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phyl2064 > Metabolism > Flashcards

Metabolism Flashcards

1
Q

What is the difference between resting metabolic rate and basal metabolic rate?

A

Metabolic rate is the energy used per unit of time (I.e. kcal/day)

resting metabolic rate refers to the number of calories burnt at rest

basal metabolic rate refers to the number of calories needed at minimum for basic functions at rest

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2
Q

Which hormones regulate basal metabolic rate?

A

Thyroid hormones (T3 & T4)

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3
Q

What is the typical basal metabolic rate for females & males?

A

Females 1400 kcal/day
Males 1700 kcal/day

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4
Q

What metabolites are carbohydrates broken down into and how are these stored?

A

glucose

stored as glycogen or used directly for energy

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5
Q

What metabolites are lipids (fats) broken down into and how are these stored?

A

fatty acids

stored as triglycerides

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6
Q

What metabolites are proteins broken down into and how are these stored?

A

amino acids

stored as proteins

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7
Q

How does the energy yield from breaking down carbs/proteins compare with that of fats?

A

fats have twice the energy yield of carbs/proteins

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8
Q

True or false… anabolic reactions require energy?

A

true

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9
Q

Where does ‘first pass’ metabolism occur? Why is this?

A

in the liver as blood from the intestinal system flows directly there via the hepatic portal vein before moving into the main bloodstream

this is because the liver is closely linked with the pancreatic blood supply so hormones like insulin and glucagon can exert their effects here first

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10
Q

Is more glucose (glycogen) stored in the liver or in the skeletal muscle?

A

skeletal muscle

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11
Q

Where does energy exist within ATP?

A

between the phosphate bonds, hence when one is broken it creates energy

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12
Q

What gives cells specificity in metabolism?

A

they produce the enzymes needed for the process

i.e. the liver produces glycogen synthase hence it can synthesise glycogen

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13
Q

Describe the process of glycogenesis

A

blood glucose enters liver cell
hexokinase changes it to glucose-6-phosphate (ATP)
then to glucose-1-phosphate
then glycogen synthase changes it to glycogen

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14
Q

Describe the process of glycogenolysis

A

glycogen in liver cell
glycogen phosphorylase changes it to glucose-1-phosphate
then to glucose-6-phosphate
glucose-6-phosphatase converts to glucose
glucose moves to blood stream

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15
Q

What key metabolic functions does the liver have?

A

gluconeogenesis (synthesis of new glucose from lactate & amino acids)
ketogenesis (synthesis of ketones from fatty acids & amino acids for alternative energy)
lipogenesis (synthesis of lipids from glucose & amino acids)

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16
Q

Does skeletal muscle only get energy from glucose?

A

usually yes- in a fasted state it can use lipids as an energy source

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17
Q

Can glycogen stored in skeletal muscle be used elsewhere in the body for energy?

A

no- skeletal muscle that stores it, uses it

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18
Q

What function does adipose tissue have other than storing lipids?

A

it is also an endocrine organ releasing hormones (aka adipokines) i.e. leptin which is used in appetite regulation

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19
Q

How low do oxygen levels need to drop to cause damage or even result in death?

A

<2mmol/L

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20
Q

How long does it take for the brain to adapt to using ketones as an energy source when glucose is low?

A

3-4 days

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21
Q

How does growth hormone interact with proteins? How does this differ with fats?

A

GH protects protein reserves & stops us ‘eating’ through them for energy, whereas it has a catabolic effect on fats to release it as energy during periods of starvation

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22
Q

Are catecholamines, cortisol and growth hormone active in fed or fasted states?

A

fasted/starvation

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23
Q

What pancreatic cells produce insulin?

A

Beta cells

24
Q

What pancreatic cells produce glucagon?

A

Alpha cells

25
Q

What 3 underlying mechanisms are common in most metabolic syndromes?

A

1) fat accumulation
2) impaired insulin sensitivity
3) low-grade chronic systemic inflammation

26
Q

What are the 6 WHO criteria for metabolic syndrome?

A

1) impaired glucose regulation
2) abdominal obesity
3) hypertriglycemia (high levels of lipids in blood)
4) low levels of HDL cholesterol
5) raised blood pressure
6) microalbuminuria (high levels of albumin in urine)

27
Q

Why do we see necrosis in adipocytes in metabolic syndrome? How does this contribute to inflammation?

A

as adipose tissue increases, blood vessels are unable to keep up with the supply due to Fick’s law (same amount of blood vessels, larger cells to service means there is greater distance for molecules to travel)

as cells die, more immune cells enter the area to clean up the dead cells hence an increase in pro-inflammatory markers

28
Q

What 3 major tissues does insulin target?

