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ENDOCRINE SYSTEM > Pituitary Gland > Flashcards

Pituitary Gland Flashcards

1
Q

Derived from the primitive gut by an upward extension (Rathke’s pouch) of the epithelium of primitive mouth cavity (stomodeum)

A

Anterior lobe (Adenohypophysis)

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2
Q

Devs as downward evagination of neural tube at the base of the hypothalamus (infundibulum)

True brain extension

A

Neural or posterior lobe (Neurohypophysis)

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3
Q

A derivative of neural ectoderm

A

Neurohypophysis

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4
Q

Pituitary gland location

A

Hypophyseal fossa in the sella tursica

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5
Q

Pituitary is protected by and covered by

A

p/b Sphenoid bone (lateral & inferior)
c/b Dura (dense CT that lines sella tursica)

Covered superiorly by diagrama sellae, a dural sheath that forms the roof of the sella

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6
Q

Pituitary gland anatomic relations:

A

Superior: Diaphragma sella
Inferior: Body of sphenoid
Lateral: Cavernous sinus
Posterior: Dorsum sellae, basilar artery, pons

S. D
I. B
L. C
P. D

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7
Q

Gross characteristics of pituitary

A

Oval, bean-shaped, symmetrical, brownish red organ

Wt. = 0.4-0.9g

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8
Q

Anterior lobe (80%)

A

Pars distalis
Pars intermedia
Pars tuberalis

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9
Q

Largest, site of hormone-producing cells

A

Pars distalis

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10
Q

Consists of the median eminence of tuber cinereum, the infundibular stem of the hypophyseal stalk, and infundibular process or posterior neural tube

A

Posterior lobe/Neurohypophysis

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11
Q
  • reach the main body of the gland thru the diaphragma sellae
  • consists of infundibular stem and the adenohypophysial tissue that is continuous w the infundibular stem
A

Pituitary (hypophysial) stalk

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12
Q

Represents the bulk of the anterior lobe in humans and receives most of its bld supply from the superior (anterior) hypophyseal portal system

Source of pituitary tropic hormones

A

Pars distalis

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13
Q

Lies between pars distalis and neural lobe

Vestigial structure in humans

Avascular & almost non-existent in humans

A

Pars intermedia

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14
Q

Elongated collection of secretory cells

Superficially envelopes that infundibular stem and extends upward as far as the basal hypothalamus

Mist vascular portion of the anterior

A

Pars tuberalis

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15
Q

Located beneath 3rd ventricle

Smol, highly vascular protrusions of the dome shaped base, designated as tuber cinereum

The floor of third ventricle is designated as infundibulum (funnel)

A

Median eminence

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16
Q

Arises in median eminence

A

Infundibular stem (neural stalk) of posterior lobe

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17
Q

Retains neural connection w the ventral diencephalon

A

Pars nervosa

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18
Q

Retains neural connection w the ventral diencephalon

A

Pars nervosa

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19
Q

Storage and secretory site for hormones; not termed as endocrine gland

A

Posterior lobe

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20
Q

Granular secretory cells that exists in two forms

A

Chromophils

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21
Q

Account for abt 80% of the chromophils and are the cellular source of prolactin and GH

A

Acidophils (eosinophils)

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22
Q

Comprise abt 20% of chromophils are source of TSG, ACTH, LH, FSH, B-lipotropic hormone (B-LPH)

A

Basophils

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23
Q

Agranular cells that are not precursors of the chromophils are now known as to have an active secretory fxn

Degranulated secretory cells

A

Chromophobes

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24
Q

The GH-secreting cells are identified as acidophilic ind std hemotoxylin prep; located in the lateral portions of the anterior lobe

Accounts for abt 50% of the adenohypophyseal cells

A

Somatotropes

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25
Q

A second but distinct acidophilic-staining cell randomly distributed in the anterior lobe is the PRL-secreting cells

Two types:
Sparsely granulated and Densely granulated

A

Lactotropes

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26
Q

Glycoprotein product are basophilic and (+) PAS stain

Least common, making up <10% of adenohypophyseal cells

Primary thyroid failure –> hypertrophy (inc gland size)

