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Fall-Foundational Sciences Year 1 > Endocrine I and II > Flashcards

Endocrine I and II Flashcards

1
Q

hypothalamus

neurosecretory cell pathway

A

produce nuerosecretory hormones >

anterior glandular lobe of pituitary gland via primary and secondary fenestrated capillary plexus + hypophyseal portal veins

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2
Q

neurosecretory products

A

SRH/GHRH
TRH
CRH
GnRH

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3
Q

anterior lobe contains

A

chromophils (acid/basophils) + chromophobes

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4
Q

acidophils

A

somatotrophs + lactotrophs (mammotrophs)

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5
Q

somatotrophs

A

stimulated by SRH/GHRH
inhibited by somatostatin

release somatotropin (growth hormone)

excessive GH in KIDS=gigantism from somatotrophic adenoma/tumor
in ADULTS=acromegaly (enlarged face, jaw, tongue, hands, feet, organs)

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6
Q

lactotrophs

aka mammotrophs

A

stimulated by PRH and TRH
inhibited by dopamine

release prolactin (for mammary glands when pregnant)

prolactinoma most common benign pituitary tumor

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7
Q

basophils

A

corticotrophs + thyrotrophs + gonadotrophs

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8
Q

corticotrophs

A

stimulated by CRH

release ACTH precursor > adrenal cortex > cortisol and corticosterone

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9
Q

thyrotrophs

A

stimulated by T-RH

release TSH (thyrotropin) >thyroid>T3T4

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10
Q

gonadotrophs

A

stimulated by GnRH

release FSH and LH > ovary and testis

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11
Q

hypothalamohypophyseal tract

A

supraoptic and paraventricular nuclei of hypothalamus

have cell bodies of neurosecretory neurons > axons make up tract > terminates in posterior lobe/neural of pituitary gland

axons and terminals have vasopressin (ADH) and oxytocin

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12
Q

posterior lobe contains

A
  1. herring bodies (granules of ADH or oxytocin)
  2. pituicytes (glia-like support cells)
  3. fenestrated capillaries

ADH = yellow urine, oxytocin = contractions in childbirth

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13
Q

thyroid gland produces

A
  1. T3 (triiodothyronine) - follicular cells
  2. T4 (tetraiodothyronine)- follicular cells
    -both reg cell/tissue metabolism and heat production
  3. calcitonin- parafollicular cells
    -reg blood calcium levels
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14
Q

T3 and T4 production

A

T4 only from follicular cells in 20:1 ratio, T3 x5 more potent than T4

T3 converted from T4 by heart, liver, kidneys

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15
Q

thyroid hormone synthesis

A
  1. follicular cells syn thyroglobulin (glycoprotein) w/ 120 tyrosine residues
  2. release into follicular lumen
  3. iodide (inactive) from bloodstream pumped into follicular cells
  4. iodide oxidized on apical membrane/colloid facing side into iodine (active) and stays there
  5. iodine iodinates tyrosine residues = MIT + DIT
  6. MIT + DIT = triodinated thyronine
  7. DIT + DIT = tetraiodinated thyronine
  8. follicular cells uptake colloid from lumen
  9. proteases cleave iodinated tyrosine residues from thyroglobulin into cell cytoplasm = uncoupled MIT + uncoupled DIT + T3 + T4
  10. thyroid hormones (inactive) released from basal aspect into extracellular space
  11. fenestrated capillary network
  12. general circulation
  13. activated in target tissues and organs

lysosomal pathway, main

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16
Q

exocrine glands vs endocrine glands

A

exocrine = products released into ducts

endocrine = products/hormones released into extracellular space > bloodstream > organs

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17
Q

hypothalamus

A

nucleus in the brain

coordinates endocrine functions and integrates endocrine/ANS functions

has neurons = neurotransmitters AND
neurosecretory cells = hormones

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18
Q

neurosecretory hormone pathway

general

A
  1. syn in hypothalamus
  2. transported to axon terminals
  3. released into ECS
  4. pass into primary capillary plexus
  5. flow into hypophyseal portal veins
  6. secondary capillary plexus (sinusoidal) @anterior pituitary
  7. parenchyma of anterior pit to influence basophils/eosinophils
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19
Q

thyroid gland

general structure

A

R lobe + isthmus (bridge) + L lobe + pyramidal lobe

surrounded by capsule of dense irreg/coll CT from deep cervical fascia

trabeculae/septa- partion into lobules and carry vessels and nerves into gland

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20
Q

parathyroid glands

A

4 @ thyroid capsule on posterior surface of thyroid gland

21
Q

thyroid follicles

A

follicle is basic structural/functional unit of thyroid gland

spherical cyst like + lumen w/ colloid and thyroglobulin

22
Q

thyroid follicle histology

A

simple squamous = low level activity
simple cuboidal = normal activity
simple columnar = highly active

surrounded by basal lamina + reticular fibers + fenestrated capillary plexus

23
Q

parafollicular cells

A

from neural crest

b/t follicles so not exposed to colloid @ basal lamina near capillaries

syn calcitonin and store it in granules

24
Q

calcitonin

A

released when blood calcium levels elevated

lowers blood Ca levels to normal via inhibiting osteoclasts AND promote Ca deposition in bones

