Endocrinology Flashcards
What is the neuro control center for reproductive hormones? What are the components of this center?
Hypothalamus
Consists of ..
Proventricular nucleus PVN
Surge center
Tonic center
T/F: the surge center of the hypothalamus is only present in females, not males
True
Both males and females have a tonic center
Hypothalamic nuclei front he surge and tonic center terminate in the _______________
Hypothalamic-hypophyseal portal system (H-HPS)
Characteristics of reproductive hormones?
Act in small quantities
Short half life
Bind specific receptors
Cause release of other hormones Can stimulate the gonads Can cause sexual promotion Can help maintain pregnancy Leuteolysis
Where is GnRH released from?
Hypothalamic nuclei
What hormones are released from the anterior pituitary?
FSH
LH
prolactin
What hormones are released from the posterior pituitary?
Oxytocin
T/F: FSH and LH are decapeptide hormones
False
GnRH is a decapeptide
FSH, LH, and inhibin are glycoproteins (large molecule requiring a receptor)
Progesterone, testosterone and estradiol are all produced from what common molecule ?
Cholesterol
(Steroid/protein) hormones travel freely through plasma membrane into cytoplasm and bind directly to specific nuclear receptors
Steroid
Results in new protein synthesis
What is the target tissue of LH in the female vs the male?
Female — ovary theca interval and luteal cells
Male —testis leydig cells
What is the target tissue of FSH in the female vs the male?
Female — ovary (granulosa cells)
Male — Sertoli cells
What factors determine the strength of hormones?
Pattern and duration of secretion
Half life
Receptor density
Receptor-hormone affinity
Episodic hormone secretion is associated with hormones under ________ control
Nervous
In what type of hormone secretion pattern does the hormone stay low, but may fluctuate at very low levels
Basal
Where are steroid hormones metabolized and excreted?
Met in liver and excreted in urine and feces
Where are protein hormones metabolized and excreted?
Met — Liver and kidney
Ex in urine
What is estrus vs anestrus?
Estrus — period of sexual receptivity
Anestrus — not cyclone
What type of estrous cycle do cattle, swine, and rodents have?
Polyestrus
What type of estrous cycle do sheep, goats and deer have?
Seasonally polyestrus, short day breeders
What type of estrous cycle do mares have?
Seasonally polyestrus, long day breeder
What type of estrous cycle does the bitch have?
Monestrus
Zonary attachments leave placental scars which require healing time
What is the dominant hormone during the follicular phase?
Estrogen
What is the dominant ovarian structure and hormone in the luteal phase
Corpora lutea
Progesterone
What are the 4 stages of the estrous cycle?
Proestrus
Estrus
Metestrus
Diestrus
What occurs in proestrus and how long does it last?
P4 drops due to luteolysis
FSH and LH are being secreted—> estrogen secretion from follicles
What occurs in estrus?
Period of sexual receptivity
Peak E2 secretion
Duration varies between species
What occurs during metestrus?
CL formation —> begins secreting progesterone
Estrogen levels begin to drop
What occurs during diestrus?
Sustained secretion of high levels of P4 from corpus luteum
Ends with luteolysis
What are signs of estrus in the cow?
Increased locomotion
Increased vocalization
twitching
Elevation of the tail
Standing to be mounted
Mounting other females
What are signs of estrus in the mare?
Increased locomotion
Tail flagging
Urination stance
Clitoral exposure by labial eversion
Signs of estrus in the bitch?
Roaming
Immobile stance
Tail deflected to one side
Urinating in presence of male
How long is anestrus in the bitch?
5 months
How long does proestrus last in the bitch?
9 days
How long does estrus last in the bitch?
9days
How long does diestrus last in the bitch?
60 days
In a Queen that is not mated what additional phase do they have in their estrous cycle?
Postestrus (7-10days)
Females that do not exhibit regular estrous cycles are in _____________
Anestrus
Can be caused by.. Pregnancy Lactation Season (photoperiod) Stress Pathology
What is true vs apparent anestrus ?
True anestrus
— insufficient hormonal stimulus
—factors: nutrition, eliminate stresses, detect and treat pathology
Apparent anestrus
—failure to detect estrus
—failure to know that she is pregnant
What is the purpose of seasonal anestrus?
Carry developing fetus during a favorable time
Give birth during an advantageous time for new born (eg lambs born in early spring)
What two speices are induced ovulatory?
Queen and llama
What is roughly the length of diestrus in mares, cows, does, and sows?
15-17days
What is the length of estrus in the mare?
4-7days
How long does estrus occur in cows, ewes, does, and sows?
1-2 days
As short as 6 hours in the cow
Up to 3 days in sow
