Thyroid And Parathyroid Glands--There's Nothing Funny About Them

Front 1

Where is the thyroid gland located? How many lobes? Where are the parathyroids in relation? What is the functional unit of this gland?

Back 1

Below the larynx on the trachea--2--just below the thyroid--functional unit is the follicle

Front 2

Which thyroid epithelial cells are the most active? Least active? Middle?

Back 2

Squamous, cuboidal, columnar

Front 3

What is contained in colloid?

Back 3

Thyroglobulin--contains various thyroid hormones in various stages of development

Front 4

What cells secrete Calcitonin? Where are they found?

Back 4

Parafollicular cells--between the follicles

Front 5

What is stored in thyroglobulin?

Back 5

T4 and T3

Front 6

Which is active? rT3 or T3?

Back 6

T3

Front 7

A person has a thyroid hormone deficiency...what might be a problem?

Back 7

Insufficient tyrosine and iodine intake

Front 8

Thyroid hormones contain what amino acid? Derived from where?

Back 8

Tyrosine--thyroglobulin protein

Front 9

What enables visualization of the thyroid gland? How does this take place? Does concentration matter?

Back 9

Radioactive tagging of iodine--active trans of iodide into the gland--no not even if 40 to 1

Front 10

What do thiocyanates do? What happens as a result?

Back 10

They bind the molecules that transport iodide--decrease in T3 and T4 levels

Front 11

We need iodine to make thyroid hormones...how do we get it? This can be blocked..by what?

Back 11

Iodine is oxidized into iodine by thyroid peroxidase--blocked by thiouracils like PROPACIL

Front 12

Iodine attaches to tyrosine and forms what two molecules? What do they do?

Back 12

MIT or DIT--when combined they form T3--when two DIT's combine they form T4

Front 13

What percent of the hormones secreted by DIT and MIT are T3? What percent are T4?

Back 13

10%--90%

Front 14

Can thyroglobulin be stored for a long time?

Back 14

Yes several months worth

Front 15

How is the colloid used? What happens as a result?

Back 15

Follicular cells bite off a piece of colloid and digest it and release it's contents into the plasma

Front 16

What happens once the colloid is released into the plasma?

Back 16

Thyroglobulin is converted to a.a.'s and Thyroid hormones--the amino acids and mit and dit and reused in the formation of more thyroglobulins and hormones

Front 17

Thyroid hormones are small..so what? Therefore?

Back 17

They must attach to a protein in order to not be filtered out--75% of T4 binds globulin, 15% of it binds prealbumin, and 10% of it binds T4. 75% of T3 binds globulin and the rest binds albumin

Front 18

True or false..only bound thyroid hormone can work in the body.

Back 18

False--only free hormone can work and there must be an equilibrium

Front 19

Which is more bioactive..T3 or T4?

Back 19

T3

Front 20

Does T4 do anything? So what is it used for?

Back 20

No! Peripherally 55% is converted to rT3 and 45% is converted to T3.

Front 21

Starvation does what with regards to thyroid hormones? What happens as a result?

Back 21

Inhibits the enzyme that converts T4 to T3--metabolic rate slows

Front 22

What effect do estrogens have on thyroxine levels?

Back 22

They increase the amount of bound thyroxine so it has less of an effect

Front 23

What drugs are used to adjust thyroxine levels? What do they do?

Back 23

Dylantin and Salicylates--they decrease the binding of thyroxine so that more is free in the plasma

Front 24

What enhances iodide trapping?

Back 24

TSH

Front 25

How does TSH stimulate the synthesis of thyroxine?

Back 25

By enhancing endocytosis of the colloid and the digestion of thyroglobulin

Front 26

What can T3 do in frogs? Humans?

Back 26

Cause the development of a tadpole into a frog--normal maturation including bones, puberty onset, fetal neural development, and surfactant production

Front 27

What is vitally necessary to a fetus a few months before birth up to two years after birth?

Back 27

Exposure to thyroid hormone

Front 28

Adults that have hypothyroidism exhibit...

Back 28

Prolonged reflex times, lethargy, and impeded neurological function

Front 29

What happens if there is a thyroid hormone deficiency with relation to growth?

Back 29

There is stunted growth due to a decrease in GH and IGF levels--they require thyroid hormone in order to work

Front 30

How does thyroid hormone regulate basal metabolic rate?

Back 30

They increase BMR by increasing mitochondrial surface area and increasing oxidative phosphorylation

Front 31

What autonomic effects do thyroid hormones possess?

Back 31

They increase beta receptor density and affinity for epi and norepi

Front 32

What sexual effects do thyroid hormones possess?

