Flashcards in Lecture 1 & 2 Deck (33):
Classify endocrine glands based on chemical components of their secretion.
Steroids: gonadal & adenocortical steroids
Small peptides, polypeptide, & proteins: insulin, glucagon, GH, LH, ACTH
Amino acids and Arachiodonic Acid analogs & deriv: catecholamines, PGs, prostacyclin, and leukotrienes (thyroid hormones)
Describe common histological characteristics
of all endocrine glands.
- cords of cells invested in reticular fibers
- fenestrated capillaries (may be called sinusoids)
- secrete hormones that act on target organs
Describe the development of the pituitary gland.
- evagination of ectoderm of oropharynx
- 3 derivatives of Rathke's pouch:
1. par distalis: anterior wall of pouch
2. pars intermedia: posterior wall of pouch
3. pars tuberalis: lateral walls of pouch
- downgrowth (embryonic infundibulum) of neuroectoderm of the floor of the diencephalon (3rd ventricle)
- 2 parts:
1. pars nervosa
Identify & describe the glandular and nervous tissue components of the pituitary gland
Anterior lobe: glandular tissue (Adenohypophysis)
- pars tuberalis
- pars distalis
- pars intermedia
Posterior lobe: neural tissue (Neurohypophysis)
- mediam eminence
- pars nervosa
State the significance of hypothalamo-hypophyseal portal system.
provides crucial link between the hypothalamus and pituitary gland. System carries the neuroendocrine secretions from their site of release in mediam eminence and infundibulum directly to the cells of the pars distalis.
Identify & describe the microscopic structures of anterior and posterior pituitary.
Anterior pituitary (cellular):
- Chromophobes: unknown
Acidophils: somatotropes (GH; inhibited by somatostatin) & mammotropes (PRL; inhibited by dopamine)
Basophils:(B-FLAT) gonadotropes (FSH & LH), corticotropes (ACTH), & thyrotropes (TSH)
- production of alpha-MSH
- colloid filled cystic cavities
- basophilic cuboidal cells
Posterior pituitary (neurohypophysis):
- Herring bodies: release hormones into blood stream
- Fenestrated capillaries
-supraoptic nucleus: production of ADH
paraventricular nucleus: production of oxytocin
List the hormones produced by the cells of anterior pituitary and describe the major functions.
Follicle stimulating hormone (FSH): stimulates follicular development in the ovary and spermatogenesis in the testis
Luteinizing hormone (LH): regulates final maturation of ovarian follicle, ovulation, and corpus luteum; in males, essential for maintenance and secretion of adrogen secretion by Leydig cells
Adrenocorticotropic hormone (ACTH): maintains structure and stimulates secretion of glucocorticoids and gonadocorticoids by zona fasciculata and zona reticularis of adrenal cortex
Thyrotropic hormone (TSH): stimulates growth of thyroid epithelial cells; stimulates production and release of thyroglobulin and thyroid hormones
Prolactin (PRL): promotes mammary gland development; initiates milk formation; stimulates and maintains secretion of casein, lactalbumin, lipids, and carbohydrates into milk
Growth hormone (GH): stimulates liver and other organs to synthesize and secrete insulin-like growth factor I, which stimulates division of progenitor cells in growth plates and in skeletal muscle
Identify & describe the structure and functions of the pars intermedia.
- surrounds a series of small cystic cavities, colloid-filled follicles (residual Rathke's pouch)
- basophilic cuboidal cells: production of MSH
Identify & describe the components of posterior pituitary.
- contains non-myelinated axons and their nerve endings (neurosecretory neurons); cell bodies lie within supraoptic nuclei and paraventricular nuclei
- axons form hypothalamophyseal tract
- connects posterior lobe to hypothalamus
List the hormones that are stored in the posterior pituitary, their origin and their effects.
- synthesized in paraventricular nuclei
- acts on uterine contractions and millk release
- synthesized in supraoptic nuclei
- increases permeability of renal collecting tubule to water and vasoconstricts
State the significance of pituicytes and Herring bodies.
Pituicyte: only cells specific to posterior lobe of pituitary gland; specialized glial cells containing intermediate filament protein, charateristic of astrocytes
Herring bodies: dilations of unmyelinated axons containing secretory granules
Describe the blood supply to the pituitary gland.
Superior hypophyseal arteries: arises from internal carotid arteries and posterior communicating arteries of circle of Willis; supplies the pars tuberalis, median eminence, and infundibulum
Inferior hypophyseal arteries: arise from internal carotid artieries; supplies pars nervosa
superior hypophyseal arteries --> fenestrated capillaries (primary capillary plexus) --> hypophyseal portal veins --> second fenestrated capillary network --> cavernous sinus at base of diencephalon --> systemic circulation
- direct communication between hypothalamus and posterior pituitary
- communication between anterior pituitary and hypothalamus is via portal system
Describe the anatomical location and blood supply to the adrenal gland.
Located at superior poles of kidneys.
Blood supply: superior, middle, and inferior suprarenal arteries --> branching before entering capsule --> capsular capillaries, fenestrated cortical sinusoidal capillaries, and medullary arterioles --> adrenomedullary collecting veins --> central adrenomedullary vein --> IVC
Identify and describe the cortical zones of adrenal gland, hormones produced there and their function
superficial to deep: (GFR)
Zona Glomerulosa: thin, most superficial layer; globular arrangement
- aldosterone: electrolyte and water balance
Zona Fasciculata: thick, longitudinal columns arrangement
Zona Reticularis: trabeculae-like arrangement
Z. Fas. & Z. Ret. produce cortisol and androgens (DHEA): increase protein, carbohydrate, and fat metabolism and suppress immune function
Identify and describe
the adrenal medulla, hormones produced there and their function.
