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Anatomy Exam 3 > Lecture 11 : Gastrointestinal System V : Nutrition and Metabolism II > Flashcards

Lecture 11 : Gastrointestinal System V : Nutrition and Metabolism II Flashcards

1
Q

Glucose is a major fuel for our body:

A

When glucose is plentiful, cells use it as their main energy source

To get maximum ATP from glucose, it must be converted to products that go through the citric acid cycle and oxidative phosphorylation

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2
Q

You can’t store ATP: excess glucose can be stored as _____

A

glycogen

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3
Q

Liver and skeletal muscles are main cell types capable of holding large stores of glycogen =

A

~600 g total, 2400 kcal

less than one day’s worth of energy

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4
Q

When glycogen stores are full, excess glucose gets converted to ____

A

fat

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5
Q

Different processes control amount of glucose available for cellular respiration:
The 4 G’s of Glucose Regulation =

A

Glycolysis
Glycogenesis
Glycogenolysis
Gluconeogenesis

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6
Q

Glycolysis =

A

(sugar splitting)

converts glucose to pyruvic acid (producing 2 ATP) – all cells

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7
Q

Glycogenesis =

A

polymerize glucose to form glycogen

(storage of glucose – occurs in liver* and skeletal muscle)

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8
Q

Glycogenolysis =

A

hydrolyzes glycogen into glucose monomers

(release glucose from storage – only liver can release to blood)

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9
Q

Gluconeogenesis =

A

forms glucose from non-carbohydrate precursors

(make new glucose from noncarbohydrate sources) – mostly in liver*

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10
Q

Helpful root words:
glyco, gluco =
lysis =
genesis =
neo =

A

glyco, gluco = sugar

lysis = splitting

genesis = the formation of; origin

neo = new

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11
Q

To fully utilize protein or fat as an energy source, they must be converted to ____

A

substrates of citric acid cycle

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12
Q

____ are the most concentrated source of energy in the body

A

Fats

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13
Q

Fats contain very little ____; yield 9 kcal/gm fat

A

water

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14
Q

Products of fat digestion transported as ______.

A

chylomicrons

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15
Q

Lipases in capillaries hydrolyze ____ through ____

A

triglycerides
lipolysis

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16
Q

Of fats, only ___ routinely oxidized for energy

A

triglycerides

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17
Q

Liver, cardiac muscle, resting skeletal muscle prefer ____ as fuel

A

fatty acids

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18
Q

___ and ____ can be taken up into most body cells and converted to acetyl CoA (through different pathways) to enter citric acid cycle

A

Glycerol
free fatty acids

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19
Q

____ allows Glycerol and Fatty Acids to be converted to energy substrates

A

Lipolysis

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20
Q

Glycerol =

A

Glycerol is a 3-carbon sugar

Converted to pyruvic acid through glycolysis pathways

Pyruvic acid converted to acetyl CoA which can enter Citric Acid cycle

Net energy ~15 ATP

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21
Q

Fatty Acids carbon-hydrogen chains broken down in cycles of
_____

A

beta oxidation

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22
Q

beta oxidation =

A

2 carbon fragments broken off

Form Reduced coenzymes along with acetyl CoA

acetyl CoA enters Citric Acid cycle

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23
Q

____ are formed from Acetyl CoA if there aren’t sufficient carbohydrate substrates for citric acid cycle to run

A

Ketone bodies

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24
Q

____ is triglyceride synthesis

A

Lipogenesis

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25
Q

Lipogenesis =

A

Occurs mainly in liver and adipose tissue during states when cellular ATP and glucose levels are high

Excess acetyl CoA (2 carbons) join together to make fatty acids

Excess glyceraldehyde 3-phosphate (glycolysis intermediate) converted to glycerol

Note these pathways are reversible

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26
Q

Amino acids can also be oxidized for energy =

A

: Occurs in the liver

we can make nonessential amino acids from keto acids

Transamination and deamination : removes amine group from an amino acid
>nitrogen converted to
ammonia and then urea

Keto acid formed in transamination reaction is modified for citric acid cycle or conversion to fats or glucose

