Endocrinology Flashcards Preview

Tim's Cards > Endocrinology > Flashcards

Flashcards in Endocrinology Deck (101)
Loading flashcards...
1
Q

What determines whether a cell membrane will be responsive to a hormone?

A

The amount of hormone

*this is because receptors are usually present in excess

2
Q

What determines whether the cell (cytoplasm) or nucleus will respond to a hormone?

A

The number of receptors

3
Q

Why are most hormones given via injection?

A

They are Peptide hormones (and as such don’t cross membranes easily)

poorly absorbed
catabolized in GI tract
short half life

4
Q

A kinase…

A phosphatase…

A

attaches phosphate

removes phosphate

5
Q

What are the 2 main types of cell-surfaces receptors for hormones?

A

Receptor Kinases
(act through tyrosine kinase)

G-Protein Coupled Receptors
(2nd messengers cAMP, IP3, Ca to activate protein kinases)

6
Q

Name 4 things 2nd Messengers have effects on.

A

Cellular traffic
Enzyme Action
Membrane effects
*DNA transcription/mRNA synth > protein synth

7
Q

T/F

Steroid hormones cross membranes easily

A

True

8
Q

How do steroid hormones often work in the cell?

A

Cross membrane, bind receptor

Steroid/Receptor complex enters nucleus, acts directly with DNA to alter transcription and protein synth

9
Q

Normally an excess of hormones will _______ receptors and a hormone deficiency will ________ receptors.

A

down-regulate

up-regulate

10
Q

How is an imbalance in hormones usually assessed?

A

considering both the endocrine gland from which they came and their target tissues

11
Q

T/F

Endocrine issues are more common in women.

A

True

12
Q

T/F

Endocrine issues are often auto-immune and run in families

A

True

13
Q

What connects the pituitary gland to the hypothalamus?

A

Pituitary Stalk

14
Q

Which lobe of the pituitary is larger?

A

Anterior

15
Q

Which part of the pituitary is considered to be an extension of the nervous system?

A

Posterior Pituitary

16
Q

Where are the hormones in the Posterior Pituitary made?

A

Hypothalamic nuclei

17
Q

How do hormones made in the hypothalamus travel to the posterior pituitary for storage/release?

A

Travel down axons

18
Q

What are the 2 Posterior Pituitary hormone?

A

ADH (antidiuretic hormone)

Oxytocin

19
Q

What is the function of ADH?

A

Concentrates urine

inhibits diuresis - urine output

20
Q

What is the function of Oxytocin?

A

Controls uterine contractions and breast milk let down

21
Q

T/F

The Anterior Pituitary is made up of one cell type.

A

False.

Contains several cell types that make and release different hormones

22
Q

How are Anterior Pituitary hormones regulated?

A

through Hypothalamic hormones

23
Q

What connects the hypothalamus to the Anterior Pituitary?

A

a Portal Venous system in the pituitary stalk

24
Q

Aside from being the hormones of the Posterior pituitary, what do ADH and Oxytocin have in common?

A

Both only 9 AA long

25
Q

What type of hormones are made in the hypothalamus?

A

Peptide hormones

26
Q

How are hypothalamic hormones secreted?

A

in pulses

27
Q

What stimulates the release of hormones from the hypothalamus to the Anterior Pituitary?

A

higher brain centers

*can be affected by stress

28
Q

Are hypothalamic hormones measurable?

A

No. Too invasive.

29
Q

What are the 4 Stimulatory hypothalamic hormones?

A

TRH - thyrotropin releasing hormone
CRH - corticotropin releasing hormone
GnRH - gonadotropin releasing hormone
GHRH - growth hormone releasing hormone

30
Q

What 2 substance inhibit hypothalamic hormones?

A

dopamine

somatostatin

31
Q

What are the 5 cell types of the Anterior Pituitary and what Hormones do they produce?

A

thyrotrophs TSH - thyroid-stimulating hormone
corticotrophs ACTH - adrenocorticotropic
gonadotrophs LH and FSH
somatotrophs GH - growth hormone
lactotrophs prolactin

32
Q

What 2 Pituitary hormones have both stiumulatory and inhibitory effectors?

A

Growth Hormone - stimulated by GHRH and inhibited by Somatostatin

Prolactin - stimulated by TRH (thyrotropin releasing hormone) and inhibited by Dopamine

33
Q

What two hormones does TRH (thyrotropin releasing hormone) stimulate?

A

TSH and Prolactin

34
Q

Name 6 Anterior Pituitary Hormones and their targets.

A
TSH     thyroid
ACTH     adrenal cortex
FSH     ovary or testis 
LH     ovary or testis 
GH     liver, all tissues
Prolactin     breast
35
Q

Outline the Thyroid feedback loop.

A

TRH > TSH > T4, T3 (thyroxine, triiodothyronine)

T4/T3 either provides feedback through TSH or directly onto TRH in hypothalamus

36
Q

What is the main function of the thyroid hormones?

