Endocrine Pancreas Flashcards
The Insulin Receptor is a membrane receptor composed of 2 alpha subunits and 2 beta subunits linked together via _________________bonds.
Disulfide
Which chain binds to insulin on the extracellular domain? Alpha or Beta
Alpha chains are entirely extracellular and bind to the insulin, while beta chains penetrate through the plasma membrane and transduce the signal.
What family of receptors does the insulin receptor belong to?
Tyrosine Kinase Receptors
What are the characteristics of GLUT-1 Transports?
A. High Affinity Glucose Transporter found in many cells
B. Cotransports 1 glucose or galactose with 2 Na+ Ions
C. Transports Glucose, galactose, or fructose at a low affinity
D. The Primary glucose transport found on neurons
E. Insulin-dependent glucose transporter
A.
What are the characteristics of GLUT-2 Transports?
A. High Affinity Glucose Transporter found in many cells
B. Cotransports 1 glucose or galactose with 2 Na+ Ions
C. Transports Glucose, galactose, or fructose at a low affinity
D. The Primary glucose transport found on neurons
E. Insulin-dependent glucose transporter
C
What are the characteristics of GLUT-3 Transports?
A. High Affinity Glucose Transporter found in many cells
B. Cotransports 1 glucose or galactose with 2 Na+ Ions
C. Transports Glucose, galactose, or fructose at a low affinity
D. The Primary glucose transport found on neurons
E. Insulin-dependent glucose transporter
D
What are the characteristics of GLUT-4 Transports?
A. High Affinity Glucose Transporter found in many cells
B. Cotransports 1 glucose or galactose with 2 Na+ Ions
C. Transports Glucose, galactose, or fructose at a low affinity
D. The Primary glucose transport found on neurons
E. Insulin-dependent glucose transporter
E.
What are the expression sites for GLUT 4 and why is it special?
Muscle, Liver and Adipose Tissue; it is insulin-dependent so it responds to rises in insulin levels in the blood
What glucose transport is incorporated into Neurons and RBCs and why is it important to note?
GLUT-1 or GLUT-3; these transporters are insulin-Independent; therefore it is important to control insulin levels or you may have these burn out
What does GLUT-5 transport?
FRUCTOSE, which is important both in the digestion and absorption of Carbohydrates, but also in the maintenance of sperm motility, in locations where fructose will not otherwise be used as a food source (spermatozoa, in the uterus and uterine tubes)
What transporter is found in the convoluted tubules of the kidneys and the intestinal mucosa?
SGLT-1; a transporter that transports 1 Glucose molecules for 2 Na+ molecules; However, it does not transport fructose
Which of the following enzymes are activated during Gluconeogenesis and glucose export? What is the final result?
Enzymes:
- PEP Carboxykinase
- G-6-Phosphatase
- F-1,6-Bisphosphatase
Result:
More Glucose in the bloodstream
What are the enzymes that are activated during Glucose Oxidation and Glycolysis? What is the result?
Enzymes:
- Glucokinase
- Pyruvate Kinase
- PFK-1 (Phosphofructose-kinase 1)
Result: More ATP in the Cell
Describe the affect that Insulin has on Fat.
Insulin decreases Lipolysis and increases the formation of Triglycerides in the adipocytes. At adipocytes, this decreases the fatty acid (and thus glucose) output and promotes the storage of both ingested and de novo triglycerides.
Describe the actions of Insulin on Amino Acids and Proteins.
Insulin promotes the transport of AAs into muscle and the removal from blood. Thus decreasing the blood AA level and promoting Protein synthesis in the target cells. Insulin prevents degradation of protein and has a net ANAbolic effect on the body.
What Type of Cell secretes Glucagon?
Alpha Cells of the Islets of Langerhans in the Pancreas, secreted into the hepatic portal circulation.
What organ is directly affected by Glucagon?
The Liver, with a lesser role at other tissues (e.g. Adipose Tissue)
Explain what happens in terms of Insulin and Glucagon in this particular situation.
“High Concentrations of Amino Acids, such as those that would occur in the blood after a meal contain protein (especially the amino acids alanine and arginine)”
Stimulate the secretion of Insulin
Stimulate the secretion of Glucagon; promotes rapid conversion of aa’s into glucose –> more glucose for the tissues
Which is increased in Patients with Hyperthyroidism or Hypercortisolemia? Glucagon or Insulin?
Glucagon; Cortisol does the opposite of Insulin….
Explain the mechanism of action if there is a high level of Glucose in connection to Glucagon secretion.
Glucose –> ATP –> activation of B-Cells/ Inactivation of A-cells –> inactivation of Ca2+ channels and increased Ca2+ sequestration in the ER = No Ca2+ present = No release of Glucagon stored in vesicles.
Explain the mechanism of action when there is a decreased Glucose level in connection to glucagon secretion.
No Glucose –> Low ATP –> Ca2+ Open –> increase intracellular Ca2+ levels –> release of glucagon carrying vessicles via exocytosis.
