Endo IV Flashcards
What is Addison’s disease? What is its cause?
- Characterized by failure of adrenal cortex to produce adrenocortical hormones (hypofunction)
- May involve total destruction of the gland
- Mostly due to atrophy of the adrenal glands due to tuberculosis and involves medulla as well as cortex
How does Addison’s disease affect glucocorticoid production? Explain the consequences on the body.
Glucocorticoid deficiency leads to:
- Decreased blood sugar (particularly between meals)
- Decreased lipolysis
- Decreased gluconeogenesis
- Lack of energy, muscular weakness, inability to take stress
How does Addison’s disease affect mineralocorticoid production? Explain the consequences on the body.
- Plasma: decreased Na+, Cl-, and H2O - all lost in urine
- Leads to decreased extracellular fluid, plasma volume, and cardiac output
- Increased K+ (hyperkalemia), H+ (acidosis) - reabsorbed from urine
- Patient dies in shock 7 days after complete absence of mineralocorticoids
What is Cushing’s disease? What is its cause?
- Characterized by the hyperplasia of the adrenal cortex due to increased circulating levels of ACTH (hyperfunction), often via pituitary tumour.
- Excessive production of glucocorticoids as well as mineralocorticoids.
Describe the problems caused by Cushing’s disease related to glucocorticoid production.
- Increased blood glucose (adrenal diabetes)
- Increased insulin secretion (if prolonged, beta cells burn out)
- Decreased protein synthesis
- Increased protein breakdown
- Osteoporosis: loss of protein and Ca2+ from bone
- Can cause masculinization in women due to increase in sex steroids
Describe the problems caused by Cushing’s disease related to mineralicorticoid production.
- Plasma: increased Na+, Cl-, H2O - reabsorbed from urine
- Leads to increased extracellular fluid, plasma volume, hypertension
- Decreased K+ (hypokalemia), H+ (alkalosis) - lost in urine
- Also causes masculinization in women due to increase in sex steroids
What are the diagnostic features of Cushing’s disease?
- Puffiness of face
- Masculinizing effect
- Hypertension
- Increased blood glucose
- Increased steroid metabolites in urine
What is the treatment for Cushing’s disease?
Surgery: subtotal removal of adrenal cortex
What is the treatment for Addison’s disease?
- Cortisol administration to improve carbohydrate metabolism
- Aldosterone administration to control electrolyte blood levels.
Where is the pancreas located?
Behind the stomach
What is the main function of the pancreas?
99% of the pancreas is exocrine and secretes digestive enzymes. However, it also has small endocrine structures called the islets of Langerhans. They have beta cells that produce insulin and alpha cells that produce glucagon.
Describe the cellular composition of the islets of Langerhans and what they produce.
- 60% of cells are beta cells, which synthesize insulin
- 25% of cells are alpha cells, which synthesize glucagon
What is the type and function of insulin and glucagon?
Small protein hormones and both control of glucose concentration in blood
Compare the importance of insulin and glucagon and explain why.
Insulin is more important than glucagon and insulin deficiency or absence compromises the wellbeing of the individual, possibly leading to death.
Glucagon function is somewhat redundant with that of glucocorticoids.
What is the main function of insulin?
It is the only hormone that acts primarily to decrease blood glucose by transporting it into the cell, where there is very little free glucose.
What is the fate of glucose once it is transported into the cell by insulin?
a) in the liver and muscle cells it is converted to glycogen
b) in the adipose tissue it is converted to fat and stored for later use
c) in many cells of the body it is oxidized to produce energy
What is the role of insulin receptors?
Stimulates the insertion of glucose transport proteins stored in the cytoplasm into the plasma membrane, increasing glucose uptake.
What is the cause of insulin deficiency?
Results when beta cells are destroyed, leading to diabetes mellitus. Make tissues cannot take up glucose and glucose accumulates in the circulation.
This will occur even without glucose in the diet because of increased gluconeogenesis.
When insulin deficiency occurs, what is the principal source of energy for cells? How does this affect the composition and pH of the circulation?
Under these conditions, free fatty acids become the principle source of energy -> increased lipolysis.
However, they are inefficiently used, leading to incomplete oxidation of fatty acids and increased circulating acetoacetic acid and beta-hydroxybutyric acid (metabolic acidosis) and acetone. -> smell of acetone in breathe of untreated diabetics.
Leads to decreased blood pH, diabetic coma, and death unless treatment is provided.
Insulin deficiency due to the destruction of beta cells leads to the condition […]
diabetes mellitus
Aside from direct impacts on the circulation, name 3 other symptoms of diabetes mellitus.
- At >180 mg% glucose spills over into the urine, causing glucosurea
- Leads to loss of water in urine, causing polyurea - dehydration and increased thirst (polydipsia). As mentioned above, untreated diabetes leads to ketosis, and metabolic acidosis.
What is the treatment for diabetes mellitus?
- Administration of insulin is needed to restore individual back to normal.
- In diabetic comas, acidosis and associated electrolyte imbalance must be corrected in addition to insulin administration.
What are the two types of diabetes mellitus? Explain the difference between them.
In adults, diabetes mellitus might be due to a deficiency of insulin (type 1) or hyporesponsiveness to insulin (type 2)
How much glucose is typically present in the bloodstream?
Present at around 80 mg/100 ml. However, there is very little free in the tissues.