25
Q

thyroglobulin synthesis

A

follicular cells syn in RER when activated by TSH

glycosylation in RER and Golgi

released into lumen via exocytosis

26
Q

iodine pathway

thyroid hormone synthesis

A
  1. iodine from diet > reduced to iodide in GI
  2. bloodstream
  3. pumped into follicular cells via sodium/iodide symporters
  4. diffuses to apical cell membrane
  5. iodide ions pumped into lumen via iodide/chloride transporter (pendrin)
  6. thyroid peroxidase oxidizes iodide into iodine
  7. thyroid peroxidase catalyzes iodination of thyroglobulin
27
Q

thyroglobulin processing pathways

A

TSH binds @basal > filopodia form @luminal surface = endocytosis

  1. lysosomal pathway
  2. transepithelial pathway
28
Q

transepithelial pathway

A
  1. thyroglobulin binds megalin (TMP on apical membrane facing colloid)
  2. evades lysosomes and transported to basolateral membrane
  3. released into blood as T3T4 still bound to thyroglobulin
29
Q

physiological effects T3T4

A

inc: cell metabolism, growth rate, mental activity, fatty acid syn

stimulate: endocrine gland function, carb metabolism

dec: formation of phospholipids, triglycerides, cholesterol

30
Q

increase thyroid hormone

A

dec body weight

inc heart rate, metabolism, respiration, muscle function, appetite

high levels = tremors, fatigue, impotence, menstrual irregularities

31
Q

hyperthyroidism

A

aka toxic goiter or graves disease

autoantibodies bind to TSH receptors = inc colloid uptake = xs thyroid hormones in circulation

exophthalmos (bulging eyes from fibrosis of rectus muscles and acc of loose CT behind eyeball) and enlarged thyroid

32
Q

cell types in parathyroid glands

A
  1. principal- syn/store/release PTH
  2. oxyphil- inactive principal/chief cells, don’t know function
  3. intermediate- inactive, don’t know function
33
Q

PTH

A

regulates calcium and phosphate levels in blood and ECF
-influences bone, kidneys, GI

inc blood calcium levels to normal if low serum
-high serum Ca inhibits PTH

calcitonin is opposite

34
Q

islets of langerhans cell types

pancreas

A

in endocrine portion

  1. alpha = glucagon (inc blood glucose)
  2. beta = insulin (dec blood glucose) and amylin (inhibit stomach emptying/glucagon release)
  3. delta = D (somatostatin-reduce smooth muscle contractions of dig tract) or D1 (vasoactive intestinal peptide- induce glycogenolysis, control smooth muscle tonus and contraction of GI)
  4. epsilon= ghrelin (induce hunger sensation)
  5. PP = pancreatic polypeptide (inhibit digestive juices)
  6. also gastrin by 1+ cells (stim HCl by parietal cells in stomach mucosa)
35
Q

exocrine portion pancreas

A

acini + duct system

produces digestive enzymes

36
Q

suprarenal cortex zones

A
  1. zonal glomerulosa- outer, mineralcorticoids (aldosterone main + deoxycorticosterone)
    -activate by ACTH and angiotensin II
  2. zona fasciculata- middle/largest layer, glucocorticoids (cortisol + corticosterone)
  3. zona reticularis- inner, weak androgens (DHEA, androstenedione, glucocorticoids)
37
Q

suprarenal cortex zones

histology

A
  1. zonal glomerulosa- cells in cords and clusters
  2. zona fasciculata- cells in radial columns w/ capillaries running b/t
  3. zona reticularis- anastomosing cords w/ lipofuscin
38
Q

suprarenal medulla

A

from neural crest, sympathetics

has chromaffin cells = epinephrine and norepinephrine (catecholamines)

release Ach

39
Q

PTH synthesis

A
  1. ribosomes on RER syn preproparathyroid hormone
  2. @RER lumen = proparathyroid hormone + polypeptide
  3. @Golgi lumen = parathyroid hormone (PTH) + polypeptide
  4. stored in secretory granules
40
Q

PTH in bone

A

1.binds osteoblast receptors (prolonged)
2.osteoblasts release osteoclast stimulating factor = triggers osteoclasts to breakdown and free Ca and P from bone

or if intermittent = anabolic effect so inc bone mass to treat osteoporosis

41
Q

PTH in kidneys

A

conserves Ca
promotes activation of vitamin D

42
Q

PTH in GI

A

regulates rate of Ca absorption from GI (directly) and activation of vitamin D (indirect in kidney)

vitamin D facilitates Ca absorption in GI more great than PTH effect

43
Q

thyroidectomy

A

complete removal of parathyroid glands = drop Ca levels

tetanic contraction of muscles (laryngeal and respiratory) = death

44
Q

tetany

A

hypoparathyroidism > hypocalcemia = tetany

neuromuscular irritability, spontaneous twitching, numbness, tingling

45
Q

urinary tract stones

A

from hyperparathyroidism > osteoclasts erode bone = hypercalcemia

stones and calcification of lungs, myocardium, stomach, blood vessels

46
Q

Diabetes Mellitus

A

hyperglycemic metabolic disorder from
1. beta cells not produce insulin
2. defective insulin receptors on targets

47
Q

Type I Diabetes

A

insulin-dependent
juvenile onset

autoantibodies cause islets to atrophy and fibrotic, not enough insulin produces

signs: polydipsia (thirst), polyphagia (eating), polyuria (urination)

48
Q

Type II Diabetes

A

non insulin-dependent
most common

over 40 yr old

49
Q

Cushing Syndrome

A

small tumors of basophils in anterior pituitary gland = excess ACTH

suprarenal cortex overstimulated = excess cortisol

obesity in face, neck, trunk, impotence (males) amenorrhea (females)

Fall-Foundational Sciences Year 1 (33 decks)

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