Endocrine Flashcards
What is the master control gland in the endocrine system?
pituitary gland
What controls the pituitary gland?
the hypothalamus through a negative feedback loop
Name the two lobes that the pituitary gland is divided into.
- anterior lobe
2. posterior lobe
Another name for the anterior lobe of the pituitary gland.
adenohypophysis
What is the function of the anterior pituitary lobe/adenohypophysis?
secretes the following hormones; ACTH, FSH, LH, GH, TSH, under the influence of releasing factors (except prolactin) from the hypothalamus
What stimulates ACTH?
corticotrophin releasing hormone (CRH)
Two names for ACTH.
adrenocorticotropic hormone or corticotropin
Function of ACTH.
governs synthesis of cortisol and pregnenolone in the adrenal cortex
What syndrome has increased ACTH?
Cushing’s syndrome
What stimulates FSH?
gonadotrophin releasing hormone (GnRH)
Function of FSH?
stimulates the follicles in the ovaries to produce estrogen and stimulates sertoli cells for spermatogenesis
What stimulates LH?
Gonadotrophin releasing hormone (GnRH)
Function of LH?
stimulates ovulation and the production of progesterone in the ovary.
stimulates the interstitial cells of Leydig in the testis to produce testosterone
What stimulates GH?
growth hormone releasing hormone (GHRH)
Another name for GH?
growth hormone of somatotropin
Function of GH?
stimulates bone and tissue growth through somatomedins A-C
What does an increase in GH result in?
gigantism or acromegaly
What does a decrease in GH result in?
dwarfism
What is TSH stimulated by?
thyrotrophin releasing hormone (TRH)
Function of TSH?
stimulates the thyroid to produce thyroxin
What does an increase in thyroxin result in?
hyperthyroidism
What does a decrease in thyroxin result in?
hypothyroidism
What is prolactin affected by?
prolactin inhibiting factor (dopamine) and TRH
Another name for the posterior pituitary lobe.
neurohypophysis
What two hormones are stored (but not secreted) in the posterior pituitary lobe/neurohypophysis?
- oxytocin
2. ADH
What structure is oxytocin secreted by?
the paraventricular nucleus in the hypothalamus
What is the function of oxytocin?
it stimulates contraction of uterine muscles during labor and the myoepithelial cells in the breast (milk ejection) and also plays a role in maternal bonding
released and stimulated by nipple stimulation
oxytocin is controlled by a positive feedback mechanism
Where is ADH released?
the supraoptic nucleus of the hypothalamus
What is the function of ADH?
it acts on the collecting ducts in the kidney and it is released in response to water deprivation
prevents water from being excreted in the urine (diuresis)
What does lack of ADH result in?
diabetes insipidus (polyuria and polydypsia)
Where is the pars intermedia located?
between the anterior and posterior pituitary lobes
What does the pars intermedia secrete?
melanin stimulating hormone
What does melanin stimulating hormone do?
it stimulates the production of melanin by the melanocytes in the skin
it is produced from pro-opiomelancortin from which MSH and ACTH are formed
What is another name for hyperthyroidism?
Graves disease
What does hyperthyroidism result in?
exophthalmos, weight loss, and tremors
What does hypothyroidism result in?
cretinism in children and myxedema in adults with weight gain, coarse hair, and decreased metabolism
What do the parafollicular cells of the thyroid gland secrete?
calcitonin
What is the function of calcitonin?
takes calcium from the blood and puts in back into the bone (tones the bones!!!!)
What is PTH secreted by?
chief cells in the parathyroid glands
What does PTH do?
it takes calcium from the bones and puts it back into the blood
increased calcium reabsorption in the kidney by acting on the cells in the distal convoluted tubules
increases calcium absorption from the gut
What is hypocalcemia due to?
hypoparathroidism
it excites the nervous system and results in tetany and muscle spasm
What is hypercalcemia due to?
hyperparathroidism
results in muscle fatigue
Name the two parts that the adrenal gland is divided into.
cortex and medulla
Name the three layers of the adrenal cortex from superficial to deep.
zona golmerulosa (salty) zona fasciculata (sweet) zona reticularis (sex)
What does the zona glomerulosa secrete?
