The Gonads 2

Question 1

Testosterone can act as a precursor which can follow two different reactions to produce other hormones

What are the names of the enzymes which converts them into the hormones and what are the names of these hormones?

Answer 1

Question 2

What can testosterone be reduced into?

Name the enzyme responsible for this reduction as well?

State what is the difference between the new hormone produced by testosterones reduction?

Answer 2

Testosterone can be reduced to form DIHYDROTESTOSTERONE (DHT) which is far more potent but will still work on the SAME androgen receptors

DHT will be produced in target tissue that has the 5a-reductase enzyme

Question 3

Testosterone can be aromatised to form …………………..

Answer 3

testosterone can be aromatised to form OESTROGENS

Question 4

How Do Men Naturally Make Estrogen?

Answer 4

Women synthesize most of their estrogen in their ovaries and other reproductive tissues.

Since men lack this female anatomy, they need to produce estrogen through a process involving an enzyme called aromatase that transforms testosterone into estradiol.

The aromatase enzyme can be found in many tissues including gonads (granulosa cells), brain, adipose tissue, placenta, blood vessels, skin, and bone

Question 5

What hormone is responsible for the virulising features in men?

Answer 5

Dihydroxytestosterone

Question 6

Why are obese men more likely to develop gynecomastia?

Answer 6

You have increased peripheral converion of androgens to oestrogens which can lead to gynecomastia?

Question 7

What effects does high oestrogen have on males?

Answer 7

Question 8

List 5 places where 5 alpha reductase is found?

Answer 8

Question 9

List 5 places where aromatase is found?

Answer 9

Question 10

What hormones can testosterone be converted into?

Answer 10

DHT and Oestrogen

Question 11

Why is it important to have 5 alpha reductase in skin?

Answer 11

Promotes facial hair growth

However can cause boldness

Question 12

How are testosterone and DHT transported around the blood?

Answer 12

Question 13

How is testoterone transported in the seminiferous fluid?

Answer 13

Androgen Binding Globulin

Question 14

What proportion of Testosterone is bound to

SHBG

ALBUMIN

FREE

Answer 14

Question 15

What organ makes SHBG?

Answer 15

Liver

Question 16

What are the principal actions of Androgens on the Fetus?

Answer 16

Question 17

What happens if you have an abscence of fetal testosterone?

Answer 17

Baby will be born with ambigous genitalia

the scrotum and labia are kind of equivalent

Question 18

List 8 effects of androgens on adults?

Answer 18

Question 19

Define Oestrogen?

Answer 19

Question 20

List 6 effects of oestrogen ( repriduction)?

Answer 20

Question 21

List 7 non-reproductive effects of oestrogen?

Answer 21

Increased salt and water reabsorption - women weight vary slighlt during the cycle

Increased plasma protein synthesis (hepatic effect)- if you are on the pill then if you require any liver metabolise drug, it will effect the dose of other drugs.

Metabolic actions (e.g. on lipids)

Tend to increase HDL levels- that is why women are less likely to have cardiovascular problems

Menopause - oestrogen levels are low so carbohydrate and lipid metabolism will be affected - women will become more susceptible to cardiovascular problems

Stimulates osteoblasts (androgens also do this)

Influences the release of other hormones (e.g. prolactin, thyrotrophin)

Behavioural effects

Feedback regulation (negative and positive)

Question 22

Define Progestogens?

Answer 22

Question 23

List 5 effects of progestogens?

Answer 23

Question 24

Draw the HYPOTHALAMO-PITUITARY-TESTICULAR AXIS

Answer 24

Question 25

What happens to the FSH and LH levels in a testectomy?

Answer 25

Increase

Question 26

Summary:Endocrine control of testicular function

Answer 26

The tesosterone and LH is needed for complete spermatogenesis. They are symbiotic

Question 27

Draw the hypothalamo-pituitary-ovarian axis

Answer 27

Question 28

What happens during the early follicular stage? State what the levels of oestrogen and progesterone are and what effect does it have?

