Reproductive Endocrinology

Question 1

The endocrine system uses _____ and _____

Answer 1

Hormones; chemical messengers

Question 2

Hormones secreted influence function of target cells at _______

Answer 2

Distant sites

Question 3

A hormone can be either _______ or _______

Answer 3

Endocrine; neuroendocrine

Question 4

_______, ________, and ______ are controlled by feedback mechanisms

Answer 4

Secretion, transport, and clearance

Question 5

Transport depends on

Answer 5

• water solubility

- whether a hormone is protein bound

Question 6

Clearance via

Answer 6

• metabolic destruction
• binding with tissues
• hepatic excretion
• renal excretion

Question 7

What are the 3 anatomical structures that produce reproductive hormones?

Answer 7

• hypothalamus
• pituitary gland
• gonads (testicles, ovaries)

Question 8

What is considered to be the “master organ”?

Answer 8

Hypothalamus

- has a combo neuro and endocrine center

Question 9

The hypothalamus regulates

Answer 9

• endocrine system
• body temp
• appetite
• sexual behavior
• fear/rage centers

Question 10

The hypothalamus controls the action of the ______

Answer 10

Pituitary

Question 11

Median eminence

Answer 11

Connects hypothalamus with the pituitary

Question 12

The portal vessel communicates with the ______

Answer 12

Anterior pituitary

Question 13

The hypothalamus secretes _____

Answer 13

Gonadotropin releasing hormone (GNRH)

• secreted by axons
• enters into portal system and carried to pituitary

Question 14

Anterior pituitary

Answer 14

• located below hypothalamus

- receives GnRH via portal system

Question 15

AP releases ____ and ______

Answer 15

• lutenizing hormone (LH)

- follicle stimulating hormone (FSH)

Question 16

_____ drives ovulation

Answer 16

LH

• is possible to stimulate an endogenous LH surge via GnRH
• could use HCG with LH-like properties

Question 17

______ drives follicular waves in cattle

Answer 17

FSH

- is exploited to super-ovulate cattle

Question 18

Release of GnRH

Answer 18

• surge center: releases large volume of GnRH

- tonic center: slow, consistent release of GnRH, and can “gush” GnRH right before ovulation

Question 19

Release of oxytocin

Answer 19

Hypothalamus makes oxytocin that is released from the posterior lobe of the pituitary

Question 20

Oxytocin

Answer 20

Formed in paraventricular nuclei of hypothalamus

• travels down nerve endings to posterior pituitary
• released by exocytosis

Question 21

Oxytocin is a _______ hormone

Answer 21

Neuroendocrine

Question 22

Oxytocin assists with

Answer 22

• milk let down

- uterine contractions

Question 23

Gonads

Answer 23

Receive hormonal stimulation from the gonadotropins released from the anterior pituitary
- FSH and LH

Question 24

Testicles secrete ____ and _____

Answer 24

Testosterone; estrogen

Question 25

LH acts on ______ to secrete ______ (males)

Answer 25

Leydig cells; testosterone

Question 26

FSH stimulates _____ to produce _____ from testosterone

Answer 26

Sertoli cells; estrogen

Question 27

Testosterone

Answer 27

Responsible for male characteristics - penis/scrotum formation - testicular descent - muscle formation

Question 28

SRY gene

Answer 28

Causes genital ridge to produce testosterone and become testes = male phenotypic sex results

Question 29

Ovaries secrete ____ and _____

Answer 29

Estrogen; progesterone

Question 30

FSH acts on the _____ to produce _____ (female)

Answer 30

Ovary (follicle); estrogen | - stimulates follicular development

Question 31

LH acts on the _____ to stimulate _____ (female)

Answer 31

Ovary; ovulation | - corpus luteum function

Question 32

What happens before ovulation?

Answer 32

Hypothalamus produces GnRH --> AP produces LH and FSH --> acts on ovary = follicular development --> follicle produces estrogen --> E2 has + feedback to the surge center and drives the cycle --> threshold of + feedback leads to GnRH surge --> tremendous release of LH = ovulation

Question 33

Inhibin

Answer 33

Suppresses additional LH release | - stops the positive feedback process and keeps animal from being a litter bearing species

Question 34

You could flood with _____ to override inhibin

Answer 34

LH

Question 35

What is happening after ovulation?

Answer 35

Corpus luteum produces progesterone --> - feedback to hypothalamus and anterior pituitary

Question 36

You could give a stallion ______ to regulate their behavior

Answer 36

Progesterone

Question 37

Male feedback system

Answer 37

GnRH produced by hypothalamus ---> causes pituitary to produce LH and FSH, which has + effect on Leydig and Sertoli ---> Leydig secretes testosterone = virilizing effects (+), behavioral effects, and a + effect on sertoli cells ---> Sertoli cell does spermatogenesis (+), or secretes inhibin which has negative feedback on pituitary and hypothalamus

Question 38

Testosterone has negative feedback on the _____ and ______

Answer 38

Pituitary and hypothalamus