Hypothalamus, Pituitary & Pineal Flashcards
(Endocrine system) Communicates via ______, secretory products
of endocrine cells, carried by bloodstream to target tissue containing
receptors
chemical messengers (hormones)
(Endocrine system) Communicates via chemical messengers (hormones), secretory products
of endocrine cells, carried by bloodstream to ______
target tissue containing
receptors
(Endocrine system) Endocrine organs composed of secretory cells of _____ origin
epithelial
(Endocrine system)
Lack ducts & secrete hormones into bloodstream
* Possess rich blood supply with ______ networks to absorb
& transport hormones.
fenestrated capillary
(Endocrine system)
_____ onset & ____ duration than nervous control
* Endocrine organs integrate function of physiologic systems
Slower onset & longer duration
Most ______ glands form discreet organs (Anterior pituitary, pineal, thyroid
and suprarenal (adrenal); in pancreas, endocrine & exocrine tissue intermixed
endocrine
____ coordinates endocrine functions of body—acts as
intermediary between autonomic nervous system & endocrine system
Hypothalamus
Suspended by a stalk from
hypothalamus
Pituitary
(Hypophysis)
(Pituitary) Rests in ____ of the
sphenoid bone, posterior to
the optic chiasm (CN II)
sella turcica
Two major divisions of Pituitary:
- Adenohypophysis
(Anterior pituitary) - Neurohypophysis
(Posterior pituitary)
Secretion of ____ hormones
controlled by hypothalamus, with
complex blood supply
pituitary
pituitary gland–Includes _____, which allows
communication with hypothalamus
hypophyseal portal
system
Hypothalamus controls secretion of
______ via hypothalamic
regulating factors (hormones)
anterior pituitary
_____ stimulate
secretion; _____
inhibit secretion
Releasing factors; inhibitory factors
_____ hormones—have non-endocrine target organ
(e.g., GH, ADH, MSH, oxytocin, prolactin)
Direct acting hormones
_____ hormones—target organ is another endocrine gland
(e.g., TSH, ACTH, FSH, LH)
Trophic hormones
Thyroid gland, adrenal cortex, & gonads all ____-
dependent endocrine glands
pituitary
Pituitary hormones: Functionally, anatomically, & embryologically, pituitary
divided into ___ portions
anterior & posterior
(Pituitary) Anterior portion contains ______ tissue &
posterior contains_____ tissue
glandular epithelial tissue; neural secretory tissue
(anterior pituitary) “Master gland”
(=adenohypophysis = pars
anterior = pars distalis)
(ant pituitary) Specialized glandular tissue, arises from
evagination of tissue from oral cavity in
region of pharynx called _____
Rathke’s pouch
Rathke’s pouch differentiates into 3 distinct
regions of anterior pituitary:
pars distalis, pars intermedia, pars tuberalis
—bulk of anterior pituitary
pars distalis
—thin layer between anterior
& posterior pituitary
Secretes MSH & ACTH
Frequently contains cystic remnants of
Rathke’s pouch
pars intermedia
—extension of anterior
pituitary; forms collar ~pituitary stalk
(=infundibulum)
pars tuberalis
Pars distalis secretes bulk of
pituitary hormones, including
both direct acting & ____
hormones
trophic
(Pars distalis) Direct acting hormones—____
* Trophic hormones—
GH & prolactin; TSH, ACTH, FSH, LH
Secretory cells of anterior
pituitary traditionally classified as
___ or
____
chromophils (which stain) or chromophobes (do not stain)
– Cells now classified by hormone
content
2 types of chromophils:
Acidophils & Basophils
—stain with acidic
dye; pink on H&E (chromophils)
Acidophils
—stain with basic dye;
pale blue to light purple on H&E (chromophils)
- Basophils
—small cells,
don’t take up either dye,
clear on H&E; represent
inactive cells
Chromophobes
Acidophils:
* ______— ~50% of cells; secrete Growth Hormone (GH or
somatotropin). Releasing: GHRH; Inhibiting: Somatostatin (GHIH).
