Module 2- Carbohydrates Flashcards
(35 cards)
What are the 3 classifications of carbohydrates?
Monosaccharides, oligosaccharides, polysaccharides
Most common isomer in the human body
B-D-glucose
What are polysaccharides?
High molecular weight
Glycogen
Starch
Are broken down by specific enzymes secreted by pancreas or intestinal wall
What is anaerobic glycolysis?
Not oxygen dependent
Splitting of glucose into 2 pyruvates to produce small amounts of ATP
What is aerobic glycolysis?
Oxidation of pyruvate in the mitochondria via the Kreb’s cycle and electron transfer chain to produce large amounts of ATP
Is anaerobic glycolysis reversible?
All steps are reversible EXCEPT conversion to G-6-P by hexokinase (liver cells can reverse this step)
What is glycogenesis vs. glycogenolysis?
Glycogenesis - excess glucose converted into glycogen
Glycogenolysis - breakdown of glycogen back to G-6-P
What is gluconeogenesis?
Synthesis of new glucose from non-carbohydrate sources
Not efficient
What occurs in glucose regulation?
Low blood glucose - release of glucagon acts to increase blood glucose levels
High blood glucose - release of insulin acts to decrease blood glucose levels
Other hormones that raise blood glucose levels
Cortisol
Epinephrine
Growth hormone
What is the renal threshold?
Maximum concentration in the blood that can be completely reabsorbed
All glucose is normally filtered and reabsorbed by kidneys
Blood levels above 10 mmol/L are unable to reabsorb all the glucose
Analysis of glucose specimens
Serum or plasma
Whole blood values are about 10% LOWER
Must separate cells within 1-2 hours
Fasting must be 10-12 hourly
Urine - glucose levels in diabetes
CSF - identifying bacterial meningitis
Glucose oxidase method
Reacts with B-D-glucose
Converts glucose to gluconic acid and hydrogen peroxide
What are 2 ways glucose oxidase can be measured?
Amperometry - uses an oxygen electrode to measure consumption of oxygen
Colormetric - Trinder’s Reaction, add a peroxidase and a chromagen to form an oxidized colored product (subject to interference)
Hexokinase method for measuring glucose
Formation of NADPH measured photometrically at 340nm
Glucose dehydrogenase method for measuring glucose
NADH formation measured at 340nm
What are the collection protocols for glucose?
Fasting glucose - at least an 8hr fast
Random glucose - any time
2 hrs glucose tolerance - 2 hours postcibal
Gestational diabetes screen - glucose tolerance test for gestational diabetes mellitus
What is the process for the 2 hour PP (glucose tolerance) test?
2 hours post pranidal
- Standard glucose load administered 75g in 300mL
- Measure blood glucose levels after 2 hours (should be less than 6.7mmol/L)
What is the process of the gestational diabetes screen?
- 50g carbohydrate load
2. Blood collected at 1 hour (result should be >11.0 mmol/L)
What are the reference ranges for glucose?
Fasting: 3.3-6.0 mmol/L
Random: 3.3-11.0 mmol/L
Critical Low: = 25.0 mmol/L
What are the reference intervals for arterial and CSF samples?
Arterial samples HIGHER by 15%
CSF about 60% of plasma levels
What are the criteria for diagnosis of diabetes mellitus (DM)?
Must have at least TWO of the following:
Fasting glucose > 7.0 mmol/L
2 hour PP > 11.1 mmol/L
Random glucose > 11.1 mmol/L with symptoms
HbA1C >= 6.5%
What is diabetes mellitus?
Disorders of HYPERGLYCEMIA Caused by: 1. Insufficient insulin secretion 2. Defective insulin action 3. Target tissue has insulin resistance
Lab findings in diabetes mellitus:
Hyperglycemia Glycosuria Increased serum and urine osmolality Ketonemia and ketonuria Wight loss Confusion
