Endocrine Flashcards
Thyroid gland
- Embryologic origin
The thyroid gland develops from an ENDODERMAL thickening in the FLOOR of the PRIMORDIAL PHARYNX, which soon thereafter forms a small outpouching called the THYROID PRIMORDIUM.
Recall - The primordium of the esophagus and oropharynx develops from the dorsal aspect of the cranial/upper foregut.
During development, the thyroid gland is connected to the tongue by what structure?
Thyroglossal duct
By ___ weeks gestation, the thyroglossal duct has normally degenerated and disappeared.
What is the embryologic remnant of the thyroglossal duct?
By SEVEN weeks gestation, the thyroglossal duct has normally degenerated and disappeared.
Foramen cecum - Posterosuperior surface of the tongue
What TWO embryologic processes are essential in the development of the thyroid gland?
- Migration - The developing thyroid migrates/descends down the neck to its final anatomical location.
- Fusion - Fusion is a process when 2 cells from different embryologic origins fuse to form an organ system. Thyroid gland development involves fusion of THYROID FOLLICLES and PARAFOLLICULAR C-CELLS
What TWO embryologic processes are essential in the development of the thyroid gland?
- Migration - The developing thyroid migrates/descends down the neck to its final anatomical location.
- Fusion - Fusion is a process when 2 cells from different embryologic origins fuse to form an organ system. Thyroid gland development involves fusion of THYROID FOLLICLES and PARAFOLLICULAR C-CELLS.
Embryologic derivation:
- Thyroid follicles
- Parafollicular C-cells
Thyroid follicles - Endodermal thickening in the floor of the primordial esophagus/pharynx (dorsal aspect of the cranial foregut)
Parafollicular C-cells - 4th branchial pouch
Thyroglossal duct cyst develops 2/2 persistent ___ that presents clinically as:
Branchial cleft cyst develops 2/2 persistent ___ that presents clinically as:
Thyroglossal duct cyst develops 2/2 persistent thyroglossal duct - Presents as painless, progressively enlarging, MOVEABLE mass that usually moves with swallowing or protrusion of tongue.
Branchial cleft cyst develops 2/2 persistant cervical sinus - Presents as a LATERAL NECK mass.
Thyroglossal duct cyst develops 2/2 persistent ___ that presents clinically as:
Branchial cleft cyst develops 2/2 persistent ___ that presents clinically as:
Thyroglossal duct cyst develops 2/2 persistent thyroglossal duct - Presents as painless, progressively enlarging, MOVEABLE mass that usually moves with swallowing or protrusion of tongue.
Branchial cleft cyst develops 2/2 persistant cervical sinus - Presents as a LATERAL NECK mass.
What are the 2 components of the fetal adrenal gland?
- Inner active fetal zone
2. Outer dormant/inactive adult zone
Part of adrenal gland immature when baby born? When functional?
Zona reticularis of adrenal cortex is immature at birth and not fully developed until 3 years after birth.
Mechanism by which fetus produces androgens in utero?
Fetus requires PLACENTAL 3β-hydroxysteroid dehydrogenase enzyme to convert pregnenolone to progesterone for synthesis of androgens.
Adrenal gland
- Embryologic derivation of cortex
- Embryologic derivation of medulla
Cortex - Mesenchyme/mesoderm
Medulla - Neuroectoderm (neural crest cells)
ADRENAL CORTEX
- 3 layers and corresponding secretory products
Zona glomerulosa
- Mineralocorticoids (ALDOSTERONE)
Zona fasciculata
- Glucocorticoids (CORTISOL)
Zona reticularis
- Androgens
ADRENAL CORTEX
- 3 layers and corresponding secretory products
Zona glomerulosa
- Mineralocorticoids (ALDOSTERONE)
Zona fasciculata
- Glucocorticoids (CORTISOL)
Zona reticularis
- Androgens
ADRENAL MEDULLA
- Cell type and corresponding secretory product
Chromaffin cells
- Catecholamines (epinephrine, NE)
Chromaffin cells are modified postganglionic sympathetic neurons that receive sympathetic input (neuroendocrine cells).
Adrenal tumors
- MCC in children
- MCC in adults
Children - Neuroblastoma (medulla)
Adults - Pheochromocytoma (medulla)
–> Episodic HTN
Venous drainage
- Left adrenal
- Right adrenal
Left: Left adrenal vein to left renal vein to IVC
Right: Right adrenal vein to IVC
SYMPATHETIC PREGANGLIONIC NEURONS release [?], which activates [?] receptors on postganglionic neurons.These postganglionic neurons release [?] to activate [?] receptors on target tissues. What are 2 exceptions to this principle?
Sympathetic preganglionic neurons release ACh, which activates AChR receptors on postganglionic neurons.These postganglionic neurons release NE to activate ADRENERGIC receptors on target tissues.
Exceptions:
1) Postganglionic neurons that innervate sweat glands release ACh, not NE.
2) Chromaffin cells of adrenal medulla - Innervated by preganglionic sympathetic nerons that release ACh and bind AChRs on chromaffin cell surface. However, these cells are MODIFIED postganglionic neurons. They release catecholamines (80% epi, 20% NE) directly into blood stream to activate adrenergic receptors in target tissues.
PREGANGLIONIC SYMPATHETIC NEURONS release [?], which activates [?] receptors on postganglionic sympathetic neurons, which subsequently release [?] to activate [?] receptors on target tissues.
What are the 2 exceptions to this principle?
Preganglionic sympathetic neurons release ACh, which activates AChR receptors on postganglionic sympathetic neurons, which subsequently release NE to activate ADRENERGIC receptors on target tissues.
Exceptions:
1) Postganglionic neurons that innervate sweat glands release ACh, not NE.
2) Chromaffin cells of adrenal medulla - Innervated by preganglionic sympathetic nerons that release ACh and bind AChRs on chromaffin cell surface. However, these cells are MODIFIED postganglionic neurons. They release catecholamines (80% epi, 20% NE) directly into blood stream to activate adrenergic receptors in target tissues.
Adrenal medulla releases catecholamines (epi, NE) that bind adrenergic receptors in what 4 locations in body to mediate acute stress response?
Heart, lungs, liver, and skeletal muscle
Adrenal medulla releases catecholamines (epi, NE) that bind adrenergic receptors in what 4 locations in body to mediate acute stress response?
Heart, lungs, liver, and skeletal muscle
Anterior pituitary gland
- Embryologic origin
- Hormones
Anterior pituitary gland = Adenohypophysis
Embryology - Derived from an UPGROWTH of oral ectoderm (Rathke’s pouch)
FLAT PiG
FSH, LH, ACTH, TSH, prolactin, GH
Chromophils are anterior pituitary cells containing granules that react with acidophilic/basophilic stains.
Acidophilic cells
- Hormones present in granules
- Color staining
ACIDOPHILS = PiG hormones
Prolactin, GH
ACIDOPHILS stain pink/red
Chromophils are anterior pituitary cells containing granules that react with acidophilic/basophilic stains.
Basophilic cells
- Hormones present in granules
- Color staining
BASOPHILS = FLAT hormones
FSH, LH, ACTH, TSH
BASOPHILS stain BLUE (blue/purple = PAS+)
“B-FLAT”
BASOPHILS - FSH, LH, ACTH, TSH
