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240 My set > Human Nutrient Use and Metabolism > Flashcards

Human Nutrient Use and Metabolism Flashcards

1
Q

Energy through eating

A

Eat food –> Digest food –> Food molecules are transported to cells, where cellular respiration takes place –> Energy currency is produced

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2
Q

Carbohydrates

A
  • Digested into small pieces, either glucose or a sugar that is easily converted to glucose, then absorbed into blood
  • Can only be stored in limited quantities, o the body is eager to use them for energy
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3
Q

Storage of carbohydrates

A
  • liver stores some of the excess (as glucose and glycogen) for distribution between meals
  • Also stored in muscle and nervous tissues
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4
Q

Function of fats

A

Long-term energy storage and insulation

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5
Q

Function of Sterols

A

Regulate growth and development

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6
Q

Function of phospholipids

A

Form the membranes that enclose cells

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7
Q

Fats/Lipids

A
  • Broken down into fatty acids, which can travel in the blood freely or associated with protein
  • If not needed, stored as triglycerides in fat cells
  • Typically provide more than half of the body’s energy needs
  • Excess carbs also stored as fatty acids
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8
Q

Proteins

A
  • Broken down into amino acids that are then used to build new proteins
  • When there is a shortage of fats or carbs, proteins can also yield energy
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9
Q

Nutrients

A
  • Carbs and fats will be used primarily for energy

- Proteins from food are broken down to provide amino acids for proteins

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10
Q

Anabolism

A

-Synthesizing large molecules from small ones

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11
Q

Catabolism

A

Breaking down complex molecules to simpler ones

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12
Q

Gluconeogenesis

A

Synthesis of glucose from a non-carb precursor

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13
Q

Glycogenesis

A

Synthesis of glycogen from glucose

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14
Q

Lipogenesis

A

Excess glucose converted to fat

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15
Q

Lipolysis

A

Breakdown of stored fats into glycerol and fatty acids

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16
Q

Ketogenesis

A

Production of ketone bodies from breakdown of fatty acids (from acetyl CoA)

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17
Q

Catabolic-Anabolic Steady state

A

Dynamic state in which organic molecules (except DNA) are continuously broken down

18
Q

Nutrient pools

A
  • Stores of amino acids, carbs, and fats
  • Pools are interconvertible because pathways are linked by common intermediates
  • Amount and direction of conversion are directed by liver, adipose tissue, and skeletal muscle
19
Q

Amino acid pools

A

-Bodys total supply of free amino acids
-Pool is the source for:
-Resynthesizing body proteins
-Forming amino acid derivatives
Gluconeogenesis

20
Q

Carbohydrate and fat pools

A

-Carbs and fats are easily interconverted through key intermediates

  • Two major differences between carb/fat pools and amino acid pool:
  • Fats and carbs are oxidized directly to produce energy in mitochondria
  • Amino acids must be first converted to a citric acid cycle keto acid

-Excess carb and fat can be stored as such (amino acids are not stores as proteins)

21
Q

Absorptive state (fed state)

A
  • Youve just eaten a meal, you want to use what you need for energy production and save the rest
  • last for about four hours after eating, when absorption of nutrients from digestive tract to cells is occurring
  • Anabolism exceeds catabolism
  • Excess nutrients are stored as fats, and to a lesser extent carbs, if not used
22
Q

Postabsorptive state

A

Youre in between meals but still need energy, now you want to use what youve stores

23
Q

Absorptive state Carbs

A
  • glucose is major cellular energy fuel
  • Can be converted in liver to glycogen or fat
  • Glycogen remains in liver, but fat joins protein to form very low density lipoproteins (VLDLs) released to blood for storage by adipose (fat) tissue
  • Glucose in blood enters cells; excess stored as glycogen in muscles or fat in adipose cells
24
Q

Absorptive state Triglycerides

A
  • Triglycerids are used for energy by adipose tissue, liver, and skeletal and cardiac muscle
  • Most glycerol and fatty acids are converted back to triglycerides for storage
25
Q

Absorptive State Amino acids

A
  • Some absorbed amino acids are de-aminated in liver
  • Removal of amino group produces keto acids that can be used in citric acid cycle for energy
  • Most amino acids are used for protein synthesis
26
Q

How is homeostasis maintained/How is everything integrated

A

Nervous system - Autonomic system

27
Q

Sympathetic nervous system

A
  • Arouses body for “fight or flight”

