lecture 27 - thyroid, parathyroid & adrenal galnds

Question 1

What hormones are secreted by the thyroid gland?

Answer 1

Thyroid hormone (T3, T4) and calcitonin

Question 2

What is the location of the thyroid gland?

Answer 2

On anterior and lateral surfaces of the trachea, inferior to the larynx

Question 3

What is the structure of the thyroid gland?

Answer 3

Composed of small spherical sacs (follicles) surrounded by follicular cells. Clear/C cells lie in clusters between follicles

Question 4

What is the function of the follicular cells of the thyroid?

Answer 4

Synthesis and storage of thyroid hormones

Question 5

Where is the hormone calcitonin made?

Answer 5

In the Clear/C cells of the thyroid gland.

Question 6

What type of cell are follicular cells?

Answer 6

Epithelial cells

Question 7

What type of hormone are thyroid hormones?

Answer 7

Lipid-soluble hormones

Question 8

How are thyroid hormones T3 and T4 made?

Answer 8

Iodine enters follicular cells and forms complexes with tyrosine from thyroglobulin proteins (TGB) made in the thyroid follicles.

Question 9

What is the structure of T3 hormone?

Answer 9

3 iodine (I) surrounding a tyrosine (Y)

Question 10

What is the structure of a T4 hormone?

Answer 10

4 iodine (I) surrounding a tyrosine (Y)

Question 11

How are thyroid hormones stored, despite being lipid soluble?

Answer 11

T3 and T4 are bound to thyroglobulin (TGB) in follicle cells until they need to be released, when they detach.

Question 12

What is the active thyroid hormone?

Answer 12

T3

Question 13

What is the more plentiful thyroid hormone?

Answer 13

T4

Question 14

How do T3 and T4 travel via the bloodstream to target cells?

Answer 14

Bound to carrier proteins called thyroid-binding globulin (TBG)

Question 15

What does TGB stand for?

Answer 15

Thyroglobulin

Question 16

What does TBG stand for?

Answer 16

thyroid-binding globulin

Question 17

What are the basic steps of thyroid hormone target cell activation?

Answer 17

Hormone travels bound to carrier protein to cell, diffuses across membrane, T3 binds to T3 receptor on mitochondria or in nucleus, complex binds to DNA and genes are activated, transcripted and translated to produce specific proteins.

Question 18

What is a common protein produced in target cells in response to activation by T3 thyroid hormone?

Answer 18

Sodium-potassium pump

Question 19

What is the response time of target cells to thyroid hormone?

Answer 19

4 minutes to several days

Question 20

What is thyroid hormone required for?

Answer 20

Growth, alertness and metabolism

Question 21

What are the effects of thyroid hormone on metabolism?

Answer 21

increased: body heat production, fatty acid oxidation, proteolysis, carbohydrate metabolism.

Question 22

How does thyroid hormone increase body heat production?

Answer 22

Increases the consumption of oxygen, and ATP hydrolysis

Question 23

What is fatty acid oxidation, in terms of metabolism?

Answer 23

Use of stored fat in many tissues

Question 24

What is proteolysis, in terms of metabolism?

Answer 24

Breaking down proteins into amino acids by proteolytic enzymes, predominantly in muscle

Question 25

Does thyroid hormone increase or decrease blood sugar concentration?

Answer 25

Neither - the glucose released by carbohydrate metabolism is used straight away by cells which have advanced uptake.

Question 26

What two processes, involving glucose, are increased by the thyroid hormone?

Answer 26

Gluconeogenesis (synthesis of glucose from non-carbohydrates) and glycogenolysis (breakdown of glycogen into glucose)

Question 27

How does thyroid hormone affect the entry of glucose into cells?

Answer 27

It enhances insulin-dependent entry of glucose into cells.

Question 28

Does the thyroid hormone increase or decrease the basal metabolic rate?

Answer 28

Increase

Question 29

How does the thyroid hormone, using a protein, increase metabolism?

Answer 29

By increasing the synthesis and transport activity of Na+/K+ pumps.

Question 30

How does basal metabolic rate change as we age?

Answer 30

Decreases with age

Question 31

Do males or females have a higher metabolic rate?

Answer 31

Males

Question 32

What is the major store of calcium within the body?

Answer 32

Bone

Question 33

How are immediate adjustments of blood calcium levels made?