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27
Q

There is no storage form of ______

A

amino acids

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28
Q

Amino acids are built into proteins when there is an excess =

A

Any given protein is only synthesized if all its amino acids are available

Every protein has a “job” – we don’t make extras just to store amino acids

If amino acids are needed for energy, we lose important protein

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29
Q

Amino acids can also be converted to glucose : gluconeogenesis

A

converted first to pyruvic acid , then converted to glucose by reversing the steps of glycolysis

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30
Q

Nutrient pools are interconvertible because their pathways are linked by ______

A

key intermediates

31
Q

The body draws on nutrient pools to meet its metabolic needs =

A

Carbohydrates are easily and frequently converted to fats

Fats and carbs are oxidized directly to supply energy

32
Q

Amino acid pools must be converted to ____ that can enter citric acid cycle

A

metabolites

33
Q

Pyruvic acid can be converted to glucose (______)

A

gluconeogenesis

34
Q

Fats and carbs can be stored, but excess amino acids can’t be – they are ______

A

oxidized for energy, or converted to fat or glycogen for storage

35
Q

________ are key in managing nutrient load and ensuring all tissues have adequate energy

A

Liver, skeletal muscle, and adipose tissue

36
Q

Prefer ____ as major energy source

Allow glucose to remain in blood for brain if glucose is in short supply

A

triglycerides

37
Q

Skeletal muscle:

A

Protein synthesis and protein breakdown
>Muscle proteins can
liberate amino acids for
gluconeogenesis

Glycogen storage

38
Q

Adipose tissue:

A

Lipolysis and lipogenesis

Major organ of triglyceride storage

Also secretes novel hormones regulating metabolism – the kind of adipose tissue matters

39
Q

Carbohydrate metabolism:

A

Convert non-glucose monosaccharides to glucose

Glycogenesis, glycogenolysis, gluconeogenesis

Converts glucose to fat

40
Q

Fat metabolism:

A

Breakdown fatty acids (FA) to acetyl CoA (beta-oxidation)

Convert excess acetyl CoA to ketone bodies (ketogenesis)

Stores fats

Synthesizes lipoproteins for transport of FA, fats and cholesterol in blood

Synthesis of cholesterol from acetyl CoA

Production of bile, converts cholesterol to bile salts

41
Q

Protein metabolism:

A

Synthesizes urea to remove ammonia from body

Deaminates amino acids for conversion to glucose or use as fuel

Synthesizes plasma proteins

Interconversion of nonessential amino acids

42
Q

Vitamins/Minerals:

A

Storage of vitamin A, D, B12, iron

43
Q

Biotransformation functions:

A

Metabolizes alcohol, drugs, hormones other toxins by inactivating them for excretion in kidney

Perform reactions to make products more active or less active

Processes bilirubin excretes bile pigments in bile

44
Q

Absorptive (fed) state =

A

Lasts about 4 hours after eating begins

Anabolism exceeds catabolism and nutrients are stored

45
Q

Post-absorptive (fasting) state =

A

Catabolism of fat, glycogen, and proteins begins

Primary goal is maintaining blood glucose levels (70-110 mg/dl)

Can be short (between meals) or long-lasting (fasting, starvation)

46
Q

Major events in the absorptive state =

A

Anabolism exceeds catabolism and nutrients are stored

Glucose is the major energy fuel

47
Q

Major metabolic pathways in the absorptive state =

A

Carbohydrates and Amino acids absorbed into blood go to liver first (via portal vein)

Most lipids travel via lymph in chylomicrons

48
Q

____ dominates hormonal control of the absorptive state

A

Insulin

49
Q

Insulin

Stimulus: rising blood glucose levels
> Beta cells of pancreas increase insulin secretion

Result:

A

Insulin promotes increased uptake of glucose and amino acids to cells

increased use of glucose by cells for energy or storage as glycogen and fats

Insulin inhibits glucose release and gluconeogenesis in liver

50
Q

Insulin is a ______ – decreases blood glucose levels

A

hypoglycemic hormone

51
Q

Lack of insulin or insulin response: _____

A

diabetes mellitus

52
Q

Major events and metabolic pathways in the
post-absorptive state =

A

Catabolism of fat, glycogen, and proteins

Goal is to maintain homeostatic glucose levels (70-110 mg/100ml)

