Physiology Lecture 4.7: Insulin

Which two hormones are crucial for normal regulation of glucose, lipid and protein metabolism?

1. Insulin

2. Glucose

What system do most nutrients travel to after meals?

Portal circulation

What is the first organ involved in fuel distribution?

Liver

What are the three second organs involved in fuel distribution?

1. Adipose tissue

2. Muscle

3. Brain

Where does glucose travel to in fuel distribution?

All tissues

Where does fat mainly travel to in fuel distribution?

Adipose

Where do amino acids mainly travel to in fuel distribution?

Amino acids

How much of carbohydrates become glucose in digestion?

Glucose

What does carbohydrates that go through digestion that don't become glucose become?

1. Fructose

2. Galactose

How much of the glucose in the portal system are absorbed by the liver?

60 - 75%

What do hepatic enzymes store glucose as?

Glycogen

How much of the sugar in blood is glucose?

95%

What two things are glucose converted into in adipose tissue?

1. Glycerol

2. Triglycerides

What is glucose converted into in muscle?

Glycogen

What is glucose transported by in the heart and brain?

Insulin

What two things do all glucose-dependent organs depend on?

1. Brain

2. RBCs

What is the path of lipids in digestion? (4)

1. Lymphatics

2. Cisterna chyli

3. Thoracic duct

4. Circulation

What two things are lipids stored as in adipose tissue?

1. Fatty acids

2. Triglycerides

What are the two organs for lipid digestion?

1. Liver

2. Adipose tissue

What does the liver couple triglycerides with?

Very low density lipoprotein

What is the primary organ for de novo synthesis of fatty acids?

Liver

What are proteins converted into in digestion?

Amino acids

What is the prominent organ for protein synthesis?

Liver

What are the two organs for protein digestion?

1. Liver

2. Muscle

What are the four carbohydrate metabolism functions of the liver?

1. Glycogenesis

2. Glycogenolysis

3. Gluconeogenesis

4. Conversion of Galactose and Fructose to Glucose

What are the three fat metabolism functions of the liver?

1. Fatty acid oxidation

2. Synthesis of cholesterol and lipids

3. Fatty acid synthesis

What are the four protein metabolism functions of the liver?

1. Synthesis of proteins

2. Interconversions of amino acids

3. Deamination of amino acids

4. Formation of urea

What are the two results of hypoglycemia?

1. Shock/coma

2. Affects organs

What are the three results of hyperglycemia?

1. Tissue injury

2. Dehydration

3. Acidosis/coma

What is the secretion of alpha cells in the pancreas?

Glucagon

What are the two secretions of beta cells in the pancreas?

1. Insulin

2. Amylin

What is the secretion of delta cells in the pancreas?

Somatostatin

What is the only hypoglycemic hormone?

Insulin

What is the hyperglycemic hormone in the pancreas?

Glucagon

How long after fasting does glucose return to normal?

2 hours

What is the structure of insulin?

Polypeptide heterodimer with two chains (A + B)

What other hormone is secreted along with insulin?

C-peptide

What form of insulin is the only regulator of glucose?

Mature insulin

What is the function of C-peptide?

Differentiate human insulin from synthetic insulin analogs

What is the half-life of insulin in blood?

6 mins

What phosphorylates glucose in pancreatic beta cells?

Glucokinase

What are the four mechanisms of glucose stimulation of insulin in pancreatic beta cells?

1. Increased GLUT2

2. Glucokinase phosphorylates glucose

3. ATP sensitive K channel/Voltage-gatedCa2+ channel

4. Increased Ca2+

What are the three insulin target organs?

1. Liver

2. Adipose tissue

3. Muscle

What does insulin cause in the liver and muscles for carbohydrate metabolism?

Glucose uptake/storage

What does insulin cause in adipose tissue for carbohydrate metabolism?

Glucose uptake

What does insulin deficiency lead to related to carbohydrate metabolism?

Increased glucose in blood

What does insulin cause in the liver for fat metabolism?

Synthesis of fat

What does insulin cause in adipose tissue for fat metabolism?

Synthesis/storage of fat

What does insulin inhibit in adipose tissue for fat metabolism?

Hormone-sensitive lipase

What are the three effects of insulin deficiency related to fat metabolism?

1. Hormone-sensitive lipase activation

2. Increased ketone bodies

3. Increased cholesterol and lipids

What does the activation of Hormone-sensitive lipase cause?

More fatty acids in circulation

What is caused by increased ketone bodies?

Ketoacidosis

In what three ways does insulin promote protein synthesis and storage?

1. Increasing amino acid transport

2. Increasing DNA transcription/ mRNA translation

3. Inhibiting protein catabolism

What are the two effects of insulin deficiency related to protein metabolism?

1. Amino acids released into plasma

2. Increased urea

Insulin deficiency increases what five things in plasma?

1. Glucose

2. Fatty acids

3. Amino acids

4. Urea

5. Ketone bodies

What does insulin interact with to promote body growth?

Growth hormone

What two things in blood are secondary factors that increase insulin secretion?

1. Free amino acids

2. Gastrointestinal hormones

What drug is a secondary factor that increase insulin secretion?

Sulfonylurea

What two conditions are secondary factors that increase insulin secretion?

1. Abnormal hormone levels

2. Obesity

What stimulation is a secondary factor that increase insulin secretion?

Parasympathetic (Beta-adrenergic)

What are the three secondary factor that decrease insulin secretion?

1. Somastostatin, Leptin, Amylin

2. Fasting

3. Alpha-adrenergic receptors

What is the structure of glucagon?

Polypeptidic, single chain

What are the metabolic effects of glucagon?

1. Increase of Glycogenolysis

2. Increase of Gluconeogenesis

What activity stimulates glucagon secretion?

Exercise

High levels of what stimulates glucagon secretion in low blood glucose?

Amino acids

What is the role of Somatostatin?

Decrease immediate use of absorbed nutrients

What are the two medical uses of glucagon?

1. Severe hypoglycemia

2. Beta blocker overdose

How does fasting affect insulin and glucagon release?

Decrease insulin

Increase glucagon

What is the hyperglycemic hormone from the adrenal cortex?

Cortisol

What is the hyperglycemic hormone from the anterior pituitary?

Growth hormone

What is the hyperglycemic hormone from the adrenal medulla?

Epinephrine

Which two hyperglycemic hormones are released due to prolonged hypoglycemia?

1. Cortisol

2. Growth hormone

Which two hyperglycemic hormones are released due to severe hypoglycemia?

Epinephrine

What are the two metabolic panels of the liver?

1. Basic

2. Comprehensive

What in the liver helps in protein catabolism?

Alkaline phosphatase

What two things in the liver helps in amino acid synthesis?

1. Aspartate Transaminase

2. Alanine Transaminase