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BRS (PHYSIO) > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

Prehormone syntheiss occurs in the __________ and is directed by a specific mRNA

A

endoplasmic reticulum

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2
Q

__________ are cleaved from prehormone. producing prohormone, which is transported to the Golgi apparatus

A

Signal peptides

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3
Q

Addtional peptide sequences are cleaved in the golgo apparatus to form the _________, which is packaged in secretory granules for later release

A

Hormone

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4
Q

Steroid hormones are derivatives of _____________

A

Cholesterol

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5
Q

Amine hormones (Thyroid hormones, epinephrine, norepinephrine) are derivatives of ___________

A

tyrosine

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6
Q

Most commonly applied principle for regulating hormone secretion

self limiting

A

Negative feedback

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7
Q

Explosive and self reinforcing regulating principle of hormone secretion

A

Positive feedback

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8
Q

Stimulates secretion of TSH and prolactin

A

Thytotropin releasing hormone (TRH)

hypothalamus

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9
Q

Stimulates secretion of ACTH

A

CRH

hypothalamus

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10
Q

Stimulates secretion of LH and FSH

A

GnRH

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11
Q

Stimulates secretion of growth hormone

A

GHRH

Hypothalamus

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12
Q

Inhibits secretion of growth hormone

A

Somatotropin release-inhibiting hormone (Somatostain)

Hypothalamus

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13
Q

Inhibits secretion of prolactin

A

Prolactin-inhibiting hormone (dopamine)

hypothalamus

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14
Q

Stimulates synthesis and secretion of thyroid hormones

A

TSH

anterior pituitary

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15
Q

Stimualtes growth of ovarian follicles and estrogen secretion.

Promotoes sperm maturation (testes)

A

FSH

anterior pituitary

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16
Q

Stimulates ovulation, formation of corpus luteum, and synthesis of estrogen and progesterone (Ovary)

Stimualtes synthesis and secretion of testosterone (testes)

A

LH

Anterior pituitary

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17
Q

Stimualtes protein synthesis and overall growth

A

GH

anterior pituitary

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18
Q

Stimulates milk production and breast development

A

Prolactin

anterior pituitary

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19
Q

Stimulates synthesis and secretion of adrenal cortical hormones

A

ACTH

anterior pituitary

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20
Q

stimulates the synthesis and secretion of adrenal cortical hormones

A

ACTH

Anterior pituitary

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21
Q

Stimulates melanin synthesis

A

MSH

Anterior pituitary

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22
Q

Milk ejection, uterine contraction

A

OXytocin

posterior pituitary

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23
Q

Stimulates water reabsorption by renal collecting ducts and contraction of arterioles

A

ADH

Posterior pituitary

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24
Q

Skeletal growth; increase oxygen comsumption, heat production, increase protein, fat and CHO use; maturation of nervous system (perinatal)

A

L-Thyroxine

Triiodothyronine

Thyroid gland

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25
Q

Stimualtes gluconeogenesis; antiinflammatory; immunosuppression

A

Glucocorticoids

adrenal cortex

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26
Q

Growth and development of female reproductive organs; follicular phase of menstrual cycle

A

Estradiol

Ovary

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27
Q

Luteal phase of menstrual cycle

A

Progesterone

Ovary

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28
Q

Spermatogenesis; male secondary sex characteristics

A

testosterone

Testes

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29
Q

Increase serum calcium, decrease serum phosphate

A

PTH

parathyroid gland

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30
Q

Decrease serum calcium

A

Calcitonin

Thyroid gland (parafollicular cells)

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31
Q

Increase renal sodium reabsorption, increase renal K secretion, Increase renal H secretion

A

Aldosterone

adrenal cortex

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32
Q

Increase intestinal sodium reabsotpion, increase bone mineralization

A

1,25 dihydroxycholecalciferol

Kidney (activation)

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33
Q

Decrease blood glucose, decrease blood amino acid, decrease blood fatty acid

A

Insulin

Pancrea (Beta cells)

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34
Q

Increase blood glucose, increase blood fatty acids

A

Glucagon

Pancrea (alpha cells)

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35
Q

increase estrogen and progesterone synthesis in copus luteum of pregnancy

A

HCG

Placenta

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36
Q

Same actions as growth hormone and prolactin during pregnancy

A

Human placental lactogen

Placenta

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37
Q

Hormones determine the sensitivity of target tissue by regulating the __________________

A

number or sensitivity of receptors

  • Down-regulation
  • Up-regulation
    • in the ovary ,estrogen upregulates its own receptor for LH
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38
Q

______are GTP proteins that couple hormone receptors to adjacent effector molecules

A

G proteins

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39
Q

G proteins are used in the ___________ and __________ second messenger systems

A

Adenylate cyclase

IP3

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40
Q

G proteins have 3 subunits ____________

A

alpha

beta

gamma

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41
Q

the _______ subunit can bind either GDP or GTP.

