(3) Pineal & Pituitary Glands

What is the most prominent cell type in the anterior pituitary gland? A. thyrotrope B. somatotrope C. corticotrope D. lactotrope E. gonadotrope

B

Tropic hormones... A. are produced by the posterior pituitary B. are secreted only by the hypothalamus C. primarily regulate hormone secretion by certain other endocrine glands D. all have non-tropic functions too E. are the hormones that stimulate athletes to win trophies

C

Where would you find clock proteins? A. pituitary gland B. pineal gland C. SCN

C

What do thyrotropes produce?

TSH (thyroid stimulating hormone)

hormone produced by thyrotropes that controls the rate of secretion of thyroid hormones, thyroxine (T4) and triiodothyronine (T3), which control the rates of most intracellular chemical reactions in the body

TSH (thyroid stimulating hormone)

Which part of the pituitary gland has a more glandular function: anterior or posterior?

anterior

self-starting genes synthesized in the cytoplasm of SCN neurons that accumulate in the cytoplasm throughout the late day & night and eventually migrate into the nucleus, where they inhibit their own synthesis during main daylight hours Main function: responsible for cyclical changes in neural output of the SCN to many targets

clock proteins

What causes jet lag?

clock proteins out of balance (SCN has to reset each day to adjust each day for any changes in light, so this messes it up since clock proteins regulate its neural output)

type of cells (basophils/beta cells) in the anterior pituitary gland that produce ACTH (adrenocorticotropic hormone) & MSH and make up about 20% of anterior pituitary cells

corticotropes

What are clock proteins responsible for?

cyclical changes in neural output of SCN (to its many targets)

Where are clock proteins synthesized?

cytoplasm of SCN neurons

Is melatonin secreted when it's light or dark?

dark

At what point are there NO clock proteins in the cytosol (because they're all in the nucleus): day or night?

day

In the late cycle of the circadian rhythm, when do clock proteins migrate into the nucleus and inhibit their own synthesis?

day (noon)

process in which a hormone receptor is internalized and can't bind to any more hormones; therefore, the cell can't respond as well to the hormone

desensitization

type of cells (basophils/delta cells) in the anterior pituitary gland that produce follicle stimulating hormone (FSH) & luteinizing hormone (LH)

gonadotropes

What are the only anterior pituitary cells to produce two different hormones?

gonadotropes (LH & FSH)

What do somatotropes produce?

growth hormone

hormone produced by somatotropes that promotes growth through protein synthesis, cell division, and differentiation

growth hormone

During the dark, there is a [higher/lower] concentration of clock protein in the cytoplasm of SCN neurons. This [increases/decreases] the SCN's ability to inhibit the pineal gland, and therefore, there is [more/less] melatonin.

higher, decreases, more

process in which one hormone causes the loss of another hormone's receptors and thus decreases its effectiveness Example: during pregnancy, progesterone inhibits responsiveness of the uterus to estrogen

hormone antagonism

process in which one hormone must be present for the full effect of another hormone on that cell Example: thyroid hormone increases the number of epinephrine receptors on epinephrine target cells

hormone permissiveness

process in which two or more hormones act in concert and their combined effect is greater than either one separately Example: one growth hormone produces a response, but two GHs produces an even greater response

hormone synergism

What is hormone antagonism?

hormones have opposing effects and one cancels out the other

How are the pituitary gland and hypothalamus connected?

hypophyseal stalk

type of cells (acidophils/epsilon cells) in the anterior pituitary gland that produce prolactin

lactotropes

How is growth hormone an example of hormone synergism?

one growth hormone produces a response, but two GHs produces a greater response

What is hormone permissiveness?

one hormone can't fully work without another hormone

slight intermediate structure in the pituitary gland (technically part of the adenohypophysis) that is avascular and secretes melanocyte stimulating hormone (MSH)

pars intermedia

What kind of hormones does the anterior pituitary gland produce: steroid, peptide, or both?

peptide (meaning they're water soluble, so their target cells have plasma membrane receptors)

structure in the brain that secretes melatonin, which keeps the body's circadian rhythms in sync with the light-dark cycle

pineal gland

Melatonin is produced by the _____ gland, and melatonin production is [stimulated/inhibited] by light because the SCN is [stimulated/inhibited].

pineal, inhibited, stimulated

Which part of the pituitary gland has a more neuronal function: anterior or posterior?

posterior

How does light influence melatonin production and secretion?

prevents it (by STIMULATING the pineal gland)

How are progesterone and estrogen an example of hormone antagonism?

progesterone inhibits responsiveness of uterus to estrogen during pregnancy

What do lactotropes produce?

prolactin

What is the only non-tropic anterior pituitary hormone?

prolactin

hormone produced by lactotropes that promotes the mammary gland development and milk production

prolactin

How does the absence of light influence melatonin secretion?

promotes it (by NOT STIMULATING the pineal gland)

In what bony structure of the skull is the pituitary gland found?

sella turcica

other name for the neuronal posterior pituitary

neurohypophysis

In the early to mid cycle of the circadian rhythm, when do clock proteins accumulate in the cytoplasm of SCN neurons?

night (basically dusk to dawn)

Generally, at what point are there the HIGHEST levels of melatonin: day or night? What is happening with the clock proteins when melatonin levels are at their HIGHEST?

night, accumulating in the cytoplasm (transcription is happening to make them so they can trigger melatonin release)

ACTH (ADRENOCORTICOTROPIC HORMONE) 1. What cells produce it? 2. Tropic or non-tropic? 3. What does it do?