A

skeletal muscle, liver & adipose

29
Q

Which lipoproteins (cholesterols) are ‘good’ and which are ‘bad’ leading to atherosclerosis?

A

‘good’ cholesterol is HDL or high density lipoproteins
‘bad’ cholesterol is VLDL or very low density lipoproteins & LDL or low density lipoproteins

these are the ones that lead to cardiovascular disease

30
Q

What is the functional unit of the pancreas?

A

Islets of Langerhans or islet cells

these produce insulin (beta cells) and glucagon (alpha cells)

31
Q

Why are beta cells and alpha cells not technically functional antagonists?

A

even though they work in opposite ways as functional antagonists do, they work on different receptors to each other

32
Q

What are the 3 P’s of diabetes mellitus?

A

polyuria (frequent urination)
polydipsia (increased thirst)
polyphagia (increased hunger)

33
Q

How does type 1 diabetes contrast with type 2?

A

type 1: impaired insulin secretion due to destruction of beta cells, early life & rapid onset, accounts for 10-20% of all cases of diabetes and is treated with insulin injections, exercise and diet

type 2: normal insulin production however insulin is resisted by target cells, late life & slow onset, accounts for 80-90% of all cases of diabetes and is treated with weight reduction, exercise, diet and some drugs

34
Q

Name 4 purposes of metabolic pathways (i.e. glycolysis & citric acid cycle).

A

1) extraction of energy
2) storage of fuels
3) synthesis of building blocks
4) elimination of waste

35
Q

True or false… the citric acid cycle only takes place in cells with mitochondria

A

true

36
Q

How much of energy in nutrient molecules is converted to energy?

A

~50%

37
Q

What is ATP used for?

A

provides energy for synthesis of macromolecules, transport pumps and muscle contraction

38
Q

Metabolic process: Glycogenesis

A

turns glucose to glycogen, decreasing glucose levels in the bloodstream

39
Q

Metabolic process: Glycogenolysis

A

turns glycogen into glucose, increasing glucose levels in the blood stream

40
Q

Metabolic process: Gluconeogenesis

A

turns amino acids into glucose, increases glucose levels in the bloodstream

41
Q

Metabolic process: Protein synthesis

A

turns amino acids into protein, decreasing amino acid levels in the bloodstream

42
Q

Metabolic process: Protein degradation

A

turns proteins into amino acids, increasing amino acid levels in the bloodstream

43
Q

Metabolic process: Lipogenesis

A

turns fatty acids & glycerol into triglycerides, decreasing the fatty acid levels in the bloodstream

44
Q

Metabolic process: Lipolysis

A

turns triglycerides into fatty acids & glycerol, increasing fatty acid levels in the bloodstream

45
Q

How much ATP is produced in glycolysis? How about the citric acid cycle? And from the electron transport chain?

A

net +2 ATP, +2 ATP, ~+28 ATP (altogether about 30 ATP)

46
Q

What happens when there is too much acetyl COA in the bloodstream due to a diet high in fat?

A

ketogenesis occurs in the liver to form ketone bodies which can be used as fuel when glucose is sparse

47
Q

What are the 4 major lipid metabolic pathways?

A

1) lipolysis
2) beta oxidation
3) lipogenesis
4) ketogenesis

48
Q

Lipolysis is a …bolic reaction that converts … to … & …

A

catabolic

converts triglycerides to glycerol & fatty acids

49
Q

Beta oxidation is a …bolic reaction which converts … into …

A

catabolic

converts fatty acids into acetyl CoA

50
Q

Lipogensis is a …bolic reaction that synthesises …

A

anabolic

synthesis of cholesterol

51
Q

Ketogenesis is a …bolic reaction that synthesises …

A

anabolic

synthesis of ketone bodies

52
Q

Where do all 4 of the lipid metabolic pathways converge to?

A

Acetyl-CoA (to be fed into the cytric acid cycle to produce ATP)

53
Q

What are the 3 ways that proteins can be metabolised and used?

A

proteins are digested to form amino acids which are either stored as tissue proteins or plasma proteins

they can also be deaminated and secreted in urine as urea or ammonium or used in metabolic pathways

they can also be turned into neurotransmitters

54
Q

Describe the pathways of amino acids when they go through transamination (as opposed to being used in tissues or plasma as proteins)

A

1) transamination: an amine group is switched from an amino acid to a keto acid
2) oxidative deamination: the amine group of glutamic acid is removed as ammonia and combined with Co2 to form urea which is excreted in urine
3) keto acid modifications: the keto acids formed during transamination are altered so they can easily enter the citric acid cycle

55
Q

Hyperglycemia can lead to other complications down the road like…

A

1) vascular damage
2) diabetic blindness
3) renal failure
4) neuropathy

phyl2064 (7 decks)

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