Back 32

Allow for normal ovarian cycling and follicular development as well as spermatogenesis

Front 33

What are the three types of hypothyroidism and what causes them?

Back 33

Primary caused by glandular problems--secondary caused by TRH deficiency--nutritional caused by a decrease in iodine in the diet

Front 34

Who experiences cretinism?

Back 34

Children with hypothyroidism--they exhibit MR, stunted development, delayed sexual maturity

Front 35

What are several symptoms of hypothyroidism in adults?

Back 35

Lethargy, lowered BMR, slow thinking, thin or brittle hair, decreased info processing, poor resistance to cold, and MYXEDEMA

Front 36

What is myxedema?

Back 36

Accumulation of mucopolysaccharides in the interstitial spaces that exert osmotic pressure

Front 37

What drugs are given to patients with hypothyroidism?

Back 37

Levoxyl and Synthroid

Front 38

What causes hyperthyroidism?

Back 38

Graves disease--which is where the body produces TSI which stimulates just like TSH but without the negative feedback system

Front 39

Eyes bugged out is called what and is a symptom of what?

Back 39

Exophthalmos is a symptom of hyperthyroidism

Front 40

There are three treatments for hyperthyroidism..what are they?

Back 40

Surgical removal of the thyroid gland, iodine 131 that gamma ray destroys some of the thyroid tissue, and thiouracils like PROPACIL that inhibit thyroxine synthesis

Front 41

A goiter is a? Caused by?

Back 41

An enlarged thyroid gland caused by hypo or hyperthyroidism

Front 42

How much calcium is absorbed in the gut? Where else is it lost?

Back 42

50%--in the urine

Front 43

True or false...the majority of calcium is transients in the distal convoluted tubule.

Back 43

False--it is mainly transients in the proximal convoluted tubule

Front 44

Calcium is present in the gut...what does this have an effect on?

Back 44

Phosphate absorption

Front 45

The excretion of phosphate is similar to...

Back 45

Glucose

Front 46

Vitamin D3 can be synthesized from a _____ called _____ which when combined with______ travels to the _____.

Back 46

cholesterol precursor--7dehydrocholesterol--UV light--liver

Front 47

Describe the journey of vitamin D3 after it is synthesized in the skin

Back 47

Travels to the liver to become 25-HCC--this compound travels to the kidney and in the presence of 1-alpha hydroxylase becomes 1,25 DiHCC(the most potent vitamin D)

Front 48

The conversion of 25-HCC to 1,25 DiHCC occurs where? It is affected by what? Where does this compound have the greatest effect? How?

Back 48

In the kidney--the presence of PTH--the gut--induces calbindin formation, which promotes calcium and phosphate absorption(by calcium proxy)

Front 49

What cells produce parathyroid hormone? What is the other kind of parathyroid cell? When do these cells present?

Back 49

Chief cells--oxyphil cells--not until puberty

Front 50

What is the effect of PTH?

Back 50

Increase Ca++ concentration and decrease phosphate levels in the plasma by increasing the activity of the osteoclasts

Front 51

What secondary effects does PTH have?

Back 51

Increases reabsorption of calcium in the distal collecting duct, decreases phosphate reabsorption in the proximal tubule by altering Tmax, and also increases the conversion producing the active form of vitamin D

Front 52

What is the sole regulator of PTH?

Back 52

plasma calcium levels(which are far more important than bone calcium levels)

Front 53

What produces calcitonin? What is seen across species?

Back 53

The parafollicular cells of the thyroid--not a lot of variety across species in this hormone but salmon calcitonin is 20 times more potent than human calcitonin so we must be careful

Front 54

What is the action of calcitonin? what causes it's release? Is a deficiency or overproduction of this hormone a concern?

Back 54

Opposite of PTH--low blood calcium levels--no

Front 55

A patient presents with tingly feelings..what could be the problem? Due to what? What tests should be run?

Back 55

Hypocalcemia caused by thyroid surgery--Chvostec test(tap at angle of jaw and if twitch then hypocalcemic) or Trousseau test(inflate BP cuff and see if contractions occur in the hand

Front 56

A parathyroid tumor can lead to what? What will be evident? What is an expression of this disorder?

Back 56

Hypercalcemia--depressed CNS and muscle function--rickets

Front 57

What causes rickets?

Back 57

Vitamin D deficiency leading to insufficient calcium absorbed in the diet so it must be harvested from the bones

Front 58

As we age, we have trouble absorbing ____, so we can't _____, which results in _____? What is this disorder called?

Back 58

Fats--absorb Vitamin D--low plasma Ca++--Osteomalacia

Front 59

What leads to osteoporosis? Treat with?

Back 59

Lack of estrogens leads to leaching of bone density--synthetic estrogens