Final - Endocrine

Question 1

Cell surface receptors.

Answer 1

interact with peptide hormone of catecholamine; generate 2nd messenger that amplifies signal and alters target cell

Question 2

Intracellular receptors.

Answer 2

steroid and thyroid (lipidy) hormones penetrate plasma and nuclear membranes to make large complexes and bind chromosomal DNA to alter transcription (lipid ligand can cross plasma membrane and bind in cytoplasm, then the structure goes into DNA and binds there)

Question 3

What are the two ways “substances” are sent from hypothalamus to the pituitary gland?

Answer 3

1. bloodstream - anterior receives via hypophyseal portal veins - true endocrine
2. nerve endings - posterior receives

Question 4

Explain what substances are sent via which method to the pituitary.

Answer 4

1. cell surface: peptides or catecholamines
2. intracellular: steroids and lipidy hormones

Question 5

What does the pituitary gland do upon receiving substances from the hypothalamus?

Answer 5

pituitary sends its own hormones out to target organs, which stimulates them to release their hormones/secretions

Question 6

List the target organs of the hypothalamus-pituitary axis (7).

Answer 6

1. gonads
2. adrenal cortex
3. thyroid
4. mammary gland
5. liver
6. kidney
7. mammary gland

Question 7

Explain the difference b/w pars nervosa and pars distalis with staining.

Answer 7

• pars nervosa: stains lighter (increase in myelin and nervous tissue)
• pars distalis: stains darker

Question 8

What histological features are located in the parts of the hypophysis?

Answer 8

1. pars intermedia: cysts, basophils, chromophobes
2. parts distalis: basophil, acidophil, chromphobes
3. pars tuberalis: highly vascular

• all have epithelial cords and clusters

Question 9

What histological features are located in the pars nervosa?

Answer 9

axons, pituicytes, herring bodies

Question 10

Are herring bodies cells?

Answer 10

no, they are ends of axons from hypothalamus - release neuropeptides - oxytocin and vasopressin

Question 11

How do acidophils, basophils, and chromophobes appear?

Answer 11

acidophils: bright purple with red
basophils: dark purple
chromphobes: cytoplasm almost non-colored

Question 12

How does the pineal gland know whether to secrete melatonin?

Answer 12

• photosensitive organ
• light stops the production of melanin
• when its dark the suprachiasmatic nucleus become uninhibited and pineal gland produces melanin

Question 13

What is the effect downstream of the pineal gland secreting melatonin?

Answer 13

melatonin inhibits neurosecretory neurons of the hypothalamus that make GNRH which leads to a decrease in gonadal steroids (decrease in FSH & LH)

Question 14

Histological features of the pineal gland.

Answer 14

1. capsule (think and continuous with pia mater)
2. parenchyma (CT trabeculae and cords of cells, 2 cell types pinealocytes and interstitial cells)
3. brain sand (calcified secretions from pinealocytes - CAPO4 - increases in age)

Question 15

Describe the histology of the thyroid gland.

Answer 15

functional units = secretory follicles
- follicle epithelium- simple cuboidal (some columnar)
- colloid - gel-like mass of thyroglobulin (T3, T4)
- parafollicular cells in basal lamina

Question 16

What is secreted from the thyroid?

Answer 16

1. follicular cells: T3 & T4
2. parafollicular cells: make calcitonin (decrease blood calcium)

Question 17

What are the effects of the secretions of the thyroid (4)?

Answer 17

• In target organs
  1. increase growth
  2. increase development
  3. increase metabolism
  4. increase heat production

Question 18

Describe the histology of the parathyroid gland.

Answer 18

vascularized epitheloid - more CT & adipose with age

Question 19

What is secreted by the parathyroid gland?

Answer 19

1. principal (chief) cells: secretes PTH (increase blood calcium and phosphorous)
2. oxyphils: unknown - maybe store high energy macromolecules

Question 20

Do we know the function of every cell in the parathyroid?

Answer 20

no, oxyphils unknown just know they don’t secrete

Question 21

What are the effects of secretions of the parathyroid?

Answer 21

• increase blood calcium and phosphorous
  1. reabsorb from bone
  2. decrease kidney excretion of calcium
  3. increase urine PO4 excretion
  4. regulate hydroxylation of D3
  5. increase intestine absorption of Ca

Question 22

Describe histology of the adrenal gland.

Answer 22

CT that extends into parenchyma as trabeculae.

Question 23

What are the secretions of each zone of the adrenal cortex and adrenal medulla?

Answer 23

1. zona glomerulosa: aldosterone
2. zona fasciculata: glucocorticoids (i.e. cortisol)
3. zona reticularis: gonadocorticoids (i.e. DHEA or weak androgen)
4. medulla: catecholamines (Epi, NER)

Question 24

What are the downstream effects of the secretions of the adrenal cortex and adrenal medulla?

Answer 24

1. aldosterone: RAAS pathway (increase bp)
2. cortisol: lipid metabolism (pos. correlation with lipid storage) & blood sugar
3. weak androgens
4. fight or flight

Question 25

Explain the specialization of the chromaffin cells in the adrenal medulla.

Answer 25

sympathetic fibers send ACH to chromaffin cells which send E/NER through fenestrated capillaries (endocrine here)

• differs from basic endocrine secretion of cortex
• chromaffin: modified neurons

Question 26

Does the hypothalamus continually secrete the hormones that it makes?

Answer 26

No, the hormones secreted by the target organs bind back to the hypothalamus and inhibit production

Ex. hypothalamus -> (TRH) -> adenohypophysis -> (TSH) -> thyroid -> (T3, T4) -> target organs -> inhibit of TRH at hypothalamus