12. Breakdown of Food (nutrients, vitamins, minerals) Flashcards
Digestion in the MOUTH:
MECHANICAL: Chewing/mastication & Swallowing
CHEMICAL: CARBOHYDRATES and FATS
Digestion/Absorption in the STOMACH:
MECHANICAL: PERISTALTIC MIXING and PROPULSION
CHEMICAL: PROTEINS & FATS
ABSORPTIN of LIPID-SOLUBLE SUBSTANCES ie Alcohol, Aspirin
Digestion/Absorption in the SMALL INTESTINE:
MECHANICAL: MIXING and propulsion, primarily SEGMENTATION
CHEMICAL: CARBOHYDRATES, FATS, POLYPEPTIDES, NUCLEIC ACIDS
ABSORPTION of PEPTIDES, AMINO ACIDS, GLUCOSE, FRUCTOSE, FATS, WATER, MINERALS, VITAMINS
Digestion/Absorption in the LARGE INTESTINE:
MECHANICAL: SEGMENTAL MIXING and propulsion
ABSORPTION of WATER*, IONS, MINERALS, VITAMINS, ORGANIC MOLECULES
(NO Chemical digestion)
what is there early ABSORPTION of in the STOMACH
LIPID SOLUBLE Substances
what is there CHEMICAL DIGESTION of in the MOUTH
CARBOHYDRATES
FATS
what is there CHEMICAL DIGESTION of in the STOMACH
PROTEINS
FATS
PROTEINS are BROKEN DOWN into AMINO ACIDS which are USED for
PROTEIN SYNTHESIS
& ENERGY PRODUCTION
COMPLEX CARBOHYDRATES are BROKEN DOWN into GLUCOSE which is USED for
ENERGY PRODUCTION (ADP -> ATP)
TRIGLYCERIDES are BROKEN DOWN into GLYCEROL and FATTY ACIDS which are USED for..
LIPID SYNTHESIS and STORAGE
& ENERGY PRODUCTION
GLYCOGEN (POLYSACCHARIDE) can be BROKEN DOWN into MALTOSE (DISACCHARIDE) by which ENZYME
AMYLASE (Salivary)
- hydrolyses alpha-1,4 glycosidic bonds
MALTOSE BREAK DOWN by MALTASE into..
GLUCOSE (x2)
SUCROSE BREAK DOWN by SUCARASE into..
GLUCOSE & FRUCTOSE
LACTOSE BREAK DOWN by LACTASE into..
GLUCOSE & GALACTOSE
GLYCOGEN BREAK DOWN by AMYLASE into…
MALTOSE
MONOSACCHARIDES (gluctose, fructose, galactose) are ABSORBED into Blood stream (to liver) by/via which CELLS
ENTEROCYTES
- ACTIVE TRANSPORT
how is GLUCOSE TRANSPORTED across ENTEROCYTES into BLOOD stream
at blood end: Na+ ACTIVELY PUMPED OUT by
Na+/K+ ATPase
- establishes a conc. gradient
at BRUSH BORDER of enterocyte:
NA+ GLUCOSE SYMPORTER
as Na+ diffuses IN, GLUCOSE CARRIED WITH IT
how is GLUCOSE TRANSPORTED across ENTEROCYTES into BLOOD stream
brush border: GLUT5 TRANSPORTER
blood end: GLUT 2 tranports FRUCTOSE and Glucose/GALACTOSE
does FRUCTOSE ABSORPTION use NA+
NO
GLUT5 and GLUT 2 TRANSPORTERS
what is SHORT BOWEL SYNDROME
a condition in which your body is UNABLE to ABSORB ENOUGH NUTRIENTS from foods
because you don’t have enough small intestine
NA+ CONC should be ABOVE …. in JEJUNAL LUMEN for WATER ABSORPTION (transported with Na+)
ABOVE 90 mmol/L
what is there PRODUCTION and ABSORPTION of in the LARGE INTESTINE (COLONIC FERMENTATION)
SHORT CHAIN FATTY ACIDS
- ANAEROBIC BACTERIA BREAK DOWN CARBOHYDRATES into short chain fatty acids (& gases)
COLONIC FERMENTATION in LARGE INTESTINE GENERATES…
ENERGY
(eg butyrate fatty acid - energy source)
800kcal a day can be generated from COLONIC FERMENTATION and Absorption
NON-DIGESTIBLE POLYSACCHARIDES in LARGE INTESTINE are BROKEN DOWN into SHORT CHAIN FATTY ACIDS and GASES (H2) By which BACTERIA?