53
Q

_____ and other hormones dominate hormonal control of the post-absorptive state

A

Glucagon

54
Q

Glucagon
Stimulus: falling blood glucose levels
> Alpha cells increase
glucagon secretion
> Beta cells decrease
insulin secretion

Result:

A

glycogenolysis and gluconeogenesis by liver restore blood glucose levels

lipolysis in adipose tissue releases fatty acids for use by tissue cells = “glucose sparing”

55
Q

Carbohydrates

absorbed by:

A

Glucose primarily

56
Q

Carbohydrates

absorptive state metabolism:

A

Used immediately for energy through aerobic pathways (glycolysis & citric acid cycle)

Stored as glycogen in liver & muscle (glycogenesis)

Excess converted to fat and stored in adipose tissue (lipogenesis)

57
Q

Carbohydrates

post-absorptive state metabolsim:

A

Glycogen polymers broken down (glycogenolysis) to glucose

58
Q

Fats

absorbed by:

A

Fatty acids, triglycerides, cholesterol

59
Q

Fats

absorptive state metabolism:

A

Stored as triglycerides primarily in liver and adipose tissue (lipogenesis)

Cholesterol used for steroid synthesis or in membranes

60
Q

Fats

post-absorptive state metabolsim:

A

Triglycerides broken down into fatty acids and glycerol (lipolysis)

Fatty acids used for ATP production through aerobic pathways (Beta-oxidation)

61
Q

Proteins

absorbed by:

A

Amino acids

62
Q

Proteins

absorptive state metabolism:

A

Most amino acids go to tissues for protein synthesis

If needed for energy, amino acids covered in liver to intermediates for aerobic metabolism (deamination)

Excess converted to fat in adipose tissue (lipogenesis)

63
Q

Proteins

post-absorptive state metabolsim:

A

Proteins broken down into amino acids

Amino acids deaminated in liver for ATP production or used to make glucose (gluconeogenesis)

64
Q

Insulin in regulation of metabolic processes =

A

Stimulates glucose uptake by cells

Stimulates amino acid uptake by cells

Stimulates glucose catabolism for energy

Stimulates glycogenesis

Stimulates lipogenesis & fat storage

Inhibits gluconeogenesis

Stimulates protein synthesis (anabolic)

65
Q

Glucagon in regulation of metabolic processes =

A

Stimulates glycogenolysis

Stimulates lipolysis & fat mobilization

Stimulates gluconeogenesis

66
Q

Insulin is necessary for cells to take glucose out of the blood =

A

No insulin = high blood glucose levels

High concentration of glucose in filtrate is lost in urine along with water (high urine production)

67
Q

Type I Diabetes :

A

autoimmune disease where immune system attacks beta cells of pancreas

little or no insulin produced (“insulin dependent diabetes”)

68
Q

Type II Diabetes:

A

Pancreas makes insulin

Receptors lose sensitivity to insulin (“insulin resistant diabetes”)

69
Q

Metabolic Syndrome

A

2-8% of world population
1 in 3 US adults

Group of conditions that increase risk of cardiovascular disease, diabetes, stroke, other diseases

Altered metabolism

70
Q

Many hormones involved in metabolism =

A

“traditional” endocrine glands

Gut hormones from enteroendocrine cells

71
Q

Recent drugs for diabetes treatment:

A

Hormone GLP-1 : Glucagon-like peptide 1

Metformin

Semaglutide

72
Q

Hormone GLP-1 : Glucagon-like peptide 1

A

secreted from intestine

doesn’t behave like glucagon

slows digestion by delaying gastric emptying

stimulates insulin secretion to lower blood glucose

73
Q

Metformin:

A

stimulates GLP-1 release

74
Q

Semaglutide:

A

(Ozempic) : GLP-1 agonist

Anatomy Exam 3 (11 decks)

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