Blomquist: Steroid Hormones Flashcards by Megan Foggia

(blank) is the precursor to steroid hormones

cholesterol

How well did you know this?

Not at all

Perfectly

C21: produced directly from cholesterol, the precursor molecule for all C18, C19 and C21 steroids. Not a hormone by itself.

pregnenolone

How well did you know this?

Not at all

Perfectly

C21: a progestagen, produced directly from pregnenolone and secreted from the corpus luteum, responsible for changes associated with luteal phase of the menstrual cycle, differentiation factor for mammary glands

progesterone

How well did you know this?

Not at all

Perfectly

C21 steroid hormones are called (blank)

pregnanes

How well did you know this?

Not at all

Perfectly

C19: an androgen, male sex hormone synthesized in the testes, responsible for secondary male sex characteristics, produced from progesterone

testosterone

How well did you know this?

Not at all

Perfectly

C21: dominant glucocorticoid in humans, synthesized from progesterone in the zona fasciculata of the adrenal cortex, involved in stress adaptation, elevates blood pressure and Na+ uptake, numerous effects on the immune system

cortisol

How well did you know this?

Not at all

Perfectly

C21: the principal mineralocorticoid, produced from progesterone in the zona glomerulosa of adrenal cortex, raises blood pressure and fluid volume, increases Na+ uptake

aldosterone

How well did you know this?

Not at all

Perfectly

C19 steroid hormones are called (blank)

androstanes

How well did you know this?

Not at all

Perfectly

C18 steroid hormones are called (blank)

estranes

How well did you know this?

Not at all

Perfectly

C18: an estrogen, principal female sex hormone, produced in the ovary, responsible for secondary female sex characteristics

estradiol

How well did you know this?

Not at all

Perfectly

What changes are most prominent in distinguishing estradiol?

methyl group lost at C19; the A ring is aromatic

How well did you know this?

Not at all

Perfectly

What changes are most prominent in distinguishing testosterone?

Loss of C20 and C21

How well did you know this?

Not at all

Perfectly

What is one thing that distinguishes estradiol in a 3D picture?

A ring is aromatic and points UP whereas in other steroid hormones it points down

How well did you know this?

Not at all

Perfectly

Modifications to cholesterol that occur to make steroid hormones

Cleavage of 6C side chain
Delta 4-5 double bond
Aromatization of A group
Formation of a ketone
Hydroxylations

How well did you know this?

Not at all

Perfectly

(blank) are extensively used in steroid hormone biosynthesis

Cytochrome P-450s

How well did you know this?

Not at all

Perfectly

A superfamily of heme-containing membrane bound proteins

cytochrome P-450s

How well did you know this?

Not at all

Perfectly

Where are cyto P-450s generally found? What is their most common reaction?

in the smooth ER of the liver and lungs and in the mito; hydroxylation reaction

How well did you know this?

Not at all

Perfectly

What is the general equation for action of a cyto P-450?

Substrate-H + O2 + NADPH + H+ –> Substrate-OH + H20 + NADP+

How well did you know this?

Not at all

Perfectly

Cholesterol 6C side chain cleavage enzyme
One of the most essential P450s
Mutations usually fatal in utero

CYP11A1

How well did you know this?

Not at all

Perfectly

CYP11A1 is the cyto P-450 that takes cholesterol to (blank)

pregnenolone (all steroids derived from pregnenolone)

How well did you know this?

Not at all

Perfectly

All steroids go through (blank) and undergo a series of (blank) reactions

pregnenolone; hydroxylase

How well did you know this?

Not at all

Perfectly

Which two steroid hormones have the 11-OH group?

corticosterone and aldosterone

How well did you know this?

Not at all

Perfectly

To form estradiol from testosterone, what must occur?

aromatase system forms an aromatic ring (and removal of a methyl group)

How well did you know this?

Not at all

Perfectly

The hormonal cascade refers to synthesis and secretion of specific releasing hormones by (blank) neurons. Releasing hormones stimulate the synthesis and release of tropic hormones from the (blank). Tropic hormones increase the synthesis and secretion of specific hormones by (blank).

hypothalmic neurons; anterior pituitary; target endocrine glands

How well did you know this?

Not at all

Perfectly

Protein hormones bind to cell membrane receptors and transmit signal across membranes. List some second messengers. Many second messengers activate protein kinases.

cAMP, cGMP, IP3, DAG

The adrenal cortex produces (blank), (blank), and (blank)

aldosterone cortisol androgens

(blank) cells of male testes produce testosterone; female ovaries produce (blank) and (blank); steroid hormones are transported via specific (blank) to protect them from degradation

Leydig; estrogen, progesterone; plasma proteins

List two releasing hormones from the hypothalamus and the hormones that they "release" from the pituitary

CRH from hypothal-->ACTH from pituitary-->cortisol | GnRH from hypothal-->LH and FSH-->LH: progesterone and testosterone FSH: estradiol

Releasing hormones are released at the (blank) level, while anterior pituitary hormones are released at the (blank) level

nanogram; microgram

Cortisol | What's the steroid producing cell? What's its signal? What's its second messenger? What's its signal system?

adrenal (zona fascicula); ACTH; cAMP, PI cycle, Ca; hypothalmic-pituitary cascade

Aldosterone | What's the steroid producing cell? What's its signal? What's its second messenger? What's its signal system?

adrenal (zona glomerulosa); angiotensin II; PI, Ca; reno-angiotensin system

Testosterone | What's the steroid producing cell? What's its signal? What's its second messenger? What's its signal system?

