Endocrinology Review Highlights

Question 1

What happens to intracell. cAMP when insulin receptor is activated?

Answer 1

Decrease. Insulin receptor is an auto. tyrosine kinase

Question 2

An example of a receptor with auto-tyrosine kinase is _

Answer 2

Insulin receptor

Question 3

An example of a receptor with docking sites to cytoplasmic tyrosine kinase is _

Answer 3

Growth hormone

Question 4

Steroid receptors are sequestered by _. They bind DNA using _. Where on DNA do they bind?

Answer 4

HSP90
Central DNA binding domain
Hormone Response Element

Question 5

In general, steroid receptors have ligand binding domain in _

Answer 5

Carboxy terminal end

Question 6

The embryological origin of the anterior pituitary is _. Posterior pituitary?

Answer 6

Roof of mouth

Neural origin

Question 7

The major area of the body that responds to ACTH is _

Answer 7

Zona fasciculata, cortisol release

Question 8

The most common cell type in the anterior pit. is _

Answer 8

somatotroph

Question 9

Of the anterior pituitary hormones, which would increase in release if the portal system between the hypothalamus and pituitary was destroyed?

Answer 9

Prolactin. Because it is tonically suppressed by PIF

Question 10

Highest levels of GH secretion is during _

Answer 10

Puberty

Second highest in childhood

Question 11

Before puberty, what is the effect of GH?

Answer 11

Via IGF, promotes the linear growth of bone before puberty

Question 12

Pituitary diabetes can progress to diabetes mellitus. True or false.

Answer 12

True. If GH over seccretion occurs for long enough, beta cells in pancreas wear out, stop insulin production

Question 13

Long loop negative feedback of GH is mediated by _ from _

Answer 13

Somatomedin from the liver

Question 14

The effect of ADH in the kidney is mediated in what region?

Answer 14

Collecting ducts

Question 15

Ethanol and caffeine have what effect on ADH?

Answer 15

The inhibit, lead to increased urination

Question 16

What is the difference between central and nephrogenic diabetes insipidus?

Answer 16

Central - Not enough ADH made

Peripheral - ADH can’t function in the kidney (mutant receptor, or Aqp2)

Question 17

What is the major rgulator of calcium levels in humans?

Answer 17

PTH, not calcitonin

Question 18

What is the major function of iodide trapping?

Answer 18

Concentration of iodine in the thyroid

Question 19

What converts iodide to iodine?

Answer 19

Thyroid peroxidase enzyme complex

Question 20

What is the organification step? What catalyzes it?

Answer 20

The reaction of iodine with tyrosine residues thyroglobulin to make MIT and DIT.
Iodinase enzyme

Question 21

In response to TSH, how is T3/T4 release?

Answer 21

Thyroglobulin in proteolyzed to yield free DIT/MIT and free T3/T4

Question 22

T3/T4 is circulated in the blood bound to _

Answer 22

Thyroid binding globulin

Question 23

What is the effect of mutant deiodinase enzyme?

Answer 23

Iodine deficiency,because the enzyme is responsible for recycling iodine from MIT and DIT

Question 24

What is the function of the monoiodinase enzyme?

Answer 24

Conversion to T4 - T3 within the cell

Question 25

Both the thyroid and steroid receptors are intracellular. How are they different?

Answer 25

Steroid receptors homodimerize, while the throid receptor heterodimerizes with RXR

Question 26

Only form of hyperthryroidism presenting with exophthalmos is _

Answer 26

Graves disease, because that is part of the auto-immune response

Question 27

How does T4 get into the cell?

Answer 27

It has specific receptors, it is not lipid soluble

Question 28

What is myxedema?

Answer 28

Hypothyroidism in adults

Question 29

How does thyroid hormone reduce circulating cholesterol?

Answer 29

By increasing its secretion in the bile. It doesn't decrease its synthesis

Question 30

Catecholamines increase / decreases glycolysis and lipolysis. True or false?

Answer 30

True, trying to make as much energy available

Question 31

Where are DOPA, dopamine, norepinephrine and epinephrine synthesized?

Answer 31

DOPA and DA - Cytoplasm | NE and Epi - Medulla

Question 32

What is the function of Phenylethanolamine-N-methyl transferase? How is it affected by cortisol?

Answer 32

It converts NE to Epi. | Activity is increased by cortisol

Question 33

How does cholesterol enter the cell?

Answer 33

Receptor mediated endocytosis via LDL receptor

Question 34

The rate limiting enzyme in steroid synthesis is _

Answer 34

Desmolase, converst cholesterol to pregnenolone

Question 35

Where is Pregnenolone converted to progesterone?

Answer 35

ER

Question 36

Where is cortisol produced?

Answer 36

In the mitochondria

Question 37

Regarding sodium and potassium, what is the effect of low aldosterone?

Answer 37

Low sodium, high potassium

Question 38

What is the molecular mechanism of aldosterone (3 proteins)

Answer 38

Increase basolateral Na/K ATPase Increase apical Na channel Increase apical K channel

Question 39

Where are the mineralocorticoid receptors expressed?