A

alpha

  • when GDP is bound = INACTIVE
  • when GTP is bound = ACTIVE
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42
Q

hormones that uses cAMP mechanism

A
  • ACTH
  • LH and FSH
  • TSH
  • ADH (v2 receptor)
  • HCG
  • MSH
  • CRH
  • B1 and B2 receptors
  • Calcitonin
  • PTH
  • Glucagon
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43
Q

Hormones that uses IP3 mechanism

A

GnRH

TRH

GHRH

ATII

ADH (V1 receptor)

Oxytocin

Alpha 1 receptors

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44
Q

Hormones that uses Steroid hormone mechanism

A

Glucocorticoids

Estrogen

Testosterone

Progesterone

Aldosterone

Vit. D

Thyroid hormone

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45
Q

Hormones that uses tyrosine kinase

A

Insulin

IGF-1

Growth hormone

Prolactin

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46
Q

Hormones that use cGMP mechanism

A

ANP

Nitric oxide

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47
Q

Adenylate cyclase mechanism

A
  1. Hormone binds to a receptor
  2. GDP is released from the G protein and relpaced by GTP
  3. Activated adenylate cyclase catalyzes ATP to cAMP
  4. cAMP activates protein kinase A
  5. cAMP is degraded to 5’ AMP by phosphodiesterase
    • inhibited by caffeine
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48
Q

IP3 mechanism

A
  1. Hormone bind to receptor activates phopholipase C
    • via cell membrane
    • via a G protein
  2. Phospholipase C liberates diacylclycerol and IP3
  3. IP3 mobilizes calcium from ER. Activates protein kinase C
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49
Q

Guanylyl cyclase

A
  • ANP
    • Acts through a receptor gyanylyl cyclase. where the extracellular side of the receptors binds ANP and the intracellular side has guanylyl cyclase activity
  • NO
    • acts through cytosolic guanylyl cyclase
    • converts GTP to cyclic GMP, which is the second messenger
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50
Q

Receptor tyrosine kinase

A
  • bind to extracellular side of the receptor
  • Intracellular side has intrinsic tyrosine kinase actovoty
    • monomer
    • dimer
      • insulin
      • insulin growth factor
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51
Q

mechanism of action of growth hormone

A

tyrosine kinase-associated receptor

  • GH binds to the extracellular side of the receptor
  • The intracellular side of the receptor does not have tyrosine activity but is non covalently associated with tyrosine kinase (JAK)
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52
Q

Steroid hormone and thyroid hormone mechanism

A
  1. Steroid hormone diffuses across the cell membrane and binds to its receptor
  2. Hormone-receptor complex enters the nucleus and dimerize
  3. The hormone-receptor dimers are transcription factors that bind to steroid responsive elements (SREs) and initiate DNA transcription
  4. New mRNA is produced
  5. the new protein hace specific physiologic functions
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53
Q

The __________lobe of the pituitary gland is linked to the hypothalamus by the hypothalamic-hypophysial portal system

A

Anterior

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54
Q

The ________ lobe of the pituitary gland is derived from neural tissues. The cell bodies are located in the hypothalamic nuclei

A

Posterior

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55
Q

TSH, LH, and FSH belong to the same glycoprotein family. The _________ subunit are identical

A

Alpha

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56
Q

ACTH, MSH, B-lipotropin and B-endorphin are derived from a single precursor, __________________

A

Proopiomelanocortin

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57
Q

______ and ______ are produced in the intermediary lobe, which is rudimentary in adult human

A

Alpha and BEta MSH

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58
Q

Most important hormone for normal growth to adult size.

A

Growth hormone

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59
Q

Growth hormone is a single chain polypeptode that is homologous with _______ and _______

A

Prolactin

human placental lactogen

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60
Q

Growth hormone is relased in a __________ manner

A

pulsatile

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61
Q

Growth hormone secretion is increased by _______________

A

Sleep, stress, hormones related to puberty, starvation, exercise and hypoglycemia

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62
Q

Growth hormone secretion is decreased by ____________

A

Somatostatin, somatomedins, obesity, hyperglycemia and pregnancy

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63
Q

__________ ar eproduced when growth hormone acts on target tissues. They inhibit secretion of GH by acting directly on the anterior pituitary and by stimulating secretion of somatostain from the hypothalamus

A

Somatomedins

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64
Q

Negative feedback control by GHRH and GH

A
  • GHRH inhibits its own secretion from the hypothalamus
  • GH also inhibits its own secretion by stimulating the secretion fo somatostatin from the hypothalamus
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65
Q

in the liver, GH generates the production of ________________, which serves as the intermediaries of several physiologic actions

A

Somatomedins (insulin-like growth factor)

  • the IGF receptor has tyrosine kinase activity
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66
Q

Growth hormone deficiency

A
  • Lack of anterior pituitary GH
  • hypothalamic dysfunction
  • Failure to generate IGF in the liver
  • Growth hormone receptor deficiency
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67
Q

