Endokrin Sistem

1
The Endocrine Pancreas
Lecture Objectives

• what are the different cell types and what do
  they secrete?
• what is the balance between insulin and
  glucagon?
• what does insulin do?
• what is Diabetes Mellitus?

2
The Pancreas

• 98 of pancreas is dedicated to exocrine
  secretion
• 2 of pancreas is dedicated to endocrine
  secretion
• islets of Langerhans
• receive both sympathetic and parasympathetic
  innervation

3
Islets of Langerhans

• islets are spread throughout the pancreas
• 4 cell types

• alpha cells secrete glucagon (20)
• beta cells secrete insulin (75)
• delta cells secrete somatostatin (lt5)
• F or PP cells secrete pancreatic polypeptide
  (rare)

4
(No Transcript)
5
Balance Between Insulin and Glucagon
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Physiological Actions of Insulin

• increases uptake and storage of glucose
• stimulates glycogenesis
• inhibits lypolysis, promotes fat uptake and
  storage
• increases protein synthesis

10
(No Transcript)
11
(No Transcript)
12
Regulation of Insulin Secretion

• primary determinant plasma glucose level
• increased plasma amino acids
• release of gastrointestinal hormones (GIP)
• parasympathetic stimulation

- triphasic response
13
Glucagon

• small protein released from alpha cells
• prevents hypoglycemia following high protein
  meal
• helps mobilize glucose during exercise

14
Physiological Actions of Glucagon

• glycogenolysis
• glyconeogenesis
• lipolytic
• ketogenic

gluconeogenesis
15
Regulation of Glucagon Secretion

• increased by decreased plasma glucose
• increased by elevated plasma amino acids
• increased by exercise
• pancreatic sympathetic stimulation

16
Diabetes Mellitus

• most common endocrine disorder
• characterized by polyuria, polydipsia, weight
  loss despite polyphagia, hyperglycemia,
  glucosuria, ketosis, acidosis
• primary cause reduced entry of glucose into
  peripheral tissues

17
Insulin Dependent Diabetes Mellitus (IDDM)

• also called type I or juvenile onset
• associated with ketosis and acidosis
• pathological changes in beta cells
• plasma insulin low or undetectable
• treatment insulin injection

18
Insulin Shock

• insulin excess causes hypoglycemia
• lack of fuel (glucose) for brain results in coma
• hypoglycemia normally triggers secretion of
• glucagon
• epinephrine
• cortisol
• growth hormone

19
Non-Insulin Dependent Diabetes Mellitus (NIDDM)

• also called type II or adult onset
• patients are generally obese
• insulin levels can be normal
• insulin receptors downregulated
• treatment diet, sulfonylureas

20
Glucose Tolerance Test

• administer a glucose challenge and monitor blood
  glucose levels
• blood glucose rises higher and returns to
  baseline more slowly in diabetics

21
Ketone Bodies and Acidosis
acetyl-CoA acetoacetate acetone B-hydroxybutyr
ate

• decreased pH
• respiration changes
• acidic urine
• can lead to coma