thyroid

Question 1

explain secretion and synthesis of thyroid hormone

Answer 1

in notes

Question 2

T3 & T4 leave the thyroid gland by

Answer 2

T3 & T4 leave the thyroid gland by diffusion.

Question 3

T3 and T4 are transported into blood by

Answer 3

by three transport proteins, Thyroxine binding globulin (TBG), transthyretin and albumin.

Question 4

which is biologically active T3 OR T4?

Answer 4

T3

but T4 has negative feedback inhibition and can be converted to T3

Question 5

There is a lot of biologically Active hormones in the blood T/F

Answer 5

false 99.7 percent is bond to TBG

Question 6

Both T3 & T4 enter their target cells

Answer 6

Both T3 & T4 enter their target cells by diffusion.

Question 7

how is T4 activated to T3

Answer 7

Deiodination (D1 AND 2) of outer ring = active T3

D3: inner ring- inactive T3

Question 8

If too much thyroid activity is present what will happen

Answer 8

If too much thyroid activity is present T4 is converted to the inactive metabolite rT3 to reduce activity.

Question 9

Function of thyroid hormones

Answer 9

The major activity of thyroid is to raise the Basal Metabolic Rate.
Increase CATABOLISM and anabolism

Question 10

raising basal metabolic rate will ?

Answer 10

limit the effect of all other hormones on their respective target systems.

Question 11

Increasing basal metabolic rate will increase temperature

Answer 11

by in creasing the UCP which is involved in brown fat and shivering . impact mito. by allowing it to release more heat .

mRNA also stimulates more mitochondria to be released

Question 12

Indirect effect of Thyroid hormone in cardiovasc.

Answer 12

increase in heat and CO2 in tissue will cause a decrease in peripheral vascular Resistance –> decease in disatolic bp –> increase in adrenergic stimulation

Question 13

Direct effect of thyroid hormone on cardiovas.

Answer 13

increase cardiac muscle, increase ventricular contraction, and decrease in peripheral vascular resistancce .

Question 14

TR Alpha 1
TR beta 1
TR beta 2

Answer 14

TRα1is strongly expressed in cardiac and skeletal muscle.
TRβ1is expressed mainly in brain, liver, and kidney.
TRβ2is expressed in the pituitary hypothalamus.

Question 15

which transporters transport T3 and T4 into cell

Answer 15

Monocarboxylate transporters (MCT8 and MCT10) transport T4 and T3

Question 16

4 ways thyroid hormones are regulated

Answer 16

Thyroid hormone feedback regulation of gland activity via suppression of TRH and TSH secretion.

Autoregulation of thyroid gland activity via the Wolf-Chaikoff Effect.

Energy intake and adipose tissue stores regulate thyroid gland activity via leptin and CNS regulation of TRH secretion.

Environmental factors regulate via CNS regulation of TRH secretion

Question 17

what nucleus does the leptin activate

Answer 17

PV and acurate

Question 18

A high uptake of iodine by the thyroid will indicate

Answer 18

hyperthyroidism

Question 19

hypothyroidism

effects on skin m cardiov., and respiratory

Answer 19

Skin and other tissues
Increased hyaluronic acid accumulation in connective tissue leading to puffy appearance (myxedema); increased dryness

Cardiovascular
Decreased cardiac output and increased peripheral resistance at rest; decreased blood volume

Respiratory
Maximum breathing capacity and diffusing capacity are reduced

Question 20

hypothyroidism

effects on GI and CNS/PNS

Answer 20

Gastrointestinal
Reduced food intake and reduced system peristaltic activity (contributes to constipation)

Central and peripheral nervous system
Reduced development, myelination, and vascularity of fetuses and infants (cretinism)
Reduced blood flow and reduced intellectual functions

Question 21

HYPOTHYROIDISM

Muscular and skeletal and renal effects

Answer 21

Muscular
Slow movement due to delayed muscle contraction and relaxation

Skeletal
Impaired growth (greatest effect on limbs)

Renal, Water & Electrolytes
Reduced renal function & blood flow; delayed water excretion
Increased water retention

Question 22

Hypothyroidism

RBCs and Reproductive

Answer 22

Hematopoietic
Reduced red blood cell mass

Reproductive
Reduced sexual maturation and delayed puberty in children
Reduced libido and ovulation in women; Reduced libido, impotence and oligospermia in men

Question 23

hyperthyroidism

effects on skin eyes., and respiratory

Answer 23

Skin has a warm moist feel; Increased diffuse pigmentation; nails may be soft and friable; hair may be fine and friable

Eyes
Retraction of upper eyelid giving “stare” or “fish eyes” appearance

Cardiovascular
Increased cardiac output and decreased peripheral at rest; increased force of contraction (induced by increased metabolism)

Question 24

hyperthyroidism

respiratory, GI, Nervous system

Answer 24

Respiratory
Vital capacity may be reduced and dyspnea is common
Gastrointestinal
Increased food intake but weight loss; Increased peristalsis
Nervous system
Nervousness, emotional lability and hyperkinesia (overall effect is similar to those associated with sympathetic nervous system activation)

Question 25

hyperthyroidism

muscular, skletal, renal

Answer 25

Muscular
Weakness and fatigability

Skeletal
Demineralization of bone; increased excretion of Ca+ and PO4-

Renal, Water & Electrolytes
Increased blood flow and mild polyuria

Question 26

hyperthyroidism

RBC, reproductive,

Answer 26

Hematopoietic
Increased red blood cell mass

Reproductive
Delayed sexual maturation in children
Abnormal menstrual cycles in women; Increased conversion of androgens to estrogens may lead to gynecomastia and erectile dysfunction in men