Growth hormone excess can be treated with ____________

A

Somatostatin analogs (octreotide) which inhibit growth hormone secretion

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68
Q

Hypersecretion of growth hormone causes __________

A

Acromegaly

  • Before puberty = increased linear growth (gigantism)
  • After puberty = causes increased periosteal bone growth, increased organ size, and glucose intolerance
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69
Q

Major hormone responsible for lactogenesis

A

Prolactin

  • Participates with estrogen, in breast development
  • structurally homologous to growth hormone
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70
Q

Prolactin secretion is tonically inhibited by _____________

A

Dopamine

  • TRH increases proalctin secretion
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71
Q

Regulation of prolactin secretion

A
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72
Q

Actions of prolactin

A
  • Stimulates milk production
  • Stimulates breast development
  • Inhibits ovulation (decreasing synthesis and relase of GnRH)
  • inhibits spermatogenesis
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73
Q

Prolactin excess

A
  • hypothalamic destruction (loss of inhibitory control)
  • prolactinomas
  • galactorrhea
  • Failure to ovulate and amenorrhea
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74
Q

Prolactin excess can be treated with _________

A

bromocriptine

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75
Q

Hormones of the posterior lobe of the pituitary

A

ADH and Oxytocin

  • synthesized in the hypothalamic nuclei
  • package in secretory granuleswith their respective neurophysins
  • travel down the nerve axons by secretion by the posterior pituitary
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76
Q

ADH originates primarily in the ___________ ofthe hypothalamus

A

supraoptic nuclei

  • Regulates serum osmolarity by increasing water permeability of the late distal tubules and collecting duct
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77
Q

Factors that increase ADH secretion

A
  • Serum osmolarity
  • volume contraction
  • Pain
  • Nasuea (powerful stimulant)
  • Hypoglycemia
  • Nicotine , opiates, antineoplastic drugs
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78
Q

Factors that decrease ADH secretion

A
  • Decrease serum osmolarity
  • ethanol
  • alpha agonists
  • ANP
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79
Q

Actions of ADH

A
  • Increase water permeability (aquaporin 2) of the principal cells of the late distal and collecting ducts (via V2 receptor and adenylate cyclase- cAMP mechanism)
  • Constriction of vascular smooth muscle (via V1 receptor and an IP3/calcium mechanism)
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80
Q

Oxytocin origanates primaruly in the ____________ of the hypothalamus

A

paraventricualr nuclei

  • causes ejection of milk from the breast when stimualted by suckling.
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81
Q

Major stimulus for oxytocin secretion

A

Suckling

  • Afferent fibers carry impulses from the nipple to the spinal cord. Relays in the hypothalamus trigger the release of oxytocin from the posterior pituitary
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82
Q

Actions of oxytocin

A
  • contraction of myoepithelial cells in the breast
  • Contraction of the uterus
    • reduce post partum bleeding
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83
Q

_______is synthesized from tyrosine in the thyroid follicular cells, packaged in secretory vesicles, and extruded into the follicular lumen

A

Thyroglobulin

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84
Q

___________ present in the thyroid follicular epithelial cells

Actively transports I into the thyroid follicular cells for subsequent incoporation into thyroid hormones

A

The iodide (I) pump or Na-I cotransport

  • Inhibited by thiocyanate and perchlorate anions
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85
Q

Oxidation of I to I2 is catalyzed by ___________ in the follicular cell membrane

A

Peroxidase

  • I2 is the reactive form, which will be “organified” by combination with tyrosine on thyroglubulin
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86
Q

The peroxidase enzyme is inhibited by _________, which is used therapeutically to reduce thyroid hormone syntheis for the treament of hyperthyroidism

A

Propylthiouracil

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87
Q

Organification of I2 involves tyrosine residues of thyroglobulin react with I2 to form _________ and ____________

A

Monoidotyrosine and Diiodotyrosine

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88
Q

High levels of Iodide inhibit organification and therefore inhibit synthesis of thyroid hormone

A

Wolff-Chaikoff effect

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89
Q

Coupling reactions of MIT and DIT

A
  • When 2 molecules of DIT combine, T4 is formed
  • when 1 DIT combines with 1 MIT, T3 is formed
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90
Q

Leftover MIT and DIT are deiodinated by ___________. The I2 that is released is reutilized to synthesize more thyroid hormones

A

Thyroid deiodinase

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91
Q

In the circulation, most of the T3 and T4 is bound to __________

A

thyroxine-binding globulin

  • In hepatic failure, TBG levels decreases, leading to decrease in total thyroid hormone levels, but normal levels of free hormone
  • In pregnancy, TBG levels increase leading to an increase in total thyroid hormone levels, but notmal levels of free hormone
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92
Q

In the peripheral tissues T4 is converted to T3 by ____________

A

5’-iodinase

  • T3 is more biologically active than T4
93
Q

Synthesis of thyroid hormones

A
  • Thyroglobulin is synthesized
  • Iodide pump or Na-I cotransport
  • Oxidation of I to I2
  • Organification of I2
  • Coupling of MIT and DIT
  • Stimulation of thyroid cells by STG
  • Binding of T3 and T4
  • Conversion of T4 to T3
94
Q

TSH increases both the synthesis and the secretion of thyroidhormones by the follicular cells via an ______________ mechanism

A

adenylate cyclase - cAMP

95
Q

_____ down regulates TRH receptors in the anterior pituitary and thereby inhibits TSH secretion

96
Q

____ are components of the immunoglobulin G fraction of plasma proteins and are antibodies to TSH receptors on the thyroid gland.

