168. Hypothalamic-Pituitary Basic Physiology Flashcards

1
Q

Confers the biologic specificity of hormones

A

beta-subunit

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2
Q

Essential for boney growth and has effects on fat, muscle, and CHO GHRH (+) and somatostatin (-)

A

Growth hormone

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3
Q

High estrogen levels of pregnancy result in hyperplasia of lactotrophs and high ___ levels

A

Prolactin

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4
Q

Stimulates gonadal steroid production

Midcycle surge triggers ovulation (release of egg) GnRH (+)

A

LH

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5
Q

Derive from an evagination of neural ectoderm of the ventral diencephalon

A

Posterior lobe of pituitary

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6
Q

Stimulates mild let-down and postpartum uterine contraction

Stimulated by suckling

A

Oxytocin

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7
Q

Mutations in these peptides give rise to combined pituitary hormone deficiency through lack of development of certain pituitary cells but hypothalamic structures are normal

A

Pit-1 and PROP-1

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8
Q

Stimulates follicle and sperm development GnRH (+)

A

FSH

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9
Q

Under tonic inhibition by the hypothalamus via dopamine

Cutting of the stalk causes hypopituitarism but also an increase in this hormone

A

Prolactin

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10
Q

Secreted by the somatotrophs (50% of pituitary cells)

Promotions of linear growth at the growth plates of bones

Increases osteoclast differentiation and activity

Increases osteoblast activity

Increases bone mass by endochondral bone formation

A

Growth hormone

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11
Q

Converts electrical signals from the retina into hormonal signals

A

Pineal gland

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12
Q

Need ___ secretion instead of continuous for adequate hormone release

A

Pulsatile

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13
Q

Localized in hypothalamic nuclei that project to the median eminence to secrete peptide and bioamine releasing and inhibiting hormones into the proximal end of the hypothalamic-pituitary portal vessels

A

Hypophysiotropic neurons

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14
Q

Made by Liver and bones after Growth Hormone has acted on them

  • most comes from liver

Then acts in a negative feedback loop on the pituitary and hypothalamus

A

IGF-1

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15
Q

Primary regulator of ADH secretion

Senses hyperosmolality (hypernatremia) which stimulates ADH release

Senses hypoosmolality (hyponatremia) which suppresses ADH release

A

Osmoreceptors in hypothalamus

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16
Q

Produced by corticotrophs (10-20% of pituitary cells)

Derived from POMC

Main product in pituitary

Stimulates adrenal cortex to produce cortisol and adrenal androgens

Little effect on aldosterone

Stimulated by CRH Stress mediated

A

ACTH

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17
Q

Secreted by pituitary lactotrophs (15% of pituitary cells)

Stimulates breast epithelium to proliferate

  • in conjunction w/ estrogen, progesterone, thyroid hormone, cortisol, and insulin

Induces milk production in the puerperium

Dopamine-receptor blockers can increase levels of this hormone

Suckling is the normal stimulus for secretion in the puerperium

A

Prolactin

18
Q

Produced by gonadotrophs (10-15% of pituitary cells)

In ovary, binds to receptors on theca cells where it stimulates the production of androgens and steroid precursors that are transported to granulosa cells for aromatization to estrogen

In testes, binds to receptors on Leydig cells where it stimulates testosterone production

Triggers ovulation if properly timed

A

LH

19
Q

Primary regulation of aldosterone is performed by ___ along with from the adrenal gland after ACTH stimulation

A

Renin-Angiotensin System

20
Q

Provide negative feedback at both the pituitary and hypothalamic levels with decreases in TRH and increases in somatostatin

A

T4 and T3

21
Q

Originate in the supraoptic and paraventricular nuclei

Traverse the pituitary stalk

Release vasopressin and oxytocin from nerve endings in the posterior pituitary

A

Neurohypophysial neurons

22
Q

Main androgen responsible for closing of epiphyseal growth plates

A

Estrogen

23
Q

Derives from Rathke’s pouch

A

Anterior lobe of pituitary

24
Q

TRH, VIP, and maybe other peptides release ___ in the setting of low dopamine

A

Prolactin

25
Q

Synthesized in magnocellular neurons in the supraoptic and paraventricular nuclei of the hypothalamus

Acts by binding V2 receptors in renal collecting ducts making them more water permeable

  • activation of aquaporin 2 channels

Primary action it to maintain normal serum osmolality through water reabsorption

Also acts on V1 receptors on vascular smooth muscle to cause muscle contraction and an increase in BP

A

ADH (vasopressin)

26
Q

From sertoli cells and ovarian granulosa cells that feeds back to inhibit FSH release

Acts on pituitary gland to inhibit FSH and LH secretion

A

Inhibin

27
Q

Controlled only by water balance

  • controlled by vasopressin and thirst
A

Serum osmolality

28
Q

Produced by the thyrotrophs (5% of pituitary cells)

Glycoprotein with an alpha and beta subunit

Stimulates all aspects of thyroid function as well as thyroid gland growth

A

TSH (Thyrotrophin)

29
Q

Stimulates amino acid uptake into tissue and increases muscle

Promotes lipolysis with fat breakdown

Causes resistance to the action of insulin (a counter-regulatory hormone)

A

Growth Hormone

30
Q

Stimulates thyroid hormone production and thyroid growth TRH (+) and somatostatin (-)

A

Thyrotropin (TSH)

31
Q

Linear growth is dependent on the stimulation of this protein from the liver and locally in other tissues, such as the epiphyseal growth plate

Measure this when wanting to assess GH status

A

IGF-1

32
Q

Can override osmotic regulation in extreme conditions

  • 10-15% blood volume or pressure drop to override the osmolality control
A

Baroreceptors (volume receptors) in chest

33
Q

Influences hormone cycles in humans more than light-dark

A

Sleep-wake cycles

34
Q

Common to TSH, LH, FSH, and chorionic gonadotrophin

A

alpha-subunit

35
Q

Act as carriers of IGF in plasma Prolong the half-life of IGF in circulation

Regulate IGF access to receptor in extracellular fluid

A

IGFBPs (IGF binding proteins)

36
Q

Binds to receptors in the breast, causing contraction of myoepithelial cells around the alveoli and ductules to eject milk

Suckling stimulates tactile receptors, sending signal to hypothalamus to release __

Released during vaginal stretching with delivery of infant and is important in causing uterine contraction then to prevent blood loss

A

Oxytocin

37
Q

Hyperglycemia suppresses __ secretion

A

Growth hormone

38
Q

Produced by gonadotrophs (10-15% of pituitary cells)

In ovary, binds to receptors on granulosa cells where it induces enzymes that are involved in estrogen synthesis and promotes follicle growth

In testes, binds to receptors on Sertoli cells where it stimulates spermatogenesis and inhibin-related proteins

A

FSH

39
Q

Stimulates water reabsorption in the kidney collecting duct

Stimulated by hyperosmolality and intravascular volume/pressure loss

A

Vasopressin

40
Q

Stimulates cortisol and adrenal androgen production and adrenal growth

Strong diurnal rhythm

CRH (+) and vasopressin (+)

A

ACTH