Answer 39

Renal epithelial cells

Question 40

2 major stimulants for aldosterone secretion are _

Answer 40

``` Plasma K+ Plasma hypovolemia (via RAAS) ```

Question 41

Major negative regulator of aldosterone is _

Answer 41

Atrial natiretic peptides from heart

Question 42

What is the cause of Cushing's disease?

Answer 42

ACTH hyper secretion

Question 43

The desmolase challenge to decrease ACTH is a test of _

Answer 43

Cushing's disease

Question 44

A tumor that oversecretes cortisol will lead to _ [high/low] levels of ACTH

Answer 44

Low

Question 45

Why does cortisol lead to hypertension on majority of patients?

Answer 45

Not enough is converted to cortisone, therefore it stimulates mineralocorticoid receptors to hoard sodium

Question 46

The means by which glucagon and somatostatin modulate insulin secretion is via _

Answer 46

GPCRs on the beta cell, increasing and decreasing intracell. PKA activity

Question 47

What type of diabetes is not associated with glucose in the urine?

Answer 47

Diabetes insipidus

Question 48

What is the indirect mechanism by which PTH increases calcium reabsorption from the intestines?

Answer 48

By increasing levels of the active form of Vit D

Question 49

Chief cells detect calcium levels using what type of receptor?

Answer 49

GPCR

Question 50

Vit. D is transported in the blood bound to _

Answer 50

Transcalciferin

Question 51

Why does excess vit. D lead to excess plasma phosphate levels?

Answer 51

Excess vit D leads to excess calcium, which feeds back to block PTH. therefore phosphate is not secreted

Question 52

The difference between osteomalacia and osteoporosis is _

Answer 52

OM - Non-mineralized bone matrix | OP - Bone matrix is resorbed

Question 53

During ovulation, the surge in LH (lesser extent FSH) is preceded by _

Answer 53

Surge in GnRH

Question 54

What is the significance of the LH surge??

Answer 54

It is required for ovulation

Question 55

What mediates postive feedback to the anterior pituitary to cause the surge in FSH and LH?

Answer 55

Progesterone and estradiol

Question 56

What is the role of inhibin B? Inhibin A?

Answer 56

B - Blocks FSH, so a second follicle is not released | A - Inhibits both FSH and LH, prevents another ovulation or follicle release

Question 57

What remains the the ovary after ovulation?

Answer 57

The corpus luteum

Question 58

What hormone mediates the conversion of the cuboidal cells to stratified cells within the vagina?

Answer 58

Estrogen

Question 59

Just know that any effects that helps in female reproductive maturation is mediated by estrogen

Answer 59

Done

Question 60

Estrogen and progesterone receptors in mammary tissue can be induced by _

Answer 60

Estrogen

Question 61

A hormone that changes the uterine endometrium to prepare for implantation, and blocks uterine contraction is _

Answer 61

Progesterone

Question 62

The major hormone that maintains pregnancy is _

Answer 62

Progesterone

Question 63

The folicular phase corresponds to the _ phase of the endometrial cycle, while the luteal phase corresponds to the _ phase.

Answer 63

Proliferative | Secretory

Question 64

During menopause, what hormones are increased (2)? what are decreased? why ?

Answer 64

Increased - FSH and LH Decreased - Estrogen, progesterone Loss of negative feed back by estrogens

Question 65

hPTH 1-34 can be given in a pulsatile fashion to women because _

Answer 65

Pulsatile PTH apparently stimulates the osteoblasts, not osteoclasts

Question 66

What is the first key hormone of pregnancy? What does it resemble? What is the significance?

Answer 66

hCG LH Prolongs the activity of the corpus luteum

Question 67

What happens to the estrogen to progesterone ratio close to birth? What is the significance?

Answer 67

Increased ratio | Can increase uterine contractility

Question 68

How is the ratio of estrogens to progesterones increased towards the end of pregnany?

Answer 68

Estrogens induce the production of progesterone binding protein, reduce the amount of free progesterone

Question 69

Breast maturation during pregnancy is mediated by _, while duct system maturation is mediated by _

Answer 69

Estrogen | Progesterone

Question 70

What forms the blood-testis barrier?

Answer 70

Sertoli cells

Question 71

True or false, estradiol and testosterone are both required for normal spermatogenesis. Where is estradiol made in the male after puberty?

Answer 71

True | Leydig cells

Question 72

What is the function of androgen binding protein? Where is it expressed? What cell type makes it?

Answer 72

It binds up androgens | Made by Sertoli cells

Question 73

What 2 hormones dictate whether a fetus is male or female?

Answer 73

Testosterone | Mullerian Inhibiting substance

Question 74

Testosterone (not DHEA) directly causes _ (3)

Answer 74

Fetal dev. of epididymis, vas def and seminal ves Musculature and skeleton changes Spermatogenesis

Question 75

How is testosterone related to prostate cancer?

Answer 75

Early on, cancer might be androgen dependent | Later on, becomes androgen independent. Can make treatment of later cancer harder

Question 76

What is eunichism?

Answer 76

Lack of testosterone before puberty

Question 77

What is adiposogenital syndrome?

Answer 77

Lack of pituitary FSH/LH. Also affects feeding center to voracious appetite is also a problem

Question 78

How does oversecretion of testosterone (e.g. Leydig cell tumor) affect bone growth?

Answer 78

Early closure of epiphyseal plate, therefore short stature

Question 79

A teratoma that hypersecretes estrogens can cause _. what of hCG hypersecretion?

Answer 79

Estrogen - Breast dev. in males | hCG - Increased testosterone and virilization