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COM - Endocrine > Hypothalamic Pituitary Axis - 2/2 Lopez > Flashcards

Hypothalamic Pituitary Axis - 2/2 Lopez Flashcards

1
Q

What is the connection between the hypothalamus and posterior lobe like?

A

Neural

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2
Q

The connection between the hypothalamus and anterior lobe are what?

A

Neural and endocrine

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3
Q

How do hormones get from the hypothalamus to the anterior lobe of the pituitary?

A

Hypothalamic-hypophysial portal vessels

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4
Q

What is a primary endocrine disorder due to a defect in?

A

Peripheral endocrine gland (target tissue i.e. Thyroid gland)

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5
Q

What is a secondary endocrine disorder due to?

A

Defect in pituitary gland

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6
Q

What is a tertiary endocrine disorder due to?

A

Defect in hypothalamus

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7
Q

What are some examples of primary endocrine disorders?

A

Thyroid, adrenal cortex, liver, gonads

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8
Q

What are the most prominent cell types within the pituitary gland?

A

Somatotrophs (50%)

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9
Q

What do corticotrophs release?

Somatotrophs?

A

ACTH

growth hormone

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10
Q

What hormone has melanocyte-stimulating hormone activity?

INC in blood levels of what can cause skin pigmentation?

A

ACTH

MSH

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11
Q

What disease is associated with INC levels of ACTH?

Symptoms?

A

Addison’s disease

Skin pigmentation

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12
Q

What is a main regulator of the HPA axis that stimulates it?

A

Stress (physical, emotional, chemical)

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13
Q

What does ACTH cause the release of in the adrenal gland that can cause negative feedback of the system?

A

Cortisol or aldosterone

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14
Q

What 2nd messenger does the HPT axis use once TRH is released?

What does this activate?

A

PLC

INC in Ca and PKC

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15
Q

After the pituitary thyrotrope has been activated, what does it release?

A

TSH

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16
Q

Once TSH has been released from the pituitary thyrotrope what does it stimulate?

What are its effects?

Ultimate end secretion product?

A

PKA

Thyroid hormone synthesis and secretion, cell growth

T3, T4

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17
Q

What inhibits TRH secretion?

What end product can also inhibit the HPT axis via negative feedback?

A

Stress

T3

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18
Q

What stimulates the synthesis and secretion of GH And where is this initial stimulus located?

What does this hormone act on to release GH?

A

GHRH from the hypothalamus

Acts on ant. Pituitary

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19
Q

What inhibits the secretion of GH?

How?

A

Somatostatin

Blocks response of ant. Pituitary to GHRH

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20
Q

When GH acts on target tissues (liver) what is produced?

How do they inhibit further secretion of GH?

A

Somatomedins (IGF)

Inhibit release from ant. Pituitary AND stimulate secretion of somatostatin from hypothalamus

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21
Q

How is GH secreted?

A

Pulsatile pattern, burst of secretion every 2 hours

22
Q

What tissues are the main targets of direct effect of GH?

Indirect?

A

Skeletal m., liver, adipose

Liver

23
Q

What are the direct effects of GH?

What is the net result?

A

Diabetogenic: DEC glucose uptake into cells
INC lipolysis in adipose
INC protein synthesis in muscle
INC production of IGF

INC in blood [glucose] and blood insulin levels

24
Q

What are the indirect effects of GH?

A

INC Protein synthesis and organ growth (INC uptake of a.a.)

INC linear growth (INC metabolism in cartilage-forming cells and chondrocytes)

25
Q

What causes GH deficiency?

A

Lack of ant. Pituitary GH
DEC GHRH due to hypothalamic dysfunction
Failure to generate IGF in liver
GH receptor deficiency

26
Q

GH excess causes what?

Mostly due to what?

A

Acromegaly

GH-secreting pituitary adenocarcinoma

27
Q

What does excess GH cause before puberty?

After?

A

Gigantism (INC linear growth)

INC periosteum bone growth, INC organ size, glucose intolerance

28
Q

How to treat GH deficiency?

Excess?

A

HGH

Somatostatin analogue (octreotide)

29
Q

What does lactogenesis induce the synthesis of?

A

Lactose, casein and lipids

30
Q

What inhibits lactation during pregnancy even though prolactin levels are high?

A

High levels of estrogen and progesterone down-regulate prolactin receptors

31
Q

What does prolactin suppress?

How?

A

Ovulation

DEC synthesis and release of GnRH

32
Q

What causes prolactin deficiency?

Result?

A

Destruction of ant. Pituitary or lactotrophs

Inability to lactate

33
Q

What causes prolactin excess?

Result?

A

Destruction of hypothalamus or hypophysial tract, prolactinomas,

Galactorrhea and infertility

34
Q

How to treat prolactin excess?

A

DA receptor agonist (bromocriptine)

35
Q

What is Sheehan syndrome?

A

Pituitary in pregnancy is enlarged and more vulnerable to infarction

36
Q

What is Cushing’s disease?

A

Pituitary tumors stimulating an increase in cortisol

37
Q

Pituitary adenomas develop in 25% of patients with what?

A

MEN 1

38
Q

What is the precursor peptide for ADH?

Oxytocin?

A

Preprossophysin

Prepro-oxyphysin

39
Q

What are the triggers for ADH secretion?

A

DEC BP
DEC arterial stretch due to low blood volume
INC Osmolarity (>280) MAIN stimulus

40
Q

What are the actions of ADH?

Ultimate result?

A

INC H20 reabsorption via V2 receptors
Vasoconstriction via V1 receptor

INC BP and INC blood volume

41
Q

What mechanism do the V1 receptors work through?

V2?

A

IP3/Ca

cAMP

42
Q

What channel does ADH activate?

Where?

A

aquaporin 2 (AQP2)

Principal cells of the late DCT and CD

43
Q

What is ADH secretion like in hyper osmolarity?

Urine concentration?

A

ADH INC

urine more concentrated

44
Q

What happens to ADH in hypoosmolarity?

Urine concentration?

A

Less ADH secreted

Urine more dilute

45
Q

What are the characteristics of General DI?

A

Lack of effect of ADH
Frequent urination
Large volume of urine is diluted

46
Q

What is the cause of central DI?

From what?

A

Lack of ADH

Pituitary damage or destruction of the hypothalamus

47
Q

What is happening nephrogenic DI?

Cause?

A

Kidneys unable to respond to ADH (INC plasma ADH)

Lithium, polycystic kidney disease, sickle cell anemia

48
Q

What drug is used to treat central DI?

Nephro DI?

A

Desmopressin

NONE

49
Q

What is SIADH?

What is it characterized by?

A

excessive secretion of ADH, excessive water secretion

Hypoosmolarity and hyponatremia

50
Q

How to treat SIADH?

A

Fluid restriction
IV hypertonic saline (3%)
V2 receptor antagonist
Demeclocycline (inhibits cAMP)

51
Q

What are the 3 hypothalamic-pituitary axises?

What do they control?

A

thyroid, adrenal, gonads (HPT, HPA, HPG)

Growth, milk production/ejection, osmoregulation

COM - Endocrine (12 decks)

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