Endocrinology

Front 1

What is the primary bound protein storage form of thyroid hormones?

Back 1

Thyroglobulin

Front 2

How to epithelial thyroid cells respond to TSH?

Back 2

They enlarge and change from squamous to cuboidal in shape.

Front 3

What symptoms result from iodide deficiencies?

Back 3

Mental and growth impairments (Cretinism), increased infant morbidity and mortality

Front 4

What is the world's most common endocrine problem?

Back 4

Iodide deficiency.

Front 5

Name the two thyroid hormones.
Which is more active?

Back 5

Thyroxine (T4) & Tri-Iodothyronine (T3)
T3 is the active form.
rT3 is also formed but is an inactive product.

Front 6

Describe "Iodide Trap."

Back 6

The active symport of Na+ and I- by an iodide carrier protein linked to Na/K ATPase on the basal membrane.

Front 7

List the inhibitors of Iodide symport.

Back 7

Anions like thiocyanate, perchlorate, and pertechnetate competitively inhibit active symport. Litium also inhibits symport.

Front 8

Describe Thyroid Autoregulation.

Back 8

Increases in iodide intake (high serum iodide) decreases the thyroid iodide uptake and hormone synthesis (Wolff-Chaikoff effect) and vice versa.

Front 9

Describe the thyroid gland regulation.

Back 9

The hypothalamus releases TRH which signals the anterior pituitary to secrete TSH to the thyroid. The hormone products, T3 and T4, inhibit the TSH secretion and the T3 inhibits TRH.
Hypothalamic Dopamine and Somatostatin exert tonic inhibition of TSH release.

Front 10

What are the two subunits of TSH?

Back 10

α-subunit: identical to FSH, LH, hCG
β-subunit: confers the biological activity

Front 11

What enzyme couples and organifies the thyroglobulin to T3 and T4?

Back 11

Thyroid Peroxidase

Front 12

What do drugs for hyperthyroidism target?

Back 12

Propylthiouracil (PTU) inhibits thyroidperoxidase, the enzyme necessary for iodination and coupling of T4/T3.

Front 13

Describe the cause of Graves' disease.

Back 13

TSH receptor antibodies are formed which mimic TSH and stimulate thyroid hormone production and growth of the thyroid gland. This is a common cause of hyperthyroidism.

Front 14

To what proteins are most thyroid hormones bound?

Back 14

Thyroxine binding globulin (TBG) mainly
Albumin
Thyroxine-binding prealbumin (TBPA) limited amts

Front 15

What are the % secretions of thyroid hormones?

Back 15

90% T4
5% T3
5% rT3

Front 16

What enzyme converts T4 to T3?

Back 16

5'-deiodinase

Front 17

How does T3 function in a cell?

Back 17

T3 acts as a steroid hormone and binds to the TR within the nucleus of the target cell. The activated TR binds heterodimerically with a retinoic acid receptor and allows a coactivation complex to bind and acetylates and activates gene transcription.

Front 18

Is a TR without T3 bound active?

Back 18

Yes, the TR-RXR heterodimer still forms and binds to a co-repressor complex which has a histone de-acetylase and represses the gene transcription near the TRE.

Front 19

What are the causes of hyperthyroidism?

Back 19

65-80% - Graves' disease
Others: thyroiditis, toxic thyroid adenoma, multinodular goiter, exogenous stimulants

Front 20

What is the best way to test the thyroid state?

Back 20

Indirect measure of T3/T4 through serum TSH levels because these levels change logarithmically compared to the arithmetic hormone levels.

Front 21

What is Hashimoto's Thyroiditis?

Back 21

An autoimmune disease with antibodies directed to the thyroid resulting in destruction of the thyroid and hypothyroidism.

Front 22

What are another name for the anterior pituitary?

Back 22

Adenohypophysis

Front 23

What are two other names for the posterior pituitary?

Back 23

Neurohypophysis and Pars nervosa.

Front 24

What is the embryological origin of the anterior pituitary (adenohypophysis)?

Back 24

The ectoderm of the roof of the primitive mouth forms Rathke's pouch which extends upwards.

Front 25

What is the embryological origin of the posterior pituitary (neurohypophysis)?

Back 25

The neuroepithelium of the diencephalon grows downwards.

Front 26

Describe the blood supply to the anterior pituitary.

Back 26

Hypophyseal Portal System:
Superior hypophyseal artery forms Primary Capillary Plexus in median eminence from hypothalamus.
Capillaries drain into the hypophyseal portal veins that deliver blood to the Secondary Capillary Plexus in Pars distalis.

