Histology of Endocrine System Flashcards
Hypothalamus hormones directly targets what endocrine organs
Anterior pituitary
Kidney and uterus - ADH, oxytocin (stored in posterior pituitary and then released when necessary)
Adrenal medulla- via sympathetics
Posterior pituitary stimulation
PP is comprised of axons from hypothalamus
These axons carry ADH and oxytocin for storage and release in the posterior pituitary
Anterior pituitary structures
Pars tuberalis
Pars intermedia
Pars distalis
Posterior pituitary structures
Infundibular stalk
Pars nervosa
Somatotropic cells
Secrete growth hormone
Corticotropic cells
Secrete ACTH and MSH
Gonadotropic cells
Secrete FSH and luteinizing hormone (LH)
Mammotropic cells
Secrete prolactin
Cells of pars distalis
Acidfils -Somatotrophs, mammotrophs
Basophils- corticotrophs, thyrotrophs, gonadotrophs
Pars nervosa
Does not manufacture hormones
Contains axons from cell bodies in the hypothalamus
Hypothalamo-hypophyseal portal system
Hypothalamic neurons synthesize and release hormones into the primary capillary plexus
That blood is carried into the anterior pituitary by veins and enters another capillary bed, and the hormones are distributed in the anterior pituitary, which responds appropriately
There is no portal system for hormone distribution to the posterior pituitary
Pineal gland
Out pocketing of diencephalons roof of third ventricle
Covered in pia mater
Role in growth, development and circadian rhythms
Synthesizes melatonin and serotonin
Contains calcium phosphate crystals which are an important radiological marker
Thyroid hormone synthesis
Generated and stored extracellularly as thyroglobulin
Thyroglobulin synthesized in rER, glycosylated in Golgi and secreted
Iodinated at apical surface, forming T3/T4 bound to thyroglobulin
TSH stimulates release of T3/T4
Parafollicular C cells
Secrete calcitonin when blood levels of calcium are high
Graves disease
Abnormal Abs stimulated TSH receptors causing over secretion of T3/T4 - hyperthyroidism
Zona glomerulosa of adrenal cortex
Releases aldosterone (mineralocorticoid)- targets kidney
Secreted in response to low blood pressure/volume
Controlled by renin-angiotensin system
Zona fasciculata of adrenal cortex
Releases cortisol (glucocorticoid) in response to ACTH from anterior pituitary
Zona reticularis
Releases androgens which influence secondary sex characteristics
Addisons disease
Hyposecretory disorder in both glucocorticoids and mineralocorticoids
Blood glucose and sodium levels drop, severe dehydration and low blood pressure
Cushing syndrome
Hypersecretion of glucocorticoids because of either ACTH secreting pituitary tumor or a tumor in adrenal cortex
High serum glucose, protein loss in muscles, muscle weakness, lethargy
Pancreatic cells
Alpha cells- secrete glucagon
Beta cells- secrete insulin
Delta cells- secrete somatostatin- slows the release of insulin and glucagon
F cells- secrete pancreatic polypeptide which inhibits somatostatin release
