feeding, fasting and exercise WF

Question 1

overview of metabolism?

Answer 1

food digested, components absorbed and circulate in blood. taken up and metabolised in cells via catabolic pathways producing intermediates, CO2, energy, reducing power. energy used to do work, and in biosynthetic reactions (anabolic pathways). reducing power trapped in reduced coenzymes, also used for anabolic pathways.

food and anabolic reactions make building blocks for growth -> cell structures

Question 2

ATP structure?

Answer 2

nucleotide - nitrogen containing base attached to a sugar (ribose) and to phosphate. ATP has 3 phosphates.

Question 3

ATP and ADP?

Answer 3

terminal phosphate of ATP is hydrolysed off, the product is ADP and energy (60kJ/mol).

ATP +H20 = ADP + Pi

Question 4

the role of ATP in energy use?

Answer 4

glucose, fatty acids, amino acids are broken down in various pathways to CO2. this is coupled with the synthesis of ADP +Pi to ATP. ATP then used for various purposes: muscle contraction, biosynthetic reactions, ion-pumping

Question 5

what is NADP? what are its forms?

Answer 5

hydrogen (and electron) carrier.
oxidised form = NADP+
reduced form = NADPH

NADP+ + 2H = NADPH + H+

Question 6

what does NADP act as?

Answer 6

currency of reducing power

Question 7

principle pathway reducing NADP? how is it reoxidised?

Answer 7

pentose phosphate pathway reduces NADP.
reoxidised in various biosynthetic pathways:
-fatty acid synthesis
-cholesterol synthesis
-synthesis of deoxyribonucleotides

Question 8

NADPH function?

Answer 8

important antioxidant
removing products of oxidation eg in red blood cells

Question 9

what age group requires the most energy per kilo?

Answer 9

babies (lots of growing)

Question 10

energy sources in a typical diet? (%)

Answer 10

carbohydrate = 49%
fat = 33%
protein = 14%
alcohol = [4]%

Question 11

energy stores in the body?

Answer 11

plasma glucose
glycogen
triacylglycerol
protein

Question 12

plasma glucose energy store: +/-?

Answer 12

+can be used by all tissues
-available store is very small

Question 13

glycogen energy store: +/-?

Answer 13

+can be rapidly metabolised
+can supply energy anaerobically
-hydrated - weight limits size of energy store

Question 14

triacylglycerol energy store: +/-?

Answer 14

+highly reduced so big energy yield
+not hydrated so no weight penalty
+the largest energy store in the body
-cannot be metabolised anaerobically - needs O2
-fatty acids cannot be used by the brain

Question 15

protein energy store: +/-?

Answer 15

+big store (muscle is 40% of body mass)
+can be converted to glucose and ketone bodies
-all protein is functional (breakdown = loss of function)

Question 16

mobilisation of energy stores - glucose?

Answer 16

glycogen broken down in glycogenolysis to glucose phosphate which is metabolised in the glycolytic pathway. metabolised to pyruvate (further oxidised to acetyl-CoA) or lactate (anaerobic)

Question 17

mobilisation of energy stores - triacylglycerol?

Answer 17

lipolysis releases free fatty acids from triacyclglycerol into plasma, taken up by tissues and oxidised in beta-oxidation pathway to acetyl-CoA

Question 18

where does ketone body production occur

Answer 18

liver

Question 19

mobilisation of energy stores - protein?

Answer 19

broken down by proteolysis into amino acids. each has a different breakdown pathway. some broken down into glucose (gluconeogenic amino acids) and some broken down into acetyl-CoA (ketogenic amino acids)

Question 20

terminal oxidation pathway?

Answer 20

TCA cycle:
acetyl-CoA oxidised to CO2
produces ATP
requires oxygen

Question 21

fuels in the blood?

Answer 21

glucose
fatty acids (bound to albumin)
ketone bodies
amino acids
lactate

Question 22

which fuels in the blood rise after fasting

Answer 22

fatty acids
ketone bodies (significant after prolonged fasting)

Question 23

when does lactate increase

Answer 23

anaerobic muscle exercise

Question 24

glucose supply features?

Answer 24

glycogen can be degraded to glucose but only liver glycogen can replenish plasma glucose
glucose cannot be made from fatty acids
glucose can be made from some amino acids

Question 25

what tissues require glucose?

Answer 25

brain erythrocytes some other tissues eg renal medulla

Question 26

what happens during exercise/fasting to triacylglycerol?

Answer 26

broken down into free fatty acids taken up by various tissues, oxidised to CO2 (with ATP release)

Question 27

liver and fatty acids?

Answer 27

liver can exclusively convert fatty acids to ketone bodies which can be used by the brain

Question 28

type 1 muscle fibres features?

Answer 28

slow contraction high myoglobin low myosin ATPase activity low creatine kinase activity high mitochondrial oxidation rate low glycolytic rate specialised for aerobic metabolism

Question 29

type 2 muscle fibres features?

Answer 29

fast contraction low myoglobin high myosin ATPase activity high creatine kinase activity low mitochondrial oxidation rate high glycolytic rate specialised for anaerobic metabolism

Question 30

what is creatine kinase?

Answer 30

creatine phosphate - small energy store in muscle creatine phosphates phosphate group is transferred to ADP by creatine kinase, resulting in ATP and creatine.

Question 31

fuels for purely anaerobic exercise?

Answer 31

1. muscle ATP 2. creatine phosphate 3. muscle glycogen

Question 32

fuels for purely aerobic exercise?

Answer 32

1. ATP, creatine-P, muscle glycogen 2. fatty acids (muscle, adipose) 3. plasma glucose (liver glycogen & gluconeogenesis)

Question 33

glucose metabolism in muscle - anaerobic?

Answer 33

glycogen store mobilised hormonally glucagon/adrenaline/AMP stimulates glycogen breakdown to glucose-1-phosphate, isomerised to glucose-6-phosphate, which can be anaerobically broken down into pyruvate which is reduced to lactate. (2 ATP per glucose)

Question 34

glucose metabolism in muscle - aerobic?

Answer 34

glycogen store mobilised hormonally glucagon/adrenaline/AMP stimulates glycogen breakdown to glucose-1-phosphate, isomerised to glucose-6-phosphate, which can be anaerobically broken down into pyruvate, which enters mitochondria, oxidised to acetyl-CoA, oxidised to CO2 (30 ATP per glucose)

Question 35

what happens to lactate?

Answer 35

enters plasma, circulates, converted back to glucose in liver and partially kidney.

Question 36

ATP cost for glucose -> lactate and lactate -> glucose?

Answer 36

glucose -> lactate = 2 ATP lactate -> glucose = 6 ATP

Question 37

adenine nucleotide pathways during exercise?

Answer 37

ATP +H2O -> ADP + Pi 2ADP -> AMP + ATP

Question 38

name for type of enzyme which transports phosphate from ATP to something else? what about the reverse?

Answer 38

kinase - phosphorylation phosphatase - dephosphorylation

Question 39

metabolic effects of AMP-activated protein kinase - activates?

Answer 39

glucose uptake glycolysis fatty acid oxidation mitochondrial biogenesis

Question 40

metabolic effects of AMP-activated protein kinase - inhibits?

Answer 40

gluconeogenesis cholesterol synthesis glycogen synthesis fatty acid synthesis protein synthesis