Front 27

Describe the blood supply to the posterior pituitary.

Back 27

Inferior hypophyseal artery supplies it

Front 28

What hormones are secreted by the chromophils of the anterior pituitary?

Back 28

Basophilic (10%): FSH, LH, ACTH, TSH
Acidophils (40%): GH, Prolactin

Front 29

What are the three regions of the anterior pituitary?

Back 29

Pars Distalis
Pars Intermedia
Pars Tuberalis

Front 30

What are the five types of chromatophils of the anterior pituitary?

Back 30

somatotrophs (GH)
gonadotrophs (LH/FSH)
mammotrophs (Prolactin)
thyrotrophs (TSH)
corticotrophs (ACTH)

Front 31

What two cell types are in the anterior pituitary?

Back 31

chromatophils & chromatophobes

Front 32

What are the hypothalamic releasing/inhibiting hormones secreted by the hypothalamic nuclei of the median eminence?

Back 32

SRH (somatostatin/GH)
PRH (prolactin)
GRH (gonadotropins)
TRH (thyrotropins)
CRH (corticotropin)

Front 33

What kind of capillaries are in the pituitary?

Back 33

Fenestrated with diaphragms and a continuous basal lamina.

Front 34

What is the Pars Tuberalis?

Back 34

A region of the anterior pituitary which surrounds the infundibulum and secretes some LH/FSH.

Front 35

What is the Pars Intermedia?

Back 35

A region of the anterior pituitary which is the remnant of Rathke's pouch and separates the anterior and posterior pituitary. It produeces POMC.

Front 36

Where are the hormones released in the posterior pituitary formed?

Back 36

Within the nuclei of the hypothalmus:
Supraoptic forms ADH
Paraventricular forms Oxytocin

Front 37

How are the hormones released in the posterior pituitary?

Back 37

The hormones are formed by the secretory neurons of the hypothalamus and are transported down the unmyelinated axons to the Herring bodies. Pituicytes support these cells.

Front 38

What kind of capillaries are in the adrenal glands?

Back 38

Fenestrated with diaphragms and a complete basal lamina.

Front 39

What is the embryological origin of the adrenal cortex?

Back 39

coelomic intermediate mesoderm from the ridge which forms the gonads.

Front 40

What is the embyrological origin of the adrenal medulla?

Back 40

ectoderma neural crest cells

Front 41

Describe the Adrenal Portal Blood Supply.

Back 41

The superior, middle, and inferior suprarenal arteries enter the adrenal cortex which continue after a capillary plexus into venules in the medulla. This causes the steroid hormones formed in the cortex to go directly into the medulla.

Front 42

What are the three distinct regions of the adrenal cortex (from the capsule to the medulla) and what hormone(s) does each secrete?

Back 42

Zona Granulosa: mineralcorticoids (aldosterone)
Zona Fasiculata: glucocorticoids (cortisol)
Zona Reticularis: androgens (DHEA, DHEA sulfate, androstenedoine)

Front 43

What are the histological characteristics of the zona glomerulosa?

Back 43

~15% of the cortex, arranged in cords just below the capsule

Front 44

What are the histological characteristics of the zona fasciculata?

Back 44

~65% of the cortex, arranged in long cords with a "spongy" appearance due to the presence of many lipid droplets.

Front 45

What are the histological characteristics of the zona reticularis?

Back 45

~15% of the cortex, irregular cells forming irregular cords with some lipid droplets. May contain some lipofuscin and lies next to the medulla.

Front 46

What is Conn's syndrome?

Back 46

The overproduction of aldosterone.

Front 47

What are three diseases associated with the adrenal cortex?

Back 47

Cushing's syndrome: overproduction of glucocorticoids
Conn's syndrome: overproduction of aldosterone
Addison's disease: adrenocortical insufficiency

Front 48

What are the characteristics of the cells of the adrenal medulla?

Back 48

Considered to be modified sympathetic postganglionic neurons which have lost their dendrites and axons.

Front 49

What unique histological chemical reaction occurs in the adrenal medulla?

Back 49

The catecholamines (NE more than Epi) react with chromium salts and turn brown in color.

Front 50

What is within the granules of cells of the adrenal medulla?

Back 50

Catecholamines: Epi>NE
Chromogranins: bind catecholamines
Dopamine-beta-hydroxylase: converts dopamine to norepinephrine

Front 51

What kind of capillaries supply the Islets of Langerhans?

