0x Histology of the Endocrine System Lecture Flashcards
endocrinology
a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones
the integration of developmental events such as proliferation, growth, and differentiation (including histogenesis and organogenesis) and the coordination of metabolism, respirations, excretion, movement, reproduction, and sensory perception dependent of chemical cues, substances synthesized and secreted by specialized cells
parenchyma
the functional tissue of an organ
stroma
the connective tissue or framework of an organ
contains blood vessels, nerves, trabeculae, and finer fiberous networks of collagen (reticular fibers) or elastin
capsule
part of the stroma; surrounds the gland
trabeculae
part of the stroma; septa
divide glands into loves or lobules
lumen
the inner open space or cavity of a tubular organ
exocrine vs endocrine
exocrine release: through ducts
- ex: sweat glands, salivary glands, mammary glands, pancreas, liver
endocrine release: directly into blood vessels or lymph
- ex: adrenal glands, testes, ovaries, pancreas
basic exocrine gland development
(starts the same as endocrine)
1) specific loci in epithelium begin to proliferate
2) dividing cells invade underlying stroma but retain “seperateness” via basal lamina
(differs here)
3) tubular duct system develops
4) remaining cells differentiate into secretory cells
basic endocrine gland development
(starts the same as exocrine)
1) specific loci in epithelium begin to proliferate
2) dividing cells invade underlying stroma but retain “seperateness” via basal lamina
(differs here)
3) connection with the surface is lost
4) secretory cells associate with blood capillaries or sinuses
describe the release of endocrine hormones and the 3 methods of action
hormone diffuses from the extracellular fluid into the bloodstream and then acts as:
endocrine - travels through the body
paracrine - acts on nearby cells/tissues
autocrine - acts on itself
name endocrine organs/glands
hypophysis cerebri - pituitary epiphysis cerebri - pineal body thyroid parathyroid adrenal pancreatic islets of langerhans
ovaries and testes
placenta
gastrointestinal tract
what are the 2 lobes of the pituitary
anterior pituitary - adenohypophysis
posterior pituitary - neurohypophysis
Describe the basic development of the adenohypophysis
1) ectoderm from the rood of the stromadeum (oral cavity) forms Rathke’s pouch
2) base of Rathke’s pouch constricts, separating it from the oral cavity
3) lumen of Rathke’s pouch may persist as the residual lumen
(the AP and PP meet and fuse to form the Pituitary)
Describe the basic development of the neurohypophysis
1) neuroectoderm of the ventral wall of the diencephalon evaginates to form the infundibulum
2) lumen of 3rd ventricle extends into infundibular stalk and persists as the infundibular recess in some species (pig, cat)
(the AP and PP meet and fuse to form the Pituitary)
what are the 2 distinct systems by which the hypothalamus communicates with the pituitary gland
AP - hypophysial portal system
PP - hypothalamo-hypophysial tract
Describe the hypophyseal portal system.
in the hypothalamus parvocellular neurons in secrete hypothalamic releasing or inhibiting factors (prohormones)
which travel down through the portal vein and are released into the paracapillary space in the adenohypophysis (anterior pituitary)
where they trigger release of other hormones that travel out to the body through the vein
What are the parts of the anterior pituitary
pars tuberalis
pars intermedia
pars distalis
What are the parts of the posterior pituitary
infundibular stalk
pars nervosa