A

Thyrotropes

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27
Q

ACTH, lipotropins (LPH) and endorphins are secreted by

A

Basophilic cells and embryonically of intermediate lobe origin

Corticotrophs represents 15-20%

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28
Q

Both LH and FSH originate from basophils, whose secretory granules are abt 200nm

10-15 of the anterior pituitary cells and they are located throughout the entire anterior lobe

A

Gonadotropes

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29
Q

Acidophilic

A

Somatotrope

Lactotropes

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30
Q

Basophilic

A

Corticotropes
Thyrotropes
Gonadotropes

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31
Q

400-550nm secretory granules

A

Corticotropes

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32
Q

They are almost exclusively postganglionic sympathetic fibers that innervate BV

A

Neurons in anterior lobe

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33
Q

Nerve fibers of the neurohypophysial sys terminate in the pars nervosa, interspersed between these neurosecretory fibers are numerous glial cells called

A

Pituicytes

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34
Q

Structural support

A

Pituicytes

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35
Q

Secretory activity of the adenohypophysis depends on activation of its cells by neurohormones called releasing factors carried to the anterior lobe by a portal system of veins called

A

Hypophyseoportal system

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36
Q

Several superior hypophyseal arteries anastomose freely around the

A

Median prominence

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37
Q

Capillaries arising from these vessels penetrate into the .edian eminence forming the

A

Primary plexus

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38
Q

These capillaries arising from venules that course downward to join an extensive network of sinusoids in the anterior lobe wc constitute the

A

Hypophyseal system

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39
Q

A basic tenet of the neurovascular hypophysis is that the conc of the hypophysiotropic hormones is greater in the

A

hypophyseoportal bld than anu other site in the vasculature

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40
Q

In humans, the capillaries at the base of the hypothalamus are formed directly from branches of the superior hypophyseal arteries wc arise from

A

Internal carotid arteries

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41
Q

The crucial regulatory connection between the hypothalamus and anterior lobe is via

A

Hypophysial portal vessels

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42
Q

The intermediate lobe isn’t perfused directly by the hypophysial portal sys but is regulated by

A

Bioaminergic secretomotor fibers originating in the hypothalamus

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43
Q

Blood supply of hypothalamus

A

Superior and inferior hypophysial arteries - branches of the internal carotid arteries

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44
Q

Venous drainage of hypothalamus

A

Intracavernous sinuses

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45
Q

Those hormones that stimulate secretion of hormonally active substances by other endocrine glands, liver or tissues

Stimulate target organs which in turn exert their effects on other body organs and tissues

A

Tropic hormones

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46
Q

Exert their major effects on nonendocrine targets

A

Nontropic hormone

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47
Q

Are a family of protein hormones having considerable sequence homology

Share common Ag determinants

All have growth promoting and lactogenic activity

A

Growth hormone-prolactin-chorionic somatomammotropin grp

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48
Q

Interact w cell surface receptors and activate adenylyl cyclase and employ cAMP as intracellular messenger

A

Glycoprotein hormone grp

FSH LH hCG

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49
Q

Consists of peptides that act as hormones

A

Pro opiomelanocortin peptide family

ACTH LPH MSH

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50
Q

Both synthesize a large precursor protein that is cleaved to form a family of hormones

A

Intermediate-lobe cells and corticotropes of the anterior lobe

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51
Q

After removal of signal peptide, this prohormone is known as

A

POMC

pro-opiomelanocortin

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52
Q

In the corticotropes, it is hydrolyzed to ACTH and B-LPH plus a small amt of B-endorphin, and these subs are secreted

A

POMC

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53
Q

In intermediate-lobe cells, POMC is further hydrolyzed to

A

corticotropin-like intermediate lobe peptide (CLIP), y-LPH and appreciable quantities of B-endorphin

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54
Q

Opioid peptide that has the 5 AA residues of met-enkephalin at its amino terminal end

A

B-endorphin

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55
Q

Act as storage foe hormones made by the hypothalamic neurons

A

Posterior pituitary

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56
Q

Released in significant amounts onli during childbirth and nursing women

A

Oxytocin

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57
Q

Used to induce labor or hasten labor that us progressing normally but at a slow pace