Answer 28

Early Follicular Phase - beginning of the menstrual cycle Oestrogen and progesterone levels are low so there is little negative feedback so there is an increase in the production of LH and FSH and GnRH LH and FSH start stimulating the development of some follicles in the ovaries There is a little rise in 17a-hydroxyprogesterone during ovulation

Question 29

What happens during the EARLY-MID FOLLICULAR PHASE? Talk about the levels of hormones?

Answer 29

There is no further increase in FSH or LH Oestrogen levels are beginning to rise dramatically (increases in the blood and in the ovaries) Progesterone does NOT change

Question 30

Draw a diagram showing the realtionship between thecal cells and granulosa cells?

Answer 30

There is no further increase in FSH or LH Oestrogen levels are beginning to rise dramatically (increases in the blood and in the ovaries) Progesterone does NOT change Ovary: Local positive feedback loop in developing follicles enhances oestradiol production THECAL cell = LH Receptor GRANULOSA cell = FSH Receptor Thecal cells respond to LH by increasing androgen production Thecal cells work somewhat like Leydig cells in the testes FSH binds to the FSH receptors on the Granulosa cells which activates AROMATASE Aromatase converts androgens (from thecal cells) to 17b-oestradiol At the beginning, FSH and LH levels are high causing a rise in oestrogen levels Oestrogens produced by the granulosa cells will bind to the oestrogen receptor on the same granulosa cell and stimulate the aromatase enzyme via a second messenger system = AUTO-POSITIVE FEEDBACK This means that the more oestrogen is produced by androgens, the more oestrogen is produced overall due to the positive feedback

Question 31

* Rising levels of plasma E2( 17 beta oestradiol) causes stimulates ................... cell growth * More .................. cells = more ability to synthesise E2

Answer 31

* Rising levels of plasma E2 causes stimulates **granulosa** cell growth * More **granulosa** cells = more ability to synthesise E2

Question 32

Because the oestrogen is rising it lowers the gonadotrophins- this causes the growing follicles suppress your pituitary and what this means is that the smaller follicle die and one of them become autonomous and survive without gonadotrophins

Answer 32

Question 33

_The Graafian Follicle_ * The largest follicle no longer requires ......... to develop and proliferate * It keeps growing and producing large amounts of ........ * It is called the Graafian follicle * Extremely high levels of ...... from the Graffian Follicle results in the positive feedback on ................. secretion

Answer 33

* The largest follicle no longer requires **FSH** to develop and proliferate * It keeps growing and producing large amounts of **E2** * It is called the Graafian follicle * Extremely high levels of **E2** from the Graffian Follicle results in the positive feedback on **GnRH / LH** secretion

Question 34

_Mid Follicular Stage_ ## Footnote At this point the rising oestrogen levels have a negative feedback effect on ........ Within the follicles, there are developing ova which are at different stages of development A lot of these follicles are ......... dependent so by removing......., you kill the cells which are still ........ dependent (ATRESIA) There is usually only ......... OVUM which can grow under its own production of local oestrogens and this is the .................. FOLLICLE Selective negative feedback loop by oestrogen and inhibin on the GnRH-FSH system results in ................... of all follicles that are still FSH dependent: GRAAFIAN follicle survives

Answer 34

At this point the rising oestrogen levels have a negative feedback effect on **FSH** Within the follicles, there are developing ova which are at different stages of development A lot of these follicles are **FSH** dependent so by removing **FSH**, you kill the cells which are still **FSH** dependent (ATRESIA) There is usually only **ONE** OVUM which can grow under its own production of local oestrogens and this is the **GRAAFIAN** FOLLICLE Selective negative feedback loop by oestrogen and inhibin on the GnRH-FSH system results in **ATRESIA (regression)** of all follicles that are still FSH dependent: GRAAFIAN follicle survives

Question 35

There is ................. ................ initially which is mainly due to inhibin acting on FSH LH will still be produced to stimulate the production of ................... but FSH is inhibited The selective negative feedback is specifically on FSH

Answer 35

There is **negative feedback** initially which is mainly due to inhibin acting on FSH LH will still be produced to stimulate the production of **androgens** but FSH is inhibited The selective negative feedback is specifically on FSH

Question 36

Ovarian hormones-negative feedback

Answer 36

Question 37

_Late Follicular Stage_

Answer 37

At this stage we have had high oestrogen in the absence of progesterone for long enough to induce an LH surge The LH surge at this point is sufficiently high to overcome the FSH negative feedback and so you get a lesser FSH surge

Question 38

What happens if fertilization doesn't occur?

