Endocrine Pancreas Flashcards
(51 cards)
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
