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Nutrient Uptake + Metabolism - Coggle Diagram
Nutrient Uptake + Metabolism
Food to nutrients
Processed + intact foods
Complex matrix
Absorb nutrients from matrix
Essential nutrients
Vitamins
Most but not all
Minerals
Essential fatty acids
Cannot be produced in the body
Essential amino acids
Conditionally-essential nutrients
Factors that cannot be synthesised fast enough
e.g. histadine
DHA
Non-essential nutrients
Factors that can be produced by the body
Gut to bloodstream
Most cannot passively diffuse
Removed from matrix first
Specialist transport systems required for absorbance
Distribution round the body
Storage
Active function
Nutritional bioavailability
Potentially site-/organ-specific or general cellular requirement
Specialist transport systems
Digestive process
Pre-intestinal digestion
Chewing + gastric motility
HCl action
Macroscopic food structure broken down
Salivary + gastric enzyme action
Homogenised chyme
Non-absorbable macronutrients
<-------
Creamy, homogenous paste
Easy access for enzymes
More important in infants
Undeveloped pancrease
People with pancreatic diseases
Small intestinal digestion
Absorption of
Di/triglycerides + amino acids
Glycerides + fatty acids
Monosaccharides
Vitamins, minerals etc.
Activated pancreatic enzymes
Digestive secretions
Pancreatic lipase
Wide range of proteases
Alpha amylase - starch degradation
Final carbohydrate metabolism at brush border enymes
Microbial metabolism
Undigested or unabsorbed dietary factors
Colonic salvage
Waste excretion + nutrient loss
Absorbance of most nutrients occurs in small intestine
Highly folded - microvilli, villi, anatomical folding within lumen
Amino acid + monosaccharide uptake
Hydrophilic nutrients
Specialist proteins to cross cell membranes
Transport stages
Lumen
Apical transport
Enterocyte
Basolateral transport
Bloodstream
Further transporters from bloodstream to cells
Often against con. gradient
E required
Active/co-transport
Lipid uptake
Cholesterol, monoglycerides + fatty acids
Cholesterol + fatty acids
Cholesterol esters
Chylomicron
Monoglycerides + fatty acids
Triacylglycerol
Chylomicron
Specific surface proteins
Target for other body tissues
e.g. ApoE + ApoC-II
Intestinal mucosal cell
via chylomicron
Lymphatic system
Metabolism overview
Energy-balancing act between anabolism + catabolism
Anabolism
Synthesis of macromolecules from smaller precursors
Endergonic
Use chemical energy stored as
ATP
NADPH
Catabolism
Production of energy by breakdown of
Carbohydrates
Lipids
Proteins
Exergonic
Oxidative breakdown of foodstuffs
Release of
Free energy
ATP
NADH
Reducing power
NADPH
Vitamins
Organic compounds
Small amounts needed for
Maintenance of metabolic integrity
Normal bodily function
Eseential for health + well-being
Mostly cannot be synthesised in the body
Deficiency
Specific symptoms
Treated by addition of vitamin to diet
Water-soluble vitamins
Vitamin B group
Cellular metabolism
Important roles within pathways
Deficiencies
Thiamine (B1)
Beri-beri
Wet
Heart + circulatory system
Dry
Tiredness
Irritability
Riboflavin (B2)
Skin lesions around mucosal surfaces
Niacin (B3)
Pellagra + other skin complaints
Biotin (B7)
No known deficiency
Links to alopecia
Pyridoxine (B6)
Irritability
Depression
Loss of responsibility
Pantothenic acid (B5)
Alopecia
'Burning foot' syndrome
Folic acid (B9)
Birth defects
Megaloblastic anaemia
Cobalamine (B12)
Pernicious anaemia
Demyelination of nerves
Vitamin C
Forms
Ascorbic acid
Dehydroascorbic acid
Sources
Green veg
Citrus fruits
Potatoes
Berries
Requirements
Most animals can synthesise vit. C