FIIRMICUTES
what happens to SHORT CHAIN FATTY ACIDS (SCFAs) produced in COLON by breakdown of carbohydrates
either used in colon
or
transported to liver or muscles
COLONIC FERMENTATION and its ENERGY PRODUCTION is particularly useful for FEEDING…
those with SHORT BOWEL SYNDROME
PROTEINS (exogenous/dietary or endogenous) is BROKEN DOWN by which ENZYMES into DI-PEPTIDES /TRI-PEPTIDES / AMINO ACIDS
- PEPSIN
- PANCREATIC PROTEASES
DI and TRI - PEPTIDES are TRANSPORTED INTO CELLS via which transporter..
PEPT1
what happens to DI and TRI - PEPTIDES Inside ENTEROCYTES before ABSORPTION into BLOOD
further DIGESTION into AMINO ACIDS
(INTRACELLULAR PEPTIDASES)
what happens to PROTEINS in the STOMACH before entering large intestine (after being chewed and swallowed)
- DENATURED by HCL
- UNFOLDING of 3D STRUCTURE to REVEAL POLYPEPTIDE CHAIN - PEPSIN digests to short SHORTER POLYPEPTIDES
what happens to PROTEINS in the SMALL INTESTINE after coming from Stomach
- TRYPSIN, CHYMOTRYPSIN, PROTEASES further digest shorter polypeptides into TRI-PEPTIDES, DI-PEPTIDES and AMINO ACIDS
- TRANPORTED into ENTEROCYTES, TRI-PEPTIDES and DI-PEPTIDES further broken down into AMINO ACIDS
-> ABSORBED INTO BLOOD
what happens to PROTEINS in the SMALL INTESTINE after coming from Stomach
- TRYPSIN, CHYMOTRYPSIN, PROTEASES further digest shorter polypeptides into TRI-PEPTIDES, DI-PEPTIDES and AMINO ACIDS
- TRANPORTED into ENTEROCYTES, TRI-PEPTIDES and DI-PEPTIDES further broken down into AMINO ACIDS
-> ABSORBED INTO BLOOD
STOMACH DIGESTS PROTEINS into…
SHORTER POLYPEPTIDES ready for further breakdown in small intestine
PROTEASE in STOMACH
PEPSIN
PROTEASES in SMALL INTESTINE
TRYPSIN,
CHYMOTRYPSIN
PEPSINOGEN (zymogen) from STOMACH CHIEF CELLS are ACTIVATED BY…
HCL from PARIETAL CELLS
-> TRYPSIN
(cleavage of extra 44 amino acids)
pepsinogen can be stored at low pH (inactive)
TRYPSINOGEN ZYMOGEN comes from…
PANCREAS via PANCREATIC DUCT
WHERE is TRYPSINOGEN ACTIVATED into TRYPSIN
DUODENUM
TRYPSINOGEN ACTIVATED into TRYPSIN BY..
ENTEROKINASE (from brush border)
what does STOMACH TURN TRIACYLGLYCEROLS INTO
(by churning)
DIGLYCERIDES and FATTY ACIDS
SMALL INTESTINE COMBINES Separated FATS/LIPIDS WITH..
