4-Carbohydrates

What function do carbs have?

-structural components in RNA and DNA

-immediate energy need

-energy for nervous system

Aldehyde vs ketone

Aldehyde= carbonyl group at end

Ketine= carbonyl group within

Fisher Projection

Drawn in this manner

Haworth Projection

Drawn in this manner

Monosaccharides

simple sugar that has a single polyhydroxyl aldehyde or ketone

What makes monosaccharides different from other sugars?

They cannot be hydrolyzed further

List 3 monosaccharides

1. Glucose

2. Fructose

3. Galactose

What are disaccharides?

2 monosaccharides bonded by an O-glycosidic bond

List 3 disaccharides

1. sucrose

2. lactose

3. maltose

What are polysaccharides?

-multiple monosaccharides linked

-serve as carbohydrate storage

What are polysaccharides referred to in regards to animals and pplants?

animals: glycogen

plants: starch

Glucose

-primary sugar in blood

-major energy source

-used to make ATP

Glycolysis

-breakdown of glucose to lactate or pyruvate

Gluconeogenesis

-new glucose from non-carbohydrate sources (protein or fat)

Glycogen

-main form of carb storage

-stored in liver or muscle

-readily converted to glucose with the help of hormone glucagon

Glycogenesis

Formation/synthesis of glycogen from glucose with the help of hormone insulin

Glycogenolysis

breakdown of glycogen to glucose

What enzymes break down disaccharides and polysaccharides

-amylase: polysaccharides

-maltase, sucrase, lactase: disaccharides

How many ATP will 1 glucose yield by the end of oxidative phosphorylation?

36-38 ATP

Free fatty acids lead to _____CoA which eventually creates acetoacetate that is then broken down to ____and ____

acetyl CoA—> acetoacetate —→ acetone and β-Hydroxybutyrate

What is the normal range for glucose

65-99 mg/dL

What is created in the alpha cells of the pancreas?

glucagon

What is glucagon responsible for?

incr glucose conc by stimulating:

-glycogenolysis

-gluconeogenesis

-lipolysis

-ketogenesis

-protein catabolism

What is created in the beta cells of the pancreas

insulin

What is insulin responsible for?

decr plasma glucose by incr GLU T transporters to push glucose into cells

Insulin is the body’s only____agent

hypoglycemic

What does insulin do overall?

decr blood glucose

What are the main target organs of insulin?

adipose tissue, liver, skeletal muscle

Insulin promotes the conversion of___to glycogen or fat

glucose

Insulin inhibits ___production by the liver

glucose

Insulin stimulates ___synthesis and inhibits____

protein synthesis; protein breakdown

At the end of insulin synthesis, it’s cleaved into insulin and ____

C-peptide

Testing for____will tell us how much insulin is in the body

C-peptide

Insulin Release: In the first phase, rapid release of____insulin ends within___mins

stored; 10 mins

Insulin release: The second phase starts at the end of the first and lasts until___is restored which is around____mins of continued insulin synthesis

normoglycemia; 60-120mins

Draw the insulin phase for early and late type 2 DM

How would the chart look for Type 1 DM

Type 1 DM do not make insulin. The curve would be flat.

What hormone appears first to counteract insulin?

• glucagon

• epinephrine: counter regulator when glucagon is impaired

Which hormones appear second to counteract insulin?

• cortisol: stimulates glycogenolysis

• growth hormone

What is the glucose value for hypoglycemia?

<55 mg/dL

Hypoglycemia Adrenergic symptoms

-sweating

-heart palpitations

-hunger

-nervousness

-faintness

-weakness

Hypoglycemia neurological symptoms

-headache

-lack of coordination

-double vision

-slurred speech

-confusion

-numbness

-can lead to seizures or coma

What is the glucose fasting value for hyperglycemia?

>99mg/dL

What type of metabolic disorder is DM and what is underused?

-carbohydrate metabolism disorder

-glucose is underused

DM pts are at risk for ___ and ____.

retinopathy and neuropathy (from renal failure)

Gestational DM

carbohydrate intolerance during pregnancy

What is a pt with gestational DM at risk for?

DM

What symptoms are present in type 1 DM?

polyuria, polydipsia, rapid weight loss

What is type 1 diabetes caused by?

insulinopenia: due to loss of beta cells of the pancreas

2 most common autoantibodies in Type 1DM

1. Islet cell cytoplasmic antibodies (ICA)

2. Insulin autoantibodies (IAA)

What is the purpose of testing for autoantibodies in type 1 DM

to asses risk in relatives of pt

What 2 major defects happen in Type 2 DM?

