Lecture 7 Flashcards
Carbohydrates
contain carbon, hydrogen, and oxygen
Contain a carbonyl group and several hydroxyl groups
What is the general formular for Carbohydrates?
Cx(H2O)y
D-glucose
seen in nature
rotates plane polarized light clockwise
L-Glucose
mirror opposite of D-Glucose
manufactured in a lab setting
rotates plane polarized light counter-clockwise
The OH group of D and L-glucose determines what?
determines the “handedness” of both forms
Monosaccharides
Simplest of carbohydrates or sugars, Cannot be hydrolyzed any further
made up of three to seven carbons
can exist as a linear chain or as ring-shaped molecules
What are the common Monosaccharides?
Glucose, Galactose, and Fructose are monosaccharide isomers
What differs the monosaccharide isomers?
same chemical formula but differ structurally and chemically
Glucose
popular monosaccharide
used in the body as a source of energy
How much glucose is in blood?
4 g of Glucose
How much glucose does the brain absorb?
120 g glucose daily
~ 60% - 70%, is used to power transport mechanisms that maintain the Na+-K+ membrane potential
required for the transmission of the nerve impulses
Monosaccharide locations
D-Glucose = Blood sugar
D-Galactose = Milk sugar (part of lactose)
D-Fructose = Fruit sugar
What else is considered a monosaccharide?
DNA and RNA
Disaccharides
Comprised of 2 monosaccharides
Broken down by hydrolysis reactions
Disaccharide types
Maltose + H2O -> 2 glucose
Lactose + H2O -> glucose + galactose
Sucrose + H2O -> glucose + fructose
Polysaccharides
3 or more monosaccharides
What are the Polysaccharide linkages?
Alpha: digestible by humans, found in most carbohydrates
Beta: not digestible by humans, fiber
Starch
glucose units bound by Alpha linkages
Cellulose
○ of glucose units bound by Beta linkages
Corn is a good example
What must happen to Polysaccharides before it is absorbed?
must be hydrolyzed to monosaccharides
What catalyzes the hydrolysis reaction of Polysaccharides?
Amylases in the mouth and stomach
What happens to fructose and galactose during absorption?
Both are converted into glucose
Where are carbohydrates stored?
Stored as glycogen in liver and muscles
What is glycogen?
highly branched polysaccharide of glucose
Glycogenolysis
breakdown of glycogen to glucose
Glycogenesis
conversion of glucose to glycogen
Glycolysis
breakdown of glucose to pyruvate/lactic acid
occurs without oxygen
Gluconeogenesis
formation of glucose from breakdown of proteins
Lipogenesis
formation of fatty acids from glucose
Glucose in CSF
CSF glucose level is 60-80% of the serum value
meningitis will lower this value
Insulin
hormone that promotes decrease in glucose levels
Glucagon
hormone that promotes increase in glucose levels
Promotes gluconeogenesis, glycogenolysis, and lipolysis: makes more available energy
Glucagon and Insulin production locations
Both made in the islets of Langerhans in the pancreas
Insulin: made in the beta cells
Glucagon: made in the alpha cells
Diabetes Mellitus
Diseases characterized by high blood glucose (hyperglycemia
Type 1 diabetes
insulin dependent
Decreased insulin production due to damages pancreas
Usually appears at an early age
Ketoacidosis promoted more
Diabetic ketoacidosis (DKA)
happens when the blood sugar is very high and acidic substances, ketones, build up to dangerous levels in the body
DKA Examples
Excessive thirst, frequent urination, nausea and vomiting, weakness or fatigue, shortness of breath*, fruity-scented breath, confusion
Type 2 Diabetes
non-insulin dependent
Usually is adult onset
insulin/glucagon levels normal
rarely results in ketoacidosis
Criteria for the diagnosis of Diabetes Mellitus
A fasting serum glucose >140 mg/dL
Two blood glucose values over 200 mg/dL at 2 hours
Brief History of Urinalysis
Ancient Indian medicine
sweet taste of urine as an indicator of poor health
Glycosylated Hemoglobin (A1C)
Condensation reactions of hgb proteins + sugars glycosylated hemoglobin + H2O
Reaction not catalyzed by any enzyme
Amount of glycosylated hemoglobin reflects average glucose levels over approx. 2-4 months
“rolling average” glucose level
Determination of Hbg A1C
Ratio of standard and patient absorbances are used to calculate patient concentration
G6PD: glucose-6-phosphate dehydrogenase
an enzyme that is essential for an RBCs ability to withstand oxidative stress
helps protect RBCs from damage and premature destruction
G6PD deficiency
develop Hemolytic Anemia, and subsequently can show a falsely lower Hgb A1C
Symptoms of G6PD deficiency
fatigue, pale color, jaundice skin, shortness of breath, rapid heartbeat, dark urine and enlarged spleen
