Endocrine I - Pituitary and Pineal Glands Flashcards
How are endocrine signals transported throughout the body?
Blood and body fluids
Which bone is the pituitary located within?
Sphenoid bone
Which tissues are the pituitary derived from?
Oral cavity tissues and neural tissue
What is another common name for the anterior pituitary?
Pars distalis
What is another common name for the posterior pituitary?
Pars nervosa
Which germ layer is the pars distalis derived from?
Oral ectoderm
Name the three cell morphologies found in the pars distalis.
- Acidophils
- Basophils
- Chromophobes
Name two pars distalis cell types that are acidophils.
Somatotropes and lactotropes/mammotropes.
What do somatotropes do? How common are they? What stimulates them and what inhibits them?
Secrete GH. Account for 50% of pars distalis cells. Stimulated by GHRH and inhibited by somatostatin.
What do lactotropes/mammotropes do? How common are they? What stimulates them?
Secrete prolactin, account for 15% of pars distalis cells but increase in number during pregnancy. Stimulated by thyroid releasing hormone (TRH) and vasoactive intestinal peptide.
What do thyrotrophs do? How common are they? What stimulates them?
Secrete TSH, which in turn stimulates the thyroid gland to secrete T3 and T4. They make up 5% of paris distalis cells. Stimulated by TRH.
What do gonadotrophs do? How common are they? What stimulates them?
Secrete FSH, LH. Make up less than 10% of paris distalis cells. Controlled by GnRH and LHRH.
What do corticotrophs do? What stimulates them?
Secrete ACTH, stimulated by CRH.
What do folliculostellate cells do?
They form an intrercellular network between endocrine cells of the pituitary with numerous gap junctions to coordinate distalis cells and perform phagocytic, neuro and immune regulation.
What germ layer is the pars nervosa derived from?
Neural tissue
What are the three parts of the pars nervosa?
Median eminence, infundibulum, pars distalis (?)
In which part of the pituitary would one find unmyelinated axons and pituicytes?
Pars nervosa
Name the two hypothalmic axons that extend into the pars nervosa.
Paraventricular and supraoptic.
What do paraventricular axons release?
Oxytocin
What do supraoptic axons release?
ADH
What are Herring bodies?
Where oxytocin and ADH are stored in the axon terminals of paraventricular and supraoptic axons, respectively.
What is the pars intermedia derived from?
Oral ectoderm.
What structure separates the pars intermedia from the pars distalis?
Remnants of Rathke’s pouch
Which hormone do pars intermedia cells secrete? What is the precursor to this hormone?
Melanocyte-stimulating hormone (MSH) made from precursor proopiomelanocortin
What two cell types are found in the pineal gland?
Pinealocytes and interstitial cells (supporting glial cells)
What do pinealocytes do? What are they derived from?
They produce melatonin from tryptophan. Epithelial-derived.
What does melatonin do?
Maintains circadian rhythms and also is thought to be a tumor suppressor due to its ability to terminate hydroxyl radicals. May also play a role in the timimg of puberty.
Describe how the pineal gland responds to light in maintaining circadian rhythms.
No light –> no norepinephrine from the sympathetic nerve fibers –> melatonin is made —> sleepy.
What are the two types of calcifications of the pineal gland?
Corpora arenacea (brain sand) and myeloconia (brain dust)
What is corpora arenacea (brain sand)?
Lumpy, dark staining aggregates that consist of hydroxyapatite and protein. They mark the midline of the pineal gland.
What is myeloconia (brain dust)?
Small crystals of calcite and glycoprotein.
What do pancreatic beta cells secrete?
Insulin
What do pancreatic alpha cells secrete?
Glucagon
What do pancreatic delta cells secrete?
Somatostatin
What do pancreatic F (gamma) cells secrete? What does this hormone do?
Pancreatic polypeptide - regulates pancreas/GI functions
What do pancreatic epsilon cells secrete?
Ghrelin (hunger hormone)