Answer 38

If fertilization does not occur, progesterone, E2 and inhibin exert a negative feedback on LH and FSH release, causing luteolysis and menstruation Luteolysis (also known as luteal regression) is the structural and functional degradation of the corpus luteum (CL), which occurs at the end of the luteal phase of both the estrous and menstrual cycles in the absence of pregnancy.

Question 39

If fertilisation occurs, you will need a lot of ................ and ...................... so the placenta, at an early stage, will start producing a molecule which mimics the effects of LH -................. ................ ...........................

Answer 39

If fertilisation occurs, you will need a lot of **oestrogen** and **progesterone** so the placenta, at an early stage, will start producing a molecule which mimics the effects of LH - **Human Chorionic Gonadotrophin (hCG)**

Question 40

After ovulation, the cells of the follicle collapse to form a corpus luteum The corpus luteum has cells which still have ......... and ........ Receptors As oestrogen and progesterone levels fall after ovulation, there is initially FSH and LH being released This stimulates the corpus luteum to produce more ...................... and ................................. ...................... and .................... levels will increase which exerts a negative feedback effect on the hypothalamo-pituitary axis ........ and ...... levels will decrease as they get inhibited by the increased negative feedback (mainly from PROGESTERONE) Unless something happens to produce ...... and ....., as the levels fall away, the corpus luteum will no longer be stimulated to produce OESTROGEN and PROGESTERONE So oestrogen and progesterone levels begin to fall As these levels fall, the negative feedback on the hypothalamo-pituitary axis is reduced so LH and FSH levels start to RISE again so they can reach a critical level at the start of the cycle again

Answer 40

After ovulation, the cells of the follicle collapse to form a corpus luteum The corpus luteum has cells which still have **FSH** and **LH** Receptors As oestrogen and progesterone levels fall after ovulation, there is initially FSH and LH being released This stimulates the corpus luteum to produce more **oestrogen** and **progesterone** **Oestrogen** and **progesterone** levels will increase which exerts a negative feedback effect on the hypothalamo-pituitary axis **FSH** and **LH** levels will decrease as they get inhibited by the increased negative feedback (mainly from PROGESTERONE) Unless something happens to produce **FSH** and **LH**, as the levels fall away, the corpus luteum will no longer be stimulated to produce **OESTROGEN** and **PROGESTERONE** So oestrogen and progesterone levels begin to fall As these levels fall, the negative feedback on the hypothalamo-pituitary axis is reduced so LH and FSH levels start to RISE again so they can reach a critical level at the start of the cycle again

Question 41

What does a rise in LH cause in women?

Answer 41

Luteinizing hormone (LH, also known as lutropin and sometimes lutrophin[1]) is a hormoneproduced by gonadotropic cells in the anterior pituitary gland. In females, an acute rise of LH ("LH surge") triggers ovulation[2] and development of the corpus luteum.

Question 42

# Define Amenorrhoea? Define Primary Amenorrhoea? Define Secondary Amenorrhoea

Answer 42

Definition : absence of menstrual cycles * primary if a women never had a single period * secondary if a women has had periods which then stop

Question 43

Some causes of primary amenhorroea

Answer 43

Question 44

Some causes of secondary amenhorroea?

Answer 44

Question 45

Define Oligomenorrhoea?

Answer 45

Oligomenorrhoea: infrequent cycles Less severe than amenorrhoea Strictly, it is menstrual periods occurring at intervals of greater than 35 days, with only four to nine periods in a year.[1]

Question 46

Define Infertility and list 5 main cause?

Answer 46

1 in 10 couples have infertility PCOS- most common endo problem in women- more than diabetes aslong as you have 2 out of the 3 symptoms ( which are in small print at the bottom of the page) you have PCOS