Organs Test 3 Sem 2

Front 1

where is thyrotropin releasing hormone made and what does it increase

Back 1

TRH is made in the hypothalamus and increases prolactin levels

Front 2

what will decrease TRH

Back 2

dopamine
somatostatin
glucocorticoids

Front 3

what will increase TRH

Back 3

cold
emotional stress
illness
seratonin
catacholamines

Front 4

what are the steps for TH secretion

Back 4

TRH released from hypothalamus

TRH binds to thyrotropes on anterior pituitary

anterior pituitary secretes TSH/thyrotropin

TSH binds to GPCR on thyroid gland causing thyroid gland to produce thyroid hormone

Front 5

how does thyrotropin stimulating hormone stimulate thyroid hormone release

Back 5

by binding to GPCR on thyroid gland causing it to secrete thyroid hormone

Front 6

what happens to TSH/TRH if there are low levels of TH

Back 6

increase production of TSH (anterior pituitary gland) and TRH (hypothalamus)

Front 7

what happens to TSH/TRH if there is too much TH

Back 7

decrease in production of TSH and TRH

Front 8

what are the thyroid hormones

Back 8

T4 - levothyroxine
- delivery molecule
- 4 iodine

T3 - liothyronine/tri-iodothyronine
- active molecule

Front 9

what form is thyroid hormone given as a drug

Back 9

T4

Front 10

what are some of the roles of thyroid hormone

Back 10

basometabolism
temp regulation
energy use
strorage of nutrients

Front 11

what happens to a fetus/new born that does not get enough TH

Back 11

cretinism (severe type of mental disorder due to lack of TH)

Front 12

what is the source of tyrosine

Back 12

thyroglobulin (Tg)

Front 13

what all must be added together to make thyroid hormone

Back 13

2 tyrosines and then addition of iodine

Front 14

where is thyroid hormone made

Back 14

colloids/follicular lumen of thyroid epithelium

Front 15

how is thyroglobulin synthesized

Back 15

Tg is made in the ER

travels to golgi

travels to lumen

*in the lumen Tg sits and waits for addition of iodine

Front 16

where does Tg get glycosylated

Back 16

in the golgi

Front 17

if one iodine is added to tyrosine what is that

Back 17

monoiodotyrosine (MIT)

Front 18

if two iodine are added to tyrosine what is that

Back 18

di-iodotyrosine (DIT)

Front 19

what is thyroid hormone built on

Back 19

thyroglobulin (Tg)

Front 20

what is the sequence of events in order for the making of T3/T4 from Tg

Back 20

iodine is added to Tg via thyroid peroxidase and hydrogen peroxide

depending on how many iodine is added you can have DIT or MIT

the thyroglobulin is reacted with thyroid peroxidase + hydrogen peroxide again to couple two tyrosine together making T3 or T4

THE THYROID HORMONE (T3/T4) IS NOT MADE UNTIL IT GETS REMOVED FROM Tg

Front 21

when does Th get cleaved from Tg

Back 21

when you go back into epithelial cells

Front 22

what puts iodine on tyrosine

Back 22

thyroid peroxidase + hydrogen peroxide

Front 23

what directly stimulates synthesis of TH

Back 23

TSH/thyrotropin

Front 24

what indirectly stimulates the synthesis of TH

Back 24

TRH
low T3/T4

Front 25

what stimulates all aspects of TH synthesis

Back 25

TSH

Front 26

how is T3/T4 secreted

Back 26

Tg w/ precursor for T4/T3 is endocytosed into a endosome

the endosome combines with a lysosome

after fusion of the endosome and lysosome, ENZYMES IN LYSOSOME CLEAVE OFF T3/T4

T3/T4 is exported into the blood
Tg is broken down and recycled

Front 27

how does T3/T4 circulate

Back 27

bound to protein

Front 28

what is the activity and affinity of bound/unbound T3/T4

Back 28

T3 is only active when unbound
T4 is not active whether bound or unbound

T3 has less of affinity for the protein compared to T4 b/c you want to release T3 faster from the proteins