- Neurotransmitter released by sympathetic neurons is norepinephrine (similar to adrenaline)

28
Q

Parasympathetic Nervous system

A
  • Predominates during relaxation, “rest and digest”

- Neurotransmitter is acetylcholine, same neurotransmitter used at neuromuscular junction

29
Q

Endocrine system

A
  • Hormones involved in blood glucose regulation
  • Insulin and glucagon
    • Both produced by pancreas
30
Q

Hormonal control of the absorptive state

A

-Primarily by insulin

  • Insulin secretion by beta cells of pancreas is stimulated by:
  • Elevated blood levels of glucose and amino acids
  • Parasympathetic stimulation
  • When insulin binds to membrane receptors, it facilitates diffusion of glucose into muscle and adipose cells (GLUT-4 transporter)
  • Brain and liver take up glucose without insulin
  • Consider why this is important
31
Q

Pancreas

A

-Produces insulin to allow cells to take up glucose

32
Q

Hormonal control of the absorptive state

A
  • Insulin is a hypoglycemic hormone that enhances:
  • Glucose oxidation for energy
  • Glycogen and triglyceride formation
  • Active transport of amino acids into cells
  • Protein synthesis

-It also inhibits glucose release from liver and gluconeogenesis

33
Q

Post-Absorptive state (Fasting state)

A
  • When GI tract is empty and energy sources are supplied by breakdown of body’s reserves
  • Catabolism exceeds anabolism
  • Goal is to maintain blood glucose between meals by:
  • Making glucose available to blood
  • Promote use of fats for energy
  • Glucose sparing saves glucose for organs that need it most, such as brain
  • Modulation of insulin effects after a high protein, low-carbohydrate meal
  • Insulin responds to high amino acid blood levels; if high-protein meal is consumed, hypoglycemic conditions may result-not good for brain
  • Glucagon modulates effect ensuring adequate blood glucose
34
Q

Sources of blood glucose

A
  • Glycogenolysis in liver: first resuerve used
  • Glycogenolysis in skeletal muscle: before glucose from liver is exhausted, glycogen stores in skeletal muscles start to break down
  • Lipolysis in adipose tissues and liver
  • Glycerol used for gluconeogensis in liver
  • Catabolism of cellular protein
  • Major source during prolonged fasting, glycogen and fat stores exhausted; limited amount of protein can be broken down before damage
  • Amount of fat in body determines how long a person can survive without food
35
Q

Glucose sparing

A
  • During prolonged periods of fasting, body uses more non-carbohydrate sources to conserve glucose
  • More fat and protein are converted to intermediates that can enter citric acid cycle
  • Brain uses bulk of glucose while other body cells switch to fatty acids as fuel source
  • Results in production of ketone bodies
  • After 4-5 days without food, brain will start to also use ketone bodies as fuel
36
Q

Hormonal and neural controls of the post-absorptive state

A
  • sympathetic nervous system interacts with several hormones to control events of post-absorptive state
  • More complex than absorptive state, which only uses one hormone, insulin

-Triggered by reduced insulin release as blood glucose levels drop

37
Q

Glucagon

A

Hyperglycemic hormone whose release is stimulated by:

  • Declining blood glucose levels
  • Rising amino acid levels
  • Glucagon promotes:
    • Glycogenolysis and gluconeogenesis in the liver
    • Lipolysis in adipose tissue, causing fatty acids and glycerol to be released
38
Q

Post-absorptive state, sympathetic nervous system

A
  • Adipose tissue is innervated by sympathetic nervous system
  • –can quickly supply glucose if blood levels are low
  • Low plasma glucose, fight-or-flight response, or exercise can trigger fat mobilization and glycogenolysis
  • –initiated by sympathetic nervous system and epinephrine from adrenal medulla
39
Q

Diabetes Mellitus

A

-Inadequate insulin production (Type 1) or abnormal insulin receptors (Type 2)

Results in:

  • -Unavailability of glucose to most body cells
  • Excessively high blood glucose levels (hyperglycemia)
  • Glucose loss in urine

Fats and proteins are used for energy instead

  • Can lead to metabolic acidosis, protein wasting, and weight loss
  • May lead to coma and death
40
Q

Type 2 Diabetes

A
  • Insulin resistant diabetes
  • Insulin levels often normal (sometimes high) but insulin receptors do not respond to it
  • May be some genetic association but more related to lifestyle

240 My set (9 decks)

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