7 Pancreatic Hormones

Question 1

What are the four cell types found within the islets of Langerhans, and what do each secrete?

Answer 1

Beta cells secrete insulin, alpha cells secrete glucagon, delta cells secrete somatostatin, PP cells secrete pancreatic polypeptide

Question 2

Which cell type is most abundant in the islets of Langerhans?

Answer 2

Beta cells

Question 3

Which pancreatic Islet hormone reduces pancreatic enzyme secretion?

Answer 3

Pancreatic polypeptide

Question 4

T/F: Pancreatic islets are highly vascularized and secrete hormones directly into the bloodstream.

Answer 4

T

Question 5

Which hormone is composed of two amino acid chains connected by two interchain disulfide bonds?

Answer 5

Insulin

Question 6

T/F: The insulin receptor is composed of two alpha subunits that protrude into the cytoplasm and two beta subunits that lie outside the cell membrane.

Answer 6

F; the opposite is true

Question 7

How does the binding of insulin to its membrane receptor initiate intracellular changes?

Answer 7

Insulin binding to alpha subunits of receptor causes autophosphorylation of tyrosine residues on beta subunits. Activated beta subunits act as a protein kinase and trigger a cascade of phosphorylation/dephosphorylation reactions, which initiate intracellular responses.

Question 8

T/F: Insulin increases cellular uptake of glucose through active transport.

Answer 8

False, increased permeability is due primarily to facilitated diffusion.

Question 9

Insulin increases cell permeability to what substances?

Answer 9

Glucose, amino acids, potassium, magnesium, and phosphate ions

Question 10

Does insulin have any affect on rates of cell translation and transcription?

Answer 10

Yes

Question 11

T/F: cAMP and calcium levels are essential second messengers for the insulin pathway.

Answer 11

F, they are important modulators, but not essential

Question 12

What effects does insulin have on carbohydrate metabolism?

Answer 12

Increases rate of glucose transport into cells, increases storage of glycogen, and inhibits glycogenolosis and gluconeogenesis.

Question 13

How does insulin enhance storage of glycogen in the liver?

Answer 13

It inhibits liver phosphorylase (glycogenolysis enzyme), increases activity of glucokinase, and increases activities of enzymes that promote glycogen synthesis.

Question 14

What happens to excess glucose when the amount of glucose entering liver cells is more than can be stored as glycogen?

Answer 14

Insulin promotes the conversion of excess glucose into fatty acids.

Question 15

T/F: Brain cells are permeable to glucose without the need for insulin.

Answer 15

T

Question 16

What are the effects of insulin on fat storage?

Answer 16

decreases fat utilization and increases fat synthesis and storage.

Question 17

What specific effects does insulin have on adipocytes?

Answer 17

promotes glucose uptake through GLUT4 transporters, promotes glycolysis, promotes conversion of pyruvate to fatty acids, and promotes formation of triglycerides from free fatty acids for fat storage

Question 18

How does insulin promote protein synthesis?

Answer 18

increases transport of amino acids, enhances translation of mRNA, increases rate of transcription of certain genes, inhibits catabolism of proteins

Question 19

T/F: Insulin acts as an antagonist to growth hormone.

Answer 19

F; insulin synergizes with GH to promote growth

Question 20

What is the most important stimulus for insulin secretion?

Answer 20

blood glucose levels

Question 21

Which amino acids strongly potentiate glucose stimulation of insulin secretion?

Answer 21

arginine and lysine

Question 22

What effect do gastrointestinal hormones have on insulin secretion?

Answer 22

They can double the rate of insulin secretion

Question 23

Name the hormones that increase insulin secretion

Answer 23

gastrointestinal hormones, GH, and cortisol

Question 24

What enzyme couples extracellular glucose to insulin secretion?

Answer 24

glucokinase

Question 25

what clinical condition does glucokinase deficiency cause?

Answer 25

neonatal diabetes mellitus

Question 26

What are the major effects of glucagon on glucose metabolism?

Answer 26

enhances glycogenolysis and gluconeogenesis

Question 27

what is the most potent regulator of glucagon release?

Answer 27

hypoglycemia

Question 28

T/F: high concentrations of certian amino acids stimulate secretion of glucagon as well as insulin.

Answer 28

T

Question 29

what hormone acts locally to depress secretion of both insulin and glucagon?

Answer 29

somatostatin

Question 30

what effect does glucagon have on insulin secretion?

Answer 30

it increases insulin secretion

Question 31

what effect does insulin have on glucagon secretion?

Answer 31

it inhibits glucagon secretion

Question 32

what is the basal insulin/glucagon ratio? postprandial? fasting/intense exercise?

Answer 32

basal insulin/glucagon ratio is 2; postprandial is 10; fasting/intense exercise is .5

Question 33

what clinical condition involves absolute insulin deficiency?

Answer 33

Type I Diabetes mellitus

Question 34

what percentage of type I diabetes cases occur in children?

Answer 34

90% of cases are juvenile onset

Question 35

T/F: type I diabetes may have a hereditary component.

Answer 35

T

Question 36

which type of diabetes is insulin dependent?

Answer 36

Type I

Question 37

which type of diabetes is prone to ketosis?

Answer 37

Type I

Question 38

What is the definition of Type II diabetes?

Answer 38

high blood glucose in the context of insulin resistance and a relative insulin deficiency

Question 39

what percentage of diabetes cases are type II?

Answer 39

90%

Question 40

what happens in the early stages of type II diabetes?

Answer 40

muscle, fat, and liver become insulin resistant

Question 41

what happens in the late stages of type II diabetes?

Answer 41

involve a lack of sufficient insulin production by pancreatic beta cells to compensate for insulin resistance

Question 42

what condition is thought to be the primary cause of type two diabetes in genetically predisposed individuals?

Answer 42

obesity

Question 43

what are the treatments for type II diabetes?

Answer 43

dietary control, increased exercise, oral hypoglycemic drugs (eg metformin, a gluconeogenesis inhibitor)

Question 44

what are the clinical signs of type I diabetes?

Answer 44

glycosuria, polyuria, polydipsia, polyphagia, weight loss, fatigue, elevated plasma ketone bodies (beta-hydroxybutyrate and acetoacetate), cellular dehydration and circulatory shock, acidosis, impaired wound healing

Question 45

what are some of the consequences of high blood glucose levels?

Answer 45

heart disease, strokes, diabetic retinopathy, kidney failure, poor limb circulation

Question 46

what is metabolic syndrome?

Answer 46

it is a prediabetic state marked by a combination of disorders, such as central obesity, insulin resistance, hypertension, hyperglycemia, and elevated plasma lipid levels, all of which lead to an increased risk of developing cardiovascular disease and diabetes

Question 47

what is obesity?

Answer 47

body fat greater than 30% of ideal weight

Question 48

how does one calculate BMI from height and weight?

Answer 48

BMI = weight (lbs)/height (in) x 703

Question 49

what area of the brain is responsible for maintenance of body weight and adjusting food intake with physical activity?

Answer 49

hypothalamus

Question 50

what are the main purposes of short term and long term regulation of food intake?

Answer 50

short term: prevents overeating at each meal

long term: maintenance of normal quantities of energy stores in the form of body fat

Question 51

name the orexigenic hormones.

Answer 51

thyroid hormone, cortisol, ghrelin, adiponectin, neuropeptide Y

Question 52

name the anorexigenic hormones.

Answer 52

CRH, Leptin, obestatin, GLP-1, CCK, insulin, peptide YY, pancreatic polypeptide, oxyntomodulin

Question 53

What can lead to insulin shock as a result of low blood glucose levels?

Answer 53

hyperinsulinism