A

Thyroid stimulating immunoglobulins

97
Q

Thyroid stimulating immunoglobulins bind to TSH and like TSH, ____________________

A

Stimualte the thyroid gland to secrete T3 and T4

98
Q

Thyroid stimulating immunoglobulins circulate in high concentrations in patients with _________, which is characterized by high circulating thyroid hormones and accordingly, low concentrations of TSH

A

Grave’s disease

99
Q

Actions of thyroid hormones

A
  • Growth
    • bone formation
    • bone maturation
  • CNS
    • Perinatal period
      • requires thyroid hormone in perinatal period
    • Adulthood
      • Hyperthyroidism
      • Hypothyroidism
  • Autonomic Nervous system
    • Upregualtes B1-adrenergic receptors in the heart
  • Basal metabolic rate
    • Increased oxygen consumption and BMR
    • Increases the syntheis of Na, K ATPase
  • Cardiovascular and Respiratory systems
    • Increased CO
  • Metabolic effects
    • glycogenolysis, gluconeogenesis, and glucose oxidation
100
Q

The overall effect of thyroid hormone is ___________

101
Q

The ________ produces aldosterone

A

zona glomerulosa

102
Q

The _______ produces glucocorticoids(cortisol) and androgens (dehydroepiandrosterone and androstenedione)

A

Zona fasciculata and reticularis

103
Q

21 carbon steroid include _________, _____________ ,______________ and _______

A

Progesterone, deoxycortisone, aldosterone, and cortisol

104
Q

_______ is the precursor for the others in the 21 carbon series

A

Progesterone

105
Q

_________ leads to the production of deoxycortisone, which has mineralcorticoid (but not glucocorticoid) activity

A

Hydroxylation at C-21

106
Q

________ leads to the production of glucocorticoids (cortisol)

A

hydroxylation at C-17

107
Q

______have androgenic acrtivity and are precursors to the estrogens

A

Androdenic activity

108
Q

If the steroid has been previously hydroxylated at C17, the C20,21 side chain can be cleaved to yield the 19-carbon steroids ____________ or __________ in the adrenal cortex

A

Dehydroepiandrosterone

androstenedione

109
Q

adrenal androgens have a ketone group at C-17 and are exrreted as __________ in the urine

A

17-ketosteroids

110
Q

in the testes, androstenedione is converted to ___________

A

testosterone

111
Q

______ have estrogenic activity

A

18 carbon steroids

  • Oxidation of the A ring (aromatization) to produce estrogens occurs in the ovaries and placenta, but not in the adrenal cortex or testes
112
Q

Secretory products of the adrenal cortex and medulla

113
Q

Synthetic pathways for glucocorticoids, androgens, and mineralocorticoids in the adrenal cortex

114
Q

glucocorticoid secretion oscillates with a 24 hour periodicity or ________

A

circadian rhythm

  • For those who sleep at night, cortisol levels are highest just before walking and lowest evening
115
Q

CRH-containing neurons are located in the _________ of the hypothalamus

A

Paraventricular nuclei

116
Q

CRH binds to receptors on corticotrophs of the anterior pituitary and directs them to synthesize __________ and secretes ACTH

117
Q

the second messenger for CRH is _____________

118
Q

ACTH increases steroid hormone synthesis in all zones of the adrenal cortex by stimulating ________ and increasing the conversion of cholesterol to pregnenolone

A

cholesterol desmolase

119
Q

Chronically increased levels of ACTH cause ___________ of the adrenal cortex

A

Hypertrophy

120
Q

The second messenger for ACTH is __________

121
Q

________inhibits the secretion of CRH from the hypothalamus and the secretion of ACTH from the anterior pituitary

122
Q

the _________ is based on the ability to inhibit of dexamethasone to inhibit ACTH secretion.

A

Dexamethasone suppression test

  • In normal persons, low dose dexamethasone inhibits ACTH secretion and, consequently, cortisol secretion
  • In persons with ACTH-secreting tumors, low dose dexamethasone does not inhibit cortisol secretion but high dose does.
  • In persons with adrenal cortical tumors, neither low nor high dose dexamathasone inhibits cortisol secretion
123
Q

an enzyme that catalyzes the conversion of angiotensinogen to angiotensin I.

124
Q

Angiotensin II acts on the ______________ to increase the conversion of corticosterone to adoseterone

A

Zona glomerulosa

125
Q

Hyper or Hypo [K] increases aldosterone secretion.

