Regulation of Reproduction

What is autocrine signaling?

Signaling where a cell targets itself

What is paracrine signaling?

Signaling where a cell signals a nearby cell

What is endocrine signaling?

Signaling where a cell targets a distant cell through the bloodstream

What is justacrine/direct signaling?

Signaling where a cell targets a neighboring cell through a gap junction

What is neuroendocrine signaling?

Signaling where a neurohormone secreted in the brain travels through the blood to reach a distant cell

How do cellular messengers know where to go?

They know where to go based on the presence or absence of receptors

What is the difference between endocrine and exocrine glands?

Endocrine glands do NOT have ducts, they secrete their products into the blood

Exocrine glands do have ducts, the secrete onto a surface (e.g. sweat onto skin)

What is an example of a gland that performs exocrine and endocrine functions?

The pancreas (insulin is endocrine and digestive enzymes are exocrine)

What are hormones?

They are substances produced by endocrine glands that act on cells, tissues, or organs at a place other than where they are produced

Are hormones water or lipid soluble?

Hormones are steroids meaning they are lipid soluble (must be attached to transport proteins to move around)

What does an episodic/pulsatile pattern of hormone release mean?

It means that the hormone is released in bursts or pulses in varying duration and quantity

What does an basal pattern of hormone release mean?

It means the hormone remains at a low concentration majority of the time and has slight fluctuations in concentration

What does an sustained pattern of hormone release mean?

It means a hormone is steadily being secreted for an extended period of time, may be steadily increasing (e.g. progesterone during pregnancy)

What are the 3 parts of a signal transduction cascade?

Reception, transduction, and response

What 2 main factors regulate a cell’s degree of response to a ligand?

Its affinity for the ligand (↑ affinity = stronger response), the number of receptors the cell has for that ligand (↑ # of receptors = stronger response)

Are nuclear receptors or cell membrane receptors faster?

Cell membrane receptors because they modulate functions that already exist

What is a plasma/cell membrane receptor?

A receptor on the cell surface or in the plasma membrane of a cell, can be enzymatic or non-enzymatic

What is a G-protein coupled receptor (GCPR)?

A cell-surface receptor that activates a G protein when a signaling molecule binds, triggering a cellular response, non-enzymatic receptor

What is a nuclear receptor?

A receptor in the nucleus of a cell, responds to steroids (hormones), has a steroid response element (SRE) that activates/inactivates gene expression, slower than cell membrane receptors because it needs to transcribe DNA and translate it into proteins to produce a response

What are channel receptors?

Receptors that allow ions in/out to activate enzymes, within the plasma membrane

What are agonists/analogs and antagonists?

Other molecules that have similar structures to a signaling molecule, agonists/analogs bind to a target molecule to activate the receptor, antagonists bind to the target cell but produce no effect and block other molecules from binding at that site

What structure controls the majority of reproductive hormones?

The hypothalamus

What hormones does the hypothalamus produce?

Oyxtocin and vasopressin?

Who secretes the hypothalamus’s hormones?

The posterior pituitary is what actually secretes the hypothalamus’s hormones into systemic circulation

What is the HPG axis?

Communication between the hypothalamus, pituitary, and gonads (hypothalamus tells the pituitary what to do and it secretes hormones to make that happen)

What is the short feedback loop?

When hormones give feedback to the pituitary

What is the long feedback loop?

When hormones give feedback to the hypothalamus

What hormones does the hypothalamus produce to regulate the pituitary?

GnRH

What hormones does the pituitary secrete in response to the hypothalamus to regulate the gonads?

LH and FSH

Which sex can provide positive feedback?

ONLY females, males cannot provide positive feedback, only negative

How does positive feedback in females work (successful ovulation)?

Hypothalamus produces GnRH, pituitary secretes LH and FSH to promote follicle growth and ovulation, if a follicle grows it will produce estrogen and progesterone, these hormones will provide positive feedback to the pituitary and hypothalamus to keep producing GnRH/LH to continue to promote the growth of the potential embryo and negative feedback on FSH as the follicle was successful and the body doesn’t need to be promoting another one at the moment

How does positive feedback in females work (unsuccessful ovulation)?

Hypothalamus produces GnRH, pituitary secretes LH and FSH to promote follicle growth and ovulation, if a follicle doesn’t grow, estrogen/progesterone don’t get produced, without those hormones there is no feedback and the hypothalamus/pituitary continues to produce GnRH/FSH/LH to continue to promote the growth of a follicle and ovulation

What neurons in the hypothalamus modulate GnRH release?

Kispeptin and KNDy

Is oxytocin a steroid?

No

What hormones are part of the feedback loop?

Testosterone, progesterone, and estrogen

What is the surge center?

A structure only present in the female, processes positive and negative feedback, part of the hypothalamus, responsible for sustained LH secretion if ovulation and embryo attachment was successful

What is the tonic center?

Present in male and female, processes negative feedback, part of the hypothalamus, regulated by KNDy neurons