carbohydrate digestion Flashcards
what is a carbohydrate?
hydrated ketones/ aldehydes
(hydrated carbons)
different types of carbs?
complex carbs - poly (chain of 10+ molecules)
simple carbs - di (2 molecules)/ mono (1)
<10 chains of saccharides= OLYGO
polysaccharides:
what affects the way amylose is metabolised?
= linear single chain of monosaccharides attached by glycosidic link
the glycosidic link
alpha 1-4
how does amylopectin differ from amylose?
FOUND IN VEGGIES/ LEGUMES
main linear chain connected by alpha 1-4 bonds
branched chain of poly
has diff bond at branching points
alpha 1-6 bond to bond branched chains to main linear ones
starch?
anything with flour has starch
polysaccharide
comes in 2 forms:
amylopectin (1-6)
amylose (1-4)
glycogen?
found in animals we eat
more branched
alpha 1-6 bonding to branched chains
linear chain alpha 1-4 bonding
why can cellulose not be digested by mammals and why is this a beneficial quality for us?
found in veg/ fruits
linear chains are bonded by alpha 1-4 but
the stack of chains bonded by BETA 1-4
-> not digested in animals
the pancreatic/ salivary can not break bond
used as fibre- not digested, removed in waste
what % of our caloric intake is from carbs?
50%
most from starch
3 major disaccharides in our diet?
1) sucrose (table sugar)
2) maltose
3) lactose
what % of our caloric intake is from sucrose?
30%
what % of our caloric intake is from lactose?
6%- sugar from milk
what % of our caloric intake is from maltose?
1-2%
3 main monosaccharides from our diet?
1) glucose - only in honey/ golden syrup in it’s simplest form
2) fructose- in fruits
3) galactose
where do polysaccharides bond?
only form of carbs our bodies can absorb?
monosaccharides - glucose, fructose, galactose
only form of carbs our bodies can absorb?
monosaccharides - glucose, fructose, galactose
salivary glands are found in pairs in the oral cavity, how many are there?
3 major pairs
multiple minor pairs
3 major pairs of salivary glands?
sublingual
submandibular
parotid
what do we find in the parotid gland?
zymogen granules (blue dots)
also found in pancreas
difference between endocrine and exocrine glands?
exocrine (have duct) - secrete enzymes
endocrine (no duct) - secrete hormones
where do endocrine glands secrete?
directly into bloodstream
are salivary glands exocrine or endocrine?
exocrine
role of salivary amylase
when saliva is mixed with food ball
salivary amylase= secreted from serous acini of PAROTID + SUB-MANDIBULAR salivary glands
hydrolyses 1-4 bonds of polysaccharides
-> produces oligo + di + tri saccharides
why is the pancreas so cool?
it IS a gland
and it had glands in it:
- endocrine (islets of lanhergans- alpha, beta, gamma cells)
- exocrine (duct will pass secretions into duodenum)
what are found in the serous acini?
zymogen granules
what are found in the serous acini?
zymogen granules
what ph does salivary amylase work best at?
6.7
role of salivary amylase once food is swallowed?
works for 1-2 hours in stomach
deactivated at PH3 by gastric acids
what does pancreatic amylase do?
- it is secrete from pancreatic exocrine acini into the duodenum
through the pancreatic duct - hydrolyses alpha 1-4 bond
- further digests complex carbs (alpha 1-4 bonds) that take longer to break down
endocrine glands of the pancreas secrete which 3 cells?
called ISLETS of Langerhans
has 3 types of cells:
1) alpha- secrete glucagon
2) beta- secrete insulin
3) gamma- secrete other hormones
significance of parotid being similar to pancreas?
zymogens being found in the serous acini of the pancreas as well? (blue dots)
beta cells have been found in the parotid gland
trying to stimulate parotid to work as pancreas in diabetic patients
difference between pancreatic amylase and salivary amylase?
1) pancreatic amylase works at wider range:
6.7-7
2) pancreatic amylase can stay active for longer as pancreas secretes bicarbonate as well
-> keeps PH alkaline
what do we get as products of hydrolysis by pancreatic amylase?
1) dextrins (disaccharides)
2) oligo saccharides
STILL NOT AT MONOSACCHARIDES
what do we get as products of hydrolysis by pancreatic amylase?
1) dextrins (disaccharides)
2) oligo saccharides
STILL NOT AT MONOSACCHARIDES
which enzymes around in intestinal epithelial cells?
brush border enzymes
OPTIMAL PH= 7.8 (pancreatic bicarbonate make ph alkaline)
found on apical side of intestinal epithelial cells
formed of folds
in folds, in microvilli, contain enzymes which are secreted into small intestine
-> further hydrolyse carbs
which sugars do brush border enzymes hydrolyse?
maltose (maltase)
sucrose (sucrase)
lactose (lactase)
deficiency in lactase enzyme?
leads to lactose intolerance
as lactose can not be hydrolysed properly
causes of deficiency of lactase enzyme?
1) congenital (certain ethnic groups have inherent lactose intolerance)
2) acquired- infections, inflammation, injury to intestinal cells
how do you get temporary lactose intolerance?
by ROTA virus (tummy bug)
not treatable
avoiding milk/ dairy reduces symptoms
- can add lactase enzyme to dairy products
how are oligo and disaccharides digested to monosaccharides?
by brush border enzymes
deficiency of some brush border enzymes can lead to which pathology?
lactose deficiency= lactose intolerance
