HP Adrenal Axis 1 Flashcards by Iseoluwa Ojo

The Pituitary Gland

Small outgrowth of the _______

Size of _____ ( ___cm; apprx ___mg)

forebrain

half a pea

<1; 500

How well did you know this?

Not at all

Perfectly

Two functional parts

______hypophysis (_______ pituitary)

Adeno; anterior

Neuro; posterior

How well did you know this?

Not at all

Perfectly

Two functional parts

The Move together during development(T/F)

Adenohypophysis
From ________ – _______ above ____

Neurohypophysis
From _______

Rathke’s pouch; ectoderm above mouth

Hypothalamus

How well did you know this?

Not at all

Perfectly

Blood and nerve supply
Hypothalamus

Anterior pituitary
Blood supply from ________ of hypothalamus – a _______

Posterior pituitary
_________ and ________ in hypothalamus

median eminence; portal system

Supraoptic and paraventricular nuclei

How well did you know this?

Not at all

Perfectly

Hypothalamic neurons release hormones directly into ______

capillary plexus

How well did you know this?

Not at all

Perfectly

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”

supraoptic nucleus

water

Concentrates ; collecting tubule

diabetes insipidus ; thirst and polyuria

sodium and osmolality

How well did you know this?

Not at all

Perfectly

Posterior pituitary hormones

Oxytocin

________________

Milk let-down

How well did you know this?

Not at all

Perfectly

Anterior pituitary hormones

List 6

TSH: Thyroid stimulating hormone

ACTH: Adrenocorticotrophic hormone
LH: Luteinising hormone

FSH: Follicle stimulating hormone

Prolactin

GH: Growth hormone

How well did you know this?

Not at all

Perfectly

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 ——-

Higher centre

negative feed back; free-Cortisol.

anterior Pituitary

ACTH

How well did you know this?

Not at all

Perfectly

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 ———.

pre-opiomelanocortin

CRH; adrenal gland ; fasciculata

glucocorticoid (Cortisol)

mineralocorticoid (Aldosterone)

melanocytes; melanin

How well did you know this?

Not at all

Perfectly

List the zones, and the hormones

zona _______ ; _______

zona ————-;_______

zona ————-;_________

glomerulosa ; mineralocorticoids (aldosterone)

fasiculata ; glucocorticoids (cortisol)

reticularis; sex steroids (androgens)

How well did you know this?

Not at all

Perfectly

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

Low

cholesterol

How well did you know this?

Not at all

Perfectly

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 ___________

gonads (testis and ovary), the adrenals

fetoplacental unit

peripheral target

central nervous system (CNS).

How well did you know this?

Not at all

Perfectly

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.

sexual differentiation; brain

maintenance of their functional state

How well did you know this?

Not at all

Perfectly

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.

peripherally; liver; target tissues

How well did you know this?

Not at all

Perfectly

• 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

How well did you know this?

Not at all

Perfectly

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

cholesterol

perhydrocyclopentanophenanthrene

How well did you know this?

Not at all

Perfectly

___________ give rise to a great number of possible stereoisomers

Study These Flashcards

Functional groups

Stereoisomerism is very important for biological activity
T/F

Study These Flashcards

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

Study These Flashcards

all

acetate

skin; intestinal mucosa

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

Study These Flashcards

exogenous cholesterol

plasma

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.

Study These Flashcards

dehydroepiandrosterone

androstenedione

Leydig

testosterone

________ is the main glucocorticoid secreted by human adrenal glands.

Study These Flashcards

Cortisol

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

Study These Flashcards

corpus luteum

placenta

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

estriol dehydroepiandrosterone sulfate (DHEAS) fetomaternal

Aromatase activity is mainly found in the _______,_________, and ———— , and is also membrane- bound. Its substrate is either _______ or ______

ovary, the placenta and the brain 4- androstenedione or testosterone.

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

CONGENITAL ADRENAL HYPERPLASIA (CAH) ACTH 21-hydroxylase deficiency Partial virilization

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

17-hydroxylase mineralocorticoid 18- hydroxylase aldosterone; cortisol

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 __________________________

male pseudohermaphroditism. androgen action at the target cell level

Defects of excess secretion of steroid hormones like ___________ (excess cortisol) Also defect of specific enzyme deficiency like ___________ (Aldosterone deficiency)

cushings syndrome Addison’s syndrome

Steroids are released into the blood circulation as soon as they are formed T/F

Secretion rates are therefore directly related to the ___________ and ______

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

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

bound to carrier proteins albumin; 20-50 corticosteroid-binding globulin (CBG) or the sex hormone-binding globulin (SHBG)

the sex hormone-binding globulin (SHBG) sometimes called __________________

sex steroid-binding protein" SBP]

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)

1-10

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

buffer reservoir peripheral metabolism liver

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

Large uptake mechanism ; binding to intracellular proteins adipose tissue; target aromatase; estrogens liver; kidneys

Steroid in target tissues Steroids have ____________-term effects.

both short- and long

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 __________

specific receptor gene transcription

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

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.

5α-DHT estradiol-17ß; brain

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

prehormone

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.

46,XY; feminised; 5α-reductase autosomal recessive normal ; cannot be converted to its active metabolite, 5α-DHT sexual differentiation

HP Adrenal Axis 1 Flashcards

(44 cards)