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Nutritional physiology > 1. Mass flow > Flashcards

1. Mass flow Flashcards

1
Q

There are three circles: metabolism, physiological output, nutritional input. By what is physiological output influenced?

A
  • Physiological status
  • Health status
  • Environment
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2
Q

There are three circles: metabolism, physiological output, nutritional input. What are the raaklijnen? Explain

A

Post prandial phase (nutr input - metabolism)
= swallow food > processed > metabolised
Post absorptive phase (phys. output - metabolism)
= use internal stores to provide nutrients for metabolic rate

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3
Q

Recall the organs of the digestion system?

A

Mouth > oesophagus > stomach > small intestine > colon > rectum > anus

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4
Q

Microbial fermentation uses x, What can it provide and what not?

A

Microbial fermentation (using nutrients that are not absorbed) can provide energy which are taken up, but NO amino acids.

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5
Q

What do proteolytic enzymes do?

A

lower activation energy of proteolysis (the breakdown of proteins)

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6
Q

5 reasons why the digestive system does not digest itself?

A
  • Activity restricted to presence of food
  • Regulation (local, distal, proximal)
  • Enzymes stored as inactive pro-enzymes (zymogens)
  • Non-digestible mucus coats the walls
  • High replacement rate (turnover) of mucosal cells
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7
Q

What is intermediary metabolism?

A
  • Interconversions of absorbed monomers
  • Anabolic reactions (synthesizing e.g. protein metabolism)
  • Catabolic reactions (energy/ATP/heat)
  • Unavailable waste products

Think about the coloured metabolism picture with fat, glycogen, protein, TCA cycle and phosphorylation

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8
Q

Storage: protein, glycogen, fat.
Absorption: …

A

amino acids, glucose, fatty acids + glycerol

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9
Q

At the post prandial phase, when input > needs, anabolic or catabolic disposal will take place (storage, interconversion, oxidation). What pathways can glucose take?

A

Intestine: glucose absorbed. Stored glycogen in liver, oxidised/released in circulation, released into the muscles, stored. Also fuels the brain, as the brain can only rely on glucose for fuel, cannot use the lipids. Therefore always glucose in blood.

If you have a lot of glucose in the blood, stored as triacylglycerol in adipose tissue (via intestine or liver)
See image p. 4

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10
Q

What is the pathway of protein (organ-wise) when at the post prandial phase?

A

Protein: amino acids from intestine to liver, used for protein synthesis here and in the muscles

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11
Q

What happens at the post absorptive phase when input < needs?

A

Turnover, interconversion, oxidation

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12
Q

What is the fate of triacylglycerol at the post absorptive phase when input < needs?

A

Triacylglycerol stores that are releasing glycerol + fatty acids. Used especially by liver + muscles. If not enough, liver can converse fatty acids to ketone bodies for muscles.

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13
Q

What is the fate of glucose at the post absorptive phase when input < needs?

A

Glucose originating from glycerol, glycogen (liver) and glucose (kidney) is used to fuel the brain.

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14
Q

What is the fate of protein at the post absorptive phase when input < needs?

A

Proteins broken down from muscle mass > amino acids in circulation > can be used by liver or kidneys to convert into glucose. (brain can use ketone bodies only in long-term fasting)
See p. 4

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15
Q

Where do the following components get absorbed (the most)?
Alcohol
Water
Monosacc, amino ac, fatty ac, glycerol, fats, water

A

Stomach: alc
Large intest: water
Small intest: Rest

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15
Q

Where do the following components get absorbed (the most)?
Alcohol
Water
Monosacc, amino ac, fatty ac, glycerol, fats, water

A

Stomach: alc
Large intest: water
Small intest: Rest

16
Q

Small intestine is divided into:

A

Duodenum, jejenum, ileum

17
Q

What are the functions of the colon?

A
  • Absorption of water + ions
  • Bacterial fermentation of nonabsorbed nutrients
  • Storage of waste and indigestible materials

Rectum:
- elimination of waste & indig. materials

18
Q

Villi: what are its components?

A

Enterocyte: single cell (layer) of the villus. Absorbs nutrients.
Goblet cell: secrete mucus (white cells on p. 7)
Lacteal: for the lymph system
Blood supply
Microvilli: cell membrane of enterocytes with finger-like projections (brush border)

19
Q

What are the four layers of the GI-tract from inside (lumen) to outside?

A
  1. Mucosa (Secretion + abs)
  2. Submucosa (vascular layer: support)
  3. Muscularis (segmental contractions)
  4. Serosa (protective layer)

See p. 7

20
Q

From oesophagus to stomach, there is an increase in..

A

Muscle mass + surface area

21
Q

So, mucosal surface area exists of..

A
  1. Lungitudinal foldings
  2. Fingerlike projections: 0.5 – 1.5 mm villi
    20-40 villi per mm2
  3. Covered with microvilli (brush border)
    Absorptive area: 250-300 m2 (tennis field 175 m2)
22
Q

What happens when free AA are absorbed into the enterocyte?

A
  1. To synthesize other proteins
  2. To be converted to other amino-acids
  3. Release to blood flow and release into portal vein > body
23
Q

What is gut retention? For which nutrients does this happen?

A

Time between having amino-acids in your lumen until you see them in circulation.
Also happens with triglycerides

24
Q

What are the three mechanisms of communication that mediate responses in the GI tract?

A
  1. Endocrine
  2. Neurocrine
  3. Paracrine
25
Q

Explain how these three mechanisms work

A

Endocrine (hormone): sensor cell > hormone > blood circulation > target cell with receptor
Neurocrine (neurones): Neurone > neurotransmitters/messengers > other neurones > target cells: release enzymes, or contraction muscle cells e.d.
Paracrine (locally): Paracrine mediator released from sensor cell > only travelling to neighbouring cells
See p.9

26
Q

Motor behaviour in the intestines: explain the two types?

A
  1. Segmentation (circular muscles): contraction (not peristaltis), creating segments within the intestine. Chopping up food bolus, enhance digestion and mixing of luminal content with food (12-16x / min)
  2. Peristalsis: Movement of the bolus from one to the other direction. Contraction circular muscles by neural reflexes..
27
Q

Three systems for absorption

A
  1. Simple diffusion (water, small lipids) over cell membrane.
  2. Facilitated diffusion (water-soluble vitamins) needs transporter to ‘catch’ compound
  3. Active transport (glucose, amino acids). Invest energy (ATP) to ‘trap’ nutrient.
28
Q

What is the MMC (migrating myoelectric complex)?
What is it used for?

A

During interdigestive phase (e.g. between having lunch – dinner) there are periodic bursts of organ responses. = constant ‘cleaning’ of the intestines (every 90 mins, also when asleep).
> prevention bacterial stasis
> final cleaning non-digestible parts

29
Q

Transit time stomach/S.I/L.I. ?

A

Stomach 1 – 5 hrs
Small intestine (almost all absorption, so very effective) 1.5 hrs
Large intestine 1 – 2 days

Nutritional physiology (26 decks)

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