Steroid Hormones- Week 3 (in week 4 CN)

Question 1

3 locations of prodcution of steroid homrones

Answer 1

Adrenal cortex, ovaries, testes— some in peripheral tissue (adipose, brain)

Question 2

Characteristics of steroids
Solubility?
Stucture?

Answer 2

Lipid soluble

From cholesterol so they are ring structures that differ in side chains

Question 3

5 types of steroid hormones and most common ones

Answer 3

Glucocorticoids- cortisol
Mineralcorticoids-- aldosterone
Androgens- testosterone
Estrogen- estradiol
Progestogens- progesterone

Question 4

Explain the packaging of cholesterol

Precursor?
Where are the enzymes that make steroids located?

Answer 4

Steroid hormones Are not packaged, but synthesized and immediately released

Precursor=- cholesterol

Enzymes for steroid hormones synthesis are in the SER and mitochondria.

Question 5

Since steroid hormones are lipid soluble, what do they need?

Answer 5

Binding proteins for transport in blood.
Corticosteroid binding globulin carries cortisol
•
Sex steroid binding globulin carries testosterone and estradiol

Question 6

Explain what happens to some androgens at the brain

Answer 6

In some cases a steroid is secreted by one cell and is converted to the active steroid by
the target cell: an example is androgen which secreted by the gonad and converted into
estrogen in the brain

Question 7

What do steroid hormones play a role in

Answer 7

1. Carb regulation (Glucocoriticoids)
2. Mineral balance (mineralcorticoids)
3. Reproductive functions (gonadal steroids)

Some play a role in inflammatory, stress responses, bone metabolism, CV fitness, behavior, cognition and mood

Question 8

Main differences between steroid and peptide synthesis. What are the results of this difference?

Answer 8

While peptide hormones are encoded by specific genes, steroid hormones are synthesized from the enzymatic modification of cholesterol.

This results in 1. More peptide than steroid hormoens 2. Steroid structures are the same between species 3. Steroidgenesis involves control of enzymes which modify cholesterols

Question 9

What is the first modication in steroid homrone synthesis? What enzyme? What’s important about this step and what is happing?

Answer 9

Cholesterol —- CYP11A1/Desmolome/—> Pregnenlone

The cholesterol is either newly synthesized froma cetyl Coa, Cholesterol esters or from LDL and the step involes SHORTENING OF THE HYDROCARBAN CHAIN and HYDOXYLATOIN.
Because the CYP11A1 are in the inner mitochondira, StAR ( Steroidgenic Acute Regulatory Protein) rocess is the transport of free cholesterol from the
cytoplasm into the inner mitochondrial membrane. This is the rate limiting step!!!

Question 10

What enzymes take pregnolone to steroid hormones and where do these change happen

Answer 10

Mixed function oxidases can be found in mitochondria and the ER and the reactions take place in both compartments.

Question 11

What steroid hormones come from each steroid syntehzing tissue

Answer 11

Adrenal Cortex- glucocorticoids(cortisol), mineralcorticoids (aldosterone), sex hormones

Ovaries and placenta- estrogen and progestins

Testes- testosteron and estrogen

Question 12

What is pregnolone and what is it’s precursor?

Answer 12

Prohormone- produced directly from cholesterol

,involved in the synthesis of progesterone, mineralocorticoids, glucocorticoids,androgens, andestrogens

Question 13

What is progesterone?
Nickname?
Precurosor?
Where is it secreted from?

Functions

Answer 13

Progesterone AKA the hormone of pregnancy. and produced from pregnolone.

Secreted from

1. Corpus Letuem after ovulation
2. Adrenal Cortex
3. Placenta during pregnancy

Functions

1. Reduces contractile of uterine SM during pregnancy, and its presence decreases near labor
2. Responsible for changes with luteal phase of the menstrual cycle
3. Works with estrogen in the development of breast

Progeste
rone is used in
hormone therapy for
transsexual women and other women with intersex conditions

Question 14

Function of cortisol?

What layer is it produced in the adrenal cortex?

Answer 14

involved in stress adaptation, elevates
blood pressure and Na+ uptake, raises
blood glucose level by stimulating
gluconeogenesis

Produced in the zona fasciculata and is the dominant glucocorticoid

Question 15

Function of aldosterone?

What layer is the adrenal cortex makes it?

Answer 15

The principal mineralocorticoid is aldosterone.
Produced from progesterone in the
zona glomerulosa
of adrenal cort

Function- Raises blood pressure and fluid volume, increases Na+
uptake