Download HCB Objectives 14 - U

HCB Objectives 14

1.
Note: Pars intermedia of the pituitary releases MSH (melanocyte
stimulating hormone) to make skin darker
Structure, function, and location of:
a.
Pituitary:
a. Structure: divided into adenohypophysis and neurohypophysis
a.
Adenohypophysis: “regular tissue” part; divided into pars
distalis (anterior lobe), pars intermedia (connection
between posterior and anterior lobes), and pars tuberalis
(tissue surrounding infundibulum).
b.
Neurohypophysis: “nervous tissue” part; divided into
pars nervosa (nervous posterior lobe) and infudibulum
(stalk connecting to hypothalamus).
b. Location: in the sella turcica at the base of the brain below the
hypothalamus
c. Function: release of hormones: FSH, LH, ACTH, TSH, Prolactin,
GH, ADH, and oxytocin
b.
Pineal body:
a. Structure: cone shaped, joined to the brain by a short stalk,
surrounded by loose CT and highly vascularized (can calcify easily
due to rich vascular supply; look for “brain sand” calcium deposits)
b. Location: midline, dorsal to the roof of the diencephalon and superior
colliculi
c. Function: release of melatonin
c.
Thyroid:
a. Structure: two lateral lobes (right larger than left) connected by an
isthmus that may or may not have a pyramidal lobe extending
anteriorly from it
b. Location: in the anterior neck adjacent to the trachea
c. Function: release of thyroid hormone and calcitonin
d.
Parathyroid:
a. Structure: small, split-pea appearance
b. Location: four glands (two upper, two lower) situated on the posterior
surface of the thyroid
c. Function: release of parathyroid hormone
e.
Adrenals:
a. Structure: flat, triangular glands separated into cortex and medulla
a.
Adrenal cortex: zona glomerulosa, zona fasciculata, and
zona reticularis
b.
Adrenal medulla: modified postganglionic neurons
b. Location: the upper poles of the kidneys
c. Function: release of steroids: mineralocorticoids (aldosterone),
glucocorticoids (cortisol, cortisone, corticosterone), sex hormones,
norepinephrine, and epinephrine
2.
Cell types present, secretory product/function of:
f.
Pituitary:
a. Cell types:
a.
Adenohypophysis:
 Acidophils (“GPA”: GH, prolactin producers):
stain eosinophilically
 Basophils (“B FLAT”: FSH, LH, ACTH, TSH
producers): stain basophilically
 Chromophobes (cells that have released
granules): do not stain (no granules)
b.
Neurohypophysis:
 Pituicytes (astrocytes): small, dense, numerous
nuclei
 Neuroendocrine cells (ADH, oxitocin
producers): large, basophilic cells with lots of
RER and defined Golgi
 Herring bodies (accumulation of granules):
basophilic staining masses
b. Secretory product:
a.
Adenohypophysis: FSH, LH, ACTH, TSH, Prolactin, GH
b.
Neurohypophysis: ADH, Oxytocin
c. Function of secretory product:
a.
Adenohypophysis:
 FSH:
 Males: Spermatogenesis
 Females: Follicular development
 LH:
 Males: Maintenance of testicular IC cells
 Females: Ovulation
 ACTH: synthesis/release of glucocorticoids
from adrenal cortex
 TSH: synthesis/release of thyroid hormone
 Prolactin: milk secretion
 GH: bone growth
b.
Neurohypophysis:
 ADH: increased water permeability in renal
collecting ducts
 Oxytocin: contraction of myoepithelial alveolar
cells in the lactating breast
g.
h.
i.
j.
Pineal body:
a. Cell types:
a.
Pinealocytes (melatonin producers): irregular, infolded,
basophilic nuclei with extensive smooth ER and
microtubules
b.
Interstitial cells (astrocytes): elongated, basophilic nuclei
b. Secretory product: melatonin
c. Function of secretory product: desire to sleep in circadian rhythms
(light sensation in the retina inhibits melatonin), inhibition of pituitary
gonadotropin synthesis
Thyroid:
a. Cell types:
a.
Follicular cells (thyroglobulin producers): polarized
cells with centrally located nucleus, lysosomes, and
colloid droplets
 Note: follicles are surrounded by epithelium
that is squamous when inactive and fills to
become columnar when active
b.
C cells (calcitonin producers): clear staining pattern cells
that stain in anti-calcitonin stains
b. Secretory product: thyroid hormone and calcitonin
c. Function of secretory product:
a.
thyroid hormone (T-3, T-4) induces metabolism via
mitochondrial respiration
b.
calcitonin decreases serum Ca2+ levels by inhibiting
osteoclasts
Parathyroid:
a. Cell types:
a.
Principal cells (parathyroid hormone producers):
smaller cells with centrally located, variably shaped
nuclei and pale staining cytoplams
b.
Oxyphil cells (unknown function): larger cells with
eosinophilic cytoplasm
b. Secretory product: parathyroid hormone
c. Function of secretory product: increases serum Ca2+ levels by
increasing osteoclast proliferation
Adrenals:
a. Cell types:
a.
Zona glomerulosa: small cells adjacent to the capsule
b.
Zona fasciculata: long fascicles perpendicular to the
gland with large, numerous lipid droplets
c.
Zona reticularis: small cells adjacent to the medulla with
few lipid droplets
d.
Adrenal medulla: polyhedral cells, surrounded by large
medullary veins
b. Secretory product:
a.
Adrenal cortex: mineralosteroids (aldosterone),
glucocorticoids (cortisol, cortisone, corticosterone), sex
hormones
b.
Adrenal medulla: epinephrine and norepinephrine
c. Function of secretory product:
a.
Adrenal cortex:
 mineralosteroids (aldosterone): promotes
reabsorption of Na+ in renal distal convoluted
tubules, gastric mucosa, salivary glands, and
sweat glands
 glucocorticoids: slows metabolism (increases
gluconeogenesis, amino-acid and fatty acid
uptake, and protein synthesis) and depresses
immune system
 sex hormones: determines individual sex
b.
Adrenal medulla:
 epinephrine: sympathetic hormone (fight or
flight)
 norepinephrine: sympathetic neurotransmitter
(fight or flight)
3.
Structural and functional pathways:
a.
Hypothalamic regulation of the pituitary:
 humoral: hormone signaling through hypothalamohypophyseal portal
system (passes through the median eminence)
 neuronal: IPSPs and EPSPs on hypothalamohypophyseal tract
b.
Light regulation of pineal gland:
 retinal light sensors inhibits release of melatonin
c.
Pituitary regulation of thyroid:
 pituitary releases TSH to stimulate thyroid
d.
Ca2+ regulation of parathyroid:
 high calcium levels inhibit parathyroid function
e.
Pituitary regulation of adrenal cortex:
 pituitary releases ACTH to stimulate zona glomerulosa and zona
fasciculata of adrenal cortex
f.
Nervous regulation of adrenal medulla:
 sympathetic input stimulates adrenal medulla