A

Natural and synthetic oxytocic drugs

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58
Q

It causes kidneys to reabsorb more water from the forming urine thus

U decreases
BV increases

A

ADH

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59
Q

ADH increases BP by causing

A

Constriction of arterioles -> vasopressin

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60
Q

Drinking alcohol beverages

A

inhibits ADH secretion and results to large amt output of urine

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61
Q

The bodies of the cells that secrete the posterior pituitary hormones are not located in the pituitary gland itself but are large neurons called

A

Magnocellular neurons

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62
Q

Location of magnocellular neurons

A

supraoptic and paraventricular nuclei of hypothalamus

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63
Q

Lowermost portion of hypothalamus

A

Median eminence

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64
Q

Connects inferiorly w the pituitary stall

A

Median eminence

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65
Q

Small arteries penetrate into the substance of the medium eminence and then additional small vessels return to its surface, coalescing to form the

A

Hypothalamic-hypophysial portal BV

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66
Q

TRH structure

A

Peptide of 3 AA

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67
Q

GnRH structure

A

Sibgle chain of 10 AA

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68
Q

CRH structure

A

Single chain of 41 AA

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69
Q

GHIH somatostatin

A

Single chain 14 AA

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70
Q

GHRH structure

A

Single chain 44 AA

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71
Q

PIH structure

A

Dopamine (a catecholamine)

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72
Q

Could facilitate transfer of regulatory substances from the CSF to pituitary

Allow post pit pept hormones, hypothalamic releasing/inhibiting hormones or anterior pituitary tropic hormones to have access to brain via CSF

A

Pituitary tanycytes

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73
Q

No direct arterial supply but receives bld from the median eminence wc contains hypothalamic releasing and inhi hormones

A

Adenohypophysis

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74
Q

Reach theur storage and release are by their axonal transport from neuron cell bodies where they are synthesized

A

Posterior pituitary hormones

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75
Q

Synthesized in situ

Secreted in response to hypothalamic peptides that reach the anterior pit by axonall transport followed by bld transport via portal veins

A

Anterior pituitary hormones

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76
Q

Paraventricular

A

TRH

CRH

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77
Q

Arcuate

A

GnRH
GHRH
PIF

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78
Q

Anterior periventricular

A

GHIH (somatostatin)

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79
Q

Target pituitary hormones of TRH

A

Thyrotropin
PRL
GH (pathological)

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80
Q

Target pituitary hormones of GnRH

A

LH
FSH
GH (pathological)

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81
Q

Target pituitary hormones of CRH

A

Adrenocorticotropin
B- and y-Lipotropin
B-endorphins

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82
Q

Target pituitary hormones of GHIH

A

GH
PRL
Thyrotropin
Adrenocorticotropin (pathological)

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83
Q

Target pituitary hormones of PIH

A

PRL
Thyrotropin
GH (pathological)

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84
Q

Characteristics of hypothalamic releasing hormones

A
  1. Secretion of pulses
  2. Sp plasma mem receptors
  3. Tranduction of signals thru Ca, mem phospholipid prod, cAMP as secondary messengers
  4. Stim of release of stored target anterior pituitary hormones via exocytosis
  5. Stim of synthesis of target ant pit hormones at transcriptional lvl
  6. Modification of biological activity of target ant pit hormones by post-translational effects such as glycosylation
  7. Stimulation of hyperplasia and hypertrophy of target cells
  8. Modulation of effects by up- or down-regulation of their own receptors
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85
Q

Peripheral gland hormones or subs that arise from tissue met cab exert feedback ctrl on both hypothalamus and ant pit gland

A

Long loop feedback

Usually (-)
Occasionally (+)

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86
Q

Neg fb by tropic hormones themselves thru effects on synthesis or discharge of related hypothalamic releasing or inhibiting hormones

A

Short loop

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87
Q

Hypothalamic releasing hormones may even inhibit their own synthesis by stimulating the discharge of a paired hypothalamic inhibiting hormone

A

Ultrashort LF

Nt bet 2 cells or transport of releasing hormone via pit tanycytes to CSF then to hypothalamus

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88
Q

Central pt of hypothalamic pituitary-peripheral gland axis

A

Anterior pituitary gland

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89
Q

Afferent impulse to the hypothalamus

A

Norepinephrine
Acetylcholine
Serotonin

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90
Q

Efferent impulses to median eminence

A 
Dopamine
Acetylcholine
y-aminobutyric acid GABA
Opioid peptide
B endorphins
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91
Q

Synthesized by the acidophils of the anterior lobe and is stored in v large amts in pituitary gland

4-10% of wet wt of pituitary gland wc is equivalent to 5-15mg

A

GH

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92
Q

GH has been synthesized in bacteria using recombinant DNA techniques, what is its structure?

