endocrine system Flashcards
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?
- endocrine signalling:hormone released into circulation and is taken to a local or distant target
- paracrine: paracrine cells releases hormone which act on adjacent cells (short distance, neighbouring cell)
- 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?
endocrine 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.
parathormone
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+.
oxyphil
adipose
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