HP Relationships

Question 1

What is the pituitary gland (hypophysis) composed of?

Answer 1

anterior pituitary (adenohypophysis) - epithelial portion
posterior pituitary (neurohypophysis) - neural portion

Question 2

What is the hypophysial stalk?

Answer 2

physical connection between the hypothalamus and pituitary gland

Question 3

What is the posterior pituitary a collection of, and what does it secrete?

Answer 3

collection of axons whose cell bodies and located in the hypothalamus: supraoptic nucleus (SON) and paraventricular nucleus (PVN)

it secretes neuropeptides: ADH (mostly SON) and oxytocin (mostly PVN)

Question 4

What hormones does the anterior pituitary secrete?

Answer 4

ACTH, TSH, FSH, LH, GH, prolactin

anterior pituitary is connected to hypothalamus by hypothalamic-hypophysial portal vessels

Question 5

What are two important implications of the hypothalamic-hypophysial portal vessels?

Answer 5

1. hormones can be delivered to the anterior pituitary directly and in high concentration
2. hormones do not appear in the systemic circulation in high concentration

Question 6

What is a primary endocrine disorder?

Answer 6

low or high levels of hormone due to defect in peripheral endocrine gland

Question 7

What is a secondary endocrine disorder?

Answer 7

low or high levels of hormone due to defect in pituitary gland

Question 8

What is a tertiary endocrine disorder?

Answer 8

low or high loevels of hormone due to defect in the hypothalamus

Question 9

What hormones do corticotrophs release?

Answer 9

ACTH

Question 10

What hormones do thyrotrophs release?

Answer 10

TSH

Question 11

What hormones do gonadotrophs release?

Answer 11

FSH and LH

Question 12

What hormones do somatotrophs release?

Answer 12

GH

Question 13

What hormones do lactotrophs/mammotrophs release?

Answer 13

prolactin

Question 14

What causes acromegaly?

Answer 14

prolonged, excessive secretion of GH in adult life
characterized by excessive growth of soft tissue, cartilage and bone in face, hands and feet - develops very gradually
can lead to HTN, accelerated osteoarthrosis, hyperglycemia, cardiomegaly
-> GH acts on chondrocytes

Question 15

What does GH stimulate?

Answer 15

somatomedin C (insulin-like growth factor 1, IGF-1) gene transcription and secretion by the liver

Question 16

How do you diagnose acromegaly and what are the medications given?

Answer 16

increase in serum IGF-1 levels, failure to supress serum GH following OGTT, pituitary mass seen on brain MRI

octoreotide/lanreotide (somatostatin analog)
pegvisomant (GH receptor antagonist)
bromocriptine/cabergoline (dopamine receptor agonists)

Question 17

What leads to a GH deficiency?

Answer 17

decreased secretion of GHRH
decreased secretion GH
failure to generate somatomedins
GH or somatomedin resistance

Question 18

What leads to a GH excess?

Answer 18

mostly due to a growth hormone-secreting pituitary adenoma
consequences depend on developmental stage
- before puberty = gigantism
- after puberty = acromegaly

Question 19

What is the diabetogenic effect?

Answer 19

increase in blood glucose concentration

• causes insulin resistance
• decrease in glucose uptake and utilization by target tissues
• increase in lipolysis in adipose tissue
• results in increase in blood insulin levels

Question 20

What do somatomedins (IGF-1) mediate?

Answer 20

increase in protein synthesis, organ growth and linear growth

Question 21

What does hyperprolactinemia supress?

Answer 21

FSH and LH secretion

Question 22

What is the function of CRH?

Answer 22

increase ACTH, MSH

Question 23

What is the function of dopamine?

Answer 23

decrease prolactin

Question 24

What is the funtion of GHRH?

Answer 24

increase GH

Question 25

What is the function of GnRH?

Answer 25

increase FSH, LH

Question 26

What is the function of prolactin?

Answer 26

decrease GnRH

Question 27

What is the function somatostatin?

Answer 27

decrease GH, TSH

Question 28

What is the function of TRH?

Answer 28

increase in TSH, prolactin

Question 29

What causes Cushing's disease?

Answer 29

high levels of ACTH

Question 30

What causes TSH-secreting adenoma?

Answer 30

high levels of TSH

Question 31

What causes acromegaly/gigantism?

Answer 31

high levels of GH

Question 32

What causes prolactinoma?

Answer 32

high levels of prolactin

Question 33

What causes a non-functioning adenoma?

Answer 33

high levels of LH and FSH

Question 34

What are the causes of hypopituitarism?

Answer 34

brain damage, pituitary tumors, non-pituitary tumors, infections, infarction, autoimmune disorders, pituitary hypoplasia

Question 35

What is Sheehan syndrome?

Answer 35

postpartum hypopituitarism due to necrosis of the pituitary gland most patients present with agalactorrhea (difficulties with lactation) amenorrhea (lack of menstruation), hypothyroidism

Question 36

What are the posterior lobe neuropeptides?

Answer 36

ADH, oxytocin

Question 37

What are the posterior lobe secreting neurons?

Answer 37

ADH (mainly from supraoptic nuclei) | oxytocin (mainly from PVN)

Question 38

What are the triggers of ADH secretion?

Answer 38

decrease in blood pressure (baroreceptor reflex) decrease in arterial strethc due to low BV (atrial stretch receptors_ increase in osmolarity (hypothalamic osmoreceptors) NOTE: secretion most sensiive to plasma osmolarity changes

Question 39

What happens to ADH in hyperosmolar state?

Answer 39

hypothalamus detects too little water -> pituitary gland release ADH -> kidneys remove less water from the blood so less water is lost in urine

Question 40

What happens to ADh in a hypo-osmolar state?

Answer 40

hypothalamus detects too much water in blood -> pituitary gland release less ADH -> kidneys remove more water from blood so more water is lost in urine

Question 41

What is diabetes insipidus?

Answer 41

lack of an effect of ADH on the renal collecting duct causes frequent urination large volume of urine is diluted

Question 42

What is central DI?

Answer 42

lack of ADH could result from damage to the pituitary, or destruction of the hypothalamus tx: desmopressin

Question 43

What is nephrogenic DI?

Answer 43

kidneys unable to respond to ADH causes: drugs like lithium, chronic kidney disorders (polycystic kidney disease) CANNOT treat with desmopressin (does NOT respond to ADH)

Question 44

What is syndrome of inappropriate ADH secretion (SIADH)?

Answer 44

excessive secretion of ADH excessive water retention hypo-osmolarity fails to inhibit ADH release