Carbohydrates (wip) Flashcards
Organisms rely on the — of complex organic compounds to obtain energy
oxidation
Three general types of organic compounds:
carbohydrates, amino acids, and lipids
are hydrates of aldehyde or ketone derivatives based on the location of the carbon-oxygen functional group.
Carbohydrates
It is the major food source and energy supply for the body or stored primarily in the liver and muscle as glycogen.
Carbohydrates
Carbohydrate storage form and where
glycogen in the liver and muscles
simple sugars that contain four to eight carbons and only one aldehyde or ketone group
Monosaccharides
The most common hexose monosaccharides include
glucose, fructose, and galactose
Formed when two monosaccharide units are joined by a glycosidic linkage
Disaccharides
The most common disaccharides are
maltose, lactose, sucrose
The chaining of 3 to 10 sugar units
Oligosaccharides
Formed by the linkage of many monosaccharide units
Polysaccharides
The most common polysaccharides are
starch and glycogen
what is plant-based glucose molecules and animal-based glucose molecules
starch and glycogen
these carbohydrates can reduce other compounds while they themselves are oxidized.
reducing substances
To be a reducing substance, the carbohydrate must contain an
active (available) ketone or an aldehyde group
Examples of common-reducing sugars include:
glucose, maltose, fructose, lactose, and galactose.
The most common nonreducing sugar is
sucrose
table sugar
sucrose
Glucose is metabolized inside the cytoplasm into
2 pyruvate molecules and 2 ATP molecules
Process where glucose is metabolized
Glycolysis
Glycolysis does not require oxygen and readily occurs in the absence of oxygen. This makes it an — process.
anaerobic
pyruvate molecules can be transformed into either lactate or ethanol by a process called
fermentation
The utilization of oxygen to transform the glycolysis by-product into high energy molecules is called
aerobic cellular respiration
When the cells of the body have high levels of ATP, pyruvate and lactate molecules can be recycled to reform the glucose via a process called
gluconeogenesis
begins the cleavage of a-1, 4-glycosidic linkages in the mouth. This breaks it down into smaller polysaccharide and oligosaccharides.
Salivary α-Amylase
These polysaccharides are inherently too large for blood transport and cell uptake. Therefore, our digestive system utilizes —- to break them down into smaller components.
proteases
the pancreas release a more potent a-amylase into the small intestine that breaks it down into disaccharides (maltose) and trisaccharide (maltotriose).
Pancreatic α-Amylase
Pancreatic α-Amylase breaks carbohydrates down into disaccharides (—) and trisaccharide (—).
maltose and maltotriose
this enzyme breaks down maltose into its glucose constituents
Maltase (brush border)
this digests maltotriose and other glucose-based oligosugars
α-Glucosidase (brush border)
breaks down limit dextrin units that have a-1, 6-linkages
α -Dextrinase
metabolism of glucose molecule to pyruvate or lactate for production of energy
Glycolysis
formation of glucose-6-phosphate from noncarbohydrate sources
Gluconeogenesis
breakdown from glycogen to glucose for use as energy
Glycogenolysis
conversion of glucose to glycogen for storage
Glycogenesis
conversion of carbohydrates to fatty acids
Lipogenesis
decomposition of fat
Lipolysis
Preparatory phase: Stage of Phosphorylation
Step 1: glucose → G6P (glucose-5-phosphate)
Step 2: G6P → F6P (fructose-6-phosphate)
Step 3: F6P → F1, 6 BP (fructose 1-6 biphosphate)
glucose → G6P (glucose-5-phosphate) is acted on by what enzyme
glucokinase or hexokinase
first irreversible step of glycolysis
glucose → G6P (glucose-5-phosphate)
G6P → F6P (fructose-6-phosphate) is acted on by what enzyme
phosphohexose isomerase
F6P → F1, 6 BP (fructose 1-6 biphosphate) is acted on by what enzyme
phosphofructokinase I
bottleneck of the pathway, 2nd irreversible step of glycolysis
F6P → F1, 6 BP (fructose 1-6 biphosphate)
Step 3 of glycolysis cofactor catalyst to make reaction faster
magnesium
Prep phase: Stage of Splitting
Step 4: F1,6BP → DHAP + G3P (dihydroxyacetone phosphate; glyceraldehyde-3-phosphate)
stage where a 6 carbon compound splits into two 3 carbon compounds
stage of splitting: F1,6BP → DHAP + G3P (dihydroxyacetone phosphate; glyceraldehyde-3-phosphate)
F1,6BP → DHAP + G3P (dihydroxyacetone phosphate; glyceraldehyde-3-phosphate) is acted on by what enzyme
aldolase
DHAP can be turned to G3P by what enzyme
phosphotriose isomerase
Pay off Phase of glycolysis
Step 5: G3P → 1,3 BPG (Biphosphoglycerine)
Step 6: 1,3 BPG → 3PG (3-phosphoglycerate)
Step 7: 3PG → 2PG (2-phosphoglycerate)
Step 8: 2PG → PEP (phosphoenolpyruvate)
Step 9: PEP → pyruvate
G3P → 1,3 BPG (Biphosphoglycerine) is acted on by what enzyme
glyceraldehyde-3-phosphate dehydrogenase or G3P dehydrogenase
1,3 BPG → 3PG (3-phosphoglycerate) is acted on by what enzyme
1,3 BPG kinase
only reversible kinase
1,3 BPG kinase
3PG → 2PG (2-phosphoglycerate) is acted on by what enzyme
phosphoglycerate mutase
2PG → PEP (phosphoenolpyruvate) is acted on by what enzyme
enolase
It is both an endocrine and exocrine organ in the control of carbohydrate metabolism
pancreas
as endocrine gland, pancreas secretes what
insulin, glucagon, somatostatin
as exocrine gland, pancreas secretes what
amylase
The primary hormone responsible for the entry of glucose into the cell
insulin
insulin is synthesized by
β-cells of the islets of Langerhans in the pancreas
the only hormone that decreases glucose levels
insulin
hypoglycemic agent
insulin
insulin has what type of relationship with glucagon?
