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Question 1

thyroid gland anatomy

Answer 1

• in the front of the neck below the thyroid cartillage
• rests againts the lungs and the trachea
• made of two lobes connected by the isthmus

Question 2

blood supply to the thyroid

Answer 2

• supperior thyroid artery (external carotid)

- inferior thyroid artery (subclavian arteries)

Question 3

blood drainage from thyroid

Answer 3

• supreior and middle thyroid veins (into internal jugular veins)
• inferior thyroid veins (into branchiocephalic veins)

Question 4

thyroid histology

Answer 4

• made up of thyroid follicles which are composed of follicular cells (simple cuboidal), filled w colloid
• follicular cells secrete thyroglobulin (makes colloid) which contains tyr which is modified into the thyroid hormones (through addition of iodine)
• parafollicular or “C cells” - in with follicular cells or as individual clusters - larger and rounder - produce calcitonin

Question 5

thyroid hormones (what are they and where are they?)

Answer 5

• T3 (thyroxine) and T4 (triiodothyronine)
• found in hollow parts of thyroid
• stored extracellularly (up to 3 months supply) - not released immediately - only producing endocrine glan that does this

Question 6

thyroid hormones (what are their functions?)

Answer 6

• increase the rate of cellular metabolism and o2 consumption
• help maintain blood pressure
• role in tissue growth and development

Question 7

what stimulates the production of thyroid hormones?

Answer 7

• TSH from the anterior pituitary targets follicular cells
• once stimulates each of the cuboidal cells take up a mouthful of colloid material
• then spit that mouthful inside the cell, where T3 and T4 are cleaved from the material and the colloid is recycled (hormones are freed into interstitial tissue and then taken up by blood vessels)

Question 8

parathyroid galnds anatomy

Answer 8

• small flat glands located on the posterior of the thyroid gland
• same blood supply as the thyroid
• 4 total (one superior and one inferior on each lobe)

Question 9

parathyroid glands histology

Answer 9

• 2 cell types: principal and oxyphil
• principal cells produce PTH which functions to regulate calcium levels (mainly increasing them) through its effects on bone (break down), the intestines (absorbtion) and the kidneys (inhibit the release into urine).
• *calcitonin is the opposite of PTH - functions to decrease Ca levels in the blood**
• oxyphil cells - no known function

Question 10

adrenal glands anatomy

Answer 10

-somewhat triangular shaped glands that rest on the top of the kidneys

Question 11

adrenal gland blood supply

Answer 11

-superior suprarenal artey (phrenic), middle suprarenal artery (aorta), inferior suprarenal artery (suprarenal artery)

Question 12

adrenal galnd blood drainage

Answer 12

-suprarenal veins

Question 13

adrenal cortex

Answer 13

• produces over 24 hormones - mostly steroid hormones synthesized from cortisol
• very important to survival
• divided into the zona glomerulosa, zona fasculata and the zona reticularis

Question 14

zona glomerulosa

Answer 14

• 15% of adrenal cortex
• composed of clusters of cells
• produces mineralocorticoids which regulate the balance of electolytes in the blood
• primary hormone secreted here is aldosterone which targets the kidneys to regulate Na & K concentrations

Question 15

zona fasculata

Answer 15

• 78-80% of the cortex
• cells are arranged in rows, dont stain as dark and appear to have a foamy cytoplasm due to the amount of liquid they contain
• stimulated by ACTH to produce and release glucocorticoids like cortisol, cortiocsterone which control to metabolism of carbs, proteins and fats

Question 16

zona reticularis

Answer 16

• 7-8% of the cortex
• small and no organization like the other two regions
• produces and secretes gonadocorticoids (w the bulk being androgens)
• roles of these hormones = pubic hair growth in men, muscle mass growth, blood cell formation and libido in women

Question 17

adrenal medulla

Answer 17

• composed of clusters/clumps of chromaffin cells
• chromaffin cells are large modified post ganglionic sympathetic meurons
• stimulated by sympathetic nerves to produce and secrete E and NE

Question 18

pancreas anatomy

Answer 18

-located behind the stomach, in the first curve of the duodenum reaching the spleen
-nodular apprearance
MIXED GLAND:
-90% exocrine function
-10% endocrine function

Question 19

pancreas histology

Answer 19

• endocrine cells are located in the islets of langerhans
• these iselts contain three major cell types:
  - alpha cells
  - beta cells
  - delta cells

Question 20

alpha cells

Answer 20

• largest and tend to occupy the periphery of the islet cell
• secrete glucagon which coverts glycogen to glucose causing blood sugar to increase
• hyperglycemic hormone

Question 21

beta cells

Answer 21

• approx 70% of islet cells
• smaller and occupy the central portion of the islet
• produce and secrete insulin which enhances glucose uptake by body cells and inhibits the conversion of glycogen into glucose, decreasing blood glucose levels
• hypoglycemic hormone

Question 22

delta cells

Answer 22

• approx 5% of islet cells
• found scattered individually around islet
• produce and secrete somatostatin which inhibits insulin and glucagon and has small effects on the GI tract

Question 23

pineal gland anatomy

Answer 23

• small, pine cone shaped

- hangs from the root of the 3rd ventricle as part of the diencephalon

Question 24

pineal gland histology

Answer 24

• composed of glial cells and pinealocytes
• pinealocytes produce and secrete melatonin into bvs which functions to control the biological clock
• also have regulatory functions w respect to the release of FSH and LH

Question 25

brain sand

Answer 25

- calcium phosphate and magnesium phosphate build uo outside pinealocytes and becomes calcified - this is called brain sand - corpora arenacea - grows as we get older but does not cause problems - use as a guide when moving through brain be the pineal gland is right in the middle of the brain and the sand appears very dark on scans