Module 2.2- Hormones Regulating Metabolism

Question 1

What endocrine hormones does the pancreas produce?

Answer 1

Insulin, Glucagon, Stomatostatin, Amylin, Pancreatic Polypeptide.

Question 2

Where is the pancreas generally located?

Answer 2

In the digestive tract, attached to the duodenum and gall bladder.

Question 3

What hormone does an alpha cell of the Pancreas produce?

Answer 3

Glucogon

Question 4

What hormones does an beta cell of the Pancreas produce?

Answer 4

Insulin, amylin

Question 5

What hormone does an delta cell of the Pancreas produce?

Answer 5

Somatostatin

Question 6

What hormone does an F cell of the Pancreas produce?

Answer 6

Pancreatic Polypeptide

Question 7

Are there any non-endocrine functioning cells in the Pancreas? If so, what are they called?

Answer 7

Yes, Exocrine pancreatic cells are acinar cells and duct cells

Question 8

How does the pancreas regulate glucose homeostasis?

Answer 8

High blood sugar promotes insulin release in pancreas which stimulates glucose uptake from blood into tissue and stimulates production of glycogen (glucose storage molecule) in the liver, lowering blood sugar levels.

Low blood sugar promotes Glucagon release in the pancreas which stimulates glycogen breakdown in the liver, releasing glucose into the blood and raising blood sugar levels.

Question 9

Which pancreatic hormone predominates in the ‘fed’ absorptive state?

Answer 9

Insulin

Question 10

Which pancreatic hormone predominates in the ‘fasted’ post-absorptive state?

Answer 10

Glucagon

Question 11

What is the insulin receptor in a cell called?

Answer 11

Tyrosine Kinase

Question 12

How does insulin work on insulin sensitive muscle and adipose cells?

Answer 12

Insulin binds to Tyrosine Kinase receptor -> Signal transduction cascade occurs -> Glut 4 protein performs exocytosis (becomes part of the cell wall) -> parts of glut 4 protein create channels or glucose to enter cell

Question 13

What are some examples of insulin sensitive cells?

Answer 13

Muscle cells, adipocytes

Question 14

How does insulin work on insulin sensitive Hepatocytes?

Answer 14

Insulin binds to Tyrosine Kinase receptor -> Signal transduction cascade occurs -> Hexokinase- mediated conversion of glucose to G-6-P keeps intracellular glucose concentrations low -> Glut 2 protein channels allow glucose to move into cell where glucose concentration is lower.

When insulin isn’t bound to Tyrosine Kinase (low blood sugar) the glucose (from glucose stores and gluconeogenesis) inside the cell moves though Glut 2 protein channels into extracellular fluid.

Question 15

What effects does increased insulin have on the functions of adipose tissue?

Answer 15

Increase in fatty acid and triglyceride synthesis, decrease in Lipolysis.

Question 16

What effects does increased insulin have on the functions of liver and muscle tissue?

Answer 16

Increase in glycogen synthesis, decrease in glycogenolysis

Question 17

What effects does increased insulin have on the functions of only liver tissue?

Answer 17

Increase in fatty acid and triglyceride synthesis, decrease in gluconeogenesis.

Question 18

Increases and decreases in what can stimulate beta cells of the pancreas to secrete insulin?

Answer 18

Increases in plasma glucose, plasma amino acids, GIP secretions, parasympathetic activity.

Decreases in sympathetic activity and epinephrine secretion.

Question 19

What stimulates Glucagon release?

Answer 19

Decreases in blood glucose levels and increased plasma amino acids

Question 20

What possibly inhibits Glucagon release?

Answer 20

Insulin

Question 21

What does Glucagon stimulate?

Answer 21

Hepatic Glucogenolysis and Gluconeogenesis

Question 22

Increases and decreases in what can stimulate alpha cells of the pancreas to secrete glucagon?

Answer 22

Decrease in plasma glucose, increase in plasma amino acids, increase in sympathetic activity, increase in epinephrine secretion.

Question 23

What effects does increased glucagon have on the functions of liver tissue?

Answer 23

Increased glycogenolysis, keytone synthesis, protein breakdown and gluconeogenesis.

Decreased glycogen synthesis and protein synthesis.

Question 24

What effects does increased glucagon have on the functions of adipose tissue?

Answer 24

Increased lipolysis.

Decreased triglyceride synthesis

Question 25

What is the normal range of blood glucose levels?

Answer 25

70-110mg/dL

Question 26

What happens when blood glucose levels fall below 70mg/dL?

Answer 26

Alpha cells secrete glucagon -> increased breakdown of glycogen to release glucose, increased breakdown of fats to fatty acids, increased synthesis and release of glucose - > blood glucose concentration rises and homeostasis is restored.

Question 27

What happens when blood glucose levels rise above 110mg/dL?

Answer 27

Beta cells secrete insulin -> increased rate of glucose transport into target cells, increased rate of glucose utilization and ATP generation, increased conversion of glucose to glycogen, increased amino acid absorption and protein synthesis, increased triglyceride synthesis -> Blood glucose concentration falls and homeostasis is restored.

Question 28

What is somatotrophin?

