Endocrine Friday, Wk1

What mechanisms do cells use to communicate about and respond to environmental changes?

autonomic nervous system and ligands

ANS is lighting fast. If we have a drop in blood pressure = ______ stimulated = increased ________ from vasomotor center.

carotid sinus; sympathetic outflow

Ligands have slower response but more steady. If there's a drop in pressure, it stimulates the _______.

juxtaglomerular apparatus

How does a ligand work?

binds to its own specific receptor to stimulate action, leading to a correction of an imbalance in homeostasis

Binding of the ligand sets off a cascade of events. These cascade of events are called what?

signal transduction pathway

What is the very common part of the signal transduction pathway?

secondary messenger systems

What are the three main ligands in endocrinology?

hormone signaling, paracrine signaling and autocrine signaling

T/F: The hormone signaling ligand uses the bloodstream to travel to target cells whereas the paracrine and autocrine ligands uses the local interstitium to travel to its target cells.

T

T/F: Some ligands can be both endocrine or autocrine at the same time.

T

Blood fluid are pushed out of the proximal capillary by ______ pressure and older blood fluid products are returned to the distal capillary by ______ pressure.

hydrostatic; oncotic

Again, what are the two types of extracellular fluid?

interstitium and intervascular

What are the three factoids sperm must swim through to get a woman pregnant?

external os, cervical canal, and internal os

The ovaries are the gonads of the female. The eggs (oocytes) nuclei are ______ and contain _____ chromosomes.

haploid; 23

The endometrium contains two layers; the stratum functionale and the stratum basale. Which layer is always replaced?

stratum functionale

What are the three types or classes of hormones?

steroid, peptide, and amino acid-derived hormones

What are the three key hypothalamic nuclei?

supraoptic, paraventricular, and arcuate

The supraoptic nucleus houses _______ neurons. It secretes _______ and _____.

magnocellular; vasopressin and oxytocin

The paraventricular nucleus houses ______ neurons and ______ neurons. It secretes ______.

parvocellular and magnocellular; corticotropin releasing hormone (CRH)

The arcuate nucleus releases _______ releasing hormone. It stimulate the _____ pituitary to release _____ and _____.

gonadotropin; anterior; LH and FSH

What are the two hormones released from the posterior pituitary?

oxytocin and vasopressin (ADH/arginine)

Why is oxytocin an important peptide hormone?

for parturition (birthing process) and lactation

What is a perfect example of a positive feedback cycle that occurs during parturition?

Ferguson's reflex (fetal ejection reflex)

Explain the Oxytocin positive feedback cycle.

1. During labor, the baby's head pushes into and stretches the cervix

2. Stretch sends nerve signal via vagal afferent in pelvic splanchnic nerves to hypothalamus (SON & PVN)

3. Magnocellular oxytocin neurons respond by making oxytocin

4. Oxytocin sent down to posterior pituitary and released into bloodstream

5. Oxytocin travels to smooth muscle cells (SMC) of myometrium of uterus

6. Binding causes calcium to rush into cytosol of SMCs to contract stronger

7. Stronger contractions pushes baby further into cervix and causes it to stretch even more

8. Stretching releases more vagal afferent signals to hypothalamus

9. Signals release more oxytocin from magnocellular neurons

10. Cycle repeats

When is pitocin given?

a synthetic form of oxytocin to stimulate stronger uterine contractions for babies that are stuck and don't want to come out

What are the AKAs for the Milk Ejection Reflex?

milk letdown reflex or the letdown reflex

The milk ejection reflex is another positive feedback cycle. What happens in this lactation cycle?

1. Suckling triggers release of oxytocin

2. Oxytocin circulates and stimulates alveoli to eject more milk into ductal system

3. Baby suckles even harder, which stimulates the nipple to squeeze milk out

4. More oxytocin is released

5. The cycle repeats

What else does oxytocin causes the release of?

dopamine which reduces stress of mom

What role does stress play on the mother during the lactation cycle?

inhibits release of oxytocin and may inhibit the milk ejection reflex

Prolactin is released from ______ which stimulates ______ to produce ______.

anterior pituitary; alveolar cells; milk

Prolactin is made by anterior pituitary cells called _______ with a primary function to drive _____.

lactotoph cells; lactation

Prolactin also plays two important roles. What are they?

reproduction and parenting behavior

T/F: Prolactin is regulated by suckling.

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Why is prolactin considered a "social hormone"?

facilitates trust, bonding, and attachment between mother and child

What is prolactinoma?

most common type of pituitary tumor made of mutated lactotroph cells

What is hyperprolactinemia?

overproduction of prolactin in the bloodstream

What is the most common clinical finding of prolactinoma?

tunnel vision (loss of peripheral vision), and frontal headaches

If a tumor in the sella turcica takes out both nasal retina, what would this be indicative of?

temporal field visual loss

High levels of prolactin in the bloodstream inhibit hypothalamic secretion of ______ releasing hormone from the ______ nucleus.

gonadotropin (LH and FSH); arcuate

Hyperprolactinemia causes what?

hypogonadotropism

What are clinical symptoms of patients with hypogonadotropism?

1. decreased lipido

2. impotence

3. male gynecomastia

4. osteoporosis

5. amenorrhea & infertility

6. failure to menstruate

Prolactin is inhibited by what two hormones?

estrogen and progesterone

What is thyrotropin releasing hormone?

prolactin releasing factor from anterior pituitary that binds to lactotrophs to stimulate release of more prolactin

T/F: Thyrotropin releasing hormone is involved in the milk ejection/letdown reflex.

F - it is oxytocin