Which of the following factors stimulating Glucagon Secretion is False? A. Increased Activity of Delta Cells B. Increased Amino Acid Concentrations C. Exercise D. Activation of B2 receptors E. Decreased Glucose in blood
A; D-Cells –> Somatostatin, the mother of all inhibitors
Glucagon inhibits protein synthesis in the liver and protein breakdown where? A. Muscle B. Everywhere C. Liver D. Kidneys/Spleen E. It doesn't
C. Liver; Glucagon stimulates protein breakdown in the liver, it does not normally affect protein in skeletal muscle.
Name 3 hormones that promote gluconeogenesis?
- Cortisol
- Growth Factor
- Glucagon
Effect of Cortisol on Protein?
In muscle –> Protein degradation
In Liver –> Protein Synthesis
Glucagon effect on Protein?
In Liver –> Protein Degradation
Growth Hormone affect on Protein?
In Liver –> Protein Synthesis
In Muscle –> Protein Degradation
What Secretes Somatostatin (SS, SST, SRIF, or GHIH)?
Pancreatic Delta Cells
What stimulates the release of Somatostatin from Pancreatic Delta Cells?
Increased blood glucose levels
What does SST inhibit?
Both insulin and glucagon
Jonathon has been on a 27 day water fast. At the end of the 27th day, Cortisol secretion promotes…..
Muscle protein wasting as a source of emergency energy.
3-4 hours after the fed state ends, which process is likely to be occurring? A. Gluconeogenesis B. Lipolysis C. Glycogenolysis D. Glycolysis E. Glycogenesis
C. GLycogenolyis; Hepatic Glycogenolysis is THE SOURCE from blood glucose in the first 4 hours after a meal, there is no role yet for gluconeogenesis, which involves the breakdown of things that were meant not to be broken down. Here we break down Glycogen a storage component that was meant to be broken down for energy.
4-24 hours after the fed state ends, which process is likely to be occurring? A. Gluconeogenesis B. Lipolysis C. Glycogenolysis D. Glycolysis E. Glycogenesis
A. Gluconeogenesis; hepatic gluconeogenesis begins with all possible precursors involved (Glycerol, alanine, glutamine, lactate etc. ) Muscle beings to provide Alanine for hepatic gluconeogenesis. Cortisol begins to be involved, stimulating muscle breakdown (proteolysis). Adipose tissue begins to break down triglycerides and FFAs from the blood and VLDL gradually replaces plasma glucose as fuels sources for most of the tissues including the skeletal muscle.
Name the 4 precursors for gluconeogenesis that could become a source for blood glucose.
- Alanine
- Glutamine
- Lactate
- Glycerol
Name the 3 ketone bodies that are formed from fat during starvation.
- Acetone
- Acetoacetate
- 3-hydroxybutyrate
What is the Range of Euglycermia? (Normal Glucose)
70-110 mg/dL is always the preferred concentration of glucose
What is the glucose levels in someone that is Hypoglycemic?
Hypo –> <60 mg/dL
What is the glucose concentration in someone that is hyperglycemic?
Hyper –> when fasting blood glucose is >125 mg/dL
A patient presents to the ER complaining of Polyphagia, Polyuria and Polydipsia. Lab findings conclude that the patients fasting Blood glucose levels are 127 mg/dL and HbA1c is 6.5%. Explain.
Patient is presenting with uncontrolled, Diabetes Mellitus (DM); uncontrolled because HbA1c of 5.7% is normal, suggesting that the patient is not taking medication for the diabetes
Describe the morphology associated with Diabetes Type 2.
- Amyloid Accumulation
2. Beta Cell atrophy of the Islets of Langerhans
Describe the morphology of Type 1 Diabetes.
- Lymphocyte Accumulation (autoimmune)
2. B-Cell Destruction of the Islets of Langerhans
The secretion of Insulin peptide hormone by the pancreatic Beta-Cells is ________________________.
Episodic
If laboratory test conclude that both the blood insulin and C-peptide levels are low, what type of Diabetes could this person have?
Type 1 DM
If laboratory test conclude that there is an excess secretion of both Insulin and C-peptide, what condition does this patient most likely have?
Type 2 DM
Blood Glucose Levels can be sensed from the ______________ side of the pancreatic cells.
Arterial Side
Insulin is secreted into the ______________ side of pancreatic Cells.
Venous
What is the primary factor driving the secretion of insulin in response to high blood glucose levels?
A. High Ca2+ levels B. High K+ Levels C. K+ channel Activation D. Glucokinase E. High Glucose
E. High Glucose
What protein transporter is present on pancreatic beta cells?
- GLUT-1
- GLUT-2
- GLUT-3
- GLUT-4
- GLUT-5
GLUT-2 Glucose Transporter
Which of the following is not a factor promoting the secretion of insulin from pancreatic beta cells?
A. High GLUT2 transporters B. High blood Glucose C. High rate of respiration D. High K+ concentration E. High ATP concentration F. High Ca2+ concentration
D. High K+ Concentration; ATP –> ATP sensitive K+ Channel and closes it causing K+ To stay in the cell and increasing depolarization which opens Ca2+ voltage-gated channels. Increased Ca2+ causes exocytosis of insulin granules into the venous blood.
Where at what is the checkpoint of insulin secretion?
respiration that generates ATP. The high ATP controls whether or not the cell depolarizes.
GLP-1 and GIP act to _________ the ___________ Pathway. This increases ___________ and ___________ via Gs subunit.
Increase the Adenylyl Cyclase pathway. This increases cAMP and PKA via the Gs subunit.