- modified post-ganglionic neurons; no axons/dendrites
- secrete catecholamines
- axonal processes extend into cortex and modulate secretion
Describe the anatomical location and blood supply to pancreas
Location: retroperitoneal of abdomen.
- Supplied by the pancreatic branches of the splenic artery.
- Head is additionally supplied by the superior (from celiac trunk) and inferior pancreaticoduodenal arteries (superior mesentery)
- Venous drainage of the head of the pancreas is into the superior mesenteric branches of the hepatic portal vein.
- Pancreatic veins draining the rest of the pancreas into the splenic vein.
List & describe the functional cell types of the endocrine pancreas.
alpha cells: located peripherally; secrete glucagon.
beta cells: located centrally; secrete insulin.
delta cells: scattered throughout; secrete gastrin and somatostatin
List the hormones produced by cells of endocrine pancreas and describe their effect
Glucagon: stimulation of glycogenolysis and glucose release from liver (glucogenesis), and lipolysis
Insulin: stimulates glycogenesis and glycolysis
Identify & describe the structure and function of the thyroid gland.
- butterfly shaped (isthmus) in the anterior of the neck, anterior to upper part of trachea
- capsule covered with CT that sends trabeculae into the parenchyma
- secretion of T3/ T4
- thyroid follicles is the functional unit of the gland
Describe the storage and secretory mechanisms of thyroid hormones.
- thyroid epithelium follicular cells (principal cells): simple cuboidal with apex towards colloid and BSM towards exterior; production of thyroid hormones T3 & T4: regulation of cell and tissue basal metabolism and heat production and influence body growth and development); short microvilli, endocytotic vesicles (colloidal resorption droplets), and lysosomes at apex for secretion and absorption; numerous rER at basal region
- colloid: thyroglobulin (inactive hormone; consists of triiodothyronine and tetraiodothyronine (or thyroxine)); secretory product of follicular cell.
Identify & describe the function and localization of parafollicular cells.
- Parafollicular cells (C cells):
at periphery of follicular epithelium; secrete calcitonin (regulation of serum calcium levels via inhibition of resorptive action of osteoclasts and promotes deposition in bones by increasing rate of osteoid calcification)
Identify & describe the structure and function of the parathyroid gland.
Location: 4 small glands embedded into the posterior part of the thyroid gland.
Function: secretion of PTH, which stimulates osteoclasts to release calcium from bone and uptake of calcium from intestines and kidneys.
- chief cells: secretion of PTH
- oxyphil cells: unknown function
Identify & describe the location, structure, and function of the pineal gland.
Location: posterior wall of the 3rd ventricle near the center of the brain
Function: endocrine/neuroendocrine gland that regulates daily body rhythm via photosensitivity; obtaining information of light and dark cycles from retina (retinohypothalamic tract: connects suprachiasmatic nucleus with sympathetic neural tracts traveling into pineal gland)
- flattened, pine cone-shaped
- interstitial (glial) cells
- corpora arenacea/brain sand
List the hormone produced by the pineal gland and its effect on target tissues.
Melatonin: increased secretion during darkness; potent antioxidant; regulation of reproductive function by inhibition of steroidogenic activity of gonads (decreases production of gonadal steroids by inhibition of GnRH, which decreases release of FSH & LH)
List, identify, & describe the cell types of pineal gland.
- pinealocytes: arranged in clumps/cords within lobules formed by CT speta; large, deeply infolded nucleus with one or more nucleoli and lipid droplets; secretion of melatonin
- interstitial (glial) cells: reminscent of pituicytes of posterior pituitary gland; astrocyte like
- corpora arenacea/brain sand: calcified concretions from precipitations of calcium phosphates and carbonates on carrier proteins
Describe the clinical signficance of corpora arenacea.
- calcified concentrations are recognizable from childhood and increase in number with age
- used as a convenient marker in radiographic (x-rays) and computed tomography (CT) studies.
Compare and contrast diabetes mellitus and insipidus
Diabetes Insipidus: absence or reduced production of ADH; two types:
- hypothalamic DI (central): no secretion of ADH
- nephrogenic DI: deficient receptor for ADH
Diabetes Mellitus: impaired ability to produce or respond to insulin
Type I: insulin-dependent; anti-pancreas Ab; inability to produce insulin; childhood onset
Type II: insulin-resistance; adult onset
Discuss pituitary adenoma and possible clinical presentation.
- benign tumor; 3 types:
- amenorrhea (absence of menstrual cycle),
- oligomenorrhea (infrequent menstrual cycle),
- galactorrhea (excessive/inappropriate production of milk),
- decreased libido
2. Acromegaly (GH secreting adenoma):
- sleep apnea
- soft tissue enlargement
- gigantism (youth), acromegaly (adult)
3. Cushing's disease (ACTH secreting adenoma):
- moon face
- buffalo hump
- thick skin
- skin striae
- decreased fertility
- weight gain
Discuss Conn's disease and possible clinical presentation.
Adrenal adenoma (aldosterone secreting adenoma)
- high serum aldosterone
- low renin levels
Compare and contrast Cushing's diease and Cushing's Syndrome.
- endocrine disorder due to hypercortisolism
- causes: external medication, cushing's disease, adrenal tumor, small cell carcinoma of lung
- pituitary adenoma that is ACTH-releasing
Describe the changes to adrenal cortex in Addison's disease.
- hyposecretion of ACTH leading to decreased glucocorticoids and mineralocorticoids
- eventual shrinkage of adrenal glands
Describe the changes seen in adrenal medulla in pheochromoctyoma.
- tumor of chromaffin cells: chromaffinoma
- abnormal hypertension
- increased production of epi/norepi
- appears more eosinophilic and enlarged cytoplasm