A

Single (lyk ü)

Unbranched polypeptide chain cont 191 AA residues

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93
Q

Like all other pituitary hormones, GH is secreted episodically in periods of

A

20-30 mins

Large diurnal fluctuations

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94
Q

A regular nocturnal peak in GH secretion occury

A

1-2 hrs after onset of deep sleep

Correlates w stage 3 or 4 slow wave sleep

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95
Q

Principal GH in humans has approx MW of

A

22K GH w 2 disulfide bridges and 191 AA residues

90% pit
10% lacks AA

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96
Q

The basal growth hormone lvl measure by immunoassay in adult is normally

A

<3ng/mL

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97
Q

GH is bound to

A

2 proteins in plasma

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98
Q

The half life of circulating GH in humans is

A

6-20 mins

99
Q

Daily GH output

A

0.2-1.0mg/d in adults

100
Q

Release of GH is mediated by what?

Thus a-adrenergic, dopaminergic, serotoninergic agonists and B-adrenergic antagonists all stimulate GH release

A

Monoaminergic and serotoninergic pathways

101
Q

Stimulate GH secretion

A

Bromocriptine
Enkephalins
Endorphins
Opiates

102
Q

A dopamine agonist

A

Bromocriptine

103
Q

Potent stimulus of GH secretion as are pharmacologic doses of glucagon and vasopressin

A

Insulin-induced hypoglycemia

104
Q

Physiologic stimuli

A
  • Hypoglycemia
  • Increased plasma conc of AA (arg, leu, lys, trp, 5-hydroxytryptophan)
  • Decreased FFA conc
  • Estrogen stim GH syn and sec
105
Q

GH can inhibit its own secretion bia a short-FL that operates between

A

Anterior lobe and median eminence

106
Q

A tetradecapeptide (14 AA residues) that has been chemically synthesized

A

Somatostatin

107
Q

A product of parvicellular neurosecretory neurons that terminate in median eminence and produce hypophysiotropic hormones

A

Somatostatin

108
Q

Blocks insulin secretion, also glucagon, gastrin, and intestinal absorption of glucose

Hypogly

A

Somatostatin

109
Q

Decrease GH secretion but their predominant effect is the interference w the metabolic actions of GH

A

Glucocorticoids

110
Q

Stimulate GH secretion

A
  • decreased bld glucose
  • decreased bld FFA
  • starvation, fasting, protein def
  • trauma, stress, excitement
  • exercise
  • testosterone, estrogen
  • deep sleep (stage 2 and 5)
111
Q

Inhibit GH secretion

A
  • inc bld glucose
  • inc bld FFA
  • aging
  • obesity
  • GHIH (somatostatin)
  • GH (exogenous)
  • somatomedins (insulin like GF)
112
Q

Stimuli that increase secretion GH

A

Def of energy substrate

  • hypogly
  • 2-deoxyglucose
  • exercise
  • fasting

Increase in circulating lvls of certain AA

  • protein meal
  • infusion of Arg and some other AA

Glucagon

Stressful stumuli (huhuhu but y am i not getting any taller jk, fat lang)

  • pyrogen
  • lys vasopressin
  • psychological stress ugh

Going to sleep ooooooohhh

L-dopa and a-adrenergic agonists that penetrate brain

Apomorphine and other dopamine receptor agonists

Estrogens and androgens

113
Q

Stimuli yhat decrease GH secretion

A 
REM sleep
Glucose
Cortisol
FFA
Medroxyprogesterone
GH
114
Q

Synthesized mainly in liver

Also termed insulin-like growth (IGF)

Effects of GH on skeletal growth are mediated by a family of polypeptides called

A

Somatomedins

115
Q

Also necessary for normal osteogenesis

A

Thyroid hormone and insulin

116
Q

GH causes the liver to form several smol proteins called

A

Somatomedins

- most important is: somatomedin C

117
Q

Has a potent effect of increasing all aspects of bone growth

A

Somatomedin C

118
Q

Stimulates proliferation of chondrocytes and appearance of osteoblasts

A

GH thru somatomedin

- the increase in thickness of epiphysial (cartilaginous) end-plate accounts for the increase in linear skeletal growth