Stimulating: ghrelin (stomach enteroendocrine cells) coordinates food
intake with GH secretion
Somatotrophs
— (= lactotrophs) ~20% of cells; secrete prolactin (controls
lactation). Releasing: PRH; Inhibiting: dopamine
Mammotrophs
(controls
lactation).
prolactin
(Cell subtypes) Basophils:
Thyrotrophs, Gonadotrophs, corticotrophs
— ~5% of cells; secrete Thyroid Stimulating Hormone (=
thyrotropin)
Thyrotrophs
— ~5% of cells; secrete Follicle Stimulating Hormone (FSH)
& Lutenizing Hormone (LH)
Gonadotrophs
— ~20% of cells; secrete Adrenocorticotropic hormone
(ACTH), Melanocyte-stimulating hormone (MSH), endorphins
Corticotrophs
- excessive
production of growth hormone
beginning in childhood
Pituitary gigantism
(Pituitary gigantism) Due to loss of feedback control
of _______ or
to GH-secreting tumor in
pituitary (adenoma
growth hormone secretion
Skeletal growth as well as
internal organs
* Significant problems with blood
glucose management
* Death usually due to heart
disease or diabetes
(complications)
Pituitary gigantism
Excessive adult production of growth
hormone
* Growth of face (prognathism), hands &
feet
Acromegaly
Increase in viscera
* Overproduction of glucose leads to
diabetes
* ?Due to loss of feedback control of growth
hormone secretion or to GH-secreting
tumor in pituitary
* Tx: surgery, radiation, growth hormone
receptor antagonist
Acromegaly
–Growth retardation resulting in
abnormally short adult stature.
–Problem can be in hypothalamus or
pituitary
–“Tx” – injections of growth hormone
Pituitary Dwarfism
(Pituitary Dwarfism–Growth retardation )
–It is caused by a variety of hereditary
and metabolic disorders.
–Pituitary dwarfism is caused by _____
insufficient
growth hormone.
(Pituitary Dwarfism–Growth retardation )
–It is caused by a variety of: ____ disorders
variety of hereditary
and metabolic disorders.
(Pituitary Dwarfism)
Growth _____ resulting in
abnormally short adult stature.
growth retardation
_____ stimulates initiation & maintenance of milk
production postpartum
Prolactin
(prolactin) Secretion is mediated primarily by inhibition control
mediated by ____
dopamine
(prolactin) Secretion is stimulated by _____ but suckling during lactation
is the primary stimulus.
PRH
As birth control: Prolactin inhibits the pulsatile secretion of
_____ which suppresses secretion of FSH & LH.
GnRH
As birth control: Prolactin inhibits the pulsatile secretion of
GnRH which suppresses secretion of ____
FSH & LH.
This tumor can grow superiorly
and impinge on the optic
chiasm producing visual field
defects (classically: bitemporal
hemianopsia)
* The tumor can also erode the
sella turcica
* A tumor large like this will
produce also increased
intracranial pressure (with
headache, nausea, and
vomiting).
Pituitary
macroadenoma
Pituitary
macroadenoma: This tumor can grow superiorly
and impinge on the ____
optic
chiasm
Pituitary
macroadenoma: This tumor can also erode the
___
sella turcica
(Pituitary
macroadenoma) bitemporal
hemianopsia
tunnel vision
Produce adrenocorticotropic hormone (ACTH) and lipotropic
hormone (LPH)
Corticotrophs
ACTH stimulates hormone release by the ____
adrenal (suprarenal) cortex
LPH stimulates ______; precise role in
humans in unknown
lipid mobilization in some mammals
Produce follicle-stimulating hormone (FSH) and luteinizing hormone
(LH)
Gonadotrophs
- stimulates ovarian follicle development/estrogen secretion or
production of androgen binding protein by Sertoli cells.
FSH
- helps control the menstrual cycle. It also triggers the release of
an egg
LH
Produce thyroid stimulating hormone (TSH) or
thyrotropin
*Stimulates thyroid gland to synthesize, store &
release thyroid hormones
Thyrotrophs
*Stimulates thyroid gland to synthesize, store &
release thyroid hormones
thyroid stimulating hormone (TSH) or
thyrotropin
Releasing: TRH
*Inhibiting: negative feedback suppression by CNS
based on amount of circulating thyroid hormones
**
Cells containing no
secretory granules
undifferentiated (stem)
cells or folliculostellate
cells - stroma to support
chromophils
Chromophobes
(chromophobes) Cells containing no
secretory granules
______
cells or _____
cells - stroma to support
chromophils
undifferentiated (stem); folliculostellate
Chromophobes: Cells with granules -
partially _____ chromophils
degranulated
______
–> 2o plexus
in pars distalis
Portal veins
Tubular sheath that extends from the pars distalis and winds around
the pituitary stalk.
Pars tuberalis
Epithelial cells (gonadotrophs) arranged in cords and
hypophyseal portal vessels are found here.