A

Hyperkalemia

126
Q

Actions of glucocorticoids (Cortisol)

A
  • Stimulation of gluconeogensis
  • Anti-inflammatory effects
  • Suppression of the immune response
  • Maintenance of vascular responsiveness to catecholamines
127
Q

Stimulation of gluconeogenesis by cortisols

A
  • Increase protein catabolis,
  • Decrease glucose utilization and insulin sensitivity of adipose tissue
  • Increase lipolysis, which provides more glycerol for the liver
128
Q

Anti-inflammatory effects of cortisol

A
  • induce syntheis of lipocortin
    • inhibitor of phospholipase A2
  • Inhibits production of IL-2 and inhbits proliferation of T lymphocytes
  • Inhibit the release of histamine and serotonin from mast cells and platelets
129
Q

Suppression of the immune response by cortisol

A
  • inhibit production of IL-2 and T lymphocytes, both of ehich are critical for cellular immunity
  • Used to prevent rejection of transplanted organs
130
Q

Maintenance of vascular responsiveness to catecholamines by the cortisol

A

Up regulates alpa 1 receptors on arterioles, increasing their sensitivity to the vasoconstrictor effects of Norepinephrine

131
Q

Actions of Mineralocorticoids (aldosterone)

A

Increase Na reabsorption (action on the principal cells of the late distal and collecting duct)

Increase renal K secretion(action of the principal cells of the distal tubule and collecting duct)

Increase renal H secretion (action on the alpha intercalated cells of the late distal tubule and collecting duct

132
Q

Addison disease

A

Primary adrenocortical insufficiency

  • most commonly caused by autoimmune destruction of the adrenal cortex and causes acute adrenal crisis
133
Q

Adrenocortical insufficiency is characterized by ____________

A
  • Decrease adrenal glucocorticoid, androgen, and mineralocorticoid
  • Increase ACTH (low cortisol levels, stimulate ACTH secretion by negative feedback)
  • Hypoglycemia (caused by cortisol deficiency)
  • Hyperpigmentation
  • Weight loss, weakness, nausea, and vomiting
  • Decrease pubic and axillary hair in women
  • ECF volume contraction, hypotension, hyperkalemia, and metabolic acidosis
134
Q

most commonly caused by autoimmune destruction of the adrenal cortex and causes acute adrenal crisis

A

Addison disease

135
Q

caused nu primary deficiency of ACTH

does not exhibit hyperpigmentation

does not exhibit volume contraction, hyperkalemia, or metabolic acidosis

A

Secondary adrenocortical insifficiency

136
Q

Adrenocortical excess

most commonly caused by the administration of pharmacologic doses of glucocorticoids

also caused by primaty hyperplasia of the adrenal glands

A

Cushing syndrome

  • Cushing disease when it is caused by overproduction of ACTH
137
Q

Cushing disease is characterized by ______

A
  • Increased cortisol and androgren levels
  • decrease ACTH (if caused by priamry adrenal hyperplasia or pharmacologic doses of glucocorticosteroids) increase ACTH if caused by overproduction of ACTH
  • hyperglycemia
  • Increase protein catabolism amd muscle wasting
  • Central obesity (round face, supraclavicular fat, buffalo hump)
  • Poor wound healing
  • Virilization of women (caused by elevate levels of adrenal androgens)
  • Hypertension (caused by elevated levels of cortisol and aldoseterone)
  • Osteoporosis (elevated cortisol levels cause increased bone reorption)
  • striae
138
Q

inhibitor of steroid hormone synthesis, can be used to treat cushing disease

A

Ketoconazole

139
Q

Hyperaldosteronism

Caused by aldosterone secreting tumor

A

Conn syndrome

140
Q

Conn syndrome is characterized by __________

A
  • Hypertension (increase sodium reabsorption)
  • Hypokalemia (increase K secretion)
  • Metabolic alkalosis (aldosterone increases H+ secretion)
  • Decrease renin secretion (increase ECF volume and BP inhibit renin secretion)
141
Q

Most common biochemical abnormality of the steroidogenic pathway

belongs to a group of dosorders characterized by adrenogenital syndrome

A

21B- Hydroxylase deficiency

142
Q

21B-hydroxylase deficiency is characterized by _________

A
  • Decrease cortisol and aldosterone levels
  • Increase 17-hyrdoxyprogesterone and progesterone levels
  • Increase ACTH
  • Hyperplasia of zona fasciculata and zona reticularis
  • Increase adrenal androgens and increase urinary 17-ketosteroids
  • Virilization in women
  • Early acceleration of linear growth and early appearance of pubic and axillary hair
  • Suppresion of gonadal function in both men and women
143
Q

17a hydroxylase deficiency is characterized by

A
  • Decrease androgen and glucocorticoid levels
  • Increase mineralocorticoid levels
  • lack of pubic and axillary hair
  • hypoglycemia
  • metabolic alkalosis, hypokalemia, and hypertension
  • Increaase ACTH
144
Q