Answer 28

A peptide growth hormone produced in the anterior pituitary.

Question 29

What hormone inhibits the production of the growth hormone somatotrophin?

Answer 29

Growth hormone inhibiting hormone (GHIH), aka stomatostatin

Question 30

What hormone promotes the production of the growth hormone somatotrophin?

Answer 30

Growth hormone releasing hormone (GHRH), aka stomatocrinin

Question 31

What cells produce the growth hormone stomatotrophin?

Answer 31

Stomatotroph cells in the anterior pituitary.

Question 32

Are the actions of the hormones stomatostatin (GHIH) and stomatocrinin (GHRH) direct, indirect or both?

Answer 32

Both

Question 33

Are the levels of growth hormones the same in the body over a day or do they change?

Answer 33

They change, peaking and falling 6-8 times over a 24hr period

Question 34

How often do growth hormone levels peak over 24hrs in an average human?

Answer 34

6-8 times

Question 35

Are the levels of growth hormones the same in the body over a lifetime or do they change?

Answer 35

They change with age.

Question 36

When is the most intense period of release of growth hormone in a single day?

Answer 36

Soon after the onset of sleep

Question 37

When is the most intense period of release of growth hormone in a lifetime?

Answer 37

During the teenage years

Question 38

Does gender affect the levels of growth hormone found in a person?

Answer 38

Yes

Question 39

What factors can affect levels of growth hormone found in the body (excluding any diseases or abnormalities)?

Answer 39

Gender, age, stress, exercise, nutrition and sleep

Question 40

What are the indirect actions of growth hormones?

Answer 40

Growth hormones cause the liver to release IGFs which then bind to target tissues stimulating both hyperplasia and hypertrophy, causing growth.

Question 41

What are the direct actions of growth hormones?

Answer 41

Stimulates stem cell divisions in connective tissues, increases breakdown of stored fats and glycogen and decreases uptake of glucose by muscles giving the overall effect of metabolising fat stores while conserving glucose for the brain.

Question 42

What is the hormone pathway for the direct effects of growth hormone on the body?

