HUBS191 Lecture 29: Endocrine V: Homeostasis of plasma glucose and Diabetes Mellitus

Flashcards about the endocrine system, focusing on plasma glucose homeostasis and Diabetes Mellitus.

What is the normal reference range for fasting plasma glucose concentration?

3.5 to 6 mmol/L

What is the normal reference range for non-fasting plasma glucose concentration?

3.5 to 8 mmol/L

Why is maintaining blood glucose concentration important?

Brain cells primarily rely on glucose for energy, and high blood glucose levels can cause problems in various organs.

Where is the pancreas located?

In the curve of the duodenum.

What percentage of pancreatic cells are exocrine glands that secrete enzymes into ducts?

99%

What are the small clusters of endocrine cells scattered amongst acini in the pancreas called?

Pancreatic islets or Islets of Langerhan’s

What hormone do alpha cells secrete and what is its function?

Glucagon, which increases blood glucose levels.

What hormone do beta cells secrete and what is its function?

Insulin, which reduces blood glucose levels.

How is insulin initially synthesized?

As preprohormone on the RER of beta cells, containing A, B, and C chains.

When is insulin (and C peptide) released from beta cells?

When blood glucose levels rise.

How does insulin correct hyperglycemia?

By facilitating glucose uptake into cells of most body tissues.

What happens to glucose without insulin?

It cannot be utilized by most cells for energy and blood glucose levels will be too high.

What are the effects of insulin on skeletal muscle?

Increased glucose entry, glycogen synthesis, amino acid transport, and protein synthesis; inhibition of protein breakdown.

How does exercise affect GLUT4?

Exercise itself causes translocation of GLUT4 to cell membrane in skeletal muscle.

What are the effects of insulin on adipose tissue?

Increased glucose transport, synthesis and storage of triacylglycerides, and inhibition of lipolysis.

What are the effects of insulin on the liver?

Uptake of glucose and conversion to glycogen, fatty acid synthesis, inhibition of glycogenolysis and gluconeogenesis, and suppression of ketone body formation.

What does insulin promote the uptake and storage of?

Nutrients, including glucose to glycogen, glucose to fatty acids and triglycerides, and amino acids to protein.

What are the effects of no insulin?

Mobilizing glycogen stores, breaking down protein, mobilizing fat stores, and increasing ketone production.

When is glucagon primarily secreted?

In response to hypoglycemia (low blood glucose).

What enzymes are activated by glucagon?

Enzymes that cause breakdown of glycogen to glucose (glycogenolysis) and promote production of 'new glucose' by hepatocytes (gluconeogenesis).

What is the effect of glucagon on adipose tissue?

Breakdown of triglycerides and release of fatty acids

What are the historical symptoms of Diabetes Mellitus?

Polyuria (passing large volumes of urine), polydipsia (excessive drinking/thirst), polyphagia (excessive hunger).

What is the cause of Type I Diabetes Mellitus?

Autoimmune destruction of pancreatic beta cells, resulting in essentially no insulin production.

What is the treatment for Type 1 Diabetes?

Insulin.

What is a risk of insulin treatment?

Hypoglycemia

What are some symptoms of Hypoglycemia?

Tachycardia, Palpatations, Diaphoresis, Tremor, Pallor, Anxiety, Headache, Dizziness, Irritability, Fatigue, Confusion, visual changes, hunger….

What are common causes of Type II Diabetes Mellitus?

Inactivity, poor diet, obesity, leading to reduced sensitivity to insulin (hyposensitivity).

What is the treatment for Type II Diabetes?

Reduce weight, metformin, drugs that cause glucose to be lost in urine, drugs to increase insulin secretion, or slow down glucose absorption from intestine.

What are some examples of pathological effects of chronic hyperglycemia?

Diabetic Retinopathy, Diabetic Nephropathy, Atherosclerosis, Diabetic Neuropathy, poor wound healing, and infection risk.