Endocrinology - Lecture 4 Flashcards
What is Addison’s Disease?
hypofunction of the adrenal cortex
Addison’s Disease is characterized by the failure of the adrenal cortex to produce what kind of hormones?
adrenocortical hormones
What can happen to the adrenal gland in Addison’s Disease?
it can be destructed
What can cause Addison’s Disease?
autoimmune attacks to the adrenal glands or tuberculosis
What is Cushing’s Disease?
hyperfunction of the adrenal cortex
Cushing’s Disease is the excessive production of what 2 steroids?
glucocorticoids and mineralocorticoids
What causes Cushing’s Disease?
increased circulating levels of ACTH or adrenal tumour
What is Cushing’s Disease characterized by?
hyperplasia of an adrenal cortex or pituitary
Where is the pancreas located?
behind the stomach
99% of the pancreas is ___ and secretes the digestive enzymes.
exocrine
What are the small endocrine structures of the pancreas called?
islets of Langerhans
What are 60% of the cells of the islets of Langerhans known as?
beta-cells
What do beta-cells synthesize?
insulin
What are the 25% of the cells of islets of Langerhans known as?
alpha-cells
What do alpha-cells synthesize?
glucagon
What are insulin and glucagon?
small protein hormones and both control glucose concentration in the blood
Which is more important: insulin or glucose?
insulin
Insulin is the only hormone that acts primarily to…
decrease blood glucose
What is the fasting level of glucose in the blood?
80mg/100mL
Why does glucose need to be transported?
because it cannot diffuse very readily into most cells
Where does glucose get transported to? (3)
- in the liver and muscle
- in the adipose tissue
- in many cells of the body
Where is glucose converted into glycogen?
in the liver and muscle cells
Where is glucose converted into fat and stored for later use?
in adipose tissue
What is the function of the insulin receptor?
it stimulates the insertion of glucose transport proteins stored in cytoplasm into plasma membrane
Do insulin receptors increase or decrease glucose uptake?
increase glucose uptake
When does insulin deficiency happen?
when beta-cells are destroyed
What kind of disease does insulin deficiency cause?
diabetes mellitus
What is diabetes mellitus?
when most tissues cannot take up glucose so it accumulates in the circulation
Why does insulin deficiency happen even if there is no glucose in the diet?
because of increased gluconeogenesis
What increases when there is insulin deficiency?
lipolysis
Why is fat inefficiently used during insulin deficiency?
because there is an incomplete oxidation of FFa and increased circulating acetoacetic acid and beta-hydroxybutyric acid and acetone
What mg% does glucose spill over into urine?
> 180mg%
What is polyurea?
loss of water in urine
What does glycosurea cause?
polyurea and polydipsia
What does untreated diabetes lead to? (2)
ketosis and metabolic acidosis
What needs to be administered in diabetes mellitus to restore individual back to normal?
insulin
What needs to be administered in diabetic comas?
acidosis and associated electrolyte imbalance and insulin
In adults, diabetes mellitus may be due to a deficiency of what 2 things?
- insulin
- hyporesponsiveness to insulin
What is type 1 insulin-dependent diabetes mellitus?
deficiency of insulin
What is type 2 insulin-dependent diabetes mellitus?
hyporesponsiveness to insulin
What happens when beta-cells of the pancreas are destructed?
synthesis of insulin does not occur
What must be administered when beta-cells in the pancreas are destroyed?
insulin
Why is it important to control the dose of insulin administered as a treatment for diabetes?
because too much insulin could lead to severe decrease in blood glucose content
When blood glucose reaches 20-30mg/100ml, the availability of glucose for the brain is not sufficient and the individual may fall into a coma known as ___ or ___.
insulin shock, hypoglycemic coma
What is type 2 diabetes mellitus?
when insulin levels are normal or abnormally high
What is insulin resistance often due to in type 2 diabetes?
decreased number of insulin receptors on target cells
What is type 2 diabetes associated with?
overeating and obesity
What is the treatment for type 2 diabetes?
proper diet and exercise
What is juvenile diabetes?
when the beta-cells in the pancreas do not produce insulin
What is the treatment for juvenile diabetes?
administration of insulin
When is the glucose tolerance test increased and decreased?
increased: in hyperinsulinism
decreased: diabetes
What is the person given after an overnight fast during the glucose tolerance test?
0.75 to 1.5g of glucose/kg body weight
In the glucose tolerance test, blood is taken before and ___ minute intervals for ___ hours.
30-60 minutes, 3-4 hours
What is the normal result for the glucose tolerance test?
glucose increases in 1 hour from 80mg/100mL to 130mg/100mL and returns back to normal after 2-3 hours
What is the result for a diabetic for the glucose tolerance test?
increase in glucose is greater and returns to normal more slowly
What responds to levels of blood glucose?
beta cells
increase in blood glucose = ___ insulin secretion
increase
decrease in blood glucose = ___ insulin secretion
decrease
What impulses to beta cells induce insulin release?
gastrin and vagal impulses
How does glucagon raise blood sugar?
by promoting glycogenolysis and glucogenesis in the liver
What kind of tissue increases the rate of lipolysis?
adipose tissue
What controls the release of glucagon?
concentrations of glucose in the circulation
decrease in glucose = ___ alpha cells synthesis of glucagon
increase
___>glucagon
insulin
What produces growth hormone?
the anterior lobe of the pituitary
What 2 things does the growth hormone increase?
- protein synthesis
- lipolysis
Are growth hormones mediated by somatomedins?
no
Where are somatomedins produced?
in the liver
What stimulates the production of somatomedins?
growth hormone
What are somatomedins structurally similar to?
insulin
What is the function of somatomedins?
increase protein synthesis and stimulate growth
What 2 hypothalmic neurohormones control the release of the growth hormone?
- somatoliberin
- somatostatin
What does somatoliberin do?
stimulates GH release
What does somatostatin do?
inhibits GH release
What happens to growth in young individuals if they have GH deficiency?
it decreases
What happens to young individuals if they have excess GH?
gigantism
What happens to adults if they have excess GH?
acromegaly (bones get longer and heavier)