Answer 42

``` Hypothalamus produces GHRH -> Produces Stomatotroph -> anti-insulin effects -> Fat cells undergo lypolysis forming Fatty acids and glycerol, carbohydrates/glucogen form glucose -> diabetogenic activity ```

Question 43

What is the hormone pathway for the indirect effects of growth hormone on the body?

Answer 43

Hypothalamus produces GHRH -> Produces Stomatotroph -> Liver produces prolactin, placental lactogen, insulin-> Fat calls undergo lypogenesis, muscle cells undergo protein synthesis, condrocytes (in bones) for cartilage causing bone growth

Question 44

What feedback mechanism are in place for the regulation of growth hormones?

Answer 44

The levels of growth hormones themselves and the livers production of stomatomedins as an inirect action of growth hormones both act to stimulate the hypothalamus into producing SST, which acts to reduce production of growth hormone in the stomatotroph cells

Question 45

What is the functional unit of the thyroid gland?

Answer 45

A folicle

Question 46

What do follicles of a thyroid gland enclose?

Answer 46

an inner lumen, making a colloid

Question 47

What is a colloid in a thyroid gland?

Answer 47

Unique extracellular storage

Question 48

What do parafollicular "C" cells in the thyroid produce?

Answer 48

calcitonin

Question 49

What is the chief constituent of a colloid in a thyroid gland folicle?

Answer 49

Thyroglobulin

Question 50

What does the Thyroglobulin in thyroid follicles do?

Answer 50

Synthesises Tetraiodothyronine (T4 or Thyroxine) and Tri-iodothyronine (T3)

Question 51

What are the four products of the thyroid?

Answer 51

Tetraiodothyronine (T4 or Thyroxine) Tri-iodothyronine (T3) Monoiodotyrosine (MIT) diiodotyrosine (DIT)

Question 52

What are the basic ingredients for the synthesis of thyroid hormones?

Answer 52

Tyrosine and Iodine

Question 53

What are the two thyroid hormones?

Answer 53

Monoiodotyrosine (MIT) and diiodotyrosine (DIT)

Question 54

What hormones form Tetraiodothyronine (thyroxine, T4)

Answer 54

Two diiodotyrosine (DIT)

Question 55

What hormones form Tri-iodothyronine (T3)?

Answer 55

One diiodotyrosine (DIT) and one Monoiodotyrosine (MIT)

Question 56

Which is more potent in biological activity, Tri-iodothyronine (T3) or Tetraiodothyronine (thyroxine, T4)?

Answer 56

Tri-iodothyronine (T3) is four times more potent

Question 57

Roughly what percentage of circulating Tri-iodothyronine (T3) is derived from Tetraiodothyronine (thyroxine, T4)?

Answer 57

Roughly 80%

Question 58

What do the liver and kidneys do to most of the Tetraiodothyronine (thyroxine, T4) they encounter?

Answer 58

It's activated and converted to Tri-iodothyronine (T3)

Question 59

Proportionally, how much of both Tri-iodothyronine (T3) and Tetraiodothyronine (thyroxine, T4) are secreted by the Thyroid

Answer 59

Roughly 90% Tetraiodothyronine (thyroxine, T4) | 10% Tri-iodothyronine (T3)

Question 60

Are thyroid hormones lipophilic or lipophobic?

Answer 60

lipophilic

Question 61

Where are the receptors for thyroid hormones found in target cells?

Answer 61

In the nucleus

Question 62

What happens in a target cell when a thyroid hormone binds to the receptor site on the nucleus?

Answer 62

Alters the rate of mRNA transcription and thus the rate of protein synthesis.

Question 63

How quickly do thyroid hormones take affect and how long does the effect last?

Answer 63

Hours to days to take affect and that effect can last for days.

Question 64

What is the first degree action of thyroid hormones?

Answer 64

Increased Basal Metabolic Rate

Question 65

What effect does thyroid hormones have on all cells of the body?

Answer 65

Increases the number and activity of mitochondria. Increased movement of Na+/K+ through ATPase. Increase in catecholamine receptors. Increase in carbohydrate metabolism (Increase in: cell glucose uptake, glycolysis, glycogenolysis, GI reabsorption) Increased fat metabolism (Increased lipid mobilisation aka lipolysis and hepatic excretion of cholesterol) Increased cardiac output, rate and depth of respiration and increased skin and hair growth

Question 66

How does the thyroid glad regulate it's hormone output?

Answer 66

Using a negative feedback mechanism. Increased levels of T4 hormone works to reduce function of the hypothalamus and anterior pituitary

Question 67

What is the basic anatomy of the adrenal gland?

Answer 67

Small pair of glands found sitting on top of each kidney (one per kidney), consists of the outer adrenal cortex (80%) and an inner adrenal medulla (20%).

Question 68

What does the Adrenal gland produce?

Answer 68

Lipid-soluble hormones derived from cholesterol (steroids) and amine derivatives of catechol made from tyrosine.

Question 69

What are the 4 regions of the Adrenal cortex (in order of furthest from the medulla to the closest)?

Answer 69

Capsule Zona glomerulosa Zona fasciculata Zona reticularis

Question 70

What are the specialised cells of the adrenal medulla called?

Answer 70

Chromaffin cells

Question 71

What kind of specialised cells are Chromaffin cells in the adrenal medulla?

Answer 71

Post-ganglionic neurons

Question 72

What do the Chromaffin cells of the adrenal medulla produce?

Answer 72

Catecholamines (adrenaline and noradrenaline) from tyrosine (aka epinephrine and norepinephrine)

Question 73

How much of the circulating adrenaline is produced by the adrenal medulla?

Answer 73

All of it

Question 74

What cells, other than the Chromaffin cells of the medulla, produce noradrenaline?

Answer 74

Postganglionic sympathetic neurons

Question 75

What is the generalised ratio of adrenaline to noradrenaline in humans?

Answer 75

80% adrenaline, 20% noradrenaline but this does vary.

Question 76

Where is adrenaline and noradrenaline stored in the body?

Answer 76

In secretory vesicles called chromaffin granules

Question 77

How is adrenaline and noradrenaline released from the storage chromaffin granules and how do they circulate in the body?

Answer 77

Released by exocytosis and circulated in the blood

Question 78

Other than catecholamines, what else stimulates the target organs of the adrenal gland?

Answer 78

Direct stimulation from the sympathetic nerves

Question 79

What is the half life of catecholamines? Is this considered high or low?

Answer 79

15 seconds, low

Question 80

how quickly do catecholamines take affect?

Answer 80

Almost immediately

Question 81

What rough percentage is the uptake of catecholamines? is this low or high?

Answer 81

More than 90%, high uptake

Question 82

What cells in the body have receptors for catecholamines?

Answer 82

Virtually all cells.

Question 83

Where on cells are the receptors for catecholamines located?

Answer 83

On the surface membranes

Question 84

What types of catecholamine receptors are there on cells?

Answer 84

Alpha and Beta

Question 85

What are the biological effects of catecholamines?

Answer 85

``` Increased: Heart rate BP Cardiac contractility Cellular oxygen consumption Lipolysis Gluconeogenesis Glycodenolysis ``` And dilation of skeletal muscle blood vessels, pupils and airways

Question 86

How does cortisol secretion effect adipose tissue?

Answer 86

Increased lipolysis

Question 87

How does cortisol secretion effect muscle and other tissue?

Answer 87

Increase protein breakdown and Decreased protein synthesis

Question 88

How does cortisol secretion effect the liver?

Answer 88

Increased gluconeogenesis

Question 89

How does cortisol secretion effect many tissues (other than muscle, liver and adipose tissues)?

Answer 89

Decreased glucose uptake and decreased amino acid uptake

Question 90

How does glucocorticoid secretion effect muscle tissue?

Answer 90

Increased protein degradation | Decreased protein synthesis, glucose utilisation and insulin sensitivity

Question 91

How does glucocorticoid secretion effect fat?

Answer 91

Increased lipolysis | Decreased insulin sensitivity, glucose utilisation

Question 92

How does glucocorticoid secretion effect liver tissue?

Answer 92

Increased glycogen storage, gluconeogenesis, enzyme amount and enzyme activity