feeding, fasting and exercise WF Flashcards
overview of metabolism?
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
ATP structure?
nucleotide - nitrogen containing base attached to a sugar (ribose) and to phosphate. ATP has 3 phosphates.
ATP and ADP?
terminal phosphate of ATP is hydrolysed off, the product is ADP and energy (60kJ/mol).
ATP +H20 = ADP + Pi
the role of ATP in energy use?
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
what is NADP? what are its forms?
hydrogen (and electron) carrier.
oxidised form = NADP+
reduced form = NADPH
NADP+ + 2H = NADPH + H+
what does NADP act as?
currency of reducing power
principle pathway reducing NADP? how is it reoxidised?
pentose phosphate pathway reduces NADP.
reoxidised in various biosynthetic pathways:
-fatty acid synthesis
-cholesterol synthesis
-synthesis of deoxyribonucleotides
NADPH function?
important antioxidant
removing products of oxidation eg in red blood cells
what age group requires the most energy per kilo?
babies (lots of growing)
energy sources in a typical diet? (%)
carbohydrate = 49%
fat = 33%
protein = 14%
alcohol = [4]%
energy stores in the body?
plasma glucose
glycogen
triacylglycerol
protein
plasma glucose energy store: +/-?
+can be used by all tissues
-available store is very small
glycogen energy store: +/-?
+can be rapidly metabolised
+can supply energy anaerobically
-hydrated - weight limits size of energy store
triacylglycerol energy store: +/-?
+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
protein energy store: +/-?
+big store (muscle is 40% of body mass)
+can be converted to glucose and ketone bodies
-all protein is functional (breakdown = loss of function)
mobilisation of energy stores - glucose?
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)
mobilisation of energy stores - triacylglycerol?
lipolysis releases free fatty acids from triacyclglycerol into plasma, taken up by tissues and oxidised in beta-oxidation pathway to acetyl-CoA
where does ketone body production occur
liver
mobilisation of energy stores - protein?
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)
terminal oxidation pathway?
TCA cycle:
acetyl-CoA oxidised to CO2
produces ATP
requires oxygen
fuels in the blood?
glucose
fatty acids (bound to albumin)
ketone bodies
amino acids
lactate
which fuels in the blood rise after fasting
fatty acids
ketone bodies (significant after prolonged fasting)
when does lactate increase
anaerobic muscle exercise
glucose supply features?
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
what tissues require glucose?
brain
erythrocytes
some other tissues eg renal medulla
what happens during exercise/fasting to triacylglycerol?
broken down into free fatty acids taken up by various tissues, oxidised to CO2 (with ATP release)
liver and fatty acids?
liver can exclusively convert fatty acids to ketone bodies which can be used by the brain
type 1 muscle fibres features?
slow contraction
high myoglobin
low myosin ATPase activity
low creatine kinase activity
high mitochondrial oxidation rate
low glycolytic rate
specialised for aerobic metabolism
type 2 muscle fibres features?
fast contraction
low myoglobin
high myosin ATPase activity
high creatine kinase activity
low mitochondrial oxidation rate
high glycolytic rate
specialised for anaerobic metabolism
what is creatine kinase?
creatine phosphate - small energy store in muscle
creatine phosphates phosphate group is transferred to ADP by creatine kinase, resulting in ATP and creatine.
fuels for purely anaerobic exercise?
- muscle ATP
- creatine phosphate
- muscle glycogen
fuels for purely aerobic exercise?
- ATP, creatine-P, muscle glycogen
- fatty acids (muscle, adipose)
- plasma glucose (liver glycogen & gluconeogenesis)
glucose metabolism in muscle - anaerobic?
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)
glucose metabolism in muscle - aerobic?
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)
what happens to lactate?
enters plasma, circulates, converted back to glucose in liver and partially kidney.
ATP cost for glucose -> lactate and lactate -> glucose?
glucose -> lactate = 2 ATP
lactate -> glucose = 6 ATP
adenine nucleotide pathways during exercise?
ATP +H2O -> ADP + Pi
2ADP -> AMP + ATP
name for type of enzyme which transports phosphate from ATP to something else? what about the reverse?
kinase - phosphorylation
phosphatase - dephosphorylation
metabolic effects of AMP-activated protein kinase - activates?
glucose uptake
glycolysis
fatty acid oxidation
mitochondrial biogenesis
metabolic effects of AMP-activated protein kinase - inhibits?
gluconeogenesis
cholesterol synthesis
glycogen synthesis
fatty acid synthesis
protein synthesis