Pars tuberalis
(Pars tuberalis) Epithelial cells (gonadotrophs) arranged in ____ and
____ vessels are found here.
cords; hypophyseal portal vessels
Pars Intermedia: Synthesize
______
proopiomelanocortin
Cords of basophilic cells
Colloid-filled follicles
Pars Intermedia:
Pars Intermedia: alpha- and -melanocyte-
stimulating hormone
which stimulates ______
production
melanin (pigment)
melanin (pigment) secretion causes a dramatic darkening of
the skin of fishes, amphibians, and reptiles
as granules of melanin spread through the
branches of specialized melanocytes called
______
melanophores.
T/F: Diseases that may be attributed to the
under- or oversecretion of MSH are not well
defined in humans.
true
NEUROHYPOPHYSIS: Posterior pituitary has 2 parts–
(pars nervosa
& infundibulum/stalk)
Downgrowth of neural ectoderm
of hypothalamus
NEUROHYPOPHYSIS:
stalk/stem carries
axons from hypothalamus,
contains portal veins & primary
capillary plexus (median
eminence)
Infundibulum
Pars nervosa - axon terminals
**
paraventricular nuclei make
oxytocin
supraoptic nuclei make
ADH
Hormones moved
from hypothalamus
via ______
with neurophysin
hypothalamo-
hypophyseal tract
Unmyelinated axons
in the infundibulum
Stored for release in _____
pars
nervosa
Posterior pituitary hormones:
ADH (Vasopressin) and Oxytocin
controls blood pressure by altering
permeability of renal collecting tubules/ducts
ADH (Vasopressin)
↓ production of ADH => ↑ urine production (as in
diabetes insipidus)
ADH (Vasopressin)
ADH (Vasopressin): Synthesized by neuron cell bodies in ______ of
hypothalamus
supraoptic nucleus
ADH: Synthesized by neuron cell bodies in supraoptic nucleus of
______
hypothalamus
—promotes smooth Mm contraction in uterus &
breast (especially during labor & lactation)
Oxytocin
Oxytocin: Synthesized by neuron cell bodies in paraventricular
nucleus of ____
hypothalamus
Oxytocin: Synthesized by neuron cell bodies in ______ of hypothalamus
paraventricular
nucleus
Axons end in the pars nervosa
*Endings form large, fusiform swellings called ____
filled with secretory product
Herring bodies
T/F: Herring bodies filled with ____ product
secretory
Pars nervosa: Surrounded by
specialized glial-like
cells called _____
pituicytes
_____ is also known as the epiphysis
cerebri or the pineal body.
The pineal gland is also known as the _____ or the pineal body.
epiphysis
cerebri
The pineal gland is also known as the epiphysis
cerebri or the ____
pineal body.
Pineal gland is found in the posterior extremity of the third ventricle and is
attached by the pineal stalk to the _____
diencephalon.
Pineal Gland: Communicates with hypothalamus; acts as ____ in lower
vertebrates
photoreceptor
Pineal Gland: Translates light intensity & _____ into endocrine
activity—important in circadian rhythms & seasonal reproductive cycles
duration (photoperiod)
important in circadian rhythms & seasonal reproductive cycles
pineal gland
Secretes hormone melatonin => change in color intensity
with reproductive cycle & serotonin (vasoconstrictor; neurotransmitter)
Pineal Gland:
stimulates melanophores,
chromatophores (pigment-containing cells) => change in color intensity
with reproductive cycle & serotonin
melatonin
Pineal Gland: Secretes hormone melatonin (stimulates melanophores,
chromatophores (pigment-containing cells) => change in color intensity
with reproductive cycle & ___
serotonin (vasoconstrictor; neurotransmitter)
(vasoconstrictor; neurotransmitter)
serotonin
In mammals,____ has anti-gonadal effect, ↓ sex activity
melatonin
Melatonin => ____ from hypothalamus => ↓ sex hormone secretion
from gonads
↓ GNRH
are the most
common cell types, comprising
95% of all cells. They are
arranged in clumps and cords
within the lobules.
Histologic characteristics:
Neuronal-like cells, they have
large, irregular nuclei.
Pinealocytes
____ cells—support cells such as
astrocytes, microglial cells
Neuroglial cells (= interstitial
cells)
–(= “brain sand”, pineal sand)
–Calcified accretions of Ca & Mg
phosphate in aging individuals..radiopaque
corpora arenacea
Synthesis and secretion of
melatonin is dramatically
affected by ____
light exposure to the
eyes.
The fundamental pattern
observed (melantonin synthesis) is that serum
concentrations of melatonin are
____ during the daylight hours,
and ____ during the
dark.
low: increase to a peak
The duration of melatonin
secretion each day is directly
proportional to the _______
length of
the night.
SAD stands for:
Seasonal Affective Disorder
