Block 5

Question 1

___ is more metabolically active than T4

Answer 1

T3

Question 2

thyroid hormones are ____ at normal concentrations

Answer 2

anabolic

Question 3

thyroid hormones are ____ when concentrations are elevated

Answer 3

catabolic

Question 4

the two most important actions of thyroid hormones are related to

Answer 4

oxygen consumption

protein synthesis

Question 5

the increase in cellular respiration due to thyroid hormone levels leads to increased energy production accompanied by

Answer 5

heat production

Question 6

what are some effects of thyroid hormone INCREASE?

Answer 6

increased BMR
increased growth rate
- of young people –> cretinism (and neurologic abnormalities)
- mental processes –> dissociated thinking, nervousness, anxiety

Question 7

TSH released from the anterior pituitary causes increased

Answer 7

• proteolysis of Tg
• release of thyroid hormone
• activity of iodide pump
• iodination of tyrosine residues on Tg
• number, size, infolding, and secretory activity of thyroid

Question 8

name two drugs that suppress thyroid activity

Answer 8

Propylthiouracil (PTU) and methimazole

Question 9

what is the MoA of PTU and methimazole?

Answer 9

inhibit throidal peroxidase

Question 10

PTU also prevents the conversion of ___ to ___

Answer 10

T4 to T3

Question 11

what happens with decreased production of TH?

Answer 11

increased secretion of TSH –> hypertrophy of thyroid gland –> enlarged thyroid

Question 12

describe the impact of high concentrations of inorganic iodides

Answer 12

• decreased thyroid activity and gland size

- decreased rate of iodide trapping –> decreased rate of iodination of Tg –> decreased synthesis of T3 and T4

Question 13

What occurs with primary hypothyroidism?

Answer 13

• due to inadequate function of the thyroid gland itself

- decreased levels of thyroxine (T4) leads to INCREASED levels of TSH

Question 14

describe what occurs in secondary hypothyroidism

Answer 14

inadequate function of the anterior pituitary or hypothalamus due to damage/trauma leads to decreased TSH and decreased T4

Question 15

What is Hashimoto disease?

Answer 15

Type of Primary Hypothyroidism

- initiated by autoimmunity against thyroid (destroys thyroid gland, leading to decreased or lack of thyroid hormone)

Question 16

what is endemic colloid goiter?

Answer 16

type of hypothyroidism caused by dietary iodide deficiency

• lack of iodine prevents production and secretion of T3 and T4
• -> this leads to excessive TSH secretion, increased stimulation of thyroid cells, and subsequent increased thyroid gland size (goiter)

Question 17

identify the type of hypothyroidism:
occurs during fetal life, infancy, or childhood
characterized by failure of body growth or mental retardation

Answer 17

cretinism

Question 18

What are symptoms of hypothyroidism?

Answer 18

fatigue
muscular sluggishness
increased body weight
slow heart rate, decreased CO
constipation
mental sluggishness
husky voice
myxedema
atherosclerosis

Question 19

how are primary and secondary hypothyroidism treated?

Answer 19

daily ingestion of tablet containing thyroxine

Question 20

what happens to TSH and thyroxine levels in primary hyperthyroidism?

Answer 20

increased thyroxine leads to decreased TSH (negative feedback)

Question 21

What is Graves Disease?

Answer 21

Autoimmune antibodies against the TSH receptor

• this causes continual activation of cAMP, leading to a prolonged stimulatory effect of the thyroid gland
• hgih levels of thyroid hormone suppress formation of TSH at the anterior pituitary

Question 22

Gs always induces ______ in smooth muscle

Answer 22

relaxation/dilation

Gs stimulates AC which produces cAMP, which activates PKA MLC phosphatase which dephosphorylates MLCK

Question 23

Gq always induces ________, unless it acts on _______ then it does…

Answer 23

contraction

unless it acts on endothelial then dilates via NO

Question 24

all beta adrenergic receptors are coupled to _____

Answer 24

Gs

Question 25

all alpha 1 adrenergic receptors and M1, M3, and M5 receptors are coupled to _____

Answer 25

Gq

Question 26

M2 and Alpha 2 are coupled to

Answer 26

Gi

Question 27

what happens with emphysema?

Answer 27

it lowers the surface area in the lungs by damaging type 1 cells, so there's less surface area for blood and gas exchange

Question 28

describe what occurs with COPD

Answer 28

air is blocked from entering or leaving the lungs, resulting in unventilated alveoli - aka physiological dead space - unventilated alveoli have low pO2, which leads to arteriole constriction - arteriole constriction leads to increased resistance - increased resistance leads to pulmonary hypertension and a large afterload (on the heart) - this leads to right ventricular heart failure

Question 29

what role does thyroidal peroxidase play in iodide trapping?

Answer 29

after iodide enters the thyroid, it converts it back into iodine

Question 30

list characteristics of protein/polypeptide synthesis/secretion

Answer 30

1 - synthesized and stored in secretory vesicles until needed 2 - synthesized in rough ER as pre-pro-hormone 3 - cleaved to "pro-hormone" in ER and transferred to Golgi 4 - packaged in vesicles, enzymatically cleaved to form active hormone + inactive fragments 5 - exocytosis 6 - they're water soluble and easily diffuse to target

Question 31

T4, T3, epinephrine, and norepinephrine are all types of

Answer 31

amine hormones