Endocrine Pancreas Flashcards
What is the Endocrine Pancreas composed of?
Clusters of cells termed islets of Langerhans
What makes up a single islet?
It contains multiple cell types, with each cell producing one type of hormone.
What lies in the center of islets? What do they secrete?
Beta cells
-Secrete insulin
What is insulin?
Major anabolic hormone
What function does insulin do?
Increases glucose uptake by tissues and leads to increased glycogen synthesis, protein synthesis and lipogenesis.
What does insulin upregulate?
Insulin-dependent glucose transporter protein (GLUT4) on skeletal muscle and adipose tissue (glucose uptake by GLUT4 decreases serum glucose)
What secretes glucagon?
Alpha cells
How does glucagon function?
It opposes insulin in order to increase blood glucose levels (e.g. in states of fasting) via glycogenolysis and lipolysis
What is Type I Diabetes Mellitus?
Insulin deficiency leading to a metabolic disorder characterized by hyperglycemia.
What is the cause of Type I Diabetes Mellitus?
Autoimmune destruction of beta cells by T lymphocytes
Type IV hypersensitivity
What are three microbiological characteristics of Type I Diabetes Mellitus?
- Characterized by inflammation of islets
- Associated with HLA-DR3 and HLA-DR4
- Autoantibodies against insulin are often present (sign of damage) and may be seen years before clinical disease develops
When does Type I Diabetes manifest?
In childhood
What is a clinical feature of Type I Diabetes?
Insulin deficiency
What is seen in the serum of Type I Diabetics?
High serum glucose
What causes high serum glucose in Type I Diabetics?
Lack of insulin leads to decreased glucose uptake by fat and skeletal muscle
What are three symptoms of Type I Diabetes related to weight?
- Weight loss
- Low muscle mass
- Polyphagia (eat a lot)
What does unopposed glucagon lead to in Type I Diabetics?
Gluconeogenesis (break down of muscle), Glycogenolysis (break down of glycogen) and Lipolysis (break down of fat) —> These further exacerbate hyperglycemia
What are three Type I diabetes symptoms related to urine output?
Polyuria (large urine volume), polydipsia (excessive thirst) and glycosuria (secretion of glucose in the urine)
What causes glycosuria in Type I diabetes?
-Hyperglycemia exceeds renal ability to resorb glucose
What does excess filtered glucose lead to in Type I diabetes?
Osmotic diuresis
What is the treatment for Type I diabetes?
Lifelong insulin
What condition are Type I diabetics at risk for?
Diabetic ketoacidosis
What is diabetic ketoacidosis characterized by?
Excessive serum ketones
When does Diabetic Ketoacidosis often arise?
With stress (e.g. infection)
How does stress (e.g. infection) contribute to DKA?
Epinephrine stimulates glucagon secretion increasing lipolysis (along with gluconeogenesis and glycogenolysis)
What does increased lipolysis cause?
Leads to increased free fatty acids (FFAs)
What does the liver do with the FFAs in Diabetic Ketoacidosis?
It converts FFAs into ketone bodies
e.g. beta-hydroxybutyric acid and acetoacetic acid
What are two common ketone bodies?
Beta-hydroxybutyric acid
Acetoacetic acid
What altered labs does DKA present with?
Hyperglycemia (>300 mg/dL), anion gap metabolic acidosis, and hyperkalemia
Why is the hyperkalemia in DKA deceiving?
Hyperkalemia in serum is lost in urine over time.
–> So over time K+ becomes low in the body
What symptoms does DKA present with?
- Kussmaul respirations
- Dehydration
- Nausea
- Vomiting
- Mental status changes
- Fruity smelling breath (due to acetone)
What is the treatment for DKA?
- Fluids (corrects dehydration from polyuria)
- Insulin
- Replacement of electrolytes (e.g. potassium)
