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Physiology > ENDO V Insulin and Glucagon > Flashcards

ENDO V Insulin and Glucagon Flashcards

1
Q

what secretes glucagon

A

alpha cells

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2
Q

what secretes insulin

A

beta cells

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3
Q

what secretes somatostatin

A

delta cells

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4
Q

what secretes pancreatic polypeptide

A

F cells

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5
Q

what does the pancreas contain

A

islets of langerhans

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6
Q

how much of the islets of langerhans do alpha and beta cells make up

A

about 85%

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7
Q

what is the majority of the pancreas composed of and what does it do

A

acinar cells that produce digestive enzymes

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8
Q

what is the exocrine portion of the pancreas

A

the acinar cells

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9
Q

what is the endocrine portion of the pancreas

A

islets of langerhans

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10
Q

what is insulin secretion associated with

A

energy abundance

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11
Q

what is insulin made of

A

two amino acid chains connected by disulfide linkages

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12
Q

what happens to insulin when A and B chains are split

A

functional activity of insulin molecule is lost

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13
Q

do proinsulin and C peptide have any insulin activity

A

no

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14
Q

what does insulin circulate bound to

A

nothing

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15
Q

what is the half life of insulin

A

6 mins

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16
Q

where is insulin formed

A

in beta cells

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17
Q

what is the process of insulin formation

A

starts as proinsulin then in the golgi proinsulin is cleaved into c-peptide and insulin

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18
Q

what are incretins

A

hormones produced by the digestive system that stimulate insulin secretion before plasma glucose is elevated

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19
Q

what are examples of incretins

A

GLP-1 and GIP

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20
Q

what is the mechanism of insulin secretion

A

-glucose enters the cell via GLUT 1 and GLUT 2 transporter
- glucose is converted into pyruvate and used to make ATP in the mitochondria
-ATP enters the ATP sensitive K+ channel and closes it which causes depolarization
- this opens VG Ca2+ channels and calcium enters the cell.
-cAMP is signaled and signals secretory granules to excytose insulin and C peptide

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21
Q

what is the sulfonylurea receptor (SUR) (K+ ATP channel)

A

binding site for some drugs that act as insulin secretagogues for treatment of type 2 diabetes