Roles
Collagen formation
Adrenaline/noradrenaline formation
Iron absorption
Antioxidant defence
Deficiency
Symptoms
Scurvy
Damaged, bleeding gums
Lack of antioxidant defence + collagen
Absorption
40-90% absorbed in small intestine
Colonic salvage absorbs what may be left after small intestine
Require transport molecules/co-factors
B12 binds to intrinsic factor to be picked up by transport molecules
Fat soluble vitamins
Stored in liver (with B12)
Must be absorbed and transported alongside dietary lipids
Vitamin A
Retinol
Retinoic acid
Retinal
Roles
Vision pigment
Epithelial differentiation
Reproduction
Antioxidant
Action through changing gene expression
Long-lasting actions
Absorbed as inactive vitamin from carotenoids
Converted to active forms within the body
Vitamin D
Ergosterol
Cholecalciferol
Roles
Proposed roles in immune/inflamm. response
Bone maintenance/calcium homeostasis
Vitamin E
Tocopherol
Tocotrienol
Roles
Membrane-bound protection against oxidative stress
Vitamin K
Phylloquinone
Menaquinone
Roles
Blood clotting
Post-translation protein modification
Bone devel. + health
Deficiencies
Toxicity
Excessive storage of vitamin A
Loss of 50% body weight
Skin peeling off
Hair loss
Nausea + diarrhoea
Uptake
High levels of dietary fat required
Co-uptake in micelles
Chylomicron released into lymphatic system
Enter bloodstream at thoracic duct
Minerals
Elements needed in small amounts for health + maintenance
Cannot be produced by the body
Bioaccesibility
Minerals from intact plant foods may be harder to release/absorb
Antinutrients
Phytates
Bind to zinc, calcium, iron
Limit their absorption
Trace minerals
Small amounts in body
Macrominerals
High amounts in body
Iron
Dietary intake
Animal products
Haem-iron
Easily absorbed
Plant products
Non-haem iron
Less bioaccessible
Iron cookware
Functions
Oxygen transport + utilisation
Haemoglobin
Myoglobin
Component of cytochromes, cofactors + some enzymes
Storage
Liver
Small intestine cells
Bound to ferritin in enterocytes
Reduces cellular toxicity when bound
Deficiency
Anaemia
Very common nutritional deficiency worldwide
Impaired immunity
Toxic in excess or unbound state
Pro-oxidant factor
Induce free radical formation
Tissue damage
Absorption
Affected by form
Fe\(^{2+}\) more readily absorbed than Fe\(^{3+}\)
Divalent ion absorbed
Difficulty absorbing when mixed with other divalent ions e.g. calcium
Epithelium ability
Physiological status
More transport proteins expressed
Pregnancy
Low iron levels
~10% dietary iron absorbed
Key regulatory point
Metabolism
Complex
RBC turnover is slow
Effect of increased iron intake can take time
Inc. in blood Hb takes time
Iodine
Component of thyroid hormones
T\(_3\)
Tri-iodothyronine
T\(_4\)
Thyroxine
Factor affecting basal metabolic rate
Common worldwide deficiency
Global iodine consumption supplemented by
Iodised salt
Cheap
Also found in fish, dairy
Dairy due to iodine disinfectant on milk tubes in production/processing
Deficiency symptoms
Goitre
Swollen thyroid gland
Foetal/developmental issues
Long-term
Mental + physical
Energy utilisation
Sources of energy
Macronutrients
Proteins
Fats
Alcohol
Carbohydrates
Total energy expenditure (TEE)
Basal metabolic rate
60-70% TTE
Many factors affecting inc/dec of BMR
Physical activity
20-30% TTE
Other thermogenic processes
Post-prandial thermogenesis
Role of pancreas
Exocrine pancreas has major role in digestion of macronutrients
Endocrine pancreas helps utilise absorbed nutrients
Glucagon
Insulin
Blood glucose regulation
During prolonged starvation
More widely available energy stores used
Skeletal muscle proteins catabolised