Endocrine System Flashcards
exocrine definition
releases its secretions onto an epithelial surface through a duct
endocrine definition
secretes hormones into blood vessels or surrounding tissue fluid
hormone types
amino acid derivatives
steroid
peptide
where is the pituitary gland
lies in Sella turcica
connected to hypothalamus by infundibulum
other names for anterior and posterior pituitary
adeno and neuro hypophysis
what is the pars distalis
cell types
part of ant pit
chromophobes and chromophils
subdivisions of chromophils
acidophils and basophils
subdivisions of acidophils
subdivisions of basophils
and their secretions
acidophils
somatotrophs: GH
Lactotrophs: prolactin
basophils
thyrotropes: TSH
gonadotrophs: LH, FSH
corticotropes: ACTH
what is the pars nervosa
cell types
part of the pos pit
mainly glial cells called pituicyte
axons of neurons in the hypothalamus
what are Herring bodies
where are they
storage sites of neurosecretory materials
pars nervosa neurons
pars intermedia
structure between pars distalis and pars nervosa
consists of mainly colloid filled cysts
where do the cell bodies of neurons whose axons are in the infundibulum originate
what hormones do they create
supraoptic and paraventricular nuclei of the hypothalamus
oxytocin and ADH
what hormones are secreted from the hypothalamus
thyroid releasing hormone
gonadotropin releasing hormone
what hormones are secreted from the ant pit and pos pit
ant pit:
GH
ACTH
TSH
FSH, LH
PRL
pos pit:
oxytocin
ADH
overproduction and deficiency of growth hormone
pituitary gigantism and dwarfism
function of PRL
promotes milk secretion
function of TSH
stimulates thyroid hormone synthesis and release
function of ACTH
stimulates the secretion of steroid hormones by adrenal cortex of adrenal gland
roles of FSH and LH
FSH promotes ovarian follicle development and estrogen secretion/spermatogenesis
LH induces ovulation/androgen secretion
what does the pos pit consist of
unmyelinated axons from hypothalamic neurons
pituicytes
deficiency of ADH
diabetes insipidus
role of oxytocin
stimulates contraction of smooth muscle of uterine wall during labour
stimulates mammary glands to release milk
histology of thyroid gland
many follicles consisting of cuboidal cells containing colloid
parafollicular cells between them
role of para follicular cells
secrete calcitonin to regulate calcium
thyroid hormone role
precursor
increase BMR, calorigenic
made from follicular cell thyroglobulin
thyroxine-binding globulin
other important carriers
liver synthesised glycoprotein to carry poorly soluble TH
transthyretin
albumin
role of calcitonin
decrease blood calcium levels
bone: inhibits osteoclasts
kidneys: inhibit reabsorption of calcium and phosphorus
iodine deficiency goitre
caused by diet
hinders synthesis of TH - hypothyroidism
leads to excess TSH production and thyroid stimulation
treated with iodine therapy
cretinism
due to congenital hypothyroidism
characterised by arrested physical and mental development
myxoedema (Gulls disease)
adult hypothyroidism
expressionless face, swelling, alopecia, loss of nails and hardening of skin
increased amount of protein and mucopolysaccharides - bind and hold water
non-pitting oedema around extremities and face
thickening of tongue and laryngopharynx mucosa
Grave’s disease
autoimmune disease leading to hyperthyroidism
TSH receptor is stimulated by thyroid stimulating immunoglobulin
hypothalamic-pituitary-thyroid axis negative feedback
TH inhibits TSH release from ant pit
also inhibits TRH release from hypothalamus to a lesser extent
location of parathyroid glands
embedded in posterior surface of thyroid gland
separated by fibrous capsule
parathyroid gland cells and their roles
chief cells: secrete PTH
oxyphil cells: no known function, accumulate after puberty with age, derived from chief cells
parathyroid hormone
produced in response to low calcium levels
stimulates production of vit D and calcium reabsorption in the kidney
activates osteoclasts
facilitates calcium absorption from small intestine
parathyroid gland histology
darker and denser than thyroid
chief cells are mostly nucleus and more purple
oxyphil cells have larger cytoplasm and are more pink
parathyroid disorders
hyperparathyroidism: serum calcium levels are increased, produces deposits in kidneys and arteries
hypoparathyroidism: serum calcium levels are decreased, causes spastic contractions of skeletal muscles, tetany
location of adrenal gland
superior poles of each kidney
histology of the adrenal gland
surrounded by capsule
medulla is darker and more purple than cortex
layers of the adrenal cortex
zona glomerulosa
zona fasciculata
zona reticularis
role of the zona glomerulosa
secretes mineralocorticoids (aldosterone)
maintains electrolyte and water balance
role of zona fasciculata
secretes glucocorticoids
accelerates glucose synthesis and glycogen formation
role of zona reticularis
secretes androgens
cortisol
(hydrocortisone)
widely used in ointments to treat inflammatory conditions of the skin
excessive and long term use can supress immune system
adrenal cortex disorders
Conn syndrome
Cushing syndrome
Addison disease
Conn syndrome
caused by excessive production of aldosterone
due to hyperplasia or tumours
results in low renin levels
poor vision, headaches, muscular weakness and spasms, fatigue, potassium deficiency, high BP and excessive urination
greater activity in DCT of Na/K ATPase
Cushing syndrome
caused by excessive production of glucocorticoids
can be caused by aldosterone
characterised by red moon face, truncal obesity, purple striae, and diabetes mellitus
Addison disease
autoimmune destruction of adrenal cortex
abdominal pain, weakness, weight loss, darkening of skin
adrenal medulla
chromaffin cells: modified sympathetic post ganglion cells, lack dendrites and axons
secrete adrenaline and noradrenaline derived from tyrosine
central vein, abundance of arranged smooth muscle
pheochromocytoma
rare tumour of adrenal medulla
composed of chromaffin cells
referred to as paraganglioma when these cells develop a tumour outside the adrenal gland
pancreas location
lies between the duodenum, spleen and stomach
pancreas histology
pale areas are islets of endocrine cells
secretions of pancreatic islet cells
alpha cells
beta cells
delta cells
F cells
alpha cells: glucagon
beta cells: insulin
delta cells: somatostatin
F cells: pancreatic polypeptide
endocrine disorders
excess GH: gigantism
insufficient GH: dwarfism
excess TH: Grave’s disease
insufficient TH: Goiter, myxoedema, cretinism
excess mineralocorticoids: Conn syndrome
excess glucocorticoids: Cushing syndrome
insufficient mineralocorticoids: Addison’s disease
insufficient glucocorticoids: Addison’s disease
insufficient insulin: T1D
insufficient ADH: diabetes insipidus
glucocorticoids
cortisol (weakest but longest half life)
dexamethasone
prednisone
betamethasone