BILE
STEPS of LIPID DIGESTION/ABSORPTION
- EMULSIFICATION by BILE from large fat droplet into small emulsified droplets (increased surface area)
- ENZYMATIC DIGESTION by PANCREATIC LIPASE from TRIGLYERIDES into FATTY ACIDS
- FORM MICELLES to transport to ENTEROCYTES where they break down
- inside enterocyte, LINK to FORM TRIGLYCERIDES
- in GOLGI APPARATUS, COMBINE with PROTEINS to FORM CHYLOMICRONS
- EXOCYTOSIS out of cell and ENTER LACTEAL (LYMPH CAPILLARY)
- LYMPH TRANSPORTS CHYLOMICRON AWAY FROM LARGE INTESTINE, into BLOOD STREAM (then processed by Liver)
STRUCTURE and FUNCTION of MICELES
HYDROPHOBIC Interior and HYROPHILIC HEADS (OUTER)
- SOLUBLE
allow FATS to be TRANSPORTED across AQUEOUS ENVIRONMENT INTO CELLS (enterocytes)
what happens to FATTY ACIDS once they reach ENTEROCYTES
FORM TRIGLYCERIDES AGAIN
COMBINE with PROTEINS in GOLGI to make CHYLOMICRONS
CHYLOMICRONS ENTER LACTEAL (LYMPH CAPILLARY)
how are FATS ABSORBED into BLOOD (transported)
by CHYLOMICRONS
using LYMPHATIC SYSTEM to be carried away
CHYLOMICRONS STRUCTURE
INNER: TRIGLYCERIDES
OUTER: PHOSPHOLIPIDS
make fats easily transportable
what are CHYLOMICRONS BROKEN DOWN into
FATTY ACIDS & a CHYLOMICRON REMNANT
what happens to the CHYLOMICRON REMNANT
taken to the LIVER and CONVERTED into CHOLESTEROL
-> cholesterol BINDS to TRIACYLGLYCEROL and carried to ADIPOSE TISSUE as a VERY LOW DENSITY LIPOPROTEIN (VLDL)
FATTY ACIDS are STORED as what in ADIPOSE TISSUE
TRIACYLGLYCEROL
ABSORPTION of products of FAT DIGESTION DEPENDS on..
SIZE
- SHORT and MEDIUM CHAIN FATTY ACIDS and GLYCEROL (SMALL) are DIRECTLY ABSORBED INTO BLOOD via capillary
only LONG-CHAIN FATTY ACIDS and MONOGLYCERIDES (LARGE) form triglycerides and are transported in chylomicrons into lymph vessels
how are SHORT and MEDIUM CHAIN FATTY ACIDS and GLYCEROL ABSORBED
DIRECTLY INTO BLOOD
no need for chylomicrons/lymph etc
what can you get what fat absorption goes wrong
Steatorrhoea
what helps the TRANSMISSION of CHYLOMICRONS from intestines into LYMPHATIC SYSTEM
APO B48
what ACTIVATES LIPASE to turn Triglycerides into Fatty Acids
APO C2
CHYLOMICRON REMNANT Transported to LIVER and the UPTAKE is MEDIATED by..
APO E
to form cholesterol or triacylglycerol -> glucose (energy generated)
which VITAMINS are PASSIVELY ABSORBED into the SMALL INTESTINE
VITAMINS A, E & K
VITAMINS A,E,K are PASSIVELY ABSORBED into SMALL INTESTINE which is FACILITATED by…
BILE
and incorporated into CHYLOMICRONS
how is VITAMIN D ABSORBED
INCORPORATED INTO CHYLOMICRONS
and VITAMIN D BINDING PROTEIN
- absorbed as FREE Vitamin in Jejunum
SOURCES of VITAMIN D
- DIET
- SUNLIGHT: activates 7-DEHYDROCHOLESTEROL to be cahnged into PRE-D3 to D3
VITAMIN D3 TRANSPORTED by what into Blood
VITAMIN D BINDING PROTEIN
VIT D3 in the LIVER is CHANGED TO
25(OH)D
- INACTIVE form
25(OH)D is TRANSPORTED from LIVER TO KIDNEY where it is CHANGED TO
1-ALPHA-25(OH)D
- ACTIVE form
where is the ACTIVE FORM of VITAMIN D made (1-ALPHA-25(OH)D)
KIDNEY
what is VITAMIN A USED for
- EPITHELIAL TISSUE MAINTENANCE
- VISION
(without: night blindness, xerophthalmia)
what is VITAMIN D USED for
- BONE CALCIFICATION (&formation)
- PARATHYROID HORMONE PRODUCTION
(without: ricketts, osteomalacia)
what is VITAMIN E USE
BIOLOGICAL ANTIOXIDANT
(without: neuromuscular problems, anaemia, retinopathy, dysarthia)