Answer 33

By exchanging calcium between blood and bone

Question 34

What are the hormones involved in maintain blood calcium homeostasis?

Answer 34

Parathyroid hormone (PTH), calcitrol, calcitonin

Question 35

Where are the parathyroid glands located?

Answer 35

Posterior to the thyroid gland, in the neck

Question 36

How many parathyroid glands are there in the body?

Answer 36

4 (2 pairs)

Question 37

What effect does parathyroid hormone (PTH) have on the kidneys?

Answer 37

Increases calcium reabsorption, converts vitamin D to calcitrol.

Question 38

What is the result of increased calcium reabsorption by the kidneys as a result of PTH?

Answer 38

Decreased urinary excretion of calcium

Question 39

What is the result of increased calcitriol production in the kidneys as a result of PTH stimulation?

Answer 39

Increased intestinal absorption of calcium from food in the digestive tract

Question 40

What effect does parathyroid hormone have on bone?

Answer 40

It increases bone breakdown (osteoclast activity)

Question 41

What is the result of increased bone breakdown due to parathyroid hormone stimulation?

Answer 41

Calcium is released from bone into the blood stream.

Question 42

Decreased plasma [Ca2+] would lead to?

Answer 42

Increased PTH release

Question 43

Increased plasma [Ca2+] would lead to?

Answer 43

Decreased PTH release

Question 44

What is the location of the adrenal glands?

Answer 44

On the superior surface of the kidneys

Question 45

How many adrenal glands are there?

Answer 45

2 - one on each kidney

Question 46

What are the two glands of the adrenal gland?

Answer 46

Adrenal cortex & adrenal medulla

Question 47

What is the outer region of the adrenal glands?

Answer 47

Adrenal cortex

Question 48

How many layers make up the adrenal cortex?

Answer 48

3

Question 49

What does the outermost layer of the adrenal cortex release?

Answer 49

Aldosterone

Question 50

What is the function of aldosterone?

Answer 50

Maintains sodium homeostasis

Question 51

What hormone is secreted by the middle layer of the adrenal cortex?

Answer 51

Cortisol

Question 52

What does the inner layer of the adrenal cortex secrete?

Answer 52

Androgens

Question 53

What is the function of androgens?

Answer 53

They have a minor reproductive role

Question 54

What is secreted by the adrenal medulla?

Answer 54

Adrenaline

Question 55

What body system is the adrenal medulla involved with (aside from endocrine)?

Answer 55

Sympathetic nervous system.

Question 56

What is adrenaline primarily released in response to?

Answer 56

Stress

Question 57

Is adrenaline water soluble or peptide soluble?

Answer 57

Water soluble - it is an amino acid derivative

Question 58

What ratios of adrenaline and noradrenaline are released by adrenal medulla secretory cells?

Answer 58

80% adrenaline, 20% noradrenaline

Question 59

What two pathways are used by sympathetic pre ganglionic fibres to stimulate adrenaline release to effector cells?

Answer 59

Fibre either stimulates adrenal medulla cells to secrete adrenaline and noradrenaline, or uses sympathetic postganglionic fibres to rapidly transmit neurotransmitters adrenaline and noradrenaline with ACh at the synapse at the sympathetic chain ganglion.

Question 60

What type of receptors does adrenaline bind to?

Answer 60

Membrane receptors

Question 61

Is adrenaline signalling fast or slow, compared to other hormones?

Answer 61

Fast

Question 62

What is the overall effect of adrenaline?

Answer 62

Make fuel (glucose and fatty acids) more readily available to cells in response to stress.

Question 63

What systems shut down in response to adrenaline aided activation of the sympathetic nervous system?

Answer 63

Systems not crucial for short term survival.

Question 64

How is adrenaline released by the adrenal medulla?

Answer 64

Acetylcholine from sympathetic pathways bind to receptors, triggering the secretion of adrenaline by the adrenal medulla.

Question 65

What tissues does adrenaline have a metabolic effect on?

Answer 65

Skeletal muscle, liver, fat

Question 66

What are the metabolic effects of adrenaline on skeletal muscle and the liver?

Answer 66

Increased breakdown of glycogen to glucose (glycogenolysis)

Question 67

What are the metabolic effects of adrenaline on fat?

Answer 67

Breakdown of fat to fatty acids