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House Clinical Pathology > HP Adrenal Axis 1 > Flashcards

HP Adrenal Axis 1 Flashcards

1
Q

The Pituitary Gland

Small outgrowth of the _______

Size of _____ ( ___cm; apprx ___mg)

A

forebrain

half a pea

<1; 500

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2
Q

Two functional parts

______hypophysis (_______ pituitary)

______hypophysis (_______ pituitary)

A

Adeno; anterior

Neuro; posterior

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3
Q

Two functional parts

The Move together during development(T/F)

Adenohypophysis
From ________ – _______ above ____

Neurohypophysis
From _______

A

T

Rathke’s pouch; ectoderm above mouth

Hypothalamus

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4
Q

Blood and nerve supply
Hypothalamus

Anterior pituitary
Blood supply from ________ of hypothalamus – a _______

Posterior pituitary
_________ and ________ in hypothalamus

A

median eminence; portal system

Supraoptic and paraventricular nuclei

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5
Q

Hypothalamic neurons release hormones directly into ______

A

capillary plexus

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6
Q

Posterior pituitary hormones

Vasopressin/Antidiuretic hormone (ADH)

Produced by ________

It Conserves _____

________ urine

Water reabsorption by _________

Deficiency:__________
Extreme ______ and ______
Increase plasma _______ and _______

Excess: inappropriate ADH “water intoxication”

A

supraoptic nucleus

water

Concentrates ; collecting tubule

diabetes insipidus ; thirst and polyuria

sodium and osmolality

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7
Q

Posterior pituitary hormones

Oxytocin

________________

A

Milk let-down

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8
Q

Anterior pituitary hormones

List 6

A

TSH: Thyroid stimulating hormone

ACTH: Adrenocorticotrophic hormone
LH: Luteinising hormone

FSH: Follicle stimulating hormone

Prolactin

GH: Growth hormone

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9
Q

HYPOTHALAMUS - corticotropin releasing hormone (CRH)

Release is Influenced by ______signals e.g. Stress, and regulated by ————- from ______

Action is to stimulate the ________ to synthesize and release ——-

A

Higher centre

negative feed back; free-Cortisol.

anterior Pituitary

ACTH

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10
Q

PITUITARY- adrenocorticotropic hormone (ACTH)

Precursor is ————-.

Released in response to ——

Main action is acute regulation of steriodogenesis in ______mainly zonal _______ hence;

maintain intergrity of adrenal cortex tissue :

-stimulation of ___________ synthesis
-with minimal effect on _______ synthesis
- Also stimulates ______ to produce ———.

A

pre-opiomelanocortin

CRH; adrenal gland ; fasciculata

glucocorticoid (Cortisol)

mineralocorticoid (Aldosterone)

melanocytes; melanin

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11
Q

List the zones, and the hormones

zona _______ ; _______

zona ————-;_______

zona ————-;_________

A

glomerulosa ; mineralocorticoids (aldosterone)

fasiculata ; glucocorticoids (cortisol)

reticularis; sex steroids (androgens)

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12
Q

Steroids are lipophilic, (low or high?) -molecular weight compounds derived from ________ that play a number of important physiological roles.

A

Low

cholesterol

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13
Q

The steroid hormones are synthesized mainly by endocrine glands such as the _______,__________ and during gestation by the ___________, and are then released into the blood circulation.

They act both on ———- tissues and the ___________

A

gonads (testis and ovary), the adrenals

fetoplacental unit

peripheral target

central nervous system (CNS).

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14
Q

Thus, gonadal steroids influence the —————— of the genitalia and of the ______, determine secondary sexual characteristics during development and sexual maturation, contribute to the ____________ in adulthood and control or modulate sexual behaviour.

A

sexual differentiation; brain

maintenance of their functional state

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15
Q

circulating steroids are extensively metabolised _____, notably in the ———, and in their ________, where conversion to an active form is sometimes required before they can elicit their biological responses.

A

peripherally; liver; target tissues

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16
Q

• Steroid metabolism is therefore important not only for the production of these hormones, but also for the regulation of their cellular and physiological actions

T/F

A

T

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17
Q

The parent compound from which all steroids are derived is ______ which has the ———— structure.

A

cholesterol

perhydrocyclopentanophenanthrene

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18
Q

___________ give rise to a great number of possible stereoisomers

A

Functional groups

19
Q

Stereoisomerism is very important for biological activity
T/F

A

T

20
Q

Cholesterol can be synthetised in ____ steroid- producing tissues from_____ in the liver, the ____ and the _____

A

all

acetate

skin; intestinal mucosa

21
Q

Steroid hormone formation in endocrine glands relies mostly on _________ ( ——- cholesterol).

A

exogenous cholesterol

plasma

22
Q

Androgen formation in the adrenals is limited to ————- and ________, whereas in the testes the presence of 17ß- hydroxysteroid dehydrogenase (17HSD) in _______ cells (under the control of LH) ensures the formation of ________, the principal “ male “ hormone.