119
Q

After epiphysial fusion, bone length can no longer be increased by GH, but

A

Bone thickening can occur thru periosteal growth. It is this growth that accounts for the changes seen in hypersomatotropism (acromegaly)

120
Q

GH has predominantly what effect on skeletal and cardiac muscle, where it stimulates the synthesis of protein, RNA, DNA

A

Anabolic effects (CHON MET)

121
Q

GH reduces circulating lvls of AA and urea (promotes nitrogen retention) wc accounts for the term

A

Positive nitrogen balance

Urinary urea conc also decreases

122
Q

GH overall effect on adipose tissue

Dec: TAGs
Inc: plasma FAs and glycerol

A

Catabolic effect (FAT MET)

123
Q

GH increases hepatic oxidation of FA to the

A

Ketone bodies
Acetoacetate
B-hydroxybutyrate

124
Q

GH is a diabetogenic hormone. Because of its anti-insulin effect, GH has the tendency to cause

A

Hyperglycemia

125
Q

GH can produce an insulin-resistance diabetes mellitus primarily because of its

A

Lipolytic effect

126
Q

These can antagonize the effect of insulin to promote glucose uptake by skeletal muscle and adipose

A

FFAs

127
Q

Excess acetyl coenzyme-A production favors

A

Gluconeogenesis

- bcs pyruvate carboxylase requires acetyl-CoA to form oxaloacetate from pyruvate

128
Q

Rate-limiting factor in pyruvate kinase

A

Oxaloacetate

129
Q

Do u remember ted mosby’s statement: “it’s funny how you just

…find things”

A

But really, they never tell you that either you keep it and hold it dear, or you lose it because of being too preoccupied by a lot of things going on in your life. It should be “isn’t it funny how you just find things, and wonder if you’ll have to let it go or hold on to it up to the end.” Ok so random

130
Q

acetyl-CoA inhibits glycolysis by inhibition of

A

PK

131
Q

FFAs stimulate hepatic glucose synthesis mainly via the stimulation of

A

fructose biphosphatase

132
Q

What are inhibited by FFAs wc bld glycolysis and gluconeogenesis favors

A

PK and phosphofructokinase

133
Q

Blocks glycolysis at the phosphofructokinase step

A

Citrate

134
Q

Because of its anti-insulin effect, GH inhibits glucose transport in

A

Adipose tissue

135
Q

Bcs adipose tissue requires glucose for TAG synthesis, GH antagonizes

A

Insulin-stimulated lipogenesis

136
Q

Mineral metabolism: GH promotes renal absorption of

A

Ca
Ph
Na

137
Q

GH promotes a positive Ca, Mg and Ph balance and causes the retention of

A

Na
K
Cl

138
Q

Essential for postnatal growth and normal carbs, lipid, nitrogen, mineral met

A

GH

139
Q

The growth related effects are primarily mediated by

A

IGF-I

  • family of insulin like gene
  • similar to proinsulin
140
Q

Elevated in newborns

A

Plasma GH

141
Q

Rise during childhood, reaching a peak at 13-17 years old

A

IGF-I

142
Q

Constant throughout postnatal growth

A

IGF-II

143
Q

Growth spurt that occurs at puberty is d/t protein anabolic effect of

A

Androgens and secretion of adrenal androgens, increases in both sexes

144
Q

Tx of these increases GH responses to stimuli s/a insulin and arginine

A

Estrogen and androgens

145
Q

Sex steroids also increase plasma IGF-I but cant inc in GH deficiency

A

Thus, it appears that the sex hormones produce an increase in amplitude of the spikes in GH secretion that increases IGF-I secretion and cause growth

146
Q

Terminate growth by causing epiphysis to fuse long bones (epiphysial closure)

A

Estrogen

  • bcs linear growth ceases
  • this is y pt w sexual precocity are apt to be dwarfed
147
Q

Why do men before puberty tend to be tall bcs estrogen prodxn is decreased and epiphysis remain open so that some growth continues past the normal age of puberty

A

Men were castrated

148
Q

Necessary for a completely normal rate of growth

A

Thyroid hormones

149
Q

Period wherein accelerated growth is partly a continuation of the fetal growth pd

