Summary Class notes - HAP2018

Course
- HAP2018
- wisa
- 2018 - 2019
- Wageningen University (Wageningen University, Wageningen)
- Nutrition and Health
492 Flashcards & Notes
1 Students
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Summary - Class notes - HAP2018

  • 1516662000 Digestive system

  • Mass flow of nutrients (through body and cells) consists of:
    Nutritional input, physiological output and metabolism
  • How do nutrients move through the body?
    Translocation and transformation
  • How are the movements of nutrients through the body regulated?
    Via neural system and endocrine system
  • What do proteolytic enzymes?
    They lower the activation energy of proteolysis
  • What does microbial fermentation by microbiota in colon?
    It provides energy (no amino acids) for the host
  • Temperature and time in which specific bonds are hydrolysed:
    1-2 hours at 37 degrees
  • Temperature and time in which random bonds are hydrolysed:
    10-12 hours at 105 degrees
  • Why does the digestive system not digest itself?
    - The activity is restricted to the presence of food
    - There is regulation: local, distal and proximal
    - Enzymes are stored as inactive proenzymes (zymogens) 
    - There is a non-digestible layer of mucus
    - High replacement rate/turnover of mucosal cells
  • What are anabolic reactions?
    Synthesis of body constituents
  • What are catabolic reactions?
    Release of energy from food or body constituents
  • Intermediairy metabolism consists of:
    -Interconversions of absorbed monomers
    -Anabolic reactions
    -Catabolic reactions
    -Unavoidable waste products
  • Post prandial phase
    Digestion, absorption and storage
    (storage, interconversion, oxidation)
    Input is larger than needs
  • Post absorptive phase
    Usage (utilisation)
    (turnover, interconversion, oxidation) 
    Input is lower than needs
  • Diet-induced thermogenesis (DIT) =
    Post prandial metabolism increases heat production (5-20% ingested ME)
  • The effect of DIT depends on:
    Ingested nutrients and metabolic settings
    (PRO > CARB > FAT)
  • DIT: ingested ME is not corrected for
    energetic costs of PPM
  • DIT: under specific conditions, consequences of PPM
    might change metabolic settings
  • Homeostasis =
    The ability of an organism to counteract (within limits of the metabolic scope) factors that disturb vital functions.
  • Examples of homeostasis:
    - Glucose
    - pH 
    - Oxygen supply
    - Body temperature
  • Nutritional paradox
    - Food and body are no natural allies 
    - The material composition of foodstuff is related to their natural function, not to our nutritional requirements 
    - Diabetes
  •  Transfer of monomers from food to body requires
    Digestion to absorbable (water soluble) components
  • Protective devices against autodigestion are
    mucus layer and high cell-turnover
  • Anatomy GI
    Mouth  oesophagus  stomach  duodenum (small intestine)  jejunum (small intestine)  ileum (small intestine)  caecum  colon (large intestine)  rectum  anus
  • Enzymes in mouth
    salivary amylase
    lingual lipase
  • enzymes in stomach
    gastric acid
    pepsin
    gastric lipase
  • alcohol
    absorbed in stomach
  • enzymes in small intestine
    pancreatic amylase
    lipase
    phospholipase
    trypsin
    chymotrypsin
    elastin
    dipeptidases
    disaccharidases
  • absorbed in small intestine
    monosaccharides
    amino acids
    fatty acids
    glycerol
    fats 
    water
  • functions of colon and rectum
    absorption of water and ions
    bacterial fermentation of nonabsorbed nutrients
    storage of waste and indigestible materials
    elimination of waste and indigestible materials
  • Secretion in duodenum
    CCK, secretin, GIP, HCO3-
  • Secretion in ileum
    PYY, HCO3-
  • Intraluminal and surface digestion is largest in
    duodenum
  • Absorption of ions, nutrients (Fe) and H2O is largest in
    duodenum
  • Absorption of bile acids and vitamin B12 in
    ileum
  • Segmentation takes place in
    digestive phase
  • Peristalsis takes place in
    interdigestive phase
  • Accessory digestive organs:

    - Teeth, tongue, salivary glands


    - Exocrine pancreas
    - Liver, gall bladder
  • Microvilli are 
    fingerlike foldings of the cell membrane also indicated as brush border
  • microvilli contains
    absorptive enterocyte
    mucus-secreting goblet cell
  • Villi have:
    - Lacteal =lymph. Lipids are first absorbed into the lymph
    - Arterial blood supply 
    - Lymphatic and venous drainage
  • Mucosa:
    - Inner layer of GI
    - Secretion and absorption
  • Submucosa:
    - Second layer from the inside
    - Vascular layer for support
  • Location of meissner plexus (muscular mucosa)
    Between submucosa and muscularis
  • Muscularis:
    - Third layer from the inside
    - Segmental contractions
  • Location of circular/longitudinal layers and Auerbach's plexus
    Between muscularis and serosa
  • Serosa
    - Outside layer of GI 
    - Protective layer
  • Plexus myentericus =
     interaction with muscles around the GI tract
  • The stomach has a 
    thick lamina muscularis (antrum)
  • The small intestine has the most 
    villi
  • Gut stimuli evoke digestive responses via 
    the enteric and the central nervous systems
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ratio of depostion and maintenance
5:1
Thermogenic effect:
PRO > CH > F
stress causes
a decrease in protein synthesis
Half life time:
0.69/ (total protein replace/total protein in body)
Costs protein synthesis:
4 kJ/g
mRNA to protein:
is energy consuming (specific AA at a specific location)
Why so much protein needed in the body?
- 60% of theorine requirement is for mucus synthesis 
- Cortisol induces gluconeogenesis and breakdown of muscle protein (acts on liver only)
Rate of protein turnover can be influenced by
external factors (nutrients)
Dynamic equilibrium:
constant turnover of tissue components
Uneven fatty acids end up with propionyl Coa:
ATP yield = 15.5 (instead of 10 from acetyl coa)