VITAMIN K USE
BLOOD CLOTTING
(bleeding in absence)
in the ABSENCE of which VITAMIN can you get NEUROMUCULAR PROBLEMS and ANEMIA
VITAMIN E
which VITAMIN is important for VISION
VITAMIN A
which VITAMIN is for BLOOD CLOTTING
VITAMIN K
which VITAMIN is for EPITHELIAL CELL MAINTENANCE
VITAMIN A
VITAMINS A/E/D/K are …SOLUBLE
FAT-SOLUBLE
in VITAMIN B12 Digestion/Absorption, what happens in the
1. MOUTH
- BINDS SALIVARY R-PROTEINS
in VITAMIN B12 Digestion/Absorption, what happens in the
2. STOMACH
Food proteins bound are DEGRADED by low pH and pepsin to RELEASE Vit B12
BIND R-PROTEINS (from PARIETAL CELLS)
in VITAMIN B12 Digestion/Absorption, what happens in the
3. SMALL INTESTINE
DUODENUM:
- CLEAVED from R-PROTEINS (degraded by pancreatic proteases)
- BIND to INTRISIC FACTOR (come from stomach parietal cells)
ILEUM:
VIT B12 with IF COMBINATION is ABSORBED in the DISTAL (last) 80 CM of ILEUM (MUCOSAL CELLS)
in VITAMIN B12 Digestion/Absorption, what happens in the
4. BLOOD
enters Blood stream BOUND to TRANSCOBALAMIN (I/II/III)
-> complex known as HOLOTRANSCOBALAMIN (ACTIVE B12)
goes to LIVER and RE-CIRCULATED (ENTERO-HEPATIC)
what does VIT B12 BIND to in its absorption throughout the body
- R-PROTEINS (Saliva, Stomach)
- INTRINSIC FACTOR (in duodenum)
- TRANSCOBALAMIN
ACTIVE VITAMIN B12 KNOWN AS
HOLOTRANSCOBALAMIN in blood
what do stomach PARIETAL CELLS SECRETE for B12 ABSORPTION
- R-PROTEINS in stomach
- INTRINSIC FACTOR
WHERE is B12 ABSORBED into BLOOD
DISTAL 80 CM of ILEUM
FUNCTION of VIT B1, THIAMINE
CARBOHYDRATE METABOLISM
FUNCTION of VIT B2, RIBOFLAVIN
HYDROGEN TRANSFER
FUNCTION of VIT B6, PYRIDOXINE
PROTEIN METABOLISM
FUNCTION of VIT B3, NIACIN
HYDROGEN TRANSFER
FUNCTION of FOLIC ACID
SINGLE-CARBON METABOLISM
FUNCTION of VIT B12, CYANOCOBALAMIN
RED BLOOD CELL FORMATION
which VITAMIN is used for CARBOHYDRATE METABOLISM
VITAMIN B1, THIAMINE
which VITAMIN is used for SINGLE-CARBON METABOLISM
FOLIC ACID
which VITAMIN is used for PROTEIN METABOLISM
VIT B6, PYRIDOXINE
which VITAMIN is used for RED BLOOD CELL FORMATION
VIT B12, CYANOCOBALAMI
which VITAMIN is used for HYDROGEN TRANSFER
B2, RIBOFLAVIN
B3, NIACIN
which VITAMIN is used for RED BLOOD CELL FORMATION
VIT B12, CYANOCOBALAMI
how is IRON TRANSPORTED INTO CELLS for absorption
- FE 2+ REDUCED to FE2+ (DCYTB)
- transported via DMT1 with H+
- HEME BOUND transported via HCP1
and releases FE2+
how is IRON ABSORBED INTO BLOOD, FROM CELLS
- FE2+ VIA FPN1 ACTIVE TRANSPORTER
- HEPH allows OXIDATION of FE2+ INTO FE3+
- FE3+ BINDS APOTRANSFERRIN
to form TRANSFERRIN
CALCIUM is ABSORBED PASSIVELY throughout SMALL INTESTINE
what happens when there is LOW CA2+?
- ACTIVE ABSORPTION
- NEEDS adequate levels of VITAMIN D - 1,25 (OH)D
which MINERALS are used as METALLOENZYMES
COPPER and ZINC
which MINERAL is used for HAEMOGLOBIN SYNTHESIS
IRON
which MINERAL is used for CARBOHYDRATE METABOLISM
CHROMIUM
which MINERAL is used for ORGANIC MATRIX of BONE
MANGANESE
which MINERAL is used for THYROID HORMONES
IODINE
which MINERAL is used for CONVERSION of T4 to T3
SELENIUM
what can you get from COPPER DEFICIENCY
Wilsons disease
anaemia
neutropenia
what can you get from ZINC DEFICIENCY
Alopecia
Dermatitis
Diarrhoea
Anorexia
Dysarthia
Pica
what are ABSORBED from LARGE INTESTINE
WATER,
ELECTROLYTES,
SMALL CHAIN FATTY ACID
