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JL Endocrinology > Week 1 > Flashcards

Week 1 Flashcards

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1
Q

What system consists of ductless endocrine glands that occur at numerous locations in the body?

A

Endocrine system

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2
Q

In the endocrine system - how is communication between glands and other tissues achieved?

A

By secretion of a hormone into blood stream and transport to a target site

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3
Q

Name three things that the endocrine system regulates?

A
  1. Nutrient metabolism
  2. H2O and electrolyte balance
  3. Red blood cell production
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4
Q

What stress hormone is long term and what is short term?

A

Long term - cortisol

Short term - Adrenaline

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5
Q

What are the three main classes of hormones?

A
  1. Glycoproteins and peptides
  2. Steroids - derived from cholsterol
  3. Tyrosine and tryptophan derivatives
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6
Q

Give two hormones in the protein and peptide class?

A

Oxytocin

Insulin

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7
Q

What is tyrosine enzymatically converted to?

A

Adrenaline

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8
Q

How are amines transported in plasma?

A

Freely - they are hydrophilic

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9
Q

What are peptides and proteins pre-synthesised from?

A

Longer precursor

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10
Q

With steroids - what is cholesterol converted to?

A

Pregnenolone - rate limiting step

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11
Q

How are steroids transported in the plasma?

A

Mainly bound to plasma proteins - hydrophobic

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12
Q

Are steroids and thyroxine soluble or insoluble in plasma?

A

Insoluble

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13
Q

Give two roles of carrier proteins?

A
  1. Increase amount transported in blood

2. Prevent rapid excretion by preventing filtration at kidneys

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14
Q

What does sex steroid-binding globulin bind to?

A

Testosterone and estradiol

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15
Q

What does albumin bind to?

A

Steroids and thyroxine

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16
Q

What does transthyretin bind to?

A

Thyroxine and some steroids

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17
Q

What helps to maintain a constant concentration of free lipophilic hormone in the blood?

A

Carrier proteins

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18
Q

Are free and bound hormones in equilibrium?

A

Yes`

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19
Q

What is the primary determinant of plasma concentration?

A

Rate of secretion

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20
Q

What does ‘tropic’ refer to?

A

A hormone that acts upon another endocrine gland to regulate its secretion of hormone

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21
Q

What secretes corticotropinreleasing hormone?

A

Hypothalamus

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22
Q

What does CTRH target which then releases Adrenocorticotropic hormone?

A

Anterior pituitary

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23
Q

What does ACTH act on which then secretes cortisol?

A

Adrenal cortex

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24
Q

Hormone receptors exist as three structurally and funtionally distinct types - name the two cell surface receptors and the one intracellualr receptor?

