Alt Of Endo Function 2

Question 1

Insulin

Answer 1

Produced by beta cells in endocrine pancreas - beta cells secrete insulin

Short half-life; any insulin secreted cleared in 15 mins - protein hormone, broken down quickly

Question 2

Insulin secretion is stimulated by…

Answer 2

Increased plasma levels of glucose (and amino acids, and to a lesser extent free fatty acids)

Plasma glucose levels, absorb the sugar and increases the blood glucose levels, secrete insulin until blood glucose levels go down

Question 3

General physiological effects

Answer 3

Receptors for insulin are on plasma membrane

Control of postprandial plasma glucose levels

Promotes glucose storage as glycogen - haepatocytoes 5-8% glycogen

Lipid and protein synthesis - stimulates excess cals to store as lipids and proteins; stimulates lipid synthesis if too much glycogen taken in

Facilitates K+ transport into cells - diffusion of glucose into the cell requires the presence of insulin and potassium

Question 4

Diabetes mellitus

Answer 4

Group of disorders associated w alterations in insulin activity resulting in chronic glucose intolerance as well as alterations in protein and lipid metabolism

Question 5

Type 1 DM

Answer 5

Insulin-dependent diabetes mellitus or juvenile onset diabetes

Autoimmune disease: autoantibodies and cytotoxic T cells that target beta cells and insulin - siblings w disorder

Possible causes: genetic and environmental factors (viral infection, diet, stress, etc)

Gene mutation doesn’t necessarily cause the disease

Question 6

Patho of type 1 DM

Answer 6

Autoimmune destruction of pancreatic beta cells leads to insulin deficiency

Alpha cells are uninsured leading to relative glucagon excess
- destruction of 80-90% of beta cells in pancreatic islets -> clinically detectable decrease in insulin secretion

Decreased glucose uptake into cell

Hyperglycemia

Cell starvation

Question 7

Osmotic diuresis

Answer 7

Hyperglycemia results in hyperosmolarity, draws fluid from the cytoplasm into the plasma

The tm for glucose is 375 mg/min which corresponds to a blood glucose level of 180 mg/dL (tm = transport max)

Individuals w diabetes who become hyperglycemic often exceed the tm for glucose reabsorption in kidneys

Glucose remaining in the filtrate will prevent water from being reabsorbed causing diuresis

Question 8

Renal tubules reach their transport max for

Answer 8

Glucose reabsorption

Question 9

Osmotic diuresis: Decreased potassium uptake into cells leads to hyperkalemia

Answer 9

Insulin deficiency, potassium isn’t transported into the cell w glucose; leads to hyperkalemia; patient who is undiagnosed, not taking meds

Question 10

Osmotic diuresis: Fat breakdown in adipose tissue

Answer 10

Insulin deficiency stimulates the breakdown of fat (lipolysis) in the adipose tissue for tissue

Process of fat breakdown liberates a molecule called ketones

Ketones are acidic molecules that will lower the pH of blood

liberation of fatty acids for fuel

Question 11

Osmotic diuresis: release of ketones

Answer 11

Kidneys get rid of them

Question 12

Clinical manifestations of uncontrolled or undiagnosed type 1 DM

Answer 12

Glycosuria

Polyuria (increased urine output)

Polydipsia (thirst)

Polyphagia (increased appetite)

Weight loss

Question 13

Acute complications of type 1 diabetes - life threatening and rapid

Answer 13

Hypoglycemia - low blood sugar

Diabetic detacidosis (DKA)

Question 14

Hypoglycemia

Answer 14

Blood glucose level <50-60 mg/dL

Most commonly seen in individuals w DM but may also occur in type 2 DM