Carbohydrates Flashcards
what are the four classifications for carbohydrates?
- size of the carbon chain
- location of C=O functional group
- number of sugar units
- stereochemistry
what are examples of monosaccharides, disaccharides, and polysaccharides?
mono: glucose, fructose, and galactose
di: maltose, lactose, and sucrose
poly: starch (plant-based glucose molecules) and glycogen (animal-based glucose molecules)
Carbohydrates are ________ substances. To do this, they must contain either what two things? What are examples of such carbohydrates?
They are reducing substances (while they themselves are oxidized). They have to contain either an active ketone or aldehyde group.
small sugars such as glucose or lactose are capable of reduction
what is the one nonreducing sugar?
sucrose
most ingested carbs are digested in the form of _______. What breaks then down? What happens to them from there?
most carbs are ingested as polymers, such as starch and glycogen
salivary and pancreatic amylase break them down into disaccharides, and then maltase breaks those down into monosaccharides (glucose), which are absorbed by the GI and transported to the liver
what is the only carb that can be used directly for energy, and what is a result from this?
glucose is the only carb that can be used directly for energy, so all other carbs have to be converted to glucose for use
what is the first step of glucose metabolism, and what is used to accomplish this?
glucose turned into G6P using ATP via the enzyme hexokinase
what are the three glucose metabolism pathways?
Eden-Meyerhof
Hexose monophosphate shunt
Glucose to glycogen (glycogenesis)
What is the process of the Eden-Meyerhof pathway?
where glucose is turned into G6P and then broken down into 2 3-carbon molecules of pyruvic acid/pyruvate (aerobic glycolysis) or lactic acid (anaerobic glycolysis)
the aerobic pathway leads to the Kreb’s cycle
what is the hexose monophosphate shunt (pentose-p) pathway?
it’s the oxidative glycolysis pathway branching off from G6P that yields 2 NADPH and nucleotides
- pentose and ribose can enter the glycolytic pathway
what are the definitions of the following:
- glycogenesis
- glycogenolysis
- glycolysis
- gluconeogenesis
- lipogenesis
- glycogenesis: the storage/conversion of glucose to/as glycogen
- glycogenolysis: breakdown of glycogen to glucose to use as energy
- glycolysis: the actual usage of glucose (conversion of it to pyruvate/lactate)
- gluconeogenesis: creation of G6P from noncarb sources
- lipogenesis: carbs turned to fatty acids
what three things (body parts) regulate carbohydrate levels?
liver, pancreas, and endocrine glands
what are the two hormones from the pancreas that directly control glucose blood levels and how do they work?
insulin from the beta pancreatic cells of islets of langerhans: lets glucose into the cell to reduce blood glucose levels
- when beta cells see increased glucose they release insulin
- secreted with C-peptide from pancreas
glucagon from the alpha pancreatic cells of islets of langerhans: works against insulin to increase blood glucose levels
- released when blood glucose levels are decreased in order to turn glycogen to glucose (glycogenolysis)
what are four other hormones that work to increase plasma glucose?
epinephrine, cortisol, somatostatin, and GH
how do epinephrine and cortisol work to increase plasma glucose?
epinephrine (during stress): inhibits insulin secretion
cortisol (also during stress): decreases intestinal entry of plasma glucose into the cell and increasing gluconeogenesis/lipolysis and decreases glycogenesis
how does somatostatin and GH increase plasma glucose?
somatostatin from delta cells in pancreas (has two forms: 14,28 amino acids) inhibits insulin, glucagon, and GH
GH: decreases entry of glucose into cells
durning non-fasting states, plasma glusoe levels of _____ are normal
less than or equal to 140 mg/dL
type 1 DM is cause by what?
rapid t-cells mediated autoimmune destruction of beta cells of the pancreas, which causes an absolute deficiency of insulin secretion
- initiated by environmental factor, (viral) infection, or genetic disposition
T1DM makes up what percentage of all DM, and when does it most commonly occur in life?
makes up 5 - 10% of all DM and most commonly occurs in childhood and adolescence
what are the signs and symptoms of T1DM? What are some complications?
the three p’s: polydipsia, polyphagia, and polyuria; rapid weight loss, hyperventilation, metal confusion, and possible loss of consciousness
complications: ketoacidosis microvascular nephropathy/neuropathy/mental confusion; increased incidence of heart disease
T2DM is the most _______ form of diabetes mellitus, and it is due to what? what is the main complication of T2DM?
most common form of diabetes, and is due to a person’s resistance to insulin, combined with a secretory insulin defect
- progressive loss of beta cells
- relative loss of beta cells
- increased body body fat distribution
main complication: hyperosmolar coma
gestational DM is a degree of glucose intolerance with onset when during pregnancy? What is the name of the test for gestational DM?
onset during second or third trimester of pregnancy
oral glucose tolerance test
what are infants are risk of developing is their mother has gestational diabetes? What happens to the baby birth due to the gestational diabetes?
increased risk of respiratory distress, hypocalcemia, and hyperbilirubinemia
fetal insulin stimulated in neonate in response to gestational diabetes, which leads to hypoglycemia in the baby at birth
What happens when the body doesn’t have enough insulin (other than increased glucagon) that is a complication of DM type 1?
ketoacidosis: the body burns fatty acids which produce ketone bodies. There’s an increase in glucose, decrease in pH, and ketoacids in the urine