A

First period

150
Q

At the time of puberty, this is d/t GH, androgens, estrogens and cessation of growth is due in large part to closure of the epiphysis by estrogens

A

Second growth spurt

151
Q

During infancy, growth isn’t a continuous process but is

A

Episodic or saltatory

152
Q

Increases in length of human infants of how many cm in a few days are separated by pds of 2-63 days during wc no measurable growth can be detected

A

0.5-2.5cm

153
Q

Inc GH

Dec somatomedin

A

Growth retardation

  • kwashiorkor
  • African pygmy (resistant to action of GH; both normal, decreased GH receptors)
154
Q

GH overproduction in adolescence

Excessive growth of long bones

A

Gigantism

8ft

155
Q

Excess GH secretion in adulthood (after epiphysial plates of long bones have fused, causes cartilage area growth persists)

A

Acromegaly

  • facial features
  • underbite (prognathism)
  • prominent brow
  • enlarged hands and feet
  • soft tissue hypertrophy (e.g cardiomegaly, hepatosplenomegaly, renomegaly)
156
Q

Decreased GH secretion in immature persons lead to

A

Stunted growth

Dwarfism

157
Q

Stunted growth or Dwarfism is accompanied by

A

Sexual immaturity
Hypothyroidism
Adrenal sufficiency

158
Q

Overall lack of anterior pituitary hormones (panhypopituitarism) or isolated genetic deficiency

A

GH def

159
Q

Rare in adults

Clinical manifestations: impaired hair growth and tendency toward fasting hypoglycemia

A

Selective GH def

160
Q

Tx of choice for hypersomatotropism

A

Selective surgical extirpation of pituitary adenoma w/o damage to other pituitary fxns

161
Q

Effective in suppressing, but not normalizing, GH lvls in most acromegalic pt

This tends to stimulate GH sec in normal indiv

A

Bromocriptine

162
Q

Disorders associated w GH def can be treated with

A

HGH

163
Q

Lactogenic hormone, mammotropic and galactopoietic hormone

A

Prolactin

164
Q

Synthesized in the pituitary acidophils

A single peptide chain containing 198 AA residues

Doesn’t regulate the fxn of a secondary endocrine gland in humans

A

Prolactin

165
Q

A putative releasing hormone for PRL

Hasn’t been identified or chemically synthesized however one of these releasing factors is TRH (vauses TSH release)

A

PRF

166
Q

Its secretion increases abt 1 hr after onset of sleep
And increases continuous throughout sleep pd

Nocturnal peak occurs later than that for GH

A

PRL

167
Q

Enhanced by exercise or stress ooof example surgery under gen anes, MI, repeated veni hahahaha aww

A

PRL

  • inc by 8th wk preg
  • peak on 38th wk preg
168
Q

Elevated in those w primary hypothyroidism who believed to have high TRH in hypophyseoportal circ

A

Serum PRL

169
Q

Stimulate PRL secretion

A

Dopamine antagonist (phenothiazine & tranquilizers)
Adrenergic blockers
Serotonin agonists

170
Q

What interferes w portal circ to pituitary gland that also cause PRL release

A

Pituitary stalk secretion and lesion

171
Q

Physiologically most important PIF

Secreted into hypophysial portal vessels

A

Dopamine

172
Q

Block PRL secretion

A

Serotonin antagonists abd dopamine agonists (bromocriptine)

173
Q

Administered during postpartum pd reduces PRL sec to nonlactating lvls abd terminates lactation

A

Bromocriptine

174
Q

Not a gonadotropic hormone in women

Doesn’t hav important role in maintaining secretory fxn of corpus luteum

A

PRL

175
Q

Immediately following preg, PRL stimulates galactocyltransferase activity, leading to synthesis of

A

Lactose

176
Q

High PRL in serum is associated w

A

suppressed LH and anovulation

  • accounts for absence of menses (amenorrhea) during postpartum lactation
177
Q

With continued nursing,

A

FSH rise

LH remain low

178
Q

In early postpartum pd,

A

FSH and LH both low

179
Q

Not rare but frequently in undiagnosed bcs galactorrhea occurs in only abt 30% of cases