reciprocal
where is insulin stored?
liver, fat, and skeletal muscles
Promotes glycogenesis, lipogenesis, and glycolysis; suppresses glycogenolysis,
insulin
sample requirement for insulin measurement
serum
serum insulin measurement result in presence of hemolysis
falsely low
insulin reference value
2.6 - 24.9 mcIU/mL
primary hormone responsible for increasing glucose – hyperglycemic agent.
glucagon
Glucagon is synthesized by the
α-cells of the islets of Langerhans in the pancreas.
glucagon is released during what states
stress and fasting states
glucagon promotes what
glycogenolysis
fasting plasma glucagon value
25 - 50 pg/mL
these are secreted by the cells of the zona fasciculata of the adrenal gland
cortisol
released from the chromaffin cells of the adrenal medulla
catecholamines
growth hormone is secreted by
anterior pituitary gland
Stimulates release of cortisol from the adrenal cortex
Adrenocorticotropic Hormones
somatostatin is secreted in two locations, what are they?
pancreas and hypothalamus
pancreatic cells that produce somatostatin
delta cells of the islets of Langerhans
somatostatin inhibits the actions of…
insulin
It is also synthesized in the paraventricular and arcuate nuclei of the hypothalamus where it participates in prohibiting the function of somatotropin and thyrotropin
somatostatin
fasting plasma glucose reference for indication of hyperglycemia
≥ 126 mg/dL
Warning signs and symptoms of — are related to the central nervous system
hypoglycemia
Whipple’s Triad
- typical symptoms are seen
- low blood sugar concentration of < 55 mg/dL
- symptoms are alleviated by glucose administration
glucagon and other glycemic hormones are released into the circulation at this value of plasma glucose
65 - 70 mg/dL
observable symptoms of hypoglycemia appear at this value of plasma glucose
50 - 55 mg/dL
is suggested to observe the hypoglycemic “dip” which is often not seen until after 3 hours.
5 hour glucose tolerance test
determines fasting hypoglycemia with blood samples drawn at 2 mins to 2 hours interval.
Tolbutamide tolerance test
determines reactive hypoglycemia by measuring the response of insulin to a “cocktail meal”
Mixed-meal tolerance test
post prandial blood sample may be drawn at —- mins with a baseline fasting plasma glucose.
15, 30, 45, 60, 90, and 120 mins
may be performed but with great caution in patients with suspected hypoglycemia because the procedure can induce severe reactive hypoglycemia, causing loss of consciousness and even shock.
glucose tolerance test
Neurogenic symptoms of hypoglycemia
tremors, palpitations, anxiety, diaphoresis
Neuroglycopenic symptoms of hypoglycemia
dizziness, tingling, blurred vision, confusion, behavioral changes
the intentional attempt to induce low blood glucose levels
factitious hypoglycemia
results from exogenous self-administration of insulin or insulin secretagogues medications
factitious hypoglycemia
Group of metabolic disorders characterized by hyperglycemia resulting from defects in insulin secretion, insulin receptors, or both.
Diabetes Mellitus
Glucosuria occurs when the plasma glucose level exceeds —- with normal renal function
180 mg/dL
— develops in DM from excessive synthesis of acetyl-CoA, as the body attempts to obtain required energy from stored fat in the absence of an adequate supply of carbohydrate metabolites.
Ketosis
In severe DM, the ratio of β-hydroxybutyrate to acetoacetae is
6:1
absolute insulin deficiency
insulinopenia
What type of DM individuals have insulinopenia due to loss of pancreatic β-cells and depend on insulin to sustain life and prevent ketosis.
Type 1
Other names for type 1 Diabetes Mellitus
Insulin Dependent Diabetes Mellitus (IDDM), Juvenile Onset Diabetes Mellitus, Brittle Diabetes, Ketosis-prone Diabetes
It is a result of cellular-mediated autoimmune destruction of β-cells of the pancreas
Type 1 Diabetes Mellitus
% reduction of β-cells required to induce symptomatic type 1 DM
80 - 90%
this locus is the major histocompatibility complex on chromosome number 6
HLA-DR/DQ
Insulin Autoantibodies (IAA) are more common in — who develop type 1 DM, whereas glutamic acid decarboxylase (GAD65) in —
young children
adults
simplest carbohydrate
glycoaldehyde
only carbohydrate to be directly used for energy
glucose