Back 51

fenestrated capillaries with diaphragms

Front 52

What four cell types are found within the endocrine clusters, Islets of Langerhans, of the pancreas and what do they secrete?

Back 52

α-cell: glucagon (20%)
β-cell: insulin (65%)
δ-cell: somatostatin (10)
f-cell: pancreatic polypeptide (5%)

Front 53

What is the embryological origin of the pancreatic endocrine cells?

Back 53

The same endodermal tissues as the exocrine pancreas, except a reticular network makes them a distinct entity.

Front 54

What are the histological characteristics of a hypoactive thyroid follicle?

Back 54

Squamous follicle epithelium with abundant, homogenously stained colloid.

Front 55

What are the histological characteristics of a stimulated thyroid follicle?

Back 55

Cuboidal/Columnar follicle epithelium with less colloid inside and regions (bubbles) lacking the colloid stain entirely.

Front 56

What type of capillaries surround the follicles of the thyroid?

Back 56

Fenestrated capillaries and lymphatics.

Front 57

What are the characteristics of the Parafollicular "C" cells of the thyroid and what do they produce?

Back 57

Cells with clearer cytoplasm located next to follicular epithelium cells. They do not touch the colloid. They form calcitonin to suppress osteoclasts and lowers blood calcium.

Front 58

What two cell types make up the parathyroid glands and what do they secrete?

Back 58

Chief cells (small basophilic): PTH
Oxyphil cells (larger acidophilic): unknown function

Front 59

What is the embryologic origin of the pineal gland?

Back 59

Derived from neural ectoderm.

Front 60

What cells/structures make up the pineal gland and what do they form?

Back 60

Pinealocytes: produces melatonin
Neuroglial cells: ie. astrocytes and microglia
Brain sand: calcified deposits which increase with age

Front 61

What is hormone sensitivity?

Back 61

The hormone concentration at which 1/2 of the max response is given.
It can be changed by altering the receptor affinity, the receptor number, or the specific rate-limiting post receptor events.

Front 62

What are the three main classes of hormones?

Back 62

amino acid derivatives
peptides and proteins
derivatives of cholesterol

Front 63

How does cAMP activate PKA?

Back 63

cAMP binds to the regulatory subunits on PKA which then release the active catalytic subunits to perform the PKA activity by phosphorylating serine and threonine residues.

Front 64

How is PKA localized in the cell?

Back 64

bound to specific sites via the regulatory subunits bind to A-kinase anchoring proteins (AKAP)

Front 65

What enzymes initiate the conversion of arachidonic acid to prostaglandins and thromboxanes?

Back 65

cyclooxygenases (COX1 and COX2)

Front 66

How do tyrosine kinase associated receptors function?

Back 66

They are similar to tyrosine kinases, however they cannot autophosphorylate. Rather, a non-covalently bound tyrosine kinase (JAK) will phosphorylate themselves and activate the residues.

Front 67

What are STAT proteins?

Back 67

They are TFs which when activated by tyrosine kinases will dimerize and activate or inhibit gene transcription.

Front 68

What is body fuel homeostasis?

Back 68

Constant internal environment maintained by physiologic mechanisms. Overall energy balance and constant body weight.

Front 69

What is the caloric equivalent of carbohydrates and how much is stored?

Back 69

4.2 kcal/gram
1% of caloric stores

Front 70

What is the caloric equivalent of fats and how much is stored?

Back 70

9.4 kcal/gram
76% of caloric stores

Front 71

What is the caloric equivalent of proteins and how much is stored?

Back 71

4.3 kcal/gram
23% of caloric stores

Front 72

What are the three fundamental processes of body fuel homeostasis?

Back 72

fuel storage and mobilization
maintenance of fuel levels in circulation
fuel uptake and use for the body's energy needs

Front 73

What is the role of the peptide leptin in energy store regulation?

Back 73

Plasma leptin levels increase with high adipose tissue and stimulate sympathetic neural activity to decrease food intake and increase metabolic rate, activity, body temp, and other hormones. These all work towards decreasing adipose tissue.

Front 74

What is extracellular fuel homeostasis vs. intracellular?

Back 74

Extracellular: maintenance of circulating fuel levels to provide for the necessary body functions.
Intracellular: use of the correct fuels by the correct tissues to provide the most efficient and necessary fuels for the running of the cell.

Front 75

hi

Back 75

hello

Hint 75

None

Front 76

Yo

Back 76

whats up