Endocrine System
,L1 & L2: Endocrine System
1. Describe the common histological elements of endocrine glands, and list the glandular
components of the endocrine system.
Endocrine Glands
● Ductless glands that develop from invaginations of epithelial surfaces (ectodermal or
endodermal) that pinch off losing contact with parent epithelium
● Consist of secretory cells (in cords, clumps, or follicles)
● Adjacent or in direct contact with abundant capillaries or sinusoids to facilitate release
and distribution of secreted peptide or steroid hormones into the bloodstream
2. Trace the hypothalamic-hypophyseal portal system and pituitary vasculature.
Hypothalamic-Pituitary Axis
● Hypothalamus controls the pituitary’s secretory activities
● Pituitary (hypophysis) connects the endocrine and nervous systems → “master gland”
due to its control and regulation of other endocrine glands
Hypothalamo-Hypophyseal Portal System
● Vessels carry neuropeptides directly from hypothalamic nuclei (dorsal, ventral, and
infundibular nuclei) to the adenohypophysis
○ Receives blood from primary capillary plexus and carry it directly to secondary
capillary plexus
Vasculature of the Pituitary Gland
● All vessels come off the internal carotid artery
○ Sup hypophyseal aa → supply median eminence and infundibulum
○ Inf hypophyseal aa → provide blood mainly for the neurophysis
○ Primary capillary plexus → receives blood from superior hypophyseal arteries
and drains into hypophyseal portal veins (carry releasing hormones)
■ Located along upper infundibulum, lower median eminence, and extends
into pars tuberalis
○ Secondary capillary plexus → fenestrated capillaries and sinusoids located
throughout pars distalis, pars tuberalis, and pars intermedia
3. Describe the regions of the pituitary and major hormone products.
Pituitary Gland/Hypophysis
● Bi-lobed gland suspended from the base of the hypothalamus by the infundibulum (stalk)
○ Anterior lobe = adenohypophysis
○ Posterior lobe = neurohypophysis
● Rests within the sella turcica of the sphenoid bone
,Hormones secreted by the Posterior Pituitary
● ADH → kidney → regulating water levels
● Oxytocin → uterus and mammary glands → labor contractions
Hormones secreted by the Anterior Pituitary
● ACTH, TSH, FSH, LH, PRL, GH
, 4. Compare and contrast the layers of the adrenal cortex in terms of their histological
structure and corresponding hormone products and functions.
Adrenal Glands
● Embedded in perirenal adipose along the superior poles of the kidneys
● Covered by a dense CT capsule with thin trabeculae
● Stroma of the gland comprised of a network of reticular fibers that support the secretory
cells
● Cells of both cortex and medulla are grouped in cords or clusters along capillaries
,L1 & L2: Endocrine System
1. Describe the common histological elements of endocrine glands, and list the glandular
components of the endocrine system.
Endocrine Glands
● Ductless glands that develop from invaginations of epithelial surfaces (ectodermal or
endodermal) that pinch off losing contact with parent epithelium
● Consist of secretory cells (in cords, clumps, or follicles)
● Adjacent or in direct contact with abundant capillaries or sinusoids to facilitate release
and distribution of secreted peptide or steroid hormones into the bloodstream
2. Trace the hypothalamic-hypophyseal portal system and pituitary vasculature.
Hypothalamic-Pituitary Axis
● Hypothalamus controls the pituitary’s secretory activities
● Pituitary (hypophysis) connects the endocrine and nervous systems → “master gland”
due to its control and regulation of other endocrine glands
Hypothalamo-Hypophyseal Portal System
● Vessels carry neuropeptides directly from hypothalamic nuclei (dorsal, ventral, and
infundibular nuclei) to the adenohypophysis
○ Receives blood from primary capillary plexus and carry it directly to secondary
capillary plexus
Vasculature of the Pituitary Gland
● All vessels come off the internal carotid artery
○ Sup hypophyseal aa → supply median eminence and infundibulum
○ Inf hypophyseal aa → provide blood mainly for the neurophysis
○ Primary capillary plexus → receives blood from superior hypophyseal arteries
and drains into hypophyseal portal veins (carry releasing hormones)
■ Located along upper infundibulum, lower median eminence, and extends
into pars tuberalis
○ Secondary capillary plexus → fenestrated capillaries and sinusoids located
throughout pars distalis, pars tuberalis, and pars intermedia
3. Describe the regions of the pituitary and major hormone products.
Pituitary Gland/Hypophysis
● Bi-lobed gland suspended from the base of the hypothalamus by the infundibulum (stalk)
○ Anterior lobe = adenohypophysis
○ Posterior lobe = neurohypophysis
● Rests within the sella turcica of the sphenoid bone
,Hormones secreted by the Posterior Pituitary
● ADH → kidney → regulating water levels
● Oxytocin → uterus and mammary glands → labor contractions
Hormones secreted by the Anterior Pituitary
● ACTH, TSH, FSH, LH, PRL, GH
, 4. Compare and contrast the layers of the adrenal cortex in terms of their histological
structure and corresponding hormone products and functions.
Adrenal Glands
● Embedded in perirenal adipose along the superior poles of the kidneys
● Covered by a dense CT capsule with thin trabeculae
● Stroma of the gland comprised of a network of reticular fibers that support the secretory
cells
● Cells of both cortex and medulla are grouped in cords or clusters along capillaries
