Lecture Quiz 9 Flashcards
Where are the adrenal glands located?
Superior and slightly medial to the kidneys
sometimes called suprarenal glands
Briefly describe the anatomy of the parenchyma of the adrenal gland
has a superficial layer - cortex
has inner part - medullar
What are the three zones of the adrenal cortex?
zona glomerulosa - outer zone
zona fasciculata - middle layer
zona reticularis - inner most layer
What does the adrenal medulla do?
acts as a separate endocrine gland from cortex produces catecholamines (epinephrine and norepinephrine)
How is the adrenal medulla stimulated?
by the nervous system
What does the zona glomerulosa release in general and what is the main example of one?
mineralcorticoids
regulate electrolytes in the extracellular space
aldosterone
What does Aldosterone do and what are the effects?
activates the gene for Na/K-ATPase in the kidneys
causes increase in Na+ reabsorption
causes K+ excretion/decrease in K+ reabsorption
water retention
How does aldosterone cause water retention and what does it result in?
water follows the sodium
helps make concentrated urine
causes increase in blood pressure
How is aldosterone regulated?
humoral regulation - Na+ and K+ ion concentration - low Na+ and high K+ stimulate production
hormonal regulation - renin-angiotensin causes production, induced by low blood pressure
atrial natriuretic peptide inhibits production - aorta stretched from water retention
ACTH has mild effect, causes secretion
What causes overproduction of aldosterone and what are the effects?
adrenal tumors
Conn’s syndrome
hypertension, edema, muscle weakness (K+ loss, no AP generated)
What does the zona fasciculata produce and what is the main example?
glucocorticoids
cortisol is the main example
What does cortisol do?
promotes formation of glucose from glycogen, fat, and proteins in response to increased fuel needs
inhibits immune reaction (anti-inflammatory)
How is cortisol produced during the day?
circadian rhythm based on needs
highest in the morning, lowest at night during rest
increases with stress
How is cortisol regulated?
by ACTH of the anterior pituitary
negative feedback effect on ACTH production
What does the zona reticularis produce and what is the main example?
gonadocorticoids
androstenedione
produces in small amounts and their effects are weaker than those produced by the gonads
What does androstenedione do?
can be converted into testosterone and estradiol
What is Addison’s disease and what are the symptoms?
autoimmune destruction of adrenal cortex
underproduction of mineralocoritcoids, glucocoritcoids, and gonadocorticoids
hyperpigmentation of the skin, dehydration, hyperkalemia, metabolic acidosis
What is Cushing’s syndrome?
excessive amounts of corticosteroids are produced
may be iatrogenic - induced by medications, or due to adrenal hyperplasia
hyperglycemia, central obesity, poor wound healing, hypertension, stria, and hirsutism (excessive hair growth)
What type of cells in the adrenal medulla release the hormones, and what are their effects on target cells?
chromaffin cells
produce epinephrine (80%) and norepinephrine (20%)
catecholamines stimulate adrenergic receptors via PiP-Ca2+
fight or flight responses
What are the effects of epinephrine and norepinephrine?
increased heart rate and contractility
increase in blood pressure
peripheral vasoconstriction (mostly due to norepinephrine)
hyperglycemia
effects are brief in comparison to glucocorticoids
How are the hormones of the adrenal medulla regulated?
exclusively neural regulation
stress, low blood sugar, and physical exercise stimulate the sympathetic nervous system
sympathetic stimulation of the adrenal medulla incudes production
What is a tumor on the adrenal medulla called and what are the side effect?
pheochromocytoma
hyperglycemia, tachycardia, and hypertension
Where is the pancreas located?
inferior and posterior to the stomach and medial to the duodenum
What type of gland is the pancreas?
exocrine and endocrine
only focusing on endocrine rn
Describe the anatomy of the endocrine glands of the pancreas - where are they kept and what is that place called
Islets of Langerhans are collections of hormone-producing cells located within the exocrine tissues of the pancreas
What are the four types of cells found in the Islets of Langerhans and what do they each produce?
alpha cells - glucagon
beta cells - insulin
delta cells - comatostatin
F-cells - pancreatic polypeptide (local hormone)
Describe insulin as a molecule and where is it stored?
polypeptide hormone
synthesized as proinsulin and stored in secretory vesicles
converted to insulin prior to release into the blood stream
How does insulin act on cells?
hydrophillic
acts on insulin receptors on target cell membranes
triggers tyrosine kinase mechanism in cells
What does insulin ultimately do (less detailed, vague overstatement)?
lowers blood glucose levels
What are the five ways insulin lowers blood glucose levels?
increases glucose uptake by the cells
increase of glycogen synthesis
increase of ATP production from glucose (glycolysis)
increase of amino acid uptake and protein synthesis
increase of triglyceride synthesis (fat)
What are the exceptions to insulin increasing glucose uptake by cells?
liver, brain, and kidneys
How is insulin regulated?
humoral
high blood glucose triggers insulin release
glucose is then used by cells and also stored for later
lowers blood glucose
What is diabetes mellitus and what are the symptoms?
an absolute or relative insulin insufficiency characterized by metabolic acidosis, polyuria and glycosuria, polydipsia, and polyphagia
Describe Type 1 diabetes
insulin-dependent diabetes
due to autoimmune destruction of beta cells
insulin not produced in adequate amount
Describe Type 2 diabetes
noninsulin dependent
relative insulin insufficiency due to abnormal insulin or the autoimmune destruction of normal insulin or insulin receptors
common in obesity - large body requires too much insulin
What is the tumor related to diabetes?
insulinoma
overproduction of insulin
very rare
insulin shock may occur due to hypoglycemia and brain starvation
What is a normal fasting glucose level?
~80 mg/dL (70-120 mg/dL)
Describe glucose blood levels after a meal
hyperglycemia occurs
levels lowered by being used (glycolysis) or stored for later (glycogen or fat)
Describe how glucose levels are maintained during fasting
glucose is released from storage to maintain normal levels
glycogen breakdown in the liver and muscles
fat is broken down
protein is broken down
carbohydrate is synthesized from the amino acids and fat
What is amylin and what are its effects?
secreted by the beta cells "helper" of insulin inhibits secretion of glucagon slows emptying of stomach sends signals of being full to the brain reduces levels of glucose
What is glucagon?
polypeptide produced by alpha cells
insulin antagonist - increases glucose levels
How does glucagon act on receptors?
via 2nd messenger - cAMP
How does glucagon increase glucose levels?
induces glycogenolysis - synthesis of glucose from glycogen
induces breakdowns of fats into fatty acids
induces synthesis of glucose from fatty acids and amino acids
How is glucagon regulated?
humoral regulation
low blood glucose triggers production and release
glucose levels rise