1. insulin resistance

2. loss of β cell function

What are the 3 common complications of chronic DM?

1. Retinopathy

2. Diabetic Nephropathy

3. Neuropathy

hgb A1C: Where does the glucose molecule attach?

N-terminus valine of Hgb A

Is Hgb A1C reversible?

No

What does A1c represent glucose wise?

represents intrgrated glucose level over 8-12 weeks

What happens with pts who have hemoglobinopathies in regards to A1c?

RBC lifespan may be shorter so will give inacacurate result

What is eAG and what does 1% change mean?

estimated average glucose= (28.7 xA1c)-46.7

For every 1% change in A1c there is 28mg/dL change in eAG

Fasting glucose abnormal is anything over ___

100mg/dL

Pre-diabetes is seen with values of :

100-126 mg/dL

DM is seen with values of:

≥ 126 mg/dL

A diet containing 1.75g carbs/kg of carbohydates for 3 days is needed for:

Glucose Tolerance Test

A low carb intake before a glucose tolerance tests can create:

a false diabetic curve

What are the requirements for a glucose tolerance test?

-in early morning

-do not eat evening meal the day before

-remain at rest during test

-refrain from smoking or eating

How many grams of glucose are give for OGTT?

-adults:100g

-children: 2g per kg of weight

When are blood specimens for OGTT taken?

1, 2, and 3 hrs after glu-cola

If hypoglycemia is suspected blood specimens are taken at __ and __hrs

4 and 5 hrs

Chart of OGTT with various pts

Know all the values for DM Dx

Screening for gestational DM

-no fasting; time doesn’t matter

-50g of glucose

-measure at 1 hr

-If glucose ≥ 140 mg/dL perform glucose tolerance test

Diagnosis for gestational DM

-fast for 8 hrs

-75g or 100g of glucose given

-at least 2 values must meet or exceed threshold

Fasting whole blood is ___% less than plasma glucose

10-15%

Fasting capillary blood glucose is___mg/dL higher than venous blood

2-5mg/dL

Analyze CSF___

immediately

CSF glucose is ~____% of blood glucose

~60%

24 hr urine needs to be preserved with 5mL of _____

glacial acetic acid

-refrigerate

_____reduces glucose ____% in _____hr

Glycolysis reduces glucose 5-7% in 1 hr

Can unspun samples be tested after an hour?

NO

What additive is a glycolytic inhibitors and extends stability to 3 days?

Sodium fluoride (gray)

What is the reference method for glucose enzymatic methods?

Glucose Hexokinase

Glucose Hexokinase method measures the___in absornbance at ___as NADPH is formed

incr in abs @340nm

Amount of____reduced is proportional to amount of glucose

NADPH

glucose oxidase and peroxidase is specific for:

β-D-glucose

What interference may the glucose oxidase and peroxidase encounter?

uric acid, ascorbic acid, bilirubin, hemoglobin, tetracycline, and glutathione cause falsely low values

What can cause a false (+) with glucose oxidase and peroxidase test?

bleach

Diabetes, with low levels of insulin, leads____ to causing an ↑
FFA

This in turns causes an accumulation of _____in the blood

Acetoacetate turns mostly into___ and a small portion goes into_____

Diabetes, with low levels of insulin, leads_lipolysis_to causing an ↑
FFA

This in turns causes an accumulation of _acetoacetate_in the blood

Acetoacetate turns mostly into_beta-hydroxybutyrate_ and a small portion goes into_acetone_

Where are ketones seen?

in impaired carbohydrate metabolism

What disease would we see ketones in?

DM, glycogen, storage diseases, alkalosis

Instead of B-hydroxybutyrate, what do small labs use for ketones?

-Acetest and Ketostix

-negative does not rule out diabetic ketoacidosis

Lactic acid is an ___in carb metabolism

intermediary

Lactic acid is an indicator of:

oxygen deprivation

Lactic acid in CSF should_____blood lactic acid conc

parallel

Lactic Acidosis Type A seen in:

-shock

-hypovolemia

-left ventricular failure

Lactic Acidosis Type B is seen:

-DM, neoplasia, liver disease

-Drugs/toxins

-inborn errors of metabolism

DM pts are at high risk for____damage

renal

Most common cause of renal failure in US

Diabetes

Microalbumin

detect low levels of albumin to identify early renal damage

How many rare inherited disorders of glycogen storage?

10

Each glycogen storage disorder is due to a deficiency of a ______

specific enzyme

Type 1 (von Gierkes), most common, with def/absence in____

glucose-6-phosphate