A

dehydroepiandrosterone

androstenedione

Leydig

testosterone

23
Q

________ is the main glucocorticoid secreted by human adrenal glands.

A

Cortisol

24
Q

Progesterone is produced by the ________ during the first 6-8 weeks of gestation, but during pregnancy the main source for this steroid is the ______.

A

corpus luteum

placenta

25
Q

Estrogen levels (and that of its metabolite _____) rise markedly during gestation.

The substrate for estrogen biosynthesis in the fetoplacental unit is ____________ which is obtained from the ______ bloodstream

A

estriol

dehydroepiandrosterone sulfate (DHEAS)

fetomaternal

26
Q

Aromatase activity is mainly found in the _______,_________, and ———— , and is also membrane- bound.

Its substrate is either _______ or ______

A

ovary, the placenta and the brain

4- androstenedione or testosterone.

27
Q

Inability to secrete normal levels of adrenals steroids may result in ___________________________ following hyperstimulation by _________________

In the majority of cases, this syndrome is due to _____________ , and is associated with increased adrenal androgen secretion and ____________ in girls

A

CONGENITAL ADRENAL HYPERPLASIA (CAH)

ACTH

21-hydroxylase deficiency

Partial virilization

28
Q

Less common adrenal enzyme deficiencies involve either ________ (with a possible increase in ________ levels) or __________ ( ________ may be deficient with normal levels of ———-).

A

17-hydroxylase

mineralocorticoid

18- hydroxylase

aldosterone; cortisol

29
Q

Defects in testicular androgen synthesis (17,20-desmolase or 17ß- hydroxysteroid dehydrogenase deficiency) can lead to ______________________

However, in more than 80% of the cases, it is assumed to result from abnormalities in __________________________

A

male pseudohermaphroditism.

androgen action at the target cell level

30
Q

Defects of excess secretion of steroid hormones like ___________ (excess cortisol)

Also defect of specific enzyme deficiency like ___________ (Aldosterone deficiency)

A

cushings syndrome

Addison’s syndrome

31
Q

Steroids are released into the blood circulation as soon as they are formed

T/F

A

T

32
Q

Secretion rates are therefore directly related to the ___________ and ______

A

biosynthetic activity of the gland and to the blood flow rate.

33
Q

unconjugated steroids are found mostly _________________ .

Binding to plasma ______ (which accounts for ____% of the bound fraction) is not specific, whereas binding to either _____________________ or the __________________ is based on more stringent stereospecific criteria

A

bound to carrier proteins

albumin; 20-50

corticosteroid-binding globulin (CBG) or the sex hormone-binding globulin (SHBG)

34
Q

the sex hormone-binding globulin (SHBG)

sometimes called __________________

A

sex steroid-binding protein” SBP]

35
Q

The “ free fraction “ ( _____ % of total plasma concentration) is usually considered to represent the biologically active fraction (i.e. hormone that is directly available for action)

A

1-10

36
Q

Other major roles of plasma binding proteins include
• Act as a “ _______ “

•_________ for active hormones

• protect the hormone from ________ (notably by _____ enzymes) and increase the half-life of biologically active form

A

buffer

reservoir

peripheral metabolism

liver

37
Q

Peripheral metabolism of circulating steroids

They have a very (small or latge?) distribution volume.

In their target tissues, steroids are concentrated by an __________ which relies on their __________

High concentration of steroids are also found in _______ though this is not a _____ for hormone action.

In the human male, adipose tissue contains _______ activity, and seems to be the main source of androgen-derived ____ found in the circulation

Most of the peripheral metabolism occurs in the _____ and to some extent in the ______, which are the major sites of hormone inactivation and elimination

A

Large

uptake mechanism ; binding to intracellular proteins

adipose tissue; target

aromatase; estrogens

liver; kidneys

38
Q

Steroid in target tissues
Steroids have ____________-term effects.

A

both short- and long

39
Q

Steroid in target tissues

Long-term effects (lasting from hours to days) usually involve interaction of the hormone with a _________

The steroid-receptor complex regulates __________

A

specific receptor

gene transcription

40
Q

Certain hormones need be converted to active form before binding to specific receptors in target tissues
This metabolic activation step is either an absolute prerequisite or a way of achieving a range of complex effects which involve interaction with more than one type of receptor.

T/F

A

T

41
Q

Conversion of testosterone to ______ is required for its action on prostate growth and function

whereas

aromatization to _______ in the ____ is mandatory for some of its developmental, neuroendocrine and behavioral effects.

A

5α-DHT

estradiol-17ß; brain

42
Q

When conversion of the circulating hormone is required for its action, the original compound is sometime called a _________.

A

prehormone

43
Q

Various disorders can result from a genetic defect in target tissue metabolism.

• In male pseudohermaphroditism (i.e. _____ individuals with a _____ phenotype) due to _______ deficiency.

Individuals with this _______ disorder have ______ plasma levels of testosterone, but this hormone _________________, in the target tissues and is ineffective.

This type of androgen resistance syndrome results notably in an abnormal ____________ of the male genitalia.

A

46,XY; feminised; 5α-reductase

autosomal recessive

normal ; cannot be converted to its active metabolite, 5α-DHT

sexual differentiation

44
Q

V

A

F

House Clinical Pathology (45 decks)

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