Lecture 1 Flashcards
three parts of the adenohypophysis?
embryonic origin?
- pars distalis
- Pars intermedia
- pars tuberalis
developed from ectoderm of the oropharynx or rathke’s pouch
parts of the neurohypophysis?
embryonic origin?
- Pars nervosa
- infundibulum
developed from neuroectoderm of the floor of the diencephalon
Acidophils of the pars distalis?
function?
- Somatotropes
they are stimulated by GHRH (growth hormone or somatotropin)
inhibited by somatostatin - Mammotropes / lactotropes
secrete prolactin
stimulate prolactin releasing hormone (PRH)
inhibited by dopamine
Basophils of the pars distalis
function?
these secrete hormones that affect other endocrine organs (tropic)
- gonadotropes
FSH
LH
stimulated by gonadotropin releasing hormone (GRH) - corticotropes
secrete ACTH (adrenocorticotropin)
stimulated by Corticotropin-releasing hormone (CRH) - Thyrotropes
TSH
stimulated by thyrotropin-releasing hormone (TRH)
Pars intermedia and tuberalis histology
remnant of Rathke’s pouch
intermedia - follicle- like structures
associated with Beta-lipotrophic hormone
tuberalis:
forms sheath around infundibulum
small follicles and squamous cells
pars nervosa function?
histology?
types of nuclei?
stores hormones produced by hypothalamic nuclei
supraoptic nucleus: ADH (vasopressin)
paraventricular nucleus: oxytocin
carried along the hypothalamo-hypophyseal tract
histology:
axons are unmyelinated
have herring bodies (contain hormones and are bound to neurophysin)
most nuclei are pituicytes (glial like cell)
secrete glial fibrillary acidic protein
for support
capillaries are fenestrated
acidophilic pituitary adenomas?
prolactinoma:
nipple secretion
amenorrhea
dysfunction
somatotropic adenoma (growth hormone):
acromegaly (if adult)
gigantism in children
addition symptoms:
headache
vision issues
basophilic pituitary adenomas
corticotropic adenoma:
Cushing disease
Thyrotropic adenoma:
hyperthyroidism
additional symptoms:
headache
vision issues
adrenal gland development
adrenal gland histology?
cortex develops from mesoderm
medulla develops from neural crest cells (sympathetic ganglion)
histology:
capsule: DCT
cortex: pale-staining (steroid producing cells)
medulla : central (large blood vessels)
Zones of the adrenal cortex?
- Zona glomerulosa
aldosterone
For salt and water balance
feedback from RAAS - Zona fasciculata
mainly cortisol (glucocorticoid)
some androgens - Zona reticularis
mainly androgens
some glucocorticoid
histology of adrenal cortex
- glomerulosa
loops or arcades of small cells
1-2 layers
aldosterone production - Fasciculata
linear cords of polyhedral cells (1-2 layers)
fenestrated capillaries
cells are called spongiocytes (lipid droplets)
stimulated by ACTH
secrete cortisol
3. Reticularis irregular cords of small cells may have brown pigment regulated by ACTH androgen and some cortisol
abnormal aldosterone production
Conn’s Syndrome (primary aldosteronism)
hypertension
potassium deficiency
Cushing’s disease vs Cushing’s syndrome
Cushing syndrome:
tumors or hypoplasia (increasing glucocorticoid secretion)
Cushing disease:
pituitary origin
increased ACTH
increased glucocorticoids
Addison’s disease (hypoadrenalism)
destruction of the adrenals (most likely autoimmune)
deficiency of all hormones
weakness, weight loss, muscle pain, hypotension, hyperpigmentation
Histology of the adrenal medulla
cell types?
Large vein
two cell types: chromaffin and ganglion
cells surrounded by fenestrated capillaries
chromaffin: modified post-ganglionic sympathetic
no axon / no dendrites
brown granulation can be seen
secrete 85% Epinephrine and Norepinephrine
stimulated by preganglionic sympathetic
ganglion cells:
innervate blood vessels of the cortex
Pheochromocytomas
excessive amounts of catecholamines due to tumor of the chromaffin cells
most secrete norepinephrine
will see large nuclei and granular cytoplasm
will be positive for chromogranin A
pineal gland or epiphysis cerebri
histology?
located posterior wall of 3rd ventricle
nerve input from postganglionic sympathetic fibers from superior cervical ganglion
secrete melatonin for sleep
histology:
will see calcium deposit (brain sand)
look for deviation of pineal gland
Thyroid gland
stimulating hormone is TSH
secrete T3 and T4
have parafollicular cells or clear cells secrete calcitonin (lowers blood Ca by osteoclast suppression)
hyperthyroidism ( toxic goiter or graves disease)
Due to excessive amounts of thyroid hormones
can be autoimmune
clinical: low TSH increased metabolic rate weight loss, heat intolerance bulging eyes, eyelid retraction
histology:
decreased colloid
columnar epithelium
parathyroid glands
cell types?
principal or chief cells:
small and dense
PTH- increase blood Ca
decrease phosphate levels
oxyphil cells:
large and acidophilic
unknown function
pancreas
endocrine units?
types of cells?
Islets of Langerhans
more towards the tail of the pancreas
Alpha cells: secrete glucagon (increase blood glucose)
beta cells: secrete insulin (decrease blood glucose)
Delta cells: somatostatin
F cells: pancreatic polypeptide
Diabetes insipidus VS Diabetes mellitus
Diabetes insipidus:
inability to concentrate the urine
polyurea, polydipsia, hypotonic urine, hyponatremia
can be hypothalamic: lack of ADH by tumor or head injury
can be nephrogenic: congenital mutation of aquaporins
Diabetes mellitus:
defective glucose metabolism
elevated blood glucose, glucosuria, polyurea, increased hunger and thirst
can be type I: childhood
loss of type B cells - less insulin secretion
could be autoimmune
Can be type II: adult onset
insulin resistance of target cells
