Insulin, Glucagon and Diabetes

Question 1

There are two major types of tissue that compose the pancreas

Answer 1

The Acini, which secrete digestive juices into the duodenum

The Islets of Langerhans, which secrete insulin and glucagon directly into the blood

Question 2

The pancreas contains between 1 and 2 million pancreatic islets which are organized _____

Answer 2

around small capillaries.

Question 3

The islets contain three major types of cells that differ in their morphological and staining characteristics

Answer 3

Alpha Cells- Secrete glucagon (about 25% of islet)
Beta Cells- Secrete insulin and amylin (about 60% of islet)
Delta Cells- Secrete somatostatin

Question 4

Insulin is a small protein hormone that is associated with “_______.”

Answer 4

energy abundance

Question 5

What is insulin composed of?

Answer 5

Two amino acid chains that are connected to each other by disulfide linkages

Question 6

Explain the synthesis of Insulin

Answer 6

Slide 11

Question 7

The primary controller of insulin secretion is the

Answer 7

glucose concentration in the blood.

Question 8

Beta cells contain a large number of membrane _____ which permit an influx of glucose at a rate proportional to the blood glucose concentration

Answer 8

glucose transporters (GLUT2)

Question 9

Glucose-6-phosphate is then oxidized into

Answer 9

ATP

Question 10

ATP inhibits membrane Potassium leak channels, which causes the cell to _____

Answer 10

depolarize

Question 11

What, in addition to ATP, can inhibit the K+ channel, increasing insulin secretion?

Answer 11

Sulfonylurea drugs

Question 12

Normal fasting level of blood glucose

Answer 12

80 to 90 mg/100 mL

Question 13

As the blood glucose concentration rises above ____, secretion of insulin rises rapidly (10-fold within 3-5 minutes)

Answer 13

100

Question 14

After insulin is secreted, it circulates almost entirely ____ and free in the plasma.

Answer 14

unbound

Question 15

To initiate its effects on target cells, insulin first needs to do what?

Answer 15

bind with and activate a membrane receptor protein (which we call the Insulin Receptor)

Question 16

Insulin receptors are made up of 2 parts - what are they?

Answer 16

2 extracellular alpha subunits and two membrane-bound beta subunits (connected by disulfide bonds)

Question 17

Proinsulin is made of

Answer 17

three peptide chains: A, B, and C

Question 18

In the golgi apparatus, most of the Proinsulin is cleaved at two sites to form _____, which is composed of disulfide-connected A and B chains

Answer 18

Insulin

Question 19

The C chain is also called “the connecting peptide,” or _____

Answer 19

C Peptide

Question 20

These IRS enzymes are responsible for ____

Answer 20

regulating the intracellular effects of insulin.

Question 21

Three locations of rapid uptake of glucose

Answer 21

muscles, adipose tissue, and the liver.

Question 22

T/F One of the most important effects of insulin is to cause most of the glucose absorbed after a meal (up to 60%) to be rapidly stored in the liver in the form of glycogen.

Answer 22

T

Question 23

The ___ does not require insulin in order to utilize glucose

Answer 23

brain

Question 24

Excess glucose is converted into ___

Answer 24

fatty acids (lipogenesis)

Question 25

insulin deficiency increases the use of ____ for energy.

Answer 25

fat

Question 26

When fats are being used for energy during insulin deficiency, _____ is produced in large quantities. This can lead to a _____ in uncontrolled diabetes,

Answer 26

acetoacetic acid; ketoacidosis

Question 27

T/F - insulin also promotes the synthesis and storage of protein after meals.

Answer 27

T

Question 28

The resulting _____ is one of the most serious of all consequences of severe diabetes

Answer 28

protein wasting

Question 29

Insulin and ____ interact synergistically to promote growth, with each performing specific function separate from that of the other.

Answer 29

Growth Hormone

Question 30

Glucagon is a ____ created by the _____ of the islets of Langerhans in the pancreas

Answer 30

polypeptide hormone; alpha cells

Question 31

overall function and purpose of glucagon is to

Answer 31

increase the blood glucose concentration.

Question 32

We call glucagon the ____ hormone

Answer 32

hyperglycemic

Question 33

As plasma glucose levels fall, the amount of glucagon that is secreted _____ several fold

Answer 33

increases

Question 34

In addition to a low blood glucose concentration, glucagon secretion can also be stimulated by

Answer 34

Exercise Increased amino acids in the blood

Question 35

When secreted into the blood, glucagon triggers these two things

Answer 35

Breakdown of glycogen from the liver (Glycogenolysis) Increased creation of glucose (Gluconeogenesis) in the liver

Question 36

Two causes of Diabetes Mellitus

Answer 36

lack of insulin secretion (Type 1 DM) decreased sensitivity of the tissues to insulin (Type 2 DM)

Question 37

Lab tests we use to diagnose and/or monitor patients with diabetes

Answer 37

Hemoglobin A1C Plasma Glucose (Fasting and postprandial) Glucose Tolerance Testing Urinary Glucose Continuous glucose monitoring systems (CGMs)