PRELIM LEC: CARBOHYDRATES Flashcards
are organic compounds composed of carbon, hydrogen and oxygen
Carbohydrates
Chemical composition of carbohydrates:
Cn(H2O)n
Two forms of CHO:
Aldose
Ketose
are the major constituents of physiologic
system: brain, erythrocyte, and retinal cells in humans.They are also the major source of energy.
Carbohydrates
carbonyl group in the middle linked to 2 other carbon atoms
Ketose
terminal end carbonyl group called aldehyde group
Aldose
most important carbohydrates
glucose
is directly used as energy source and or stored as glycogen in the liver or muscles.
glucose
3 carbon:
triose sugar
5 carbon:
pentose sugar
6 carbon:
hexos sugar
Classification of CHO based on Location of carbonyl group:
aldose
ketose
classificatios of carbohydrates:
- Location of carbonyl group
- Number of carbon
- Number of sugar units
Classification of CHO based on the number of sugar units:
Monosaccharides
Disaccharides
Polysaccharides
Oligosaccharide
two monosaccharides are joined by a glycosidic linkage
Disaccharides
-simple sugars that cannot be hydrolyzed to a simpler form
- can contain 3 or more carbon atoms
Monosaccharides
-linkage of many monosaccharide units
-on hydrolysis, will yield more than 10 monosaccharides
Polysaccharides
2-10 carbohydrates
Oligosaccharide
example of aldose with 3 carbon
glyceraldehyde
example of ketose with 3 carbon
dihydrogenase
example of aldose with 5 carbons
ribose
example of ketose with 5 carbons
ribulose
example of aldose with 6 carbons
glucose
example of ketose with 6 carbons:
galactose
fructose
Monosaccharides:
oGlucose
oFructose
oGalactose
Disaccharides:
oSucrose
oLactose
oMaltose
most important CHO; major metabolic fuel
glucose
Fructose + Glucose
Sucrose
fibrous substances consisting of polysaccharides and forming the major constituent in the exoskeleton of arthropods and the cell wall of fungi
Chitin
Galactose + Glucose
Lactose
polysaccharides:
oStarch
oGlycogen
oChitin
Glucose + Glucose
Maltose
stored in liver and muscles
Glycogen
storage form of glucose in the body
Glycogen
breakdown of carbon or sugar
hydrolysis
bind polysaccharide and oligosaccharide
glycocidic acid
- saivary enzymes
- salivary amylase
Ptyalin
pancreatic amylase
amylopsin
acid in stomach
hydrochloric acid
As food enters the mouth and oral cavity, food begins to be broken down by ____, an enzyme produced by the parotid gland that helps in the initial metabolism of food
Glucose Metabolism
ptyalin
a stomach enzyme that serves to digest proteins found in ingested food
pepsin
When food reaches the stomach, the acidity inactivates ptyalin and acid hydrolysis occurs. There is no carbohydrate digestion in the stomach, but** protein digestion **happens through the enzyme _____
Glucose Metabolism
pepsin
When food reaches the intestines, ____, an enzyme produced by the pancreas, further degrades the food and convert polysaccharides into monosaccharides.
Glucose Metabolism
amylopsin
Glucose then enters the bloodstream and increases glucose uptake by the ____.
Glucose Metabolism
cells
glucose levels rise:
Glucose Metabolism
After 30 min
gluose levels peak
Glucose metabolism
After 1 hour
glucose levels go back to normal
Glucose metabolism
After 2 hours
hormone needed in order for the glucose to enter the cells and bind to surface receptors
Glucose metabolism
insulin
Embden-Meyerhoff Pathway:
aerobic
anaerobic
provides energy for the body
Embden-Meyerhoff Pathway
– glucose to lactate
Embden-Meyerhoff Pathway
anaerobic
glucose to pyruvate
Embden-Meyerhoff Pathway
aerobic
glucose transporters:
glut
pyruvate to lactate
lactate dehydrogenase
glucose to pyruvate or lactate to produce energy
Glycolysis
Glucose Metabolic Pathway
- Embden-Meyerhoff Pathway
- Hexose- Monophosphate Shunt
- Glycogenesis
production of reduced
NADPH and ribose-5-phosphate
Hexose- Monophosphate Shunt
breakdown of glycogen to glucose for energy
Glycogenolysis (fasting state)
formation of glucose-6-phosphate from non-carbohydrate sources (when non-carbohydrate will be used for energy)
Gluconeogenesis
glucose to glycogen for storage
Glycogenesis
conversion of carbohydrates to fatty acids
Lipogenesis
Decomposition of fat
Lipolysis
Hormones Regulating Glucose Metabolism:
Insulin
Glucagon
Somatostatin
Cortisol
Catecholamines
Thyroid hormones
Growth Hormone
Adenocorticotropic Hormone
only hormone that decreases glucose
Insulin
produced by the β cells of the islets of Langerhans in the
pancreas
Insulin
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promotes glycolysis, glycogenesis, lipogenesis
Insulin
primary hormone that decreases glucose for increasing
glucose levels
Glucagon
produced by the α cells of the islets of Langerhans in the
pancreas
Glucagon
promotes glycogenolysis and gluconeogenesis
Glucagon
produced by the δ cells of the islets of Langerhans in the pancreas (regulatory hormone)
Somatostatin
inhibition of pancreatic hormone release of insulin and
glucagon
Somatostatin
inhibition of gastric acid secretion
Somatostatin
produced by the zona fasciculata of the adrenal cortex
Cortisol
promotes hepatic gluconeogenesis and lipolysis
Cortisol
Catecholamines:
epinephrine and non-epinephrine
produced by the chromaffin cells of the adrenal medulla
Catecholamines
produced by the thyroid gland
Thyroid hormones
inhibits insulin secretion and promotes glycogenolysis
Catecholamines
- promotes glycogenolysis and intestinal absorption of
glucose
Thyroid hormones
produced by the anterior pituitary gland
Growth Hormone
promotes glycogenolysis and lipolysis
Growth Hormone
produced by the anterior pituitary gland
Adenocorticotropic Hormone
promotes glycogenolysis and gluconeogenesis
Adenocorticotropic Hormone
mmediate precursor of insulin
Proinsulin
test that is based on the presence of proinsulin that helps in the differential diagnosis of Type 1 from type 2 Diabetes Mellitus and the diagnosis of insulinomas
C-Peptide
2 functions of pancreas:
endocrine
exocrine
endocrine:
insulin
glucagon
somatostatin; ductless
exocrine:
amylase; presence of ducts
- important for cells that cant produce atp
- protection for cells from oxidative damage
NADPH
release by mitochondria
adenosine triphosphate