Leydig cell; LH; cAMP; hypothalmic-pituitary cascade

Estradiol | What's the steroid producing cell? What's its signal? What's its second messenger? What's its signal system?

ovarian follicle; LH; cAMP; hypo-pituitary cascade

Progesterone | What's the steroid producing cell? What's its signal? What's its second messenger? What's its signal system?

corpus luteum; LH; cAMP; hypo-pituitary cascade

Vit D | What's the steroid producing cell? What's its signal? What's its second messenger? What's its signal system?

kidney; PTH; cAMP; sunlight, plasma calcium

Give an overview of hormonal stimulation of steroid hormone biosynthesis

Peptide hormone binds to receptor, confirmational change in protein, GDP to GTP, which binds to AC, increases cAMP, leads to activation of PKA, phosphorylates cholesterol esterase, frees cholesterol from vesicles, StAR protein allows for its uptake into the mito matrix, CYP11A1 can then make modifications and release the hormone into the bloodstream

Discuss the activation of ACTH on adrenal fasciculata cells

ACTH binds, activates a G protein, activates cAMP, activates PKA, PKA releases cholesterol from vesicles, cholesterol transported to mito via StAR, side chain cleavage and other steps in cortisol production occur here, then it is released into the cytosol and into the bloodstream.

(blank) plays a minor role in aldosterone regulation

IP3 signaling system

7-Dehydrocholesterol is synthesized in the liver and is found in the skin. It is taken to previtamin D via (blank), then the ring spontaneously opens, and forms Vit D. T

sunlight, UV radiation

What is the major effect of vitD?

To stimulate Ca+ and phosphate absorption from the lumen. Also increases Ca+ pump molecules and calbindins

How are steroid hormones transported in the blood?

Corticosteroid binding globulins Sex hormone binding globulin Androgen binding protein Albumin

Cortisol binds primarily to corticosteroid binding a2-globulin (transcortin). About 15 % of cortisol is (blank) cortisol and this is what crosses cell membranes and binds to cortisol receptors in cells

free

What percentage of testosterone is bound to sex hormone binding protein? What percentage of estrogen is bound to sex hormone binding protein?

65%; 60%

Androgen binding protein is also called testosterone-estrogen binding globulin: this protein helps maintain a high level of (blank) within testes and seminal fluid and is important for development and maturation of (blank)

testosterone; sperm

What does progesterone bind to primarily?

transcortin and albumin

Subfamily of receptors including steroid hormone, Vit D, thyroxine, and retinois (Vit A) receptors

nuclear receptor subfamily

3 important domains on nuclear receptors

poorly conserved transcription-activation domain highly conserved DNA binding domain ligand binding domain

Steroid receptors bind to DNA as (blank); they increase or decrease (blank)

homodimers; transcription

T/F: Steroid hormones can travel THROUGH cell membrane, unlike peptide hormones which cannot. Some glucocorticoid receptors are free in the cytoplasm and are transported to the nucleus when bound by their hormone; others steroid receptors are already in the nucleus when unbound.

True

This domain on the steroid receptor protein is variable

trx activation domain

This domain on the steroid receptor protein contains zinc fingers

DNA binding domain

This domain on the steroid receptor protein is at the end and is specific to what it binds

ligand binding domain

(blank) and (blank) have nuclear receptors in the same family as steroid receptors

retinoic acid; T3

Caused by adrenal insufficiency

Addison's disease

Caused by increased cortisol secretion due to a tumor on the pituitary gland

Cushing syndrome

Result from loss of function in one of several genes involved in adrenal corticol steroid hormone synthesis. Results in accumulation of of steroid intermediates proximal to the defective enzyme. Common forms result from loss of function of 21-hydroxylase or 11-hydroxylase.

Congenital adrenal hyperplasias (CAH)

lipoid congential adrenal hyperplasia adrenal and gonadal steroid production severly impaired What causes this?

non-functional StAR

DNA binding domains have 8 cys groups of 4 tetrahedrally coordinately binding 2 Zn+2 ions; many have (blank) on DNA that have two half site sequences 5' AGAACA 3' for steroid receptors

hormone response elements

Name a C18 steroid. Name a C19 steroid. Name 3 C21 steroids.

estrogen; testosterone; progesterone, cortisol, aldosterone

Where is the unbound receptor for glucocorticoids found? When does it dimerize and move to the nucleus?

in the cytoplasm; when the steroid hormone binds

What distinguishes progesterone from pregnenolone?

double bond moves from C5 to C4

Also called testosterone-estrogen binding globulin; helps maintain a high level of testosterone in the seminferous tubules

androgen binding protein