What glands are included in the endocrine system?
- pituitary (anterior/posterior)
- pineal gland
- thyroid
- parathyroid
- endocrine pancreas
- adrenal
What controls the release of hormones from the pituitary?
Inhibitory factors secreted by the hypothalamus
What is secreted by the posterior pituitary?
oxycytocin + ADH
What is the role of oxycytocin?
plays a role in social interaction, sexual reproduction, childbirth
What are the cell types found in the anterior pituitary?
- somatotrophs
- lactotrophs
- corticotrophs
- gonadotrophs
- thyrotrophs
What is the most common anterior pituitary cell type and what is its secretion?
Somatotrophs (50%)
secretes GH
What do lactotrophs secrete?
Prolactin (lactation)
What do thyrotrophs secrete?
Thyroid stimulating hormone (TSH)
What do gonadotrophs secrete?
secrete gonadotrophins (e.g. leutinising hormone, follicle stimulating hormone)
What are sustentacular cells?
support pituicytes or other cell types
found throughout body (e.g. sertoli cells)
What might be an effect of a benign tumour of pituitary (pituitary adenoma)?
tumour will expand sella tusica, and press on the optic chiasm (causing loss of temporal visual field)
Where is the pineal gland found?
below the posterior portion of the corpus callosum
What is secreted by pinealocytes and what stimulates this?
secretes melatonin in response to autonomic stimulation
sometimes arranged in rosettes (several pinealocytes around central area with cell processes directed towards a central capillary)
What makes the pineal gland easy to see on an X-ray?
calcium may accumulate (particularly with age) - brain sand
helps to locate midline of brain
What is the structure of the thyroid gland?
consists of follicular epithelial cells (simple cuboidal) which secrete colloid into centre
What is the cycle of follicular cell thyroxine production?
- when dormant, follicular cells secrete thyroglobulin and store it within colloid
- when active, follicular cells reabsorb and break down thyroglobulin and convert it into the active hormone
- active hormone secreted into blood
- when active, follicular cells become columnar (normally cuboidal)
What cell type other than follicular cells are found in the thyroid gland?
C-cells
secrete calcitonin (antogonistic to parathormone secreted by parathyroid)
sit between follicles
What cell types are found in the parathyroid glands?
- Chief cells
- oxyphil cells
- adipocytes
What is the function of chief cells in the parathyroid?
secrete PTH (parathyroid hormone)
rasies serum calcium in bones, kidney, gut
mostly nucleus
What cell types are found in the islets of langerhans of the pancreas?
- B-cells - insulin
- a-cells - glucagon
- D-cells - somatostatin
- PP cells - pancreatic polypeptide (digestion?)
What hormone types do the parts of the adrenal glands produce?
outer cortex produces steroid hormones
inner medulla secretes adrenaline/noradrenaline
What are the layers of the adrenal cortex?
- zona glomerulosa
- outer, thin, incomplete layer
- zona fasciculata
- middle, most prominent layer
- zona reticularis
- inner layer
What do the layers of the adrenal cortex secrete?
zona glomerulosa - mineralocorticoids (e.g. aldosterone)
zona fasciculata - glucocorticoids (e.g. cortisol)
zona reticularis - androgenic steroids (e.g. testosterone)
Are hormones made in adrenal cortex stored?
No, once hormones are made, they are discharged into sinusoids between cells
some fats/cholesterol stored to help produce the hormones (gives macroscopic yellow appearance)
