176. Intermediary Metabolism

Question 1

In severe fasting state, ___ are mobilized from body protein stores and serve for ___

Answer 1

Amino acids

liver gluconeogenesis

Question 2

Protein thats activity leads to glycogen synthesis in the liver and muscle after insulin binds to its receptor on the cell membrane

Answer 2

IRS-1

Question 3

Produced in equimolar concentration from proinsulin and is released along w/ insulin

Better marker for endogenous insulin production than insulin given the longer half life

Answer 3

C-peptide

Question 4

Lipids are either __ in peripheral tissue or converted to __ in liver during fasting state

Answer 4

Oxidation

Ketones

Question 5

Stimulates insulin secretion from beta cells

- prevents excessive hyperglycemia

Answer 5

Glucagon

Question 6

Main regulator of the rate of release of insulin and C-peptide from secretory vesicles

Answer 6

Plasma glucose levels

Question 7

Cell depolarization activates ___ channels

Leads to a rise in cellular Ca2+
- augmented by Calcium release from the ER

Answer 7

Voltage-gated calcium

Question 8

Insulin-dependent glucose transporter

Glucose uptake in muscle and fat cells trigger transposition of this transporter

Answer 8

GLUT-4

Question 9

Sensitivity to __’s effect may be decreased in persons with chronic obesity

Inactivating mutations in the genes encoding __ or its receptor lead to massive obesity

Answer 9

Leptin

Question 10

Main insulin dependent tissues are found in (3 things)

• (insulin-sensitive)
• stimulated in fed state

Answer 10

Muscle
Fat
Liver

Question 11

Responsible for:

• glucose uptake in target tissues by transposition of GLUT-4
• Stimulation of glycogen synthesis and inhibition of glycogenolysis in the liver –> increased net uptake of glucose
• Induction of genes regulating storage of energy carriers in the form of glycogen and TG synthesis, mainly in the muscles and liver
• Induction of genes responsible for increased protein synthesis (anabolic effect)
• Decrease glucagon secretion

Answer 11

Insulin

Question 12

Secreted by cells in the intestine (jejunum) in response to food intake

Facilitates insulin secretion from beta cells following oral intake

Agonists are used for the treatment of diabetes

Answer 12

GLP-1

Question 13

ATP sensitive ___ channels on the cell membrane of beta cells react to the increase of ATP/ADP after glucose has entered the beta cells and become inhibited
- leads to cell depolarization

Answer 13

K+ (KATP channels)

Question 14

Organ that can only use glucose for energy metabolism

Answer 14

Brain

Question 15

List of energy resources from most to least:

Answer 15

Fat
Carbs
Protein

Question 16

Secretes insulin

Answer 16

Beta-cells of islets of Langerhans

Question 17

Inhibitory signals for __:

• somatostatin
• inflammatory cytokines
• NE
• Leptin
• IGF-1

Answer 17

Insulin

Question 18

2 sources of glucose in hepatocytes from glycogenolysis and gluconeogenesis

Answer 18

Glycogen

Oxalate (leads to PEP from pyruvate)

Question 19

Inhibitory signals for __:

• Glucose
• Insulin
• Somatostatin
• Ketones
• Free fatty acids
• GLP-1

Answer 19

Glucagon

Question 20

Secreted by alpha cells in the islets of Langerhans

Counteracts insulin in respect to glucose uptake and metabolism

Answer 20

Glucagon

Question 21

Glucose transporter in fat and muscle

Answer 21

GLUT4

Question 22

Secreted by adipose tissue proportional to its mass

Induces satiety, increases energy expenditure

Currently being explored for treatment of obesity and/or diabetes

Answer 22

Leptin

Question 23

Stimulatory signals for __:

• Amino acids
• ACh
• EPI
• NE
• GIP
• CCK

Answer 23

Glucagon

Question 24

Activates glycogen breakdown after cAMP acts on it

Blocked by insulin

Answer 24

PKA

Question 25

Displays a diurnal variation in plasma levels Relates to conditioning to common times when one eats

Answer 25

Ghrelin

Question 26

Rise in intracellular calcium triggers fusion of __ and __ containing vesicles with the cell membrane and exocytosis of these prestored proteins

Answer 26

Insulin and C-peptide

Question 27

Released mainly by cells in the stomach and intestinal wall Levels ride during fasting - induce hunger and promote energy conservation

Answer 27

Ghrelin

Question 28

GLUT4 responds to __ action after it is phosphorylated by the Insulin/IGF-1 receptors Translocates GLUT4 to cell membrane to let glucose enter the cell

Answer 28

Cbl

Question 29

Plasma glucose is sensed by beta cells via free entry of glucose into beta cells through what transporter? Insulin-independent

Answer 29

GLUT-2

Question 30

Enhances glucose stimulated insulin Inhibits glucagon secretion Delays gastric emptying Induces satiety Acts through a G-coupled cell membrane receptor

Answer 30

GLP-1

Question 31

After glucose enters the beta cells via GLUT-2, it causes oxidative metabolism of itself leading to an increase in the what?

Answer 31

ATP/ADP ratio

Question 32

Peptide hormone with a relatively short half-life that binds to tyrosine kinase receptors to initiate an intracellular signaling cascade

Answer 32

Insulin

Question 33

Deactivated by phosphorylated PKB Can no longer inactivate glycogen synthesis

Answer 33

GSK3

Question 34

Acts on a GPCR that leads to activation of PKA to inactivate glycogen synthase Also helps leads to glycogen breakdown

Answer 34

Glucagon

Question 35

Stimulatory signals for __: - Glucose - GLP-1 - Glucagon - Amino acids - Fatty acids - ketones - ACh - VIP - EPI

Answer 35

Insulin

Question 36

Peptidase that degrades GLP-1 Target of inhibition in diabetic medications

Answer 36

DPP-4