aldosterone
What does the zona fasciculata secrete?
cortisol
What does the zona reticularis secrete?
pregnenolone
What is aldosterone?
a mineralocorticoid (salt)
What is the function of aldosterone?
it acts on the kidney to regulate Na reabsorption from the distal convoluted tubule
causes water retention and an increase in blood pressure
Aldosterone is under the influence of renin. Which cells secrete renin?
juxtaglomerular cells
What disease is excess aldosterone seen in?
primary hyperaldosteronism aka Conn’s syndrome
What does hyperaldosteronism aka Conn’s syndrome result in?
high Na+, hypertenstion, and low K+
What is cortisol?
a glucocorticoid (sweet)
What is the function of cortisol? (THERE ARE 6)
regulates metabolism of the following:
- fat- increases lipogenesis by increaseing adipocyte lipoprotein lipase activity
- carbohydrates- increases glycogenesis by stimulation of glycogen synthetase activity
- proteins- increases gluconeogenesis through increased protein breakdown
- maintains blood pressure by upregulating alpha-1 receptors in arterioles
- decreased bone formation resulting in osteoporosis by increasing osteoclastic activity
- suppresses inflammation by inhibiting phospholipase A2 activity
What hormones are derived from androsteinone which is derived from pregnenolone (sex)?
estrogen, progesterone, and testosterone
What disease occurs as a result from destruction of the adrenal cortex?
Addison’s disease
What does Addison’s disease cause?
weight loss, low blood pressure, and bronzing of the skin
What are all adrenal cortex hormones produced from?
cholesterol
What does the adrenal medulla secrete?
epinephrine (80%) and nor-epinephrine (20%)
What is the function of the adrenal medulla?
behaves like a sympathetic ganglion as it is supplied by preganglionic sympathetic splanchnic fibers which pass through the celiac ganglion
What is nor-epinephrine produced from?
tyrosine which is derived from phenylalanine
What neurotransmitter is removed by the reuptake from the synaptic cleft into the nerve ending where it is destroyed by the mono-amine oxidase (MAO)?
nor-epinephrine
Epinephrine and nor-epinephrine are hormones and neurotransmitters within the sympathetic nervous system and are responsible for the fight or flight response which includes…
increased heart rate
dilate arteries to skeletal muscle and the heart
dilate the bronchi and the pupil
decreases gut motility
constrict the bladder and bowel sphincters and blood vessels to the skin
contract the erector pili muscles in the skin
decrease salivary secretion and increase sweat production
Increased secretion of nor-epinephrine is seen in ___________________.
pheochromocytoma
Pheochromocytoma results in the 4 P’s… What are they?
perspiration
heart palpitations
paroxysms of hypertension
pressure headaches
Where are the endocrine cells of the pancreas found?
in the islets of Langerhans
What is insulin secreted by?
beta type of islet cells
What is the function of insulin?
moves glucose from in the blood to inside the cells
What are the 4 GLUT tissue specific transporters that carry glucose and their functions?
GLUT 1 : erythrocytes and brain
GLUT 2 : liver and beta islet cells
GLUT 3 : neurons
GLUT 4 : skeletal muscle and adipose tissue
What does insulin promote?
synthesis of fat, glycogen, and protein and cellular uptake of potassium
What does insulin inhibit?
gluconeogenesis, lipolysis, and protein degradation
When is excess insulin seen?
in insulin secreting tumors (insulinoma)- produces low blood sugar levels
Insulin secretion is stimulated by which two amino acids?
alanine and leucine
What does a decrease in insulin secretion or function result in?
diabetes mellitus and produces polyuria, polydypsia, polyphagia, and pruritus
What is glucagon secreted by?
alpha cells
What is the function of glucagon?
causes the liver to convert glycogen to glucose (promotes glycogenolysis)
When is glucagon released?
when blood glucose levels are low
What is somatostatin secreted by?
delta cells of the pancreas
D cells in the stomach
hypothalamus
Somatostatin is also known as growth hormone inhibitory hormone and inhibits these 5 substances.
Renin Insulin Growth hormone Gastrin Glucagon