_______link beta cells to each other, aplha cells to each other, and beta cells to alpha cells for rapid communication

A

gap junctions

145
Q

The major factor that regulates glucagon secretion is the ________________

A

blood glucose concentration

  • Increased blood amino acids stimulate glucagon secretion, which prevents hypoglycemia caused by unopposed insulin in response to a high potential meal
146
Q

The second messenger for glucagon is

147
Q

Glucose increases the blood glucose concentration

A
  • Increase glycogenolysis
  • increase gluconeogenesis
148
Q

Glucagon increases blood fatty acid and ketoacid concentration

A
  • Glucagon increases lipolysis. The inhibition of fatty acid synthesis in effect “shunts” substrates toward gluconeogenesis
149
Q

Ketoacids (B-hydroxybutyrate and acetoacetate) are produced from ___________

A

acetyl CoA

150
Q

Glucagon increases urea production

A

Amino acids are used for gluconeogenesis (stimulated by glucagon), and the resulting amino group are incorporated into urea

151
Q

Comparison of Insulin and Glucagon

152
Q

Secrete insulin

A

Beta cells

Central islet

153
Q

Secrete glucagon

A

alpha cells

outer rim of islet

154
Q

Secretes somatostanin and gastrin

A

Delta cells

Intermixed

155
Q

the _______ is packaged and secreted along with insulin, and its concentration is used to monitor beta cell function in diabetic patients who are receiving exogenous insulin

156
Q

major factor that regulates insulin secretion

A

Blood glucose concentration

  • increased blood glucose stimulates insulin secretion
157
Q

Mechanism of insulin secretion

A
  • Glucose, the stimulant for insulin secretion, binds to the glut2 receptor on the beta cells
  • Glucose is oxidized to ATP, which closes K channels in the cell membrane and leads to depolarization of the beta cells.
  • Depolarization opens Calcium channels, which leads to increase in tracellular calcium and then to secretion of insulin
158
Q

The ____ subunits of insulin receptor span the cell memnrane and have intrinsic tyosine kinase activity.

159
Q

Actions of Insulin

A
  • decreases blood glucose concentration
    • Increases uptake of glucose
    • Promotes formation of glycogen
    • decrease gluconeogenesis (increases the production of 2,6 biphosphate)
  • Decreases blood fatty acid and ketoacid concentraions
    • stimualtes fat deposition and inhibits lipolysis
    • inhibits ketoacid formation in the liver
  • Decreases blood amino acid concentration
    • insulin is anabolic
  • Decreases Blood K concentration
    • increases K uptake into the cells
160
Q

Secreted by the delta cells of the pancrease

Inhibits the secretion of insulin, glucagon, and gastrin

A

Somatostatin

161
Q

40% of the total Ca in blood is __________

A

bound to plasma proteins

  • 60% of the total Ca in blood is not bout nad is ultrafilterable
    • calcium complexed to anions
    • free ionized Ca
162
Q

_____ calcium is biologically active

A

Free, ionized

163
Q

Is seen in growing children

Intenstinal ca absorption exceeds urinary excretion, and the excess is deposited in the growing bones

A

Positive Calcium Balance

164
Q

Seen in women during pregnancy or lactation

intestinal calcium absorption is less than calcium excretion, and the deficit comes from the maternal bones

A

Negative Calcium Balance

165
Q

Major hormone for the regulation of serum calcium

synthesized and secrered by chief cells

A

Parathyroid hormones

166
Q

Secretion of PTH is controlled by serum calcium binding to _____________ in the parathyroid cell membrane

A

Ca-sensing receptors

  • Decreased serum calcium increases PTH secretion
    • decreased binding to the calcium sensing receptor
  • Mild decreases in serum [Mg] stimulte PTH secretion
  • Severe decreases in serm [Mg] inhibit PTH secretion and produce symptoms of hypoparathyroidism (hypocalcemia)
167
Q

second messenger for PTH secretion by theparathyroid gland is ____________

168
Q

Actions of PTH

A
  • increase in serum calcium and a decrease in serum phosphate
169
Q

The second messgener for PTH actions on its target tissues is ________

170
Q

PTH _________ bone resorption, which brings both calcium and phosphate from bone mineral into the ECF

171
Q

Resorption of the organic matrix of bone is reflected in increased_____________excretion

A

hydroxyproline

172
Q

PTH inhibits renal phosphate _________ in the proximal tubule and therefore, increases phosphate excretion (phosphaturic effect).

A

Reabsorption

173
Q

cAMP generated as a result of the action of PTH on the proximal tubule excreted in the ________

A

urine (urinaru cAMP)

174
Q

PTH increases renal calcium reabsorption in the __________.

A

Distal tubule

175
Q

PTH increases intestinal Calcium absorption indirectly by stimulating the production of ______________

A

1,25 dihydroxycholecalciferol in the kidney

176
Q

Primary hyperparathyroidism is most commonly caused by _________

A

parathyroid adenoma

  • Characterized by
    • increase serum calcium
    • decrease serum phosphate
    • increase urinary phosphate excretion (phosphaturic effect of PTH)
    • Increase urinary calcium excretion (increased filtered load of calcium)
    • Increase urinary cAMP
    • increase bone resortption
177
Q

caused by PTH-related peptide (PTH-rp) secreted by some malignant.

