Thyroid & Adrenal

Question 1

Describe the structure of the thyroid.

Answer 1

Bi-lobe –> either side of trachea, different among species

Question 2

Where are the parathyroid glands found?

Answer 2

Beside the thyroid

Question 3

What is the functional unit of the thyroid?

Answer 3

Thyroid follicles

Question 4

Thyroid follicles

Answer 4

Spherical arrangement of epithelial cells

Question 5

What do thyroid follicles produce?

Answer 5

Thyroid hormones

Question 6

An intrafollicular fluid rich in thyroglobulin

Answer 6

Colloid

Question 7

Where are parafollicular cells located?

Answer 7

Beside the follicular cells, b/w thyroid follicles

Question 8

What is another name for parafollicular cells?

Answer 8

C-cells

Question 9

What hormone do C-cells produce?

Answer 9

Calcitonin

Question 10

Functional unit of the parathyroid

Answer 10

Parathyroid cells, or chief cells

Question 11

What do chief cells produce?

Answer 11

Parathyroid hormone (PTH)

Question 12

T/F: Parafollicular and parathyroid cells are the main producers of thyroid hormones (T3 and T4).

Answer 12

False

Question 13

What are the 2 precursors necessary for synthesizing thyroid hormones?

Answer 13

1. Tyrosine

2. Iodide

Question 14

Which protein is rich in tyrosine?

Answer 14

Thyroglobulin

Question 15

What is the process called where iodide is obtained from the diet and taken up in the blood to the follicular cells?

Answer 15

Iodide trapping

Question 16

What is the important enzyme that catalyzes synthesis reactions?

Answer 16

Thyroid peroxidase (TPO)

Question 17

Where is thyroid peroxidase produced?

Answer 17

Follicular cells/ epithelial cells

Question 18

Briefly discuss synthesis of thyroid hormones.

Answer 18

1. Oxidation of iodide –> iodine (iodide trapping)
2. Iodination of tyrosines - addition of iodine onto tyrosine (organification of iodide)
3. Coupling –> T3 & T4

Question 19

Which is more abundant, T3 or T4?

Answer 19

T4

Question 20

Thyroid peroxidase is a precursor for thyroid hormone synthesis.

Answer 20

False

Question 21

Where is thyroid releasing hormone (TRH) produced?

Answer 21

Hypothalamus

Question 22

What produces thyroid stimulating hormone (TSH)?

Answer 22

Thyrotropes

Question 23

Where does TSH travel to?

Answer 23

By way of the circulatory system to target organ- thyroid follicular cells

Question 24

T/F: T3 & T4 are water soluble hormones.

Answer 24

False, lipophilic or fat soluble

Question 25

T/F: T3 & T4 are usually bound to transport proteins in the circulatory system, and are biologically inactive.

Answer 25

True

Question 26

Where are thyroid binding proteins produced?

Answer 26

Liver

Question 27

Give an example of an important thyroid binding protein.

Answer 27

Thyroid binding globulin (TBG)

Question 28

T/F: In the circulation, more abundant and less bioactive T4 is converted to less abundant and more bioactive T3 by tissue specific deiodinases.

Answer 28

True

Question 29

What is the objective of calcitonin?

Answer 29

Decrease blood calcium

Question 30

What tissues does calcitonin target?

Answer 30

Bone, kidney, digestive tract

Question 31

What is the primary action of parathyroid hormone?

Answer 31

Increase blood calcium levels

Question 32

Describe the location of the adrenal glands.

Answer 32

Paired above cranial aspect of respective kidneys

Question 33

3 parts of the adrenal gland

Answer 33

Capsule, adrenal cortex, adrenal medulla

Question 34

What are the 3 zones of the adrenal cortex?

Answer 34

Zona glomerulosa, zona fasiculata, zona reticularis

Question 35

What is the adrenal cortex made up of?

Answer 35

Corticosteroids: mineralocorticoids (aldosterone), glucocorticoids (cortisol) Sex hormones

Question 36

What is produced by the medulla?

Answer 36

Catecholamines (epinephrine, norepinephrine, dopamine)

Question 37

What is another name for epinephrine?

Answer 37

Adrenaline

Question 38

What are mineralocorticoids stimulated by?

Answer 38

Signals from the kidneys and pituitary

Question 39

What are glucocorticoids stimulated by?

Answer 39

Signals from the hypothalamus and pituitary

Question 40

What are catecholamines stimulated by?

Answer 40

Signals from the sympathetic nervous system (ANS)

Question 41

What is the main precursor for mineralocorticoids?

Answer 41

Cholesterol

Question 42

Zona glomerulosa

Answer 42

Mineralocorticoids (aldosterone)

Question 43

Zona fasiculata

Answer 43

Glucocorticoids (cortisol)

Question 44

Zona reticularis

Answer 44

Sex hormones

Question 45

Main stimulants of aldosterone

Answer 45

* Low blood Na+ * High blood K+ * Low blood volume and pressure

Question 46

Major functions of aldosterone

Answer 46

Regulate Na+ and K+ through the distal tubules in kidneys

Question 47

Is feedback of aldosterone positive or negative?

Answer 47

Negative

Question 48

T/F: The main stimulus for aldosterone secretion is high blood Na+ and low blood K+.

Answer 48

False, opposite

Question 49

What is a major function of cortisol?

Answer 49

Maintain homeostasis regarding blood glucose

Question 50

T/F: primary regulation of cortisol is by negative feedback of increased blood glucose.

Answer 50

False

Question 51

Stimulation of adrenal gland catecholamine is via the parasympathetic or sympathetic nervous system?

Answer 51

Sympathetic