measure the uptake of radioactively modified substrates
70
What is special about phosphofructokinase?
It is allosterically regulated - inhibited by high ATP and stimulated by high AMP Also hormonally regulated - stimulated by insulin and inhibited by glucagon
71
How is glycolysis metabolically regulated?
high NADH or low NAD = inhibition
72
How is pyruvate kinase hormone regulated?
Increased by low insulin and high glucagon
73
What is glycerol phosphate?
Intermediate in glycolysis -> important to triglyceride and phospholipid biosynthesis Produced in adipose and in liver
74
How does the RBC recycle the NADH produced from the anaerobic stages of glycolysis?
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
What is hyperlactaemia?
Lactate is below renal threshold
76
What is lactic acidosis?
Above renal threshold - blood pH lowered
77
What is the pentose phosphate pathway?
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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