Pancreas Pt 1 Quiz

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Questions and Answers

What is the purpose of the C-peptide test?

To evaluate the efficiency of insulin treatment

All of the above (correct)

To determine if insulin is being produced by the pancreas

To differentiate between type 1 and type 2 diabetes

What is the primary function of the Golgi apparatus in the insulin synthesis process?

To synthesize pre-proinsulin

To cleave the B-peptide from proinsulin

To package proinsulin into vesicles (correct)

To remove the signal sequence from pre-proinsulin

Which of the following is NOT a factor that influences insulin release?

Genetic factors (correct)

Neural variables

Nutritional status

Endocrine factors

What is the purpose of the disulfide bridges in the structure of active insulin?

To hold the alpha and beta peptide chains together Signup and view all the answers

How do sulfonylureas (e.g., glipizide) work to decrease glucose levels?

By closing the potassium channels of the pancreatic beta cells Signup and view all the answers

Which step in the insulin synthesis process occurs in the rough endoplasmic reticulum (rER)?

Synthesis of pre-proinsulin Signup and view all the answers

What is the relationship between canine and porcine insulin?

Canine and porcine insulin have the same amino acid sequence Signup and view all the answers

Which of the following is an example of a secretagogue that is important for omnivores?

Glucose Signup and view all the answers

What is the primary function of GLUT-2 transporters on beta cells?

Help in the diffusion of glucose into beta cells Signup and view all the answers

Which step triggers depolarization in a pancreatic beta cell during insulin secretion?

Closure of ATP-sensitive potassium channels Signup and view all the answers

During the acute phase of insulin secretion, what triggers the quick spike of insulin release?

Storage vesicles releasing pre-synthesized insulin Signup and view all the answers

Which protein is responsible for the activation of insulin gene expression in beta cells?

CREB (calcium responsive element binding protein) Signup and view all the answers

What triggers the chronic phase of insulin secretion in beta cells?

Synthesis and secretion of insulin Signup and view all the answers

In a pancreatic beta cell, what occurs when potassium channels close?

Depolarization takes place Signup and view all the answers

Which event directly precedes the opening of voltage gated calcium channels in a beta cell?

Closure of potassium channels and depolarization Signup and view all the answers

What is the immediate cellular response triggered by calcium entry through voltage-gated calcium channels in beta cells?

Insulin gene expression activation via CREB Signup and view all the answers

What is the main reason for the delayed response time to glucose stimulation during the chronic phase of insulin releasing patterns?

Insulin has to be produced first before it can have an effect Signup and view all the answers

What is the primary effect of insulin on insulin-sensitive tissues like muscle and adipose tissue?

All of the above Signup and view all the answers

How does resistance exercise affect glucose uptake in muscle cells?

Resistance exercise stimulates the translocation of GLUT-4 transporters to the muscle cell membrane Signup and view all the answers

What is the net effect of insulin on blood concentrations of glucose, fatty acids, and amino acids?

Insulin decreases the blood concentrations of these compounds Signup and view all the answers

What is the catabolic effect of insulin?

Insulin promotes the conversion of glucose, amino acids, and fatty acids to their storage forms Signup and view all the answers

How does insulin affect glycogen synthesis in muscle tissue?

Insulin stimulates the enzymes involved in glycogen synthesis, promoting glycogenesis Signup and view all the answers

Which of the following statements about the Islets of Langerhans is true?

They consist of alpha, beta, delta, and f-cells. Signup and view all the answers

What is the primary energy source used by muscles in the absence of insulin?

Fatty acids Signup and view all the answers

How does insulin promote muscle growth?

By promoting amino acid usage, not storage Signup and view all the answers

How does insulin affect fatty acid synthesis in the liver?

Insulin promotes fatty acid synthesis within the hepatocytes Signup and view all the answers

How does insulin affect lipolysis in adipose tissue?

Insulin inhibits lipolysis Signup and view all the answers

How does the liver uptake glucose in the presence of insulin?

