Physiology of the Endocrine Pancreas and Glucose Metabolism

Question 1

What are the main hormones secreted from each cell type in the islets of Langerhans?

Answer 1

• alpha - secrete insulin and amylin (60% of islet cells)
• beta - secrete glucagon (25% of islet cells)
• delta - secrete somatostatin (10% of islet cells)

Question 2

What are the ‘glucose lowering hormones’ and the ‘glucose raising hormones’?

Question 3

What is the goal of insulin secretion during fasting? What quantity of insulin is secreted during this time? High or low rate?

Question 4

Be able to describe Phase 1 insulin secretion – when it happens/what type of insulin is released (preformed or synthesized directly)/etc…

Question 5

Be able to describe Phase 2 insulin secretion – when it happens/what type of insulin is released (preformed or synthesized directly)/etc…

Question 6

What does insulin do to transport of glucose into liver, muscle and other cells?

Question 7

Understand the negative feedback associated with insulin secretion and blood glucose.

Question 8

The Pancreas:
Two major types of tissue

Answer 8

• Acini
• islets of Langerhans

Question 9

secrete digestive enzymes/fluids
into the duodenum

Answer 9

Acini

Question 10

secrete
hormones into the blood

Answer 10

islets of Langerhans

Question 11

Organized around capillaries in order to secrete
hormones as needed

Answer 11

islets of Langerhans

Question 12

Insulin inhibits ____________ secretion

Answer 12

glucagon

Question 13

Amylin inhibits _________ secretion

Answer 13

insulin

Question 14

Somatostatin inhibits the secretion of both ___________ and _____________

Answer 14

insulin, glucagon

Question 15

• Increased blood glucose
• Increased blood free fatty
acids
• Increased blood amino acids
• Gastrointestinal hormones
▫Gastrin, GIP, GLP-1, CCK,
Secretin
• Glucagon, growth hormone,
cortisol
• Parasympathetic stimulation
• B-adrenergic stimulation
• Insulin resistance (ex obesity)

Answer 15

Increase Insulin Secretion

Question 16

• Decreased blood glucose
• Fasting
• Somatostatin
• a-adrenergic activity
• Leptin

Answer 16

Decrease Insulin Secretion

Question 17

If the blood glucose concentration is suddenly
increased to a level two to three times normal and
kept at this high level…
-Plasma insulin concentration increases almost 10-fold
within 3 to 5 minutes after the elevation of the blood
glucose
-Results from immediate dumping of preformed insulin
from the beta cells of the islets of Langerhans
-Sustained response for 5-10 minutes before decreasing
This is known as Phase ___

Answer 17

Phase 1

Question 18

If the blood glucose concentration is suddenly
increased to a level two to three times normal and
kept at this high level…
-Beginning at about 15 minutes, insulin secretion rises a
second time and reaches a new plateau in 2 to 3 hours
-Usually at a rate of secretion even greater than that in the
initial phase
-Release of preformed insulin and from activation of the
enzyme system that synthesizes and releases new insulin
This is known as Phase ____

Answer 18

Phase 2

Question 18

Any rise in blood glucose increases insulin
secretion, and the insulin in turn increases
transport of glucose into __________, __________, and other
cells, thereby reducing the blood glucose
concentration back toward the normal value
- Regulation is rapid and robust

Answer 18

liver, muscle

Question 19

Amino acids strongly potentiate (effect) the glucose
stimulus for insulin secretion, these are:

Answer 19

Arginine
Lysine

Question 20

Insulin in turn promotes transport of amino acids
into the ______________ as well as __________________of protein

Answer 20

tissue cells, intracellular
formation

Question 21

Definition: hormones released from the SMALL
intestines following oral ingestion of nutrients
resulting in…
▫glucose dependent increased insulin secretion
▫glucose dependent decreased glucagon secretion
▫local effects on the BETA CELL
▫systemic effects

Answer 21

Incretin Hormones

Question 22

• Glucagon-like Peptide 1 (GLP-1)
• Glucose Dependent Insulinotropic Polypeptide (GIP)

Answer 22

Incretin Hormones

Question 23

Insulin and Carbohydrate Metabolism:
The insulin in turn causes rapid uptake, storage,
and use of glucose by almost all tissues of the
body, but most importantly:

Answer 23

Muscles
Adipose tissue
Liver

Question 24

Immediately after a _____________________, the glucose that is absorbed into the blood causes rapid secretion of insulin

Answer 24

high-carbohydrate meal

Question 25

Insulin and Carbohydrate Metabolism: Promotes conversion of excess glucose into ________________ and inhibits gluconeogenesis in the liver

Answer 25

fatty acids

Question 26

Insulin and Fat Metabolism: Promotes and is required for fat synthesis and storage

Answer 26

Conversion of excess glucose to fatty acids

Question 27

Insulin and Fat Metabolism: Insulin deficiency _______________ (increases/decreases) use of fat for energy

Answer 27

increases

Question 28

(T/F) Brain cells are permeable to glucose and can use glucose without needing insulin

Answer 28

T

Question 29

Secreted by the alpha cells of the endocrine pancreas

Answer 29

Glucagon

Question 30

Most functions are diametrically opposed to insulin

Answer 30

Glucagon

Question 31

Hypoglycemic hormone is

Answer 31

insulin

Question 32

Major effects of glucagon on glucose metabolism:

Answer 32

▫Breakdown of liver glycogen (glycogenolysis) ▫Increased gluconeogenesis (conversion of many of the amino acids to glucose) in the liver Both result in increasing glucose available in the body

Question 33

Glucagon activates ___________________ - increased quantities of fatty acids available to the energy systems of the body

Answer 33

adipose cell lipase

Question 34

Glucagon inhibits storage of ______________ in the liver, preventing removal of fatty acids from the blood

Answer 34

triglycerides

Question 35

The ___________________ primarily functions to maintain blood glucose control

Answer 35

endocrine pancreas

Question 36

Beta cells and _________

Answer 36

insulin

Question 37

Alpha cells and _________

Answer 37

glucagon

Question 38

______ functioning as a blood glucose buffering

Answer 38

Liver

Question 39

Why is blood glucose regulation so important?

Answer 39

Glucose is the only nutrient that normally can be used by the brain, retina , and germinal epithelium of the gonads and maintaining sufficient amounts is vital to their function

Question 40

Hyperglycemia can be detrimental by:

Answer 40

-Exerting a large amount of osmotic pressure in the extracellular fluid (cellular dehydration) -Loss of glucose in the urine and the associated osmotic diuresis -Sustained increases in blood glucose may cause damage to many tissues (e.g. vascular injury in people)

Question 41

(high blood glucose) occurs when there is too much sugar in the blood

Answer 41

Hyperglycemia