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22
Q

what is the key regulator of insulin secretion

A

glucose levels

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23
Q

what glucose levels stimulate insulin synthesis

A

greater than 3.9 mmol/L

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24
Q

what else besides insulin regulate insulin secretion

A

amino acids, ketones, various nutrients, GI peptides and NTs

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25
in the beginning of insulin secretion what insulin is released
pre formed insulin
26
after 10-20 minutes of insulin secretion what insulin is released
pre formed insulin and newly synthesized insulin
27
what is normal fasting blood glucose
80-90 mg/ 100 ml
28
at what levels of blood glucose does insulin secretion rise
above 100 mg/100 ml
29
what blood glucose is peak secretion of insulin
400-600 mg/100 ml
30
can insulin be secreted past 400-600 mg/ 100 ml of blood glucose
no
31
what is the relationship between glucagon and blood glucose levels
glucagon levels decrease as blood glucose levels increase
32
what type of receptor is the insulin receptor
tyrosine kinase linked receptor
33
what is the FAST target cells response to insulin binding to its receptor
increased glucose uptake especially by muscle cells and adipocytes due to translocation of vesicles containing GLUT 4 to the membrane
34
what does the membrane become more permeable to when insulin binds to its receptor
amino acids, potassium and phosphate ions
35
what is the SLOWER target cells response to insulin binding and how long is this
10-15 minutes, change in enzyme activity leading to changes in metabolism
36
what is the SLOWEST target cells response to insulin binding and how long is this
hours-days, changes is gene expression and growth
37
what happens to insulin when it binds
it forms a dimer
38
what are the results of insulin
-glucose transport - protein synthesis -fat synthesis -glycogen synthesis - growth and gene expression
39
what are the effects of insulin on muscle
-increases glucose uptake and metabolism - anabolic effect - increases glycogen storage in skeletal muscle - increases protein synthesis and inhibits protein degradation
40
what is the permeability of resting muscles to glucose
slightly permeable
41
what is the relationship between insulin and growth hormone to promote growth
synergism
42
what does lack of insulin cause
protein depletion and increased plasma amino acids
43
what is the effect of insulin on the liver
promotes uptake and storage of glucose as glycogen
44
what is the mechanism of increasing uptake and glucose storage in the liver
-increased glycogen synthase leading to glycogen synthesis - decreased breakdown of glycogen by inhibiting liver phosphorylase -increases glucose uptake
45
what is the effect of insulin on gluconeogenesis
inhibitory
46
what does insulin promote conversion of excess glucose into
fatty acids
47
what is the mechanism of insulin promoting fat synthesis and storage
-increased glucose transport into liver TG+ lipoprotein released from liver -activates lipoprotein lipase in the capillary walls of adipose tissue, splitting triglycerides into fatty acids, and absorption into adipocytes
48
what are the essential effects of insulin for fat storage in adipose tissue
-inhibits action of hormone sensitive lipase (HSL) -enhances glucose transport into adipocytes -alpha glycerol phosphate - glycerol and fatty acids -> TG
49
what does lipoprotein lipase do
brings more lipids into adipocytes
50
what does lack of insulin cause in adipocytes
lipolysis and release of FFA and increases plasma cholesterol and phospholipids concentrations
51
what does HSL do
exports triglycerides from adipocyte into the blood
52
what are the major target tissues of insulin
muscle, liver, adipose tissue
53
what is the effect of insulin on ketoacids in plasma
decreased ketoacids
54
what is the effect of insulin on amino acids in plasma
decreased
55
what causes increased insulin secretion
-increased blood glucose -increased blood FFAs -increased blood AAs - incretins -glucagon, GH, cortisol which all increase blood glucose - PNS stimulation, AcH -Beta adrenergic stimulation - insulin resistance, obesity, -sulfonylurea drugs
56
how do incretins work when binding to receptor
increase cAMP in beta cell
57
how do sulfonylurea drugs work in beta cell
close K ATP channel in beta cell
58
what caused decreased insulin secretion
- decreased blood glucose - fasting - somatostatin -alpha adrenergic activity -leptin
59
glucagon is the hormone of "_____"
starvation
60
what is the relationship between blood glucose and glucagon
inverse
61
what is glucagon secretion stimulated by
hypoglycemia, epinephrine (Beta 2), vagus nerve
62
what is the primary target tissue of glucagon
liver to increase blood glucose
63
how does glucagon increase blood glucose in the liver
-stimulating glycogenolysis and inhibiting glycogen synthesis - increasing gluconeogenesis -increases blood fatty acid and ketoacid levels to provide more substrates for gluconeogenesis
64
what are the ketoacids released by the liver
acetone, acetoacetate, beta-hydroxybutyrate
65
what is diabetes mellitus
metabolic disorder characterized by hyperglycemia due to insufficient insulin or cellular resistance to insulin
66
what is the difference between a normal individual and a DM individual's blood glucose levels
with DM it takes longer to reduce blood glucose levels and glucose levels dont reach the control level
67
which type of diabetes is hypoinsulinemia
type 1
68
what are symptoms of DM
-polyuria -polydipsia -polyphagia - extreme fatigue -blurry vision -cuts/bruises slow to heal -weight loss (type 1) -tingling, pain, or numbness in hands and feet (type 2)
69
approximately 25% of patients with type 1 DM initially present with___
diabetic ketoacidosis, hyperglycemia greater than 250 fasting blood glucose
70
how is DM diagnosed
casual plasma glucose greater than 200 mg/dl and hyperlgycemia symptoms
71
what is fasting plasma glucose in normal individuals vs DM
normal- 100 DM- 126
72
what is normal and DM A1C
normal- less than 5.6 DM- greater than 6.5
73
what is the pathophyiology of DM type 1
-autoimmune destruction of pancreatic beta cells
74
what percentage of diabetes cases are type 1
5-10%
75
what are the risk factors for type 1 diabetes
-genetic predisposition -environmental triggers stimulate autoimmune response such as viral infections or chemical toxins
76
when does type 1 onset
usually less than 40, non- obese younger patients
77
when does hyperglycemia occur in type 1 DM
when 80-90% of cells destroyed
78
what does hyperglycemia in type 1 DM lead to
-polyuria -polydipsia - polyphagia -glucosuria -weight loss -fatigue -hyperkalemia due to lack of insulin which normally activates the sodium potassium pump
79
what is diabetic ketacidosis due to
increased lipolysis to fatty acids to produce ketoacids
80
what is DKA a response to
a cellular starvation brought on by relative insulin deficiency and counterregulatory or catabolic hormone excess such as glucagon, catecholamines, cortisone and GH
81
what is the pathophysiology of DKA
-osmotic diuresis and dehydration (hyperglycemia) - metabolic acidosis (accumulation of ketones) - fluid and electrolyte imbalances
82
what type of diabetes does DKA occur with
type 1
83
what causes DKA
-trauma -stress -infection -reduced daily insulin injections
84
what are signs and symptoms of DKA
-fruity breath - nausea/abdominal pain -dehydration -tachycardia -lethargy -coma -kussmaul respirations
85
what is the goal of kussmaul respirations
blow off CO2 to reverse acidosis
86
what are the three categories of DKA and explain each
-mild (pH 7.25-7.3) individual is alert - moderate (pH 7-7.25) individual is drowsy - severe (pH less than 7) individual will be in a stupor or coma
87
what does acidosis do to neuronal function and why
depresses it because it block inward current of Na+ and Ca2+
88
what is type 2 DM
fasting hyperglycemia despite availability of insulin - insulin resistance
89
what are risk factors for type 2 DM
-history of diabetes in parents or siblings - obesity - physical inactivity -race/ethnicity -women -patients with hypertension
90
what is the pathophysiology of T2DM
-hyperinsulinemia due to insulin resistance -beta cell dysfunction with impaired insulin secretion -due to down regulation of insulin receptors in target tissues and insulin resistance
91
what occurs in metabolic syndrome
-obesity -insulin resistance - fasting hyperglycemia - lipid abnormalities -hypertension
92
what do individuals with metabolic syndrome have increased risk for
CVD (atherosclerosis) and insulin resistance
93
what are complications of both type 1 and type 2 DM
-retinopathy -nephropathy -neuropathy - vascular disease - myopathies
94
what are oral manifestations of DM
- periodontal disease -salivary and taste dysfunction -oral bacterial and fungal infections -oral mucosa lesions -diminished salivary flow and burning mouth syndrome - delayed mucosal wound healing -xerostomia
95
what is the effect of diabetes on periodontal disease and treatment
diabetes leads to periodontal disease and vice versa. treatment of periodontal disease may improve glycemic control

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