Glucose enters the liver using the GLUT-2 transporter and does not require insulin Signup and view all the answers

How does insulin affect fatty acid oxidation in muscle tissue?

Insulin decreases fatty acid oxidation Signup and view all the answers

What is the primary function of insulin on adipose tissue?

Increase lipogenesis Signup and view all the answers

What is the effect of insulin on gluconeogenesis in the liver?

Insulin inhibits gluconeogenesis Signup and view all the answers

How does insulin affect glycogenolysis in the liver?

Insulin inhibits glycogenolysis Signup and view all the answers

Which of the following statements about the endocrine pancreas is true?

More than 1 choice is correct Signup and view all the answers

Which of the following statements about pancreatic hormones is false?

They circulate bound to carrier proteins in the blood. Signup and view all the answers

What is the primary function of the beta cells in the Islets of Langerhans?

Secrete insulin in response to hyperglycemia. Signup and view all the answers

Which cell type in the Islets of Langerhans is responsible for secreting glucagon?

Alpha cells Signup and view all the answers

What is the primary function of the acini surrounding the Islets of Langerhans?

Secrete digestive enzymes (exocrine function). Signup and view all the answers

Which statement about the pancreas is incorrect?

It contains only one lobe positioned behind the stomach. Signup and view all the answers

What is the primary function of the f-cells in the Islets of Langerhans?

Secrete pancreatic peptide. Signup and view all the answers

Study Notes

Pancreas: Structure and Function

Located in the abdominal cavity, the pancreas has two lobes: one behind the stomach and one adjacent to the proximal duodenum
Consists of exocrine and endocrine components

Exocrine Pancreas

Composed of acinar cells that produce digestive enzymes and duct cells
Digestive enzymes are secreted into the duodenum through the pancreatic duct

Endocrine Pancreas

Composed of four types of cells (alpha, beta, delta, and f-cells) organized into islets (Islets of Langerhans)
Involved in glucose metabolism and regulation of blood glucose levels
Comprises 2-3% of the pancreas

Islets of Langerhans

Consists of acini (exocrine function) and four cell types:
- Alpha cells: secrete glucagon
- Beta cells: secrete insulin in response to hyperglycemia
- Delta cells: secrete somatostatin
- F-cells: secrete pancreatic peptide

Pancreatic Hormones

All pancreatic hormones are polypeptides
Examples: somatostatin, pancreatic peptides, glucagon, insulin
Circulate unbound in blood due to hydrophilicity and have a short half-life of ≤ 30 minutes
Bind to cell surface receptors

Insulin Secretion

Beta cells use GLUT-2 insulin-dependent transporters to facilitate glucose entry
Glucose stimulates insulin secretion through a series of steps:
- Glucose enters the beta cell
- Glucose is converted to ATP
- High ATP concentration triggers depolarization
- Depolarization opens voltage-gated calcium channels
- Calcium influx triggers insulin gene expression and secretion

Insulin Release Pattern

Insulin secretion follows biphasic kinetics:
- Acute phase: pre-synthesized insulin is released
- Chronic phase: insulin is synthesized and secreted

Insulin Action

Increases glucose uptake in insulin-sensitive tissues (muscle and adipose tissue) by increasing GLUT-4 transporters
Net effect: decreases blood glucose, fatty acid, and amino acid concentrations
Promotes intracellular conversion of glucose, fatty acids, and amino acids to their storage forms

Insulin Action on Muscle

Stimulates glycogen synthesis enzymes
Promotes glycogenesis and glucose use as an energy source
Inhibits fatty acid oxidation

Insulin Synthesis

Proinsulin is synthesized in the rER
Signal sequence is removed to form proinsulin
Proinsulin is cleaved to form mature insulin in the golgi apparatus

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Description

Test your knowledge about the pancreas, a glandular organ located in the abdominal cavity with exocrine and endocrine functions. Explore topics such as acinar cells, digestive enzymes, and the different types of endocrine cells in the islets of Langerhans.