Lecture 70: Reproductive Endocrinology Flashcards

1
Q

The _____________ is the neural control center for repro hormones.

A

Hypothalamus

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2
Q

Describe the simple neural reflex of regulation of reproduction

A

Employs the nerves that release simple neurotransmitters directly into target tissue

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3
Q

Describe the Neuroendocrine Reflex regulation of reproduction

A

Requires a neurohormone (released by a neuron) to enter the blood and act on remote target tissue

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4
Q

The pituitary gland is positioned in the depression of the sphenoid bone, called the _______ _______.

A

Stella turcica

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5
Q

The third ventricle separates the ________ portions of the hypothalamus.

A

Lateral

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6
Q

What is the Hypothalamo-Hypophyseal Portal System (HHP)?

A

The HHP system allows minute (picograms) quantities of releasing hormones to act on the anterior pituitary before they are diluted by the general circulation

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7
Q

What is the relationship between the portal vascular system (PVN) and the posterior pituitary?

A

Axons from neurons originating in the hypothalamus (PVN) extend into the posterior pituitary where they release their neurohormones into a capillary plexus

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8
Q

True or False: The posterior pituitary has a portal system.

A

FALSE
Neurohormones are deposited directly into systemic circulation

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9
Q

Which repro hormones are classified as hypothalamic hormones?

A

Gonadotropin Releasing Hormones (GnRH)

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10
Q

Which repro hormones are classified as Pituitary Hormones?

A

Follicle Stimulating Hormone (FSH)
Luteinizing Hormone (LH)
Prolactin
Oxytocin

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11
Q

Which repro hormones are classified as gonadal hormones?

A

Estradiol (E2)
Progesterone (P4)
Prostaglandin F2-alpha
Equine Chorionic Gonadotropin (ECG)
Human Chorionic Gonadotropin (HCG)

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12
Q

Which repro hormones are classified as neurohormones and what is their mode of action

A

GnRH, FSH, LH, Oxytocin

Synthesized by neurone and are released directly into the blood to cause a response in a target tissue somewhere else in the body

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13
Q

Which repro hormones are classified as releasing hormones and what is their mode of action

A

GnRH

  • Synthesized by neurons in the hypothalamus and causes release of other hormones from the anterior pituitary
  • They can also be classified as neurohormones because they are synthesized and released by neurons
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14
Q
A
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15
Q

Which repro hormones are classified as sexual promoters and what is their mode of action

A

Estrogen, Progesterone, Testosterone, cEG, hCG
- Secreted by the gonads to stimulate the repro tract, regulate the function of the hypothalamus and anterior pituitary, and regulate reproductive behavior

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16
Q

Which repro hormones are classified as pregnancy maintenance hormones and what is their mode of action

A

Progestins and Placental Lactogen

High concentration during pregnancy
Responsible for maintaining pregnancy and assisting the female in lactation ability

16
Q

Which repro hormones are classified as luteolytic hormones and what is their mode of action

A

PGF2-alpha

Causes destruction of the corpus luteum

16
Q

Which repro hormones are classified as general metabolic hormones and what is their mode of action

A

Thyroxin, Adrenal corticoids, and growth hormone

Promote metabolic well-being

17
Q

State which repro hormones are biochemically classified as peptides, glycoproteins, steroids, and prostaglandins

A

Peptides: GnRH is a decapeptide, Prolactin and Relaxin
Glycoproteins: FSH, LH, Inhibin
Steroids: Progesterone, estradiol, testosterone
Prostaglandins: PGF2-alpha and PGE2

18
Q

Protein hormones bind to what type of receptors?

A

Plasma bound receptors

19
Q

Steroid hormones bind to what type of receptors?

A

Travel freely through plasma membrane into the cytoplasm and bind directly to specific nuclear receptors

20
Q

Describe the difference in a fast response vs slow response from a steroid hormone. Give examples of each

A

Fast response: binds to a membrane receptor causing protein production
example: Estradiol increases myometrial contractions and progesterone decreases myometrial contractions

Slow response: Binds to nuclear receptor inside cell causing protein production
example: estradiol causes mucous secretion by the female tract and progesterone causes uterine gland secretion

21
Q

How does the CNS regulate the reproductive system?

A

Receives, processes and interprets sensory inputs (such as olfactory, visual, feedback systems, and photoperiod

These inputs ultimately regulates GnRH release

22
Q

What is the main role of the hypothalamo-pituitary gonadal axis?

A

Regulates reproduction based upon a positive and negative feedback system

Hormones can have both positive and negative feedback on different areas

23
Steroid hormones are metabolized where? What about protein hormones?
Steroid hormones are metabolized by the liver Protein hormones are degraded in the liver and kidneys
24
Which of the following does the pituitary secrete? A) Oxytocin, FSH, LH B) Testosterone and Inhibin C) FSH and Progesterone D) Estrogen and Inhibin
Oxytocin, FSH and LH
25
Do males have a surge center?
NO! The surge center in females is essential for ovulation, males obviously don't need this
26
What is the mechanism of "Defeminization" in the male?
Testosterone produced by the testes of the developing male fetus penetrates the blood-brain barrier. Once the testosterone is in the brain, it is converted to Estradiol Actually is estradiol that defeminizes the hypothalamus and causes the surge center to not develop
27
How does estradiol not cause defeminization in the female brain?
In the female, estradiol is bound to alpha-fetoprotein which prevents the estradiol from crossing the blood brain barrier
28
What is puberty?
The process of acquiring reproductive competence
29
The onset of puberty is dependent upon what?
Dependent upon the ability of the hypothalamic neurons to produce GnRH in sufficient quantities to support gametogenesis
30
In the male, the onset of puberty is brought about because of decreased hypothalamic sensitivity to what?
Decreased hypothalamic sensitivity to negative feedback by Testosterone and Estradiol
31
What is a factor that causes accelerated puberty in sows?
Boar exposure (pheromones)
32