DM Epidemiology and Pathophys - Exam 4 Flashcards
**What is normal fasting glucose? ____ of glucose from meal → stored, released later as needed by the body
70-99
⅔
______ is secreted in response to postprandial serum glucose changes. How is glucose stored?
insulin
stored in liver and skeletal muscle as glycogen
What is a triglyceride made up of?
3 fatty acids linked by a glycerol molecule
Once a glycogen molecule is stored in the skeletal muscle, can it be broken down and used in the blood stream?
NO! once its in the skeletal muscle it can only be used for energy but the muscle
Once a glycogen molecule is stored in the liver, can it be broken down and used in the blood stream?
YES! liver glycogen can be used by the entire body
______ hepatic synthesis of glucose
from amino acids, glycerol, and lactic acid
gluconeogenesis
_____ is the most efficient form of fuel storage. ______ convert TGs to fatty acids and glycerol
Fat Metabolism
lipase
______ are converted to ____ by liver, then released for energy. _____ can be used by the brain for energy when glucose is not available. Can FA be made directly into glucose?
Fatty acids
ketones
ketones
NO!! FA cannot be made directly into glucose
How is excessive protein stored? When are protein broken down and used for energy?
limited facility for storage of excess amino acids
Excess amino acids → fatty acids, ketones, or glucose
in periods of fasting/starving. AA are broken down as substrates for gluconeogenesis when glucose is NOT available
What are the 2 types of Islets of Langerhan cells? What is their function?
alpha cell: secrete glucagon
beta cell: secretes insulin and amylin
secrete hormones into the blood
What are the 2 types of pancreatic acini cells? What do they secrete?
exocrine cells
F cell: secretes pancreatic polypeptide
Name 3 substances that are produced in the beta cells. What is the function of each?
Preproinsulin - initially synthesized polypeptide chain
Proinsulin - Created by removal of signal peptide and linkage between A and B chains
Insulin - active form; created by cleavage and removal of C-peptide chain
How is proinsulin created? How is insulin created?
by removal of signal peptide and linkage between A and B chains
active form; created by cleavage and removal of C-peptide chain
How is mature insulin stored and released? How can you assess insulin function?
Mature insulin molecule and C-peptides are co-stored in the beta cells and released together
order a C-peptide level because you cannot measure insulin directly because it is not very stable
What does a low C-peptide level indicate?
that the pancreas is NOT producing insulin
____ is the primary regulator of beta cell secretion of insulin. What does it bind to?
Glucose
binds to specific cell membrane transporter proteins known as GLUT
What is the role of GLUT- 2 (and/or GLUT 1)? GLUT-4?
GLUT-2 (and/or GLUT-1) - transport glucose into numerous body cells, including beta cells
GLUT-4 - skeletal muscle, adipose tissue - in an inactive position until stimulated by insulin
Once within the Beta cell, how does glucose stimulate the release of insulin? Why do we need to know this process?
glucose is phosphorylated → ATP generation → inhibition of an ATP-sensitive K+ channel
Inhibition of this channel leads to depolarization of the beta cell
Depolarization → opening of voltage-gated calcium channel → insulin secretion
because different medications target diff areas of the process
What are the 2 major actions of insulin on glucose metabolism?
insulin increases glucose transport into skeletal muscle and adipose tissue
insulin increases synthesis of glycogen which decreases gluconeogenesis
What are the 3 major effects of insulin on fat metabolism?
Transport - ↑ transport of fatty acids into adipose cells
Synthesis - ↑ synthesis of fatty acid and TG synthesis
Breakdown - ↓ TG breakdown
What are the 3 major action of insulin on protein metabolism?
Transport - ↑ transport of amino acids into cells
Synthesis - ↑ synthesis of proteins
Breakdown - ↓ breakdown of proteins
What is the function of glucagon? Where it is produced? When is glucagon the highest?
increased gluconeogensis
increased glycogen breaken (to pull glucose out of storage to used for energy)
increases adipose breakdown by activating lipase in adipose cells
increases transport of AA to the liver to use for gluconeogenesis
glucagon is highest during periods of not eating aka first thing in the morning
What is the role of amylin? Where is it produced?
Works with insulin to regulate plasma glucose concentrations, decreases post meal glucagon secretion, slows gastric emptying and increases satiety
secreted by beta cells along with insulin and C-peptide
Somatostatin secreted by _____ in the Islets of Langerhans, as well as by other cells throughout the body. What is its function?
delta cells
Inhibitory hormone - suppresses release of several hormones, including insulin and glucagon
_____ are gut-derived hormones that promote insulin release after oral nutrient load. Accounts for ____ of postprandial insulin secretion. What is another function?
Incretins
~50%
Slowed gastric emptying and increased satiety aka slows down appetite
What is the effect of epinephrine on blood glucose levels?
increases blood glucose during periods of stress
Increased - glycogenolysis in liver and muscle tissues; lipolysis in adipose tissues
Decreased - release of insulin by the pancreas
Growth Hormone is normally ____ by insulin and elevated glucose levels. What does a chronic hyper secretion of growth hormone result in?
insulin resistance, elevated glucose, and
increased overall risk of DM
Why does glucocorticoids increase blood glucose levels?
because it increases gluconeogenesis in the liver