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Flashcards in endocrine system Deck (35)

difference between exocrine and endocrine?

exocrine: hormones secreted into a duct
endocrine: hormones secreted directly into circulation


what two main endocrine glands are located in the brain?

pineal and pituitary.


difference between endocrine and neuroendocrine?

endocrine: hormone secreted directly into blood stream and is taken to a local or distant target
neuro: axon terminal releases neurotransmitter onto endocrine gland


what type of tissue is endocrine?

secretory epithelium


do all hormones need cytosolic receptors?

NO. some dont need them for example lipids, they are lipophillic and use receptors inside the cell.


what are three types of signalling?

1. endocrine signalling:hormone released into circulation and is taken to a local or distant target
2. paracrine: paracrine cells releases hormone which act on adjacent cells (short distance, neighbouring cell)
3. autocrine: autocrine cells release hormone and they act on the cell they were released from.


the thyroid gland is what type of gland? it is made up of follicles containing what? what type of cells are located next to the follicular cells and what do they secrete?

protein colloid (which is a storage form of T3/T4).
parafollicular cells: secretes and synthesizes calcitonin, these cells are also called clear cells.


what is the role of calcitonin? what does it oppose?

calcitonin responds to increased levels of Ca2+ and decreases the amount. it opposes parathormone which releases Ca2+ from bone when levels are low.


the follicular cells surrounding the follicle in the thyroid gland are often what type?

simple cuboidal or squamous depending on activity (if more active= cuboid and if less active= squamous).


what happens when a goiter occurs?

deficiency of iodine (which is essential for T3/T4 formation), this causes overproduction of TSH from hypothalamus and stimulates hypertrophy of follicular cells causing the enlargement of the thyroid.


how many parathyroid glands do we usually have? where are they located? what hormone do they release? what two types of cells are present?

2-6 (pairs)
embedded in capsule of thyroid gland (capsule indicates collagenous connective tissue), also located on posterior part of thyroid gland.
chief cells (major one)/oxyphil cells


in identification pictures, the parathyroid gland is always next to?

thyroid gland (look for follicles).


what are the function of chief cells in the parathyroid gland? which cells are larger, chief or oxyphil? as we age what type of tissue is located in parathyroid gland?

parathormone secretion in response to low levels of plasma Ca2+.


where are the adrenal glands located? adrenal gland is made up of what two layers?

on top of kidney (triangular shaped)
cortex (outer): consists of steroid hormones (such as aldosterone, glucocorticoids and sex hormones)
medulla (inner): epinephrine and norepinehrine (sympathetic NS)


what huge structure is located in the medulla layer of the adrenal gland? entire gland is covered in? what are the three different zones starting with after medulla? these three zones make up what?

suprarenal vein.
capsule (therefore collagenous CT)
zona reticularis, zona fasciculata and zona glomerulosa (outer).
the cortex


which cells in medulla make the epinephrine (adrenalin) and norepinephrine (noradrenalin)?

chromaffin cells.


pituitary gland (part of hypothalamus) is what type of gland? anterior pituitary is called? posterior?

ant= adenhypophysis
post= neurohypophysis


anterior pituitary is under what control? which tissues does it send hormones to? ant is made up of what?

releasing and inhibiting hormones
adrenal, thyroid, ovaries, testes and liver.
different secretory cells


posterior acts on which tissues?

kidney, uterus and mammary glands.


tumors of the pituitary can cause what?

damage to optic chiasm fibres therefore can cause visual field defects (usually temporal field)


in the posterior pituitary there are two nuclei that synthesize and secrete a certain hormone, what are they and which hormone do they secrete?

paraventricular nucleus: secretes oxytocin (acts on uterus in prego)
supraoptic nucleus: secretes ADH (preserves water in kidneys)


what is located between the anterior and posterior pituitary?

intermediate zone


what are the three different cell types in the anterior pituitary?

basophils (blue), eosinophils (pink) and chromophobes (clear)


does the posterior pituitary have cells in it?

NO almost acellular except for pituocyte (type of glial cell supporting axons) nuclei. also has blood vessels.


what is an adenoma?

tumor in any kind of glandular tissue


pineal gland is located where? how big is it? it is located on what in the third ventricle?

stalk (attached by pineal stalk to roof of 3rd ventricle)


what is the only type of cell in the pineal gland? pineal gland is thought to synchronize what? what is the night hormone? day hormone? one other cell is located here what is it?

pinealocytes which produce melatonin.
body rhythms to light cycle.
melatonin= night hormone (increased levels at night or early morning), dopamine= day hormone (increased levels during the day)
glial cells (and blood vessels).


pineal gland is thought to be what in lower vertebrates?

third eye.


what is the pathway that drives melatonin synthesis?

retina (special track of axons go to the SCN)->SCN (suprachiasmatic nucleus, acts as a master clock which acts on pineal gland)-> pineal-> drives melatonin synthesis.


what is brain sand?

located in the brain, calcifications related to aging.


photoreceptors can synthesize and secrete?



when we go from dark to light what happens to cones? rods? overall this causes what?

elongation (bringing outer segments closer toward RPE and away from light source)
pigment dispersion (melanin moves from cytoplasm to apical processes)


when we go from light to dark what happens to cones? rods? overall?

cones elongate
rods contract
overall we get pigment aggregation (melanin going from apical processes to cytoplasm).


both pigment dispersion and aggregation are caused by what?

actin in inner and outer segments.


levels of IOP are what at night and day in humans? in birds?

IOP is high at night and low in day
birds it is opposite.