A

Hyperprolactinemia

180
Q

Hyperprolactinemia in women and men

A

Women: infertility and amenorrhea
Men: a cause of impotenxe and decreased libido

181
Q

PRL hypersecretion tx

A

Bromocriptine

182
Q

A dopamine agonist that lowers PRL lvls and usually restores normal gonadal fxn

A

Bromocriptine

183
Q

Causes vasoconstriction of arterioles and increase in systemic BP

A

Vasopressin

184
Q

Biologically active form of ADH in humans

A

Arginine vasopressin

185
Q

A hypothalamic hormone synthesized in the supraoptic and paraventricular nuclei in ventral diencephalon

A

ADH or vasopressin

186
Q

What synthesize, store and secrete ADH

A

Unmyelinated neurosecretory neurons

187
Q

Terminates in pars nervosa or posterior lobe of the pituitary gland (Neurohypophysis)

A

Supraopticohypophyseal tract

188
Q

Peptidergic neurons that conduct action potentials

A

Neurosecretory neurons

189
Q

The hypothalamic nuclei that synthesize and secrete ADH are collectively called

A

Magnocellular neurosecretory neurons

190
Q

Polypeptide specifically octa or nonapeptide w a molecular wt of 1000

A

ADH

191
Q

If 2 cysteine residues are considered as a single cysteine residue, ADH is an

A

Octapeptide

192
Q

If 2 cysteine residues are numbered individually

A

Nonapeptide

193
Q

Physiologic carrier proteins for intraneural transport of ADH and are released into the circulation w neurosecretory products (ADH oxytocin) without being bound to the hormone

A

Neurophysins

194
Q

Biological half life of ADH

A

16-20 mins

195
Q

Major stimuli for ADH secretion

A

Hyperosmolality and effective circulating BV depletion

196
Q

Prime determinant of ADH secretion and most common physiologic factor altering the osmolality of bld is water depletion or water excess

A

Hyperosmolality

1-2% increase in plasma osmolality

197
Q

Located in the anterior hypothalamus and are distinct from the cells that sybthesize ADH

A

Osmoreceptors

  • lowest threshold (most sensitive) to changes in osmolal conc of plasmA
  • stimulation causes reflex secretion of ADH
198
Q

Cross tha BBB relatively slowly

Are potent stimulators of ADH release

A

Na and mannitol

199
Q

Less potent stimulus for ADH prod and secretion that hypernat for same lvl of osmolality

A

Hyperglycemia

200
Q

Hyperglycemia associated w insulin def

A

Uncontrolled DM

201
Q

Decreased effective circulating BV

More dominant stimulus to ADH release that js hyperosmolality

A

Hypovolemia

202
Q

Will evoke ADH release

A

10-25% decrease in BV

203
Q

Sufficient to cause release enough ADH to participate in immediate regulation of BP

A

10% decrease in BV

204
Q

May cause ADH release

A

Contraction of BV without an alteration in the tonicity of body fluids

205
Q

Baroreceptors. Hemodynamic changes (changes in BV, BP or both) are mediated by

A

Autonomic (parasympathetic) afferents

  • they arise in pressure (vol) - sensitive receptors in the atria, aortic arch, carotid sinus, great veins and pulmonary vessels and traject via the vagal and glossopharyngeal nerves to primary synapses in the nucleus tractus solitarius in the brain stem
206
Q

Primary mediators of vol effects on ADH secretion

A

Low pressure (stretch) receptors

207
Q

Inhibits ADH-producing cells

A

Inc BP

208
Q

Reduces firing frequency of baroreceptors, causing stimulation of ADH syn and release

A

Decreased BP

209
Q

Can be a dominant stimulus but isn’t the physiologic regulator of ADH secretion

A

Baroregulation of ADH secretion

210
Q

Expansion of intracellular vol of osmoreceptors secondary to hyposmolality of ECF

A

Inhibits ADH secretion

211
Q

What contributes to hyposmolality of ECF

A

Water ingestion

212
Q

Inhibits ADH release

A

Increased arterial pressure secondary to vascular of ECF volume expansion

Also inc tension in left atrial wall, great veins sec to inc intrathoracic BV dt hypervolemia, a reclining position, neg pressure breathing and water immersion up to neck

