Endocrine Pancreas Flashcards
What are the 3 regions of the gut
What are their blood supplies
Which part of gut does the pancreas develop from?
Therefore, what is the pancreas’s blood supply?
Foregut- Coeliac trunk supplies blood
Midgut- Superior Mesenteric Artery
Hindgut- Inferior Mesenteric Artery
Pancreas develops from Foregut (as an outgrowth), so supplied by Coeliac Trunk
What are the 2 functions of the Pancreas
Which tissue forms most of the bulk of the gland
Exocrine: Digestive enzymes secreted into duodenum
Endocrine: Hormone production from Islets of Langerhans
Exocrine (99%, Endocrine 1%)
Name 4 endocrine hormones secreted by pancreas, and which cells they’re secreted from
Insulin by Beta cells
Glucagon by Alpha cells
Somatostatin by Delta cells
Ghrelin by Epsilon cells
What are the overall effects of Insulin and Glucagon
Regulation of metabolism of Carbohydrates, Proteins and Fats
Compare Insulin and Glucagon in regards to;
- Signal from eating
- Target tissues
- Which metabolic substances are affected
- Anabolic or Catabolic
Insulin;
- Feeding
- Liver, Adipose, Skeletal muscle
- Carbs, Proteins, Lipids
- Anabolic
Glucagon;
- Fasting
- Liver, Adipose
- Carbs, Lipids
- Catabolic
Which organ uses glucose at the fastest rate?
What is the normal Plasma glucose range?
What is it normally, after a meal?
What is the Renal Threshold?
Brain
Normal: 3.3-5 mmol/L
After a meal: 7-8 mmol/L
Renal threshold= Point at which not all plasma glucose can be reabsorbed, 10 mmol/L
What do you call excess glucose in urine?
How do pregnancy and old age affect the renal threshold
Glycosuria
Pregnancy decreases the renal threshold
Old age increases the renal threshold
What are the half-lives of Insulin and Glucagon?
How can they be inactivated by their target cells?
Half life: 5 mins
Receptor-hormone complex can be internalised
How does Insulin affect;
- Gluconeogenesis
- Lipolysis
- Ketogenesis
- Glycognesis in liver
- AA uptake, protein synthesis in Liver, Muscle, Adipose
- Anti- Gluconeogenic
- Anti- Lipolytic
- Anti- Ketogenic
- Stimulates glycogenesis in liver
- Stimulates AA uptake and protein synthesis
Describe the structure of Insulin
- 2 chains (A and B), linked by 2 Disulphide bonds
- A 3rd Disulphide bond from one part of chain A to another
In 5 steps describe Insulin synthesis and secretion
- Made as Pre-proinsulin
- Enters ER, signal peptide cleaved-> Proinsulin
- Proinsulin folds, transported to Golgi, packed into storage vesicles
- Proteolysis in vesicles removes a C-peptide-> Mature insulin (2 chains A and B)
- Entire contents of vesicles exocytosed (Insulin, C-peptide, some proinsulin)
After proteolysis of Proinsulin, what is the ratio of Mature Insulin to C-Peptide?
What is the clinical significance of this?
Equimolar amounts (1:1)
Plasma C-peptide can be measured to monitor endogenous insulin secretion
Explain the effect of Low Metabolism on Insulin secretion, via KATP channels
- Low metabolism-> Low ATP
- KATP channels open -> K+ efflux
- Hyperpolarization-> Ca channels close
- Vesicles DON’T exocytose
Explain the effect of High Metabolism on Insulin secretion, via KATP channels
- High metabolism-> High ATP
- KATP channels closed -> No K+ efflux
- Depolarization-> Ca channels open
- Ca influx-> Exocytosis of vesicles
Which GLUT channel is Insulin-dependent?
Which GLUT channel is the major glucose transporter in Liver and Pancreas?
GLUT4 is Insulin-dependent
GLUT 2 is the major glucose transporter in Liver and Pancreas