1. corticotropes, 2. tropic, 3. regulates secretion of cortisol

FSH (FOLLICLE STIMULATING HORMONE) 1. What cells produce it? 2. Tropic or non-tropic? 3. What does it do?

1. gonadotropes, 2. tropic, 3. controls growth of ovaries and testes

LH (LUTEINIZING HORMONE) 1. What cells produce it? 2. Tropic or non-tropic? 3. What does it do?

1. gonadotropes, 2. tropic, 3. controls growth of ovaries and testes

PROLACTIN 1. What cells produce it? 2. Tropic or non-tropic? 3. What does it do?

1. lactotropes, 2. non-tropic, 3. promotes mammary gland development and milk production

GROWTH HORMONE 1. What cells produce it? 2. Tropic or non-tropic? 3. What does it do?

1. somatotropes, 2. tropic, 3. stimulates cellular/overall growth

TSH (THYROID STIMULATING HORMONE) 1. What cells produce it? 2. Tropic or non-tropic? 3. What does it do?

1. thyrotropes, 2. tropic, 3. regulates secretion of T3 and T4

What is hormone synergism?

2+ hormones act together to create a greater combined effect than separately

How many different anterior pituitary cell types are there? How many prominent hormones are produced?

5 types, 6 hormones (+ 1 lesser hormone - MSH)

hormone produced by corticotropes that controls the secretion of adrenocortical hormones, which control glucose, protein, and fat metabolism

ACTH (adrenocorticotropic hormone)

What do corticotropes (beta cells/sigma cells) produce? (mainly)

ACTH (also MSH)

Melatonin is produced in the... A. anterior pituitary B. posterior pituitary C. pineal gland D. hypothalamus E. thyroid gland

C

Permissiveness of hormones refers to the fact that... A. hormones permit cellular processes to occur B. hormones permit their target organs to function at the optimal rate C. in some instances an adequate amount of one hormone must be present for the full exertion of another hormone's effect, even though the first hormone itself does not directly elicit the response D. the nervous system through numerous neuroendocrine relationships permits the endocrine system to function E. the tropic hormones permit other endocrine glands to secrete their hormones

C

Identify the gonadotropic hormone(s). A. LH B. FSH C. testosterone D. only A and B E. all of the above

D

hormones produced by gonadotropes that control the growth of ovaries and testes and their hormonal production

FSH (follicle stimulating hormone), LH (luteinizing hormone)

What do gonadotropes produce?

FSH and LH

What does the pars intermedia of the (anterior) pituitary gland secrete?

MSH (melanocyte stimulating hormone)

other name for the glandular anterior pituitary

adenohypophysis

What are four things that a target cell can do to respond to a hormone?

down regulation of receptor, hormone permissiveness, synergism, antagonism

How do the cells of the anterior pituitary appear?

epithelial (glandular)

Ultimately, what is the main role of melatonin? other roles include: - inhibiting reproductive hormones - triggering seasonal animal behaviors - serving as an antioxidant to slow aging

induce sleep

The inhibition of clock proteins peaks at about noon (when transcription is halted), and then their level in the nucleus decreases over time until what happens?

inhibition is relieved, process starts over

When a hormone binds to a target cell, there can be down regulation of the hormone receptor, in which the receptor is ____ with the hormone and degraded; therefore, it is no longer available to bind to the hormone on the cell surface.

internalized

During the light, there is a [higher/lower] concentration of clock protein in the cytoplasm of SCN neurons. This [increases/decreases] the SCN's ability to inhibit the pineal gland, and therefore, there is [more/less] melatonin.

lower, increases, less

receptor used for a specialized set of 1-2% of the retinal ganglion cells so that they can respond to presence/absence of light to stimulate/inhibit melatonin secretion

melanopsin

What does the pineal gland secrete?

melatonin

type of cells (acidophils/alpha cells) in the anterior pituitary gland that produce growth hormone and make up 30-40% of the anterior pituitary cells

somatotropes

collection of neurons in the hypothalamus functioning as the master biological clock that serves as the pacemaker for circadian rhythms Function: signals to the pineal gland to stimulate/not stimulate melatonin secretion + produces clock proteins

suprachiasmatic nucleus (SCN)

Special photoreceptor cells in the retina pick up light signals via the melanopsin receptor and relay them to what structure in the hypothalamus? What does this signal to the pineal gland?

suprachiasmatic nucleus, stop melatonin secretion

How are thyroid hormone and epinephrine an example of hormone permissiveness?

thyroid hormone increases the number of epinephrine receptors on epi target cells

type of cells (chromophobes) in the anterior pituitary gland that produce thyroid stimulating hormone (TSH)

thyrotropes

type of hormones released by the anterior pituitary that regulate the secretion of hormones by another endocrine organ and maintain its structural integrity examples: TSH, ACTH, FSH, LH, GH

tropic

True or false: Pretty much the whole pituitary gland is avascular.

true