Test 3 - Quiz 8 - Thyroid & GI Endocrinology

Question 1

What is the largest gland in the body?

Answer 1

Thyroid

• Larger in men than women
• Increases with age and body weight
• decreases as dietary iodine intake decreases

**EXTREMELY WELL VASCULARIZED

Question 2

Increasing or decreasing thyroid hormone does what?

Answer 2

Changes basal metabolic rate

Question 3

If its cold outside, hypothalamus stimulates thyroxin (T3, T4) from what?

Answer 3

Thyroid

*This increases metabolic rate and generates heat to raise body temp

Question 4

If it is warm outside, hypothalamus inhibit’s thyroxin (T3, T4) release from what?

Answer 4

Thyroid

*This decreases metabolic rate, reducing heat production

Question 5

When you hear thyroid hormone, what is being referred to?

Answer 5

T3 AND T4

Question 6

T3 can work independently from the what?

Answer 6

Thyroid

Question 7

T4 is dependent upon what?

Answer 7

Thyroid

Question 8

Know the negative feedback loop on slide 5 of her lecture.

Answer 8

In your photos..

Question 9

T4 is turned into what two things?

Answer 9

rT3, and T3

*rT3 is inactive, while T3 is very active

Question 10

Thyroglobulin is what and found where and what is in it?

Answer 10

Colloid proteins

Found in thyroid

T3 and T4

Question 11

The size of the follicle determines what in regards to the gland?

Answer 11

Inactive - Large follicles

Active - Small follicles

Question 12

What are the two main endocrine functions of the thyroid gland?

Answer 12

Secretion of T4 and T3

Secretion of calcitonin

Question 13

Calcitonin is secreted by what cells?

Answer 13

Parafollicular cells (aka C cells)

Question 14

What does calcitonin do?

Answer 14

Lowers Ca2+ in serum

-Decreases osteoclast activity

Question 15

What does parathyroid hormone (PTH) do?

Answer 15

Stimulates osteoclasts

Question 16

What secretes PTH?

Answer 16

Chief cells in parathyroid glands (in response to low blood calcium)

Question 17

1,25-Dihydroxycholecalciferol is formed from what?

Answer 17

Vitamin D in skin via sun and hydroxylation in liver and kidneys

Question 18

What does 1,25-dihydroxycholecalciferol do?

Answer 18

Increases Ca2+ absorption in intestines

Increases Ca2+ stored in bones

Question 19

T3 and T4 are _______ - philic.

Answer 19

LIPO

Question 20

What can synthesize T3 and T4?

Answer 20

Iodine

And tyrosine portions of thyroglobulin

Question 21

T4 is produced exclusively where?

Answer 21

Thyroid only

Question 22

T3 is primarily produced from what?

Answer 22

Extrathyroidally from T4

• Liver
• Intestines

Question 23

Almost all T4 produced is quickly converted to what once released from thyroglobulin stores?

Answer 23

T3

Question 24

T3 is ____ times more potent than T4.

Answer 24

4

Question 25

rT3 is inactive and made mostly where?

Answer 25

Liver

Question 26

What enzyme converts T4 to T3?

Answer 26

5’ deiodinase enzyme

Question 27

If the enzyme catalyzes another rxn, after T3 is formed, what is formed?

Answer 27

rT3

Question 28

T3 and T4 are considered what? (______genic)

Answer 28

Calorigenic

Question 29

T3 can act independently of what?

Answer 29

HPT axis regulation

Question 30

Many chronic stress-like conditions lead to what?

Answer 30

Hypothyroidism

Question 31

Stress, dietary iodine, illness, fasting, and cortisol (steroids) are all able to alter the activity of what enzyme?

Answer 31

Deiodinase

Question 32

W/o sufficient iodine, one may develop what?

Answer 32

Goiter *W/o iodine, thyroid hormones are not released from thyroglobulin and TSH builds up

Question 33

Look at practice question on slide 14 of her lecture.

Answer 33

In your photos

Question 34

Look at practice question on slide 15 of her lecture.

Answer 34

In your photos

Question 35

Thyroid hormones: Synthesis and storage Release from parent cell T-port in blood 1/2 half Location of receptor Example

Answer 35

Made in advance Simple diffusion Bound to carrier proteins Long Nucleus (Lipophilic) Thyroxine

Question 36

What are the only cells in the body that can absorb iodine?