Front 29

which type of TH is found more in our blood

Back 29

T4

Front 30

what occurs in the conversion of T4 to T3 (metabolism of TH)

Back 30

5' deiodinase converts T4 to T3 by removing and Iodine.
- depenending on which the iodine is removed from T4 you can form T3 or REVERSE T3 (inactive form of T3)

Front 31

what are the inactive forms of T3

Back 31

bound T3
reverse T3

Front 32

what kind of receptor are thyroid hormone receptors

Back 32

nuclear

Front 33

where are TH receptors located

Back 33

inside the nucleus of the cell of almost every tissue

THEY DON'T HAVE EXTERNAL DOMAIN

Front 34

what are the forms of TH receptor

Back 34

alpha
beta

Front 35

what are the isotypes of 5' deiodinase

Back 35

D1
D2

Front 36

what is differentiates TH receptors from steroid receptors

Back 36

TH receptors can bind to DNA w/o the ligand (hormone)

Front 37

what are the properties of TH receptors

Back 37

once they bind hormone they act as transcription factors and regulate (up or down) gene expression/transcription depending on whether they recruit activators or repressors

TH receptors have non genomic activities (functions/activities outside the nucleus but inside the cell)

Front 38

where do TH receptors bind

Back 38

they bind to DNA at thyroid response elements (TRE)

Front 39

what can bind to TH receptors and what do they activate

Back 39

T3 and T4 can both bind to TH receptors but only T3 gets activated

Front 40

what receptors are TRE associated with

Back 40

alpha/beta TH receptors
retinoid receptors

they have also been associated w/ a combo btwn TH receptor and other intracellular receptors such as retinoid receptors

Front 41

what is TRE part of

Back 41

the DNA that TH receptor binds to

Front 42

what activates gene expression

Back 42

ONLY T3 ACTIVATES GENE EXPRESSION

Front 43

what are examples of nuclear receptors

Back 43

Vit A, Vit D, retinoic acid, steroid receptors

Front 44

what does serca 2a do

Back 44

ATP dependent Ca pump
pumps Ca back into the sarcoplasmic reticulum when we want our muscles to relax

Front 45

what regulates serca 2a

Back 45

phospholamban (PLB)

Front 46

what does phospholamban

Back 46

regulates serca 2a

Front 47

when is PLB used

Back 47

when we want to contract

Front 48

how is PLB inactivated and when does this occur

Back 48

PLB is inactivated when it gets phosphorylated by a kinase

this occurs when we want our muscle to relax

Front 49

what effects does T3 have on the heart

Back 49

increases gene expression/translation of Serca 2A (this puts more Serva 2a on SR and allows us to pump Ca back in quicker)

increases gene expression/translation of alpha myosin heavy chain (this gives us a greater contractility)

down regulates the gene expression/translation of PLB (this takes away the inhibition of Serca 2a allowing us to pump more Ca in)

Front 50

how does T3 increase HR

Back 50

because greater contractility (due to increase of alpha myosin heavy chain) and greater relaxation (due to increase of Serca 2A)

you have a quicker HR because you are contracting harder and relaxing quicker

Front 51

what happens to your HR when there is excess TH

Back 51

tachycardia due to increase in force of contraction and rate of relaxation

Front 52

what happens to your HR when there is little TH

Back 52

bradycardia

Front 53

how does T3 mediate changes in gene expression that directly affect the function of the heart

Back 53

by changing the gene expression/transcription of

ALPHA MYOSIN HEAVY CHAIN
PLB
SERCA 2A

Front 54

how does T3 indirectly effect the heart

Back 54

by altering the sensitivity to catecholamines (upregulates Beta 1 adrenoceptors which increase HR by binding epinephrin)

Front 55

how does T3 effect the HR

Back 55

upregulation of B1 adrenoceptors
upregulation of Serca 2A
upregulation of alpha myosin heavy chains
downregulation of PLB

