Chapter 10: Carbohydrates

Carbohydrates

Are hydrates of aldehyde or ketone derivatives based on the location of the carbon-oxygen functional group.

Carbohydrates

They are grouped as monosaccharide, disaccharides, oligosaccharides, and polysaccharides.

Glycolaldehyde

Is the simplest carbohydrate (CH0).

Glucose

Is the only carbohydrate to be directy used for energy or stored as gylcogen.

It does not accumulate in the muscle.

Insulin

Glucose does not enter the muscle cell freely, and when it gains entry with the help of _____, it is quickly metabolized.

Two thirds

______ of glucose utilization in resting adults occurs in the CNS.

Pyruvic acid, Lactic acid, and Acetylcoenzyme A

Glucose metabolism generates _____, ______, and _____ as intermediate products.

Carbon dioxide, water, and ATP

Complete oxidation yields _____, _____, and _____.

Pyruvate carboxylase

Is the principal regulatory enzyme in gluconeogenesis.

Hyperglycemia

In the absence of insulin, glucose will remain in the blood resulting in _____.

Glucose, Maltose, Fructose, Lactose, and Galactose

Reducing substances/sugars: ____, _____, _____, _____, and _____.

A double bond and a negative charge in the enol anion

The presence of _____ and _____ makes glucose an active reducing substance.

Sucrose

Is the most common non-reducing sugar.

Non-reducing sugars

Do not contain an active ketone or aldehyde group.

Pancreas

It is both an endocrine and exocrine organ in the control of carbohydrate metabolism.

Insulin, Glucagon, and Somatostatin

(Endocrine gland) Pancreas secretes _____, _____, and _____ from different cells residing in the pancreatic islets of Langerhans.

Amylase

(Exocrine gland) Pancreas secretes _____ which is responsible for the breakdown of ingested complex carbohydrates.

Insulin

It is the primary hormone responsible for the entry of glucose into the cell.

Insulin

It is synthesized by the B-cells of the islets of Langerhans in the pancreas.

Insulin

It is normally released when glucose levels are high.

Insulin

It is the only hormone that decreases glucose levels (hypoglycemic agent).

Insulin

It is stored in the liver, fat, and skeletal muscles.

Insulin

It has a reciprocal relationship with glucagon.

Insulin

It promotes glycogenesis, lipogenesis, and glycolysis; suppresses glycogenolysis.

Insulin

It enhances membrane permeability to cells in the liver, muscle, and adipose tissue.

12 hours

Patient preparation for Insulin: For _____ before specimen collection, do not take multivitamins or dietary supplemens containing biotin (vitamin B7).

Biotin (vitamin B7)

Patient preparation for Insulin: For 12 hours before specimen collection, do not take multivitamins or dietary supplemens containing _____, which is commonly found in hair, skin, and nail supplements and multivitamins.

Serum

Sample requirement for Insulin.

Hemolysis; Insulin-degrading enzyme

Sample precautions for Insulin: Serum insulin measurements may be falsely low in the presence of _____. An _____ found in RBCs as well as in other tissues is responsible for this discrepancy.

2.6 - 24.9 mcIU/mL

Reference values for Insulin.

Glucagon

It is the primary hormone responsible for increasing glucose (hyperglycemic agent).

Glucagon

It is synthesized by the a-cells of the islets of Langerhans in the pancreas.

Glucagon

It is released during stress and fasting states.

Glucagon

It enhances catabolic functions during fastin periods; promotes glycogenolysis.

25 - 50 pg/mL

Fasting plasma glucagon.

Cortisol and corticosteroids (Glucocorticoids)

Catecholamines

Growth hormone (Somatotrophic)

Thyroid hormones

Adrenocorticotropic hormone (ACTH)

Somatostatin

Other hormones that tend to increase blood glucose concentration.

Cortisol and corticosteroids (Glucocorticoids)

These are secreted by the cells of the zona fasciculata of the adrenal cortex.

Cortisol and corticosteroids (Glucocorticoids)

They decrease intestinal entry of glucose into the cell.

Cortisol and corticosteroids (Glucocorticoids)

They promote gluconeogenesis and lipolysis.

Catecholamines

These are released from the chromaffin cells of the adrenal medulla.

Catecholamines

They inhibit insulin secretion and promote glycogenolysis and lipolysis.

Growth hormone (Somatotrophic)

It is secreted by the anterior pituitary gland.

Growth hormone (Somatotrophic)

It decreases entry of glucose into the cell.

Growth hormone (Somatotrophic)

It promotes glycogenolysis and glycolysis.

Thyroid hormones

They promote glycogenolysis, gluconeogenesis, and intestinal absorption of glucose.

Adrenocorticotropic hormone (ACTH)

It stimulates release of cortisol from the adrenal cortex.

Adrenocorticotropic hormone (ACTH)

It promotes glycogenolysis and gluconeogenesis.

Pancreas and hypothalamus

Somatostatin is secreted in two locations: _____ and _____.

Somatostatin

In the pancreas, it is produced by the delta cells of the islet of Langerhans and inhibits the action of insulin.

Somatostatin

It is also synthesized in the paraventricular and arcuate nuclei of the hypothalamus (a neuroendocrine hormone) where it participates in prohibiting the function of somatotropin and thyrotropin.

Paraventricular and arcuate nuclei

Somatostatin is also synthesized in the _____ and _____ of the hypothalamus (a neuroendocrine hormone) where it participates in prohibiting the function of somatotropin and thyrotropin.

Somatotropin and thyrotropin

Somatostatin is also synthesized in the paraventricular and arcuate nuclei of the hypothalamus (a neuroendocrine hormone) where it participates in prohibiting the function of _____ and _____.

Somatostatin

It inhibits the action of glucagon and growth hormone.

Hyperglycemia and Hypoglycemia

Clinical conditions related to carbohydrate metabolism.

Hyperglycemia

It is characterized by an increase in blood glucose concentration.

Hyperglycemia

It is toxic to beta-cell function and impairs insulin secretion.

Stress, severe infection, dehydration, pregnancy, pancreatectomy, hemochromatosis, and insulin deficiency or abnormal insulin receptor.

Causes of hyperglycemia:

≥ 126 mg/dL

A fasting plasma glucose of _____ is indicative of hyperglycemia.

Hypoglycemia

It results from an imbalance between glucose utilization and production.

Hypoglycemia

It involves decreased glucose levels and can have many causes.

CNS

The warning signs and symptoms of hypoglycemia are related to the _____.

Whipple’s Triad

A diagnosis of hypoglycemia should not be made unless a patient meets the criteria of _____:

Low blood glucose concentration

Typical symptoms are seen

Symptoms alleviated by glucose administration

A diagnosis of hypoglycemia should not be made unless a patient meets the criteria of Whipple’s Triad: _____, _____, and _____.

65 - 70 mg/dL

Glucagon and other glycemic hormones are released into the circulation.

50 - 55 mg/dL

Observable symptoms of hypoglycemia appear.

≤ 50 mg/dL

Considered low value and abnormal for infants (requires further diagnostic test).

< 50 mg/dL

Impairment of cerebral function starts.

≤ 55 mg/dL (3.0 mmol/L)

Hypoglycemia symptoms with a plasma glucose level of _____ (_____) in an individual who is not receivinng medications for diabetes require further evaluation.

55 mg/dL to 60 mg/dL

Healthy males will maintain plasma glucose of _____ to _____ for several days…

40 mg/dL

Healthy females will produce ketones faster and allow plasma glucose to decrease to _____.

Approximately 55 mg/dL

Symptoms of hypoglycemia develop at a mean plasma glucose concentration of _____.