Endocrinology

Question 1

3 major classes of hormones

Answer 1

peptides, amines, steroids

Question 2

peptides

Answer 2

• water soluble, don’t require carrier proteins
• usually fast onset but short acting response

Question 3

amines

Answer 3

• synthesized from tyrosine
• cathecolamines (NE, epi) water soluble
• thyroid hormone, not water soluble, requires a carrier protein

Question 4

steroids

Answer 4

• synthesized from cholesterol
• lipid soluble
• slow onset but last lasting response because requires altered gene expresion

Question 5

metabolic clerance rate

Answer 5

volume of plasma cleared of a hormone per minute
* hormones removed by metabolism.binding in the tissues, hepatic, and renal excretion

Question 6

measuirng hormone levels

Answer 6

• radioimmunoassay (RIA)
• ELISA

Question 7

G-protein coupled receptors

Answer 7

most targeted by current drugs, activate signals by conformational change

Question 8

ligand gated ion channels

Answer 8

important in PNS, CNS, and excitable tissues

Question 9

receptor tyrosine kinase

Answer 9

GF, cytokine receptors

Question 10

nuclear hormone receptors

Answer 10

• located in cytosol, translocate to nuclease
• typically ligand activated transcription factors

Question 11

eicosanoid second messengers

Answer 11

• binding of first hormonal messenger to its receptor can result in generation of second messenger
• eicosanoids are group second messengers that are derived from arachidonic acid (pathway serves as targer for many drugs)

Question 12

primary hormones that affect glucose levels

Answer 12

insulin, glucagon, somatostatin

Question 13

secondary hormones that affect glucose levels

Answer 13

incretins, GH, CORT, cathecholamines

Question 14

alpha cells

Answer 14

in the periphery and secrete glucagon

Question 15

beta cells

Answer 15

located in the center and secrete insulin

Question 16

delta cells

Answer 16

secrete somatostatin

Question 17

when do insulin levels increase?

Answer 17

• after eating a carb rich meal
• supposed to go down after meal
• if there isn’t enough insulin ou will still have glucose in your body

Question 18

when do glucagon levels increase?

Answer 18

• increase when you haven’t eaten
• increase glucose production to feed cells and brain
• glucagon stimulates insulin because of glucose production

Question 19

what does somatostatin do?

Answer 19

inhibits insulin and glucagon

Question 20

insulin synthesis and secretion

Answer 20

• proinsulin synthesized first with three domains: A, B, C
• a and b chains of proinsulin are joind by disulfide bridges to form insulin

Question 21

insulin

Answer 21

• peptide hormone synthesized by beta cells
• cleaved into active precursor

Question 22

insulin effects

Answer 22

• increases glucose entry into muscle and fat tissues
• increase glycogen in liver and muscle
• increases expression of enzyme endothelial lipoprotein lipase –> releases fatty acids and glycerol from circulating triglycerides
• inhibits hormone sensitive lipase
• increases aa uptake-protein synthesis

Question 23

control of insulin secretion

Answer 23

• glucose is taken up via GLUT2 and oxidized to produce ATP
• increase in cellular ATP and ADP concentration inhibits ATP-sensitive K+ channels resulting in depolarization of beta cell membrane potential
• depolarization activates the voltage gated sensitive Ca++ channels cuaing influx in Ca++
• Ca++ induced release augements an increase in intracellular Ca++ triggers exocytosis of secretory granules containing insulin

Question 24

situations requiring increased insulin

Answer 24

pregnancy, thyrotoxicosis, fever, stress

Question 25

glucagon

Answer 25

• antagonizes the actions of insulin to increase blood glucose concentration
• transcription and translation of glucagon occurs in alpha cells

Question 26

glucagon actions and control

Answer 26

• main target organ for glucagon is the liver
• effects are to increase hepatic production of glucose and ketones (beta hydroxybutyrate and acetoacetic acid) because ketones provide an alternative energy source to glucose in many tissues
• high conentartions stimulate lipolysis and proteolysis to maintain a supply of substrates required for cellular energy metabolism
• protein rich meal stimulates glucagon secretion

Question 27

incretin hormones

Answer 27

• GLP-1 stimulates insulin secrtion, inhibits gastric emptying, inhibits glucagon secretion
• GIP: gastric inhibitory peptide
• both promote beta-cell proliferation in the pancreas and inhibit apoptosis
• release is stimulated by nutrient ingestion and peptides are degraded by DPP-4

Question 28

somatostain tumor

Answer 28

• will inhibit production of insulin therefore decreased insulin levels
• however because insulin inhibits glucagon and there is no levels of glucagon increase
• increase glucagon therefore increase glucose
  decreased insulin, increased glucagon, increased glucose

Question 29

diabetes mellitus

Answer 29

• group of disorders involved in regulation of insulin production/secretion or in the cellular actions of insulin –> hyperglycemia
• diabetes leading cause of blindess, nontraumatic lower extremity amputation, end stage renal disease

Question 30

how is diabetes and pre-diabetes diagnosed?

Answer 30

• A1C test
• fasting blood sugar test
• oral glucose tolerance test

Question 31

A1C test

Answer 31

• measures percentage of blood sugar attached to oxygen carrying protein in RBC
• the higher your blood sugar levels the more hemoglobin you’ll have with sugar attached
• 5.7% is normal
• between 5.7 and 6.4% is prediabets
• 6.5% or higher on 2 separate tests indicates type 2 diabetes

Question 32

fasting plasma glucose test

Answer 32

testing how fast body processes sugar
* when fasting glucagon increase so CORT increase and BP while insulin decreases

Question 33

oral glucose tolerance test

Answer 33

• used to diagnose diabetes only during pregnancy
• blood sample taken after you fast then given a sugar solution and measure blood sugar level