Endocrine part 1 - Hypothalamus, Pituitary & Pineal Flashcards
What is the function of the endocrine system?
communicates via chemical messengers (hormones) and are carried by bloodstream to target tissue
What are the characteristics of the endocrine system?
- made of secretory cells of epithelial origin
- lakcs ducts
- secretes hormones into bloodsteam
- possess rich blood supply
- slower onset and longer duration
What type of capillary networks does the endocrine system have?
fenestrated
What endocrine organ coordinates endocrine functions of the body and acts as an intermediary between ANS and endocrine system?
hypothalamus
Most endocrine glands form _______ organs
discreet
The pituitary is suspended by a stalk from what organ?
hypothalamus
Where does the pituitary rest?
in sella turcica of the sphenoid bone
What is the pituitary posterior to?
optic chiasm (CN II)
What are the two divisions of the pituitary?
- Adenohypophysis (anterior)
- Neurohypophysis (posterior)
What is the median eminence a part of?
hypothalamus
What is the infundibulum (pituitary stalk) part of?
posterior pituitary (neurohypophysis; pars nervosa)
What part of the pituitary is the pars tuberalis from?
anterior pituitary (Adenohypophysis)
What part of the pituitary is the pars distalis from?
anterior pituitary (Adenohypophysis)
What allows communication from the hypothalamus and the pituitary gland?
hypophyseal portal system
What controls the secretion of pituitary hormones?
hypothalamus
What part of the pituitary is the secondary capillary plexus located?
anterior pituitary (Adenohypophysis)
What hormones have a non-endocrine target organ?
- direct acting hormones
ex:
growth hormone (GH)
antidiuretic hormone (ADH)
melanocyte-stimulating hormone (MSH)
oxytocin
prolactin
What hormones have a target organ that is another endocrine organ?
- trophic hormones
ex:
thyroid stimulating hormone (TSH)
adrenocorticotropic hormone (ACTH)
follicle stimulating hormone (FSH)
luteinizing hormone (LH)
What organs are pituitary-dependent endocrine glands?
thyroid gland
adrenal cortex
gonads
What does the anterior part of the pituitary contain (from development)?
glandular epithelial tissue (from oral cavity)
What does the posterior part of the pituitary contain (from development)?
neural secretory tissue
What is considered the master gland?
anterior pituitary (adenohypophysis; pars distalis)
Where does the specialized glandular tissue of the anterior pituitary arise from?
oral cavity in the pharynx called rathke’s pouch
What are the three parts of the anterior pituitary from rathke’s pouch?
pars distalis
pars intermedia
pars tuberalis
What part of the anterior pituitary makes up the bulk of it?
pars distalis
What part of the anterior pituitary is the thin layer between anterior and posterior pituitary?
pars intermedia
What does pars intermedia secrete?
MSH and ACTH
What does the pars intermedia sometimes contain?
cystic remnants of rathke’s pouch
What part of the anterior pituitary is an extension of it that forms the collar or pituitary stalk (infundibulum)?
pars tuberalis
What hormones does the pars distalis secrete?
- bulk of them
direct
- GH
- prolactin
trophic
- TSH
- ACTH
- FSH
- LH
What are the two types of secretory cells in the anterior pituitary?
chromophils (stain)
- acidophils
- basophils
chromophobes (don’t stain; inactive)
What are the two types of acidophils?
somatotrophs (50%)
mammotrophs (20%)
What are the three types of basophils?
thyrotrophs (5%)
gonadotrophs (5%)
corticotrophs (20%)
What type of chromophil secretes growth hormone?
somatotrophs
Somatotrophs are regulated by…
releasing =
inhibiting =
releasing = GHRH
inhibiting = Somatostatin (GHIH)
What type of chromophil secretes prolactin?
mammotrophs
Mammotrophs are regulated by…
releasing =
inhibiting =
releasing = PRH
inhibiting = dopamine
What type of chromophil secretes TSH?
thyrotrophs
What type of chromophil secretes FSH and LH?
gonadotrophs
What type of chromophil secretes ACTH, MSH, LPH, and endorphins?
corticotrophs
What causes pituitary gigantism?
- excessive production of growth homone
- loss of feedback control or GH-secreting tumor
What are the symptoms of pituitary gigantism?
- skeletal growth
- internal organ growth
- acromegaly
- growth of face (prognathism)
- increase in viscera
- blood glucose managment issues
- death due to heart disease or diabetes
What causes pituitary dwarfism?
- hereditary and metabolic disorders (insufficient growth hormone)
What is the function of prolactin?
- stimulates initiation and maintenance of milk production
- inhibits pulsatile secrete of GnRH (suppresses secretion of FSH and LH)
What does a pituitary macroadenoma cause?
- impinge optic chiasm (bitemporal hemianopsia)
- erode sella turcica
- increase intracranial pressure (headache, nausea, vomiting)
What is the function of follicle stimulating hormone (FSH)?
- stimulates ovarian follicle development and estrogen secretion (females)
- production of androge binding protein by sertoli cell (males)
What is the function of lutenizing hormone (LH)?
- helps control the menstrual cycle (release the egg)
What is the funciton of thyroid stimulating hormone (TSH)?
stimulates thyroid gland to synthesize, store, and release thyroid hormones
What’s not inside a chromophobe?
no secretory granules
Where does blood go after the portal veins of the pituitary?
secondary plexus in the pars distalis
What is in the infundibulum (stalk) of the posterior pituitary?
axons from hypothalamus
protal veins
primary capillary plexus
What is in the pars nervosa?
axon terminals
Where are hormones stored for release?
pars nervosa
What are the posterior pituitary hormones?
ADH (vasopressin)
Oxytocin
What does ADH (vasopressin) do?
controls blood pressure by altering permeability of renal collecting tubes/ducts
Where is ADH synthesized?
neuron cell bodies in supraoptic nucleus of hypothalamus
What does oxytocin do?
promotes smooth muscle contraction in uterus and breast
Where is oxytocin synthesized?
neuron cell bodies in paraventricular nucleus of hypothalamus
The endings of axons in the pars nervosa form large fusiform swellings called…
herring bodies
What are the specialized glial-like cells in the pars nervosa?
pituicytes
What is another name for the pineal gland?
epiphysis cerebri
pineal body
Where is the pineal gland located?
in the psoterior extremity of the 1/3 ventricle and attached by the pineal stalk to the diencephalon
What does the pineal gland act as in lower vertebrates?
photoreceptor
What organ is important in circadian rhythms and seasonal reproductive cycles?
pineal gland
What does the pineal gland secrete?
melatonin and serotonin
What affect does melatonin have on GNRH?
decrease
What affect does melatonin have on sex activity?
anti-gonadal effect
decreases sex activity
What are the most common cells in the pineal gland?
pinealocytes
- arranged in clumps and cords
- neuronal-like
Where can you see corpora arenacea (brain sand)?
pineal gland
What is brain sand and where is it found?
- calcified accretions of Ca and Mg phosphate in aging individuals
- pineal gland
Synthesis and secretion of melatonin is dramatically affected by _______________________
light exposure to the eyes
What are the symptoms of seasonal affective disorder?
depression
lack of energy
increased need for sleep
craving of sweets
weight gain