Also recumbent, inc central BV leads to atrial pressure

Also sleep, prod of a conc urine dt redxn of BP

213
Q

Stimuli

Postive pressure breathing

A

Physiologic:

Hyperosmolality
Upright
Exercise

Patho:

Dec BV
NS
Cirrhosis
CHF
Hypothalamic dse
Pulmonary dis
CNS dis
Hypothyroidism
Na def
Vasovagal rxn lipong
Pain nausea emotional stress haixt
DM

Pharmacologic:

Li
Morphine high dose
Barbiturates
Nicotine
Ache
Diuretics
Isoproterenol
Nitroprusside
Trimethaphan
Histamine
Bradykinin
Angio II
Insulin
2-deoxy-D-glucose
Cholinergic
B-adrenergic agonists
214
Q

Inhibitors

Neg PB

A

Hyposmolality
Recumbent positio

DI
Inc BP
Hyposmolality
SIADH

Norepi
Ethanol
Caffeine
Anticholinergic
CO2
Marphine low dose
Phenytoin
Li
215
Q

Major site of ADH action

A

Receptor in basolateral membrane of principal cells of the cortical and medullary collecting ducts where ADH increases that permeability to water

216
Q

ADH w its effect on increased water reabsorption

A

Leads to prodxn of urine w a decreased vol and increased osmolality

217
Q

ADH stim ACTH from the

A

Anterior lobe of pituitary gland

218
Q

Plays a role in ctrl aldosterone secretion

A

ACTH

219
Q

Excessive or inappropriate secretion of ADH from posterior lobe or from an ectopic (nonhypothalamic) source, s/a malignant tumor – bronchogenic carcinoma

A

SIADH

220
Q

Water retention occurs leading to

A

Expansion of bld and ECF volumes

221
Q

Present dt suppression of aldosterone secretion

A

Hypernatriuria

Hyponatremia

222
Q

SIADH tx

A

Demeclocycline

223
Q

A tetracycline that blocks effect of ADH

A

Demeclocycline

224
Q

May cause nephrogenic diabetes

A

Demeclocycline
Li carbonated
Amphotericin B
Methoxyflurane

225
Q

Complete or partial faulure to either ADH sec or renal response to ADH

A

DI

226
Q

Characterized by a decrease renal watee reabsorption by collecting ducts

A

DI

227
Q

Dec watee reabsorption = diuresis of dilute U

3-20L/day

A

Polyuria

228
Q

U output is directly related to the volume of water delivered to the coll ducts

A

Nephrogenic diabetes

229
Q

Thirst and inc qater intake

A

Polydipsia

230
Q

Diagnosis of diabetes insipidus in a polyuric pt is confirmed by

A

Insignificant diuresis or prodxn of hypertonic urine following water restriction by hypertonic saline infusions

231
Q

Response to injected vasopressin

A

Neurogenic DI

232
Q

Lack response to vasopressin

A

Nephrogenic DI

233
Q

Neurogenic DI hormonal therapy

A

ADH administration as vasopressin tannate or nasal lysine vasopressin

234
Q

Neurogenic DI non-hormonal therapy

A

Oral hypoglycemia agents (chlorpropamide)
Thiazide diuretics w Na restriction
Carbamazepine
Clofibrate

235
Q

Nephrogenic DI tx

A

Thiazide

236
Q

Inhibits Na reabsorption in diluting segment (ALH)

A

Thiazide

237
Q

A nonapeptide

Synthesized in cell bodies of peptidergic neurons of magnocellular neurosecretory sya

Mainly in paraventricular nuclei of hypothalamus

Stored un posterior lobe same w ADH

A

Oxytocin

238
Q

Brought abt by stimulation of cholinergic nerve fibers

A

Oxytocin secretion

239
Q

Reflex (milk letdown or ejection) secretion of oxytocin into bldstream and to milk release ff a latent pd of

A

30-60 seconds

240
Q

Excitation of adrenergic fibers to the hypothalamus

A

Inhibits peptide release (oxytocin)

241
Q

What else inhibits oxytocin secretion?

A
  • activation of sympa w concomitant release of norepi and epi
242
Q

What inhi oxytocin release?

A

enkephalins

243
Q

Inhibits endogenous oxytocin release resulting in reduced myometrial contractility

A

Ethanol

ENDOCRINE SYSTEM (6 decks)

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