Answer 36

Thyroid cells *Good outlook for thyroid cancer patients

Question 37

Urine iodine excretions of >70% of dietary iodine intake is what?

Answer 37

Iron deficiency *For adults, that is urine excretion of >/= 105 mcg/day

Question 38

Goiter is the result of too much what? (2 things)

Answer 38

TSH Human chorionic gonadotropin (HCG)

Question 39

Goiters are found in what autoimmune disease and what type of cancer?

Answer 39

Hashimoto’s Thyroid cancer

Question 40

What are two disorders with iodine deficiency?

Answer 40

Iodine deficiency disorder (goiter) Cretinism -Growth retardation

Question 41

Hypothyroidism and hyperthyroidism can both give the patient goiter. Tell me why each one can.

Answer 41

Hypo (Hashimoto’s) - Reduced T3 and T4 causes ant pit to overproduce TSH, causing thyroid to enlarge - goiter Hyper (Graves) - TSH levels decrease, auto-antibodies attack thyroid, and thyroid hypertrophies. Thyroid overproduced T3 and T4 leading to goiter.

Question 42

4 GI functions.

Answer 42

Secretion Digestion Absorption Gut motility

Question 43

What types of hormonal communication involves the GI?

Answer 43

Endocrine, paracrine, neurocrine

Question 44

What hormone acts in all three hormonal communication fashions?

Answer 44

CCK

Question 45

The are two types of events that maintain homeostasis. Name and describe them.

Answer 45

Stimulatory - Smelling food, food hitting stomach Inhibitory - bowel dissension **Constant balance for homeostasis

Question 46

What is the enteric nervous system?

Answer 46

The GI’s own localized nervous system, INDEPENDENT of parasympathetic and sympathetic innervations.

Question 47

GASTRIN Type Source Stimuli for release Action

Answer 47

GI hormone G cells Stomach distention, peptides Stim gastric acid secretion and proliferation of gastric mucosa

Question 48

CHOLECYSTOKININ (CCK) Type Source Stimuli for release Action

Answer 48

GI hormone I cells Digestive products from fats, fatty acids, monoglycerides Contracts gall bladder - expelling bile into duodenum

Question 49

SECRETIN Type Source Stimuli for release Action

Answer 49

GI hormone S cells Acidic pH in small intestine Stims pancreas to release bicarb (neutralize acids)

Question 50

GASTRIC INHIBITORY PEPTIDE (GIP) Type Source Stimuli for release Action

Answer 50

GI hormone Mucosa of upper small intestine FA, AA, carbs Inhibits gastric secretions and motility, increases insulin release when food in duodenum and blood glucose is high

Question 51

GLUCAGON Type Purpose Action Release due to: Inhibition due to: Deficiency due to: Excess

Answer 51

Pancreatic hormone Counter-regulatory assistance for insulin Release of glucose from cells Low blood sugar High blood sugar Hypoglycemia Hyperglycemia

Question 52

INSULIN Type Purpose Action Release due to: Inhibited by: Deficiency Excess

Answer 52

Pancreatic hormone Regulate blood glucose Absorption of glucose from cells High blood sugar Low blood sugar Diabetes Hypoglycemia

Question 53

SOMATOSTATIN Type Purpose Action Release due to: Inhibited by: Deficiency Excess

Answer 53

Pancreatic hormone Regulates GI hormones in pancreas and GI tract Slows production of insulin, glucagon, gastrin, and other hormones High hormone levels Low hormone levels No deficiency Diabetes

Question 54

What is the continuous process by which thyroid hormones are produced and stored w/in thyroid follicles?

Answer 54

Iodine ions absorbed Diffusion and attaches 1 or 2 activated iodide ions to the tyrosine portions of a thyroglobulin resulting in 4 to 8 molecules of T3, T4, or both Thyroglobulin from follicle by endocytosis Lysosomal enzymes break down thyroglobulin, AA are then recycled and used to synthesize more thyroglobulin T3 and T4 diffuse across bsmt membrane into blood. Attached to blood transport proteins called thyroid-binding globulins.

Question 55

T/F - T3 and T4 release into blood and into follicles is a continuous process.

Answer 55

TRUE