Reproductive Endocrinology Flashcards
What is a simple neural reflex?
Nerves that release simple neurotransmitters directly onto the target tissue.
What is a neuroendocrine reflex?
Needs a neurohormone to enter blood and act at a remote location.
What is the neural control center for repro hormones?
Hypothalamus/pituitary
What organ deposits neurohormones directly into circulation?
Posterior pituitary
What regulates GnRH?
Male: Tonic center
Female: Tonic and Surge centers
What quantity of repro hormones do you need?
Small quanitities
How long are repro hormone half-lives?
Short
Where does GnRH come from?
Hypothalamic nuclei
Where do FSH, LH and prolactin come from?
Anterior Pituitary
Where does Oxytocin come from?
Posterior pituitary
Which repro hormones are a peptide?
GnRH
Which repro hormones are a glycoprotein?
FSH
LH
Inhibin
Which repro hormones are steroids?
Progesterone
Testosterone
Estradiol
What does PGF2a do?
Lyses the corpus luteum
What does PGE2 do?
Relaxes the cervix
How do protein hormones cause their actions?
Bind to plasma membrane bound receptors
How do steroid hormones cause their actions?
Travel freely through the plasma membrane into the cytoplasm and bind to the specific nuclear receptors
What does binding of hormones result in?
New protein synthesis
What are two functions of pheromones?
Influence the onset of puberty
Lets the male know who is in heat
What 4 things affect the strength of a hormone?
Pattern and duration of secretion
Half-life
Receptor density (this is really important)
Receptor-hormone affinity
NOTE: We can play with receptor-hormone affinity to make synthetic hormones that bind better than the natural hormone.
What are3 different patterns and duration of secretion?
Episodic
Basal
Sustained
What is Episodic secretion?
Burst or pulse
NOTE: generally associated with hormones under nervous control.
What is Basal secretion?
Secretion stays low, but fluctuates with low amplitude pulses.
What is Sustained secretion?
Hormone remains elevated, but in a steady fashion for a long period.
NOTE: Steroids tend to be secreted this way.
Where are steroids metabolized and excreted?
Metabolized: Liver
Excreted: Urine and feces
What organ is usually larger in high producing dairy cows?
Livers
Why can pregnancy tests be a urine test?
Because the protein hormones (eg. hCG) are metabolized in the liver and excreted by the kidneys.
What is estrus?
“Heat” or secual receptivity
What is estrous?
Length of the estrous cycle
What is an estrous cycle?
The period between one estrus and the next.
What is anestrus?
Not cycling
What does estrual mean?
Something related to estrus.
What 3 species are polyestrus?
Cattle
Swine
Rodents
What 4 species are seasonally polyestrus short-day breeders?
Sheep
Goats
Deer
Elk
What species is seasonally polyestrus long-day breeders?
Horses
What 3 species are monestrus?
Dogs
Wolves
Bears
What is the follicular phase?
Follicles are dominant structure
What hormone is dominant during the follicular phase?
Estrogen
What is the luteal phase?
Corpora lutea are dominant structure.
What hormone is dominant during the follicular phase?
Progesterone
What are the 4 stages of the estrous cycle?
Proestrus
Estrus
Metestrus
Diestrus
What 2 stages of the estrous cycle are in the follicular phase?
Proestrus
Estrus
What 2 stages of the estrous cycle are in the luteal phase
Metestrus
Diestrus
During what stage of the estrous cycle does estrogen secretion begin?
Proestrus
During what stage of the estrous cycle does estrogen secretion peak?
Estrus
During what stage of the estrous cycle does prostaglandin secretion being?
Metestrus
During what stage of the estrous cycle is progesterone secretion sustained at high levels?
Diestrus
Why do you need to watch progesterone levels in dogs?
Because they have a longer period of receptivity.
What is important to remember about diestrus in the bithc?
It is always 2 months no matter what.
What is important to remember about cats?
They are induced ovulators.
What are 5 conditions that would result in anestrus?
Pregnancy Lactation Seasons Stress Pathology
What are 3 factors that might cause a true anestrus?
Nutrition
Stresses
Pathology
What are 2 causes of apparent anestrus?
Failure to detect estrus
Failure to know that she is pregnant
What species are induced ovulators?
Llamas and Queens
