Repro Chapter 1 Part 1

Question 1

What steroid hormones are involved in male and female reproduction?

Answer 1

androgens, estrogens, progesterone

Question 2

The establishment of _______________ coincides with attainment of puberty.

Answer 2

Hypothalamo-Hypophyseal-Gonadal axis

Question 3

What controls attainment of puberty?

Answer 3

gene expression and repression

Question 4

When is an animal said to have reached puberty?

Answer 4

When the animal is able to release gametes and manifest complete reproductive behavior.

Question 5

Imprinting of the brain is associated with what centers of the brain in males and females?

Answer 5

females: tonic center and surge center
males: tonic center

Question 6

At what age does puberty occur in sheep, swine, cattle, and horses?

Answer 6

sheep and swine: 6-7 months

cattle: 11 months
horse: 15-18 months

Question 7

At what age does puberty occur in cats and dogs?

Answer 7

Cats: 8-13 months

Dogs: 9-12 months

Question 8

Removal of gonads results in lost of ______ and _____ function.

Answer 8

exocrine; endocrine

Question 9

What happens to LH / FSH levels when gonads are removed?

Answer 9

LH / FSH levels increase

Question 10

When is castration performed on farm animals and what is the purpose?

Answer 10

During pre-pubertal period

Manage farm animals

Question 11

What are bulls, stallions, rams, and boars called after castration?

Answer 11

steers, geldings, wethers, barrows

Question 12

What hormones are produced by the hypothalamus?

Answer 12

GnRH, PIH, GnIH, oxytocin

Question 13

Oxytocin cannot be stored. True or false?

Answer 13

False. Oxytocin is stored in the posterior pituitary until the stimulus arrives for its secretion

Question 14

How does oxytocin travel to the PP? Where is it traveling from?

Answer 14

neuronal processes from the hypothalamus

Question 15

What are GnRH and GnIH?

Answer 15

Protein / peptide hormones

Gonadotropin Releasing Hormone

Gonadotropin Inhibiting Hormone

Question 16

How is GnRH formed?

Answer 16

It is syntheszied from the cleavage of a 92 AA protein precursor forming GnRH and GAP.

Question 17

GnRH inhibits prolactin secretion. True or false?

Answer 17

False; GAP inhibits prolactin secretion.

Question 18

GnRH is a decapeptide. True or false?

Answer 18

True

Question 19

How many amino acids is GAP? What is the function of GAP?

Answer 19

56 AA; inhibit prolactin secretion

Question 20

Where is GnRH released?

Answer 20

into the hypophyseal portal circulation

Question 21

What degrades GnRH and how long does it take?

Answer 21

Degraded by proteolysis within a few minutes of release.

Question 22

GnRH is highly conserved throughout ________.

Answer 22

evolution

Question 23

Where are GnRH neurons located?

Answer 23

Scattered throughout the anterior and medial part of the hypothalamus and preoptic septal areas

Question 24

In what pattern is GnRH secreted?

Answer 24

In a pulsatile manner.

Question 25

Where is the GnRH pulse generator located?

Answer 25

In the arcuate nucleus of the mediobasal hypothalamus

Question 26

How are frequency and amplitude of the GnRH pulse dictated?

Answer 26

By the spontaneous activity of the pulse generator

Question 27

________ plays an important role in the synchronization of GnRH neurons.

Answer 27

Kisspeptin

Question 28

What factors stimulate GnRH secretion?

Answer 28

low levels of sex steroids (androgens and estrogens)

high levels of estrogens at certain threshold - acts at surge center

catecholamines

Question 29

What factors inhibit GnRH secretion?

Answer 29

high levels of progesterone and androgens (exert negative FB on GnRH)

corticotrophin releasing hormone (CRH) and opioids

autocrine regulation of GnRH production

GnIH

Question 30

How many AAs long is GnIH?

Answer 30

12 AAs - dodecapeptide

Question 31

What is GnIH secreted by?

Answer 31

by neurons in hypothalamus and septal area

Question 32

______ stimulates the synthesis and secretion of GnIH.

Answer 32

estradiol

Question 33

Where are GnIH receptors present?

Answer 33

Different regions of the brain and gonads (regulation at multiple levels)

Question 34

Where is GnIH released?

Answer 34

1. Into the hypothalamus

2. Into median eminence (reaches par distalis)

Question 35

What are the physiological effects of GnRH?

Answer 35

stimulate synthesis and release of LH / FSH

regulated turnover of its own receptors on gondatrophs

involved in mating behavior

Question 36

GnRH can both stimulate and suppress the reproductive functions. True or false?

Answer 36

True; it depends upon time and manner of presentation

Question 37

Hourly injection of GnRH ________ production of gonadotropins which _______ reproductive processes.

Answer 37

stimulates; stimulates

Question 38

Frequent administration of GnRH (long term use) results in _______ of gonadotropin production which _____ reproductive processes.

Answer 38

inhibittion; inhibits

Question 39

Frequent administration of GnRH (long term use) results in _______ of gonadotropin production which _____ reproductive processes.

Answer 39

inhibition; inhibits

Question 40

Clinically, why would you stimulate reproduction function and what would you use?

Answer 40

To synchronize cattle or initiate ovulation; use GnRH

Question 41

Clinically, why would you inhibit reproduction function and what would you use?

Answer 41

For fertility control in pets and wild animals

Treat polycystic ovarian disease

GnRH

Question 42

What is an example of controlling reproduction function in wildlife using GnRH?

Answer 42

GnRH darts are used to control doe population in Colorado