A

Humoral hypercalcemia of malignancy

  • PTHrp has all the physiologic actions of PTH
    • Increase serim calcium
    • Decrease serum phosphate
    • increase urinary phosphate excretion (phosphaturic)
    • decrease serum PTh levels
178
Q

Hypoparathyroidism is most commonly a result of __________ or ______________

A

thyroid surgery or congenital

  • characterized by
    • Decrease serum calcium and tetany
    • increase serum phosphate (hyperphosphatemia)
    • decrease urinary phosphate excretion
179
Q

______is the result of defective Gs protein in the kidney and bone, which causes end-organ resistance to PTH

A

Psudohypoparathyroidism type 1a - ALBRIGHT HEREDITARY OSTEODYSTROPHY

  • Hypocalcemia
  • hyperphosphatemia
  • circulating PTH levels are elevated
180
Q

Effects of Chronic renal failure

A
  • Increased serum phosphate
  • decreased ionized calcium
  • Decreased production of 1,25 dihydroxycholecalciferol
  • Decreased causes secondary hyperparathyroidism
  • Renal osteodystrophy
181
Q

autosomal dominat disorder with decreased urinary calcium excretion and increased serum calcium

caused by inactivating mutations of the calcium sensing receptors that regulate PTH secretion

A

Familial hypocalciuric hypercalcemia (FHH)

182
Q

Provides calcium and phosphate to ECF for bone mineralization

183
Q

Vitamin D deficiency in children

184
Q

In adults, vitamin D causes

A

Osteomalacia

185
Q

Vitamin D metabolism

A
  • Cholecalciferol, 25-hydroxycholecalciferol, and 24,25 dihydroxycholecalciferol are inactive
  • 1,25 dihydroxy cholecalciferol is the active form
    • catalyzed by the enzyme 1a-hydroxylase
186
Q

1a-hydroxylase activity is increased in _______

A
  • Decrease serum calcium
  • Increase PTH levels
  • Decrease serum phosphate
187
Q

Actions of 1,25 dihydroxycholecalciferol

A

coordinated to increase both calcium and phosphate in ECF to mineralize new bone

  • Increases intestinal calcium absorption. Vitamin D-Dependent Ca-binding protein (calbindin D-28K) is induced by 1,25 dihyroxycholecalciferol
  • Increase intestinal phosphate absorption
  • Increases renal reabsorption of calcium and phosphate
  • Increases bone resorption
188
Q

Calcitonin is synthesized and secreted by the __________ of the thyroid

A

Parafollicular cells

189
Q

Calcitonin secretion is stimulated by __________

A

increase in serum calcium

190
Q

Calcitonin acts primarily to ________

A

inhibit bone resorption

191
Q

_____ is defined by sex chromosone XY in males, and XX in females

A

Genetic sex

192
Q

Defined by the presence of tests in males and ovaries in females

A

Gonadal sex

193
Q

defined by the characteristics of the internal genital tract and the external genitalia

A

Phenotypic sex

194
Q

The testes of gonadal males secretes ____________ and ________

A

anti-mullerian hormone and testoterone

195
Q

____ stimulates the growth and differentiation of the wolffian ducts, which develop into male internal genital tract

A

Testosterone

196
Q

_____ causes atrophy of the mullerian ducts (which would have become the female internal genital tract

A

Anti-mullerian hormone

197
Q

Sexual differentiation in males and Female

198
Q

The ovaries of gonadal female secretes ______, but not anti -mullerian hormone or testosterone

199
Q

Testosterone is the major androgen synthesized and secreted by the _______

A

Leydig cells

200
Q

Leydig cells do not contain __________ or ________ and therefore do not synthesize glucocorticoids or mineralocorticoids

A

21B-hydroxylase

11B- hydroxylase

201
Q

____increases testosterone synthesis by stimulating cholesterol desmolase, the first step in the pathway

202
Q

Accessory sex organs contain _____, which converts testosterone to its active form, dihydrotestosterone

A

5a reductase

203
Q

Finasteride is __________ and may be used to treat benign prostatic hyperplasia. because they block the activation of testosterone to dihydrotestosterone in prostate

A

5 alpha reductase

204
Q

________ of the hypothalamus secrete GnRH into the hypothalamic -hypophysial portal blood.

A

Arcuate nuclei

  • GnRH stimualtes the anterior pituitary to secrete FSH and LH
205
Q

FSH acts on the _____ to maintain spermatogenesis.

A

Sertoli cells

  • The sertoli cells also secretes inhibin which is involved in negative feedback of FSH secretion
206
Q

LH acts to the ____ to promote testosterone synthesis.