A

GPCR
Receptor kinases

nuclear receptors

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25
What are class 1 nuclear receptors activated by?
Steroid hormones
26
What are class 2 nuclear receptors activated by?
Lipids
27
What are hybrid class nuclear receptors activated by?
Thyroid hormone
28
What type of receptor is this: binding of insulin causes autophosphorylation of intracellular tyrosine residues. recruitment of multiple adapter proteins, notibly IRS1, that are also tyrosine phosphorylated?
Receptor kinases
29
What are nuclear receptors?
Ligand-gated transcription factors
30
What four cells are in pancreatic islets - in order of most abundant first?
1. Beta-cells 2. Alpha-cells 3. Gamma-cells 4. PP cells
31
What do beta-cells secrete?
Insulin
32
What do alpha cells secrete?
Glucagon
33
What do gamma cells secrete?
Somatostatin
34
What do PP cells secrete?
Pancreatic polypeptide
35
What is synthesised in the rough ER of pancreatic beta-cells as a larger single chain preprohormone - preprosinsulin?
Insulin peptide
36
During secretion of insulin: how does glucose enter beta-cells and what phosphorylates it>
GLUT2 glucose transporter | Glucokinase
37
What phosphorylates glucose at very low concentrations?
Hexokinase
38
What does an increased metabolism of glucose lead to in relation to intracellular ATP concentration>
An increase
39
In relation to insulin secretion: what does ATP inhibit?
ATP-sensitive K+ channel Katp
40
During insulin secretion: what depolarises the cell membrane?
Inhibition of Katp
41
During insulin secretion: what does depolarisation of cell membrane result in?
Opening of voltage-gated Calcium channels
42
During insulin secretion: what does an increase in internal calcium concentration lead to?
Fusion of secretory vesicles with the cell membrane and release of insulin
43
How is the release of insulin described?
Biphasic
44
Name the two Katp channel proteins?
Kir6.1 - inward rectifier subunit, pore subunit | SUR1 - sulphonylurea receptor, regulatory subunit
45
What structure are Katp channels?
Octomeric
46
What class of drugs directly inhibits Katp?
Sulphonylurea - tolbutamide or glibenclamide
47
What drug stimulates Katp?
Diazoxide - which inhibits insulin secretion
48
What do HNF transcription factors play a key role in?
Pancreas foetal development and neogenesis and regulate beta cell differentiation and function
49
When can sulphonylurea be used instead of insulin?
When there has been robust genetic screening to differentiate MODY from type I diabetes
50
What type of diabetes involves a loss of insulin secreting beta cells?
Type I
51
What type of diabetes involves defective glucose sensing in the pancreas and/or loss of insulin secretion?
MODY
52
What type of diabetes is initially hyperglycemoa with hyperinsulinemia so the primary problem is reduced insulin sensitivity in tissues?
Type II diabetes
53
What family of receptors does insulin receptor belong to?
Receptor tyrosine kinases
54
Is protein phosphorylation reversible?
Yes
55
What do protein kinases promote?
Protein phosphorylation
56
Name the three amino acids that protein phosphorylation occurs on? (any hydroxyl group)
Serine Threonine Tyrosine
57
What is introduced onto proteins when they get phosphorylated~?
A large negative charge
58
Name a dimeric tyrosine kinase?
Insulin receptor
59
What is insulin receptor composed of?
2 Extracellular alpha subunits and two transmembrane beta subunits linked by disulfide bonds
60
What binds to alpha subunit in insulin receptor?
Hormone-binding (insulin) domains
61
What binds to beta subunits in the insulin receptor?
ATP-binding and tyrosine kinase domains
62
How does the insulin receptor work?
Binding of insulin to alpha subunits causes beta subunits to phosphorylate themselves, thus activating the catalytic activity of the receptor
63
What two pathways does IRS activate once the insulin receptor substrates are phosphorylated?
1. Ras/MAP kinase pathway and gene expression | 2. PI3K, PKB, and glycogen synthesis
64
During insulin signalling simplified - what does PKB stimulate?
GLUT 4
65
What three things does the biological effect of insulin stimulate?
1. DNA synthesis 2. Protein synthesis 3. Glycogen synthesis in liver and muscle
66
What two things does the biological effect of insulin uptake?
1. Amino acid uptake in muscle | 2. Glucose uptake in muscle and adipose tissue
67
What are lipolysis and gluconeogenesis in the liver a biological effect of?
Insulin
68
Severe insulin resistance and diabetes can be due to a mutation in what?
AKT2
69
What disease is a rare autosomal recessive genetic trait, involves mutations in the gene for the insulin receptor, severe insulin resistance and is caused by defects in insulin binding orr insulin receptor signalling?
Leprechaunism or Donohue syndrome
70
Give three developmental abnormalities of leprechaunism or donohue syndrome?
1. Elfin facial appearance 2. Growth retardation 3. Absence of subcutaneous fat, decreased muscle mass
71
What is the rare autosomal recessive genetic trait that involves severe insulin resistance, hyperglycemia and compensatory hyperinsulinemia, developmental abnormalities and acanthosis nigricans?
Rabson Mendenhall syndrome
72
Where are ketone bodies formed?
In liver mitochondria - derived from acetyl-CoA fro, beta-oxidation
73
What does ketone body formation depend on?
Oxaloacetate
74
What is oxaloacetate consumed for?
Gluconeogenesis
75
What type of diabetes is ketoacidosis most associated with?
Type I

JL Endocrinology (12 decks)

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