Front 56

what kind of thyroid dysfunction will you see insulin resistance

Back 56

hyperthyroidism (thyrotoxicosis)

Front 57

what effects does TH have on cholesterol

Back 57

TH upregulates LDL receptors on the liver which take up cholesterol from the blood into the liver

TH converts cholesterol into bile acids

TH enhances the lipolytic effects of catecholamines (epinephrin)

Front 58

what happens in iodine deficiency

Back 58

hypothyroidism b/c not enough iodine to make thyroid hormone

Front 59

what happens in thyroiditis

Back 59

may have hypothyroidism

inflammation of the thyroid
low or normal T3/T4
high TSH/TRH

Front 60

is there a goiter in ion deficiency

Back 60

yes

GOITER DUE TO EXCESS Tg

-in response to low TH the hypothalamus is upregulated making TRH which goes to the anterior pituitary and makes more TSH telling the thyroid gland to make more TH.

THYROID GLAND CAN'T MAKE MORE TH B/C NO IODINE BUT IT DOESN'T KNOW THAT AND MAKES A LOT OF Tg WHICH ENLARGES THE GLAND

Front 61

what occurs in primary hypothyroidism

Back 61

thyroid gland isn't functioning properly and you can't produce sufficient TH

Front 62

what is hyperthyroidism

Back 62

FREE thyroid hormone in circulation is elevated

Front 63

what is graves disease

Back 63

AUTOIMMUNE DISEASE

hyperthyroidism due to auto-antibodies bind to TSH receptors on the thyroid gland and cause TH production

Front 64

what are TRH/TSH levels in graves disease

Back 64

low TRH/TSH

low TSH b/c the hypothalamus is telling the pituitary gland to stop making TSH, TRH is also low b/c the body is trying to drop TH levels

TH REMAINS HIGH B/C THE TSH RECEPTORS ON THE THYROID GLAND ARE NO LONGER RESPONDING TO TSH BUT THE AUTOANTIBODIES OF GRAVES DISEASE

Front 65

what occurs in thyroid nodules

Back 65

not immune cause

hyperthyroidism

part of thyroid gland ignores signals from pituitary gland or hypothalamuc and just produces TH

Front 66

is there a goiter in thyroid nodules

Back 66

goiter but no exopthalmos

Front 67

what happens if someone is hyperthyroid for an extended period

Back 67

osteoporosis (bone loss) may occur due to the TH causing bone turnover, and excess TH causes a lot of bone turnover

Front 68

what occurs in central hypothyroidism

Back 68

don't make enough TSH/TRH therefore can't make enough TH

secondary(pituitary) - TSH
tertiary(hypothalamus) - TRH

Front 69

what is hashimotos thyroiditis

Back 69

autoimmune disease

autoantibodies against thyroid peroxidase or Tg (thyroid proteins)
thyroid epithelium undergoes apoptosis and you lose thyroid function
high TSH/TRH

Front 70

what is the most common cause of hypothyroidism

Back 70

hashimotos thyroiditis

Front 71

is there a goiter in hashimotos thyroiditis

Back 71

goiter b/c inflammation not b/c gland working too hard

Front 72

when is non goiterous hypothyroidism seen

Back 72

in patients who's thyroids have been killed by radioactive iodine

burned out graves - after period of hyperthyroidism TH production diminishes

Front 73

what are the causes of hypothyroidism

Back 73

pituitary defect - tumors therefore don't make enough TSH
thyroid gland dysfunction
-iodine deficiency
-cancers
hashimoto's thyroiditis

Front 74

what is the range of hypothyroidism

Back 74

subclinical
myxedema
hyponatriemia

Front 75

what is hyponatriemia

Back 75

impared Na absorption due to lack of TH

TH upregulates Na/K ATPase therefore if TH is low we lose Na in urine

Front 76

what is myxedema

Back 76

need to get IV TH immediately, hydrophilic mucopolysaccharides in tissue

Front 77

when does exopthalmos occur

Back 77

only in graves disease