A

Leydig cells

  • Testosterone acts via an intratesticular paracrine mechanism to reinforce the spermatogenic effects of FSH in the Sertoli cells
207
Q

______inhibits the secretion of LH by inhibiting the release of GnRH from the hypothalamus and by directly inhibiting the release if LH from the anterior pituitary

A

Testosterone

208
Q

______produced by the sertoli cells, inhibits the secretion of FSH from the anterior pituitary

209
Q

Actions of testosterone

A
  • Differentiation of epididymis, vas deference and seminal vessels
  • Pubertal growth spurt
  • Cessation of pubertal growth spurt (epiphyseal closure)
  • Libido
  • Spermatogenesis in sertoli cells (paracrine effect)
  • Deepening of voice
  • Increased muscle mass
  • Growth of penis and semonal vesicles
  • Negative feedback on anterior pituitary
210
Q

Actions of dihydrosterone

A
  • Differentiation of penis, scrotum, and prostate
  • Male hair pattern
  • Male Pattern baldness
  • Sebaceous gland activity
  • Growth of prostate
211
Q

caused by deficiency of andrigen receptors in target tissues of males

Testosterone and dihydrotestosterone actions in target tissues are absent

A

Androgen insensitivity disorder (testicular feminizing syndrome)

  • Female external genitalia but there is no genital tract.
  • Testosterone levels are elevated due to lack of testosterone receptors in the anterior pituitary (lack of feedback inhibition)
212
Q

In childhood, hormone levels are lowest and FSH____LH

A

greater than

213
Q

At puberty and during the reproductive years, hormone levels increase and LH _____ FSH

A

greater than

214
Q

In senesence, homone levels are highest and FSH ____ LH

A

Greater than

215
Q

Theca cells produce ______ (stimulated at the first step by LH). Andorstenedione diffuses to nearby granulosa cells, which contain 17B-hydroxysteroid dehydrogenase, which converts androstenedione to testosterone and aromatase which converts testosterone to 17B estradiol (stimulated by FSH)

A

testosterone

216
Q

FSH and LH stimulate the following in the ovaries

A
  • Steroidogenesis in the ovarian follicle and corpus luteum
  • Follicular development beyond the antral stage
  • Ovulation
  • Luteinization
217
Q

Actions of estrogen

A
  • Has both negative and positive feedback effects on FSH and LH secretion
  • causes maturation and maintenance of the fallopian tube, uterus, cervix, and vagina
  • Causes development of female secondary sex characteristics at puberty
  • Causes the development of the breasts
  • Upregulates estrogen, LH, and progesterone receptors
  • Causes proliferation and development of ovarian granulosa cells
  • Maintains pregnancy
  • lowers the uterine threshold to contractile stimuli during pregnancy
  • Stimulates prolactin secretion (but then blocks its action on the breast)
218
Q

Actions of progesterone

A
  • Has negative feedbacks effects on FSH and LH secretion during luteal phase
  • Maintains secretory activity of the uterus during the luteal phase
  • Maintains pregnancy
  • Raises the uterine threshold to contractile stimuli during pregnancy
  • Participates in development of the breasts
219
Q

Follicular Phase

A
  • days 0 to 14
  • A primordial follicle develops to the graafian stage, with atresia of neighboring follicles
  • :LH and FSH are upregulated in theca and granulosa cells
  • Estradiol levels increase and cause proliferation of the uterus
  • FSH and LH levels are suppressed by the negative feedback effect of estradiol on the anterior pituitary
  • Progesterone levels are low
220
Q

Ovulation

A
  • day 14
  • 14 days before menses, regardless of cycle length
  • LH surge (positive feedback)
    • burst of estradiol
  • Ovulation occurs as a result of the estrogen-induced LH surge
  • Estrogen decrease just after ovulation
  • Cervical mucus increases in quantity
221
Q

Luteal phase

A
  • day 14 to 28
  • the corpus luteum begins to develop, and it synthesizes estrogen and progesterone
  • Vascularity and secretory activity of the endometrium increase to prepare for receipt of a fertilized egg
  • Basal body temperature increases because the effect of the progesterone
  • If fertilization does not occur, the corpus luteum regresses at the end of the luteal phase. As a result, estradiol and progesterone levels decrease abruptylu
222
Q

Menses

A
  • Days 0 to 4
  • The endometrium is sloughed because of the abrupt withdrawal of estradiol and progesterone
223
Q

Menstrual cycle

224
Q

If fertilization occurs, the corpus luteum is rescued from regression by ___________ which is produced by the placenta

A

human chorionic gonadotropin

225
Q

The major placental estrogen is __________

226
Q

Prolactin levels ______ steadily during pregnancy

227
Q

Lactation does not occur during pregnancy because ______ and _____ block the action of prolactin on the breast

A

Estrogen and progesterone

228
Q

Ovulation is suppressed as long as ________ continues

A

lactation

  • Inhibits hypothalamic GnRH secretion
  • Inhibits the action of GnRH on the anterior pituitary and consequently inhibits LH and FSH secretion
  • Antagonizes the actions of LH and FSH on the ovaries

BRS (PHYSIO) (14 decks)

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