Carbohydrates Flashcards
Carbohydrates
major food source and energy supply for the body and are stored primarily as liver and muscle glycogen
Hyperglycemia
increase in plasma glucose levels caused by imbalance of hormones
Hypoglycemia
decreased plasma glucose levels; result of imbalance in the rate of glucose appearance and disappearance from the circulation
smallest carbohydrate
glyceraldehyde -3 carbons
two forms of carbohydrates
aldose (derived from aldehyde) and ketose (derived from ketone)
stereoisomer
central carbons are chiral (4 different groups attached to the carbon atoms), thus have different spatial arrangements of the groups and different properties
Monosaccharide
simple sugars that cannot be hydrolyzed to a simpler form; examples include glucose, fructose, galactose
Disaccharide
formed when two monosaccharide units are joined by a glycosidic linkage; on hydrolysis, disaccharides will be split into monosaccharides; examples include maltose, lactose, and sucrose
Polysaccaride
formed by the linkage of many monosaccharide units; on hydrolysis, polysaccharides will be split into monosaccharides; examples include starch and glycogen
Reducing Carbohydrate
can reduce other compounds; must have ketone or aldehyde group; examples include glucose, maltose, fructose, lactose, and galactose (all monosaccharides are reducing carbohydrates)
Non-reducing carbohydrate
bond is on the anomeric carbon and no longer reduces other compounds; example is sucrose
Glucose metabolism
source of energy for humans - nervous system, including brain, depends on glucose for the surrounding extracellular fluid (ECF); Glucose is used as energy or stored as glycogen
Embden-Meyerhof pathway
glycolysis - conversion of glucose to pyruvate or lactate
Gluconeogenesis
conversion of amino acids by the liver (and other specialized tissue) to substrates that can be converted to glucose; also conversion of glycerol, lactate, and pyruvate to glucose
Glycogenesis
glycogen synthesis from glucose for storage
Glycogenolysis
process of conversion of glycogen to glucose-6-phosphate
Lipogenesis
conversion of carbohydrates to fatty acids
Lipolysis
decomposition of fat
Action of Insulin
increases glycogenesis and glycolysis; increases lipogenesis; decreases glycogenolysis (increased movement of glucose into cells)
Action of Glucagon
increases glycogenolysis; increases gluconeogeneisis (fasting and resting states)
Diabetes Mellitus
group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both.
Type I diabetes
Insulin dependent; Beta-cell destruction; absolute insulin deficiency; autoantibodies (islet cel, insulin, glutamic acid decarboxylase, and tyrosine phosphates IA-2 and IA-2B); commonly in children and adolescence;
Type II diabetes
non-insulin dependent; insulin resistance with an insulin secretory defect; relative insulin deficiency
Gestational Diabetes
glucose intolerance during pregnancy due to metabolic and hormonal changes
Other types of diabetes
associated with secondary conditions -genetic defects of beta-cell function, pancreatic disease, endocrine disease, drug or chemical induced, insulin receptor abnormalities, other genetic syndromes
Diagnosis of Diabetes Mellitus
fasting plasma glucose >/=126mg/dL
HbA1C >/=6.5%
OGTT >/=200mg/dL
random plasma glucose >/=200mg/dL plus symptoms
von Gierke disease
glucose-6-phosphatase deficiency type I; most common glycogen storage disease; autosomal recessive; severe hypoglycemia with metabolic acidosis, ketonemia, and elevated lactate and alanine
Galactosemia
Failure to thrive syndrome in infants; congenital deficiency in one of three enzymes involved in galactose metabolism (most common is galactose-1-phosphatate uridyltransferase); diarrhea and vomiting; mental retardation and cataracts; hypoglycemia, hyperbilirubinemia, and galactose accumulation; removal of galactose from diet
glycosylated hemoglobin
formation of a hemoglobin compound produced when glucose reacts with the amino group of hemoglobin forming a ketoamine; reflects the average blood glucose level over the previous 2-3 months;HbA1c is most commonly detected glycosylated hemoglobin and is more reliable than plasma glucose for monitoring; normal range is 4-6%; specimen is whole blood in EDTA
Albuminuria
increase in urinary albumin; used to diagnose early kidney disease; persistent albuminuria is ration of albumin-creatinine of 30-299 mg/g creatinine in 2 out of 3 urine collections over 6 months
Ketoacidosis
high level of ketones in the blood which act as a poison; most frequent in diabetes;
DKA
diabetic ketoacidosis