A

Energy expenditure

37
Q

Outline the Adrenal feedback loop:

A

CRH > ACTH > Cortisol

Cortisol either provides feedback through ACTH or CRH directly

38
Q

Outline the Gonad Feedback loop:

A

GnRH > FSH/LH > Estrogen/Testosterone

with feedback at either tertiary (hypothalamic) or secondary level
*Kisspeptin starts this cascade

39
Q

What effects GnRH directly and is regulated by higher brain centers?

A

Kisspeptin

40
Q

What is Kisspeptin coded by and where is it made?

A

KISS1 gene

mainly hypothalamus

41
Q

Outline the Growth feedback loop:

A

GHRH > GH > IGF-1 (insulin like growth factor1)

feedback at secondary or tertiary (hypothalamic) level

42
Q

What 3 hormones possibly effect the expression of Growth Hormone?

A

IGF-1 (through regulation feedback loop)
GHRH (stimulation from hypothalamus)
Somatostatin (inhibition)

43
Q

Outline Prolactin feedback:

A

No suckling > Dopamine > Prolactin inhibited > no milk

Suckling > inhibits dopamine > Prolactin > milk

44
Q

What might cause a hormone deficiency?

What might cause hormone excess?

A

Hypothalamic lesion

Tumors

45
Q

What are the 3 main questions to address with a pituitary tumor in making a diagnosis?

A

Tumor produce hormones?
Pituitary mass effects?
Other pituitary hormones affected?

46
Q

What does excess GH cause?

A

acromegaly or gigantism

47
Q

What does excess ACTH cause?

A

excess cortisol (Cushing disease)

48
Q

What does excess TSH cause?

A

hyperthyroidism

*very rare

49
Q

In what 3 ways does excess Prolactin manifest?

A

breast milk, no menses, infertility

50
Q

What does excess FSH/LH cause?

A

no disease

51
Q

What are some pituitary tumor mass effects?

A

headache from stretched dura
optic damage (peripheral)
cranial nerve defects
sinus invasion

52
Q

What are the 3 main treatments for pituitary pathologies?

A

Tumor Mass - surgery/radiation
Hormone excess - Antagonist
Hormone deficiency - replacement of target hormone or pituitary hormone

53
Q

Individual cell type failure in the pituitary or the failure of the entire gland (panhypopituitarism) can be caused by:

A

tumor
infiltration (Fe deposits)
infection (TB)
auto-immune

54
Q

What is the usual progression of loss in the pituitary when a mass is present?

A

GH, FSH, and LH first

TSH and ACTH second

55
Q

Why would a mass cause prolactin to increase?

A

Pressure on the pituitary stalk prevents dopamine inhibition from the hypothalamus

56
Q

How would pituitary failure present at the target tissues?

A

*low ACTH/cortisol - can’t handle medical stress
low TSH/thyroid hormones - hypothyroidism
low FSH, LH, sex hormones - no menses, infertility, etc
low prolactin - no lactation
low GH/IGF-1 - growth failure in children

57
Q

Name 6 causes of high prolactin:

A
Tumor
Stalk damage
Chest wall trauma
Kidney failure
Antipsychotics (suppress dopamine)
Hypothyroidism (high TRH from hypothalamus)

*remember TRH affects both TSH and prolactin

58
Q

What is an effective treatment for a pituitary tumor causing high prolactin output?

A

Dopamine or agonist

this inhibits prolactin and causes tumor to shrink

59
Q

What does high levels of prolactin suppress?

A

Kisspeptin

  • so bad for gonad function/fertility
60
Q

What cause fits these metabolic conditions:
increased FA mobilization
Insulin resistance
More protein synth

A

Tumor producing GH

61
Q

What does too much GH cause if the onset is before/after puberty?

A

before - gigantism

after - Acromegaly

62
Q

What is one of the first signs of excessive Growth Hormone?

A

enlarged sweat glands

63
Q

What is a useful test for Acromegaly?

A

a GH increase after an oral glucose load

no one knows why this works

64
Q

What is an appropriate treatment for Acromegaly?

A

Somatostatin (suppresses GH)
GH antagonist

*remember, goal is to suppress GH and get IGF-1 normal

65
Q

What are 4 main tools to use in endocrinology?

A

Carbohydrate counting
Growth charts
DXA scan
FRAX test

66
Q

Describe the thyroid feedback system:

A

TRH > TSH > T4/T3

67
Q

What do the thyroid hormones do?

A

Regulates energy expenditure, growth, etc

68
Q

What are the hormones released from the thyroid?

A

T4 and T3

thyroxine and triiodothyronine
*T3 is active form

69
Q

What is unique about the thyroid hormones?

A

They contain iodine

70
Q

What transports iodide from the blood into the thyroid cells?

A

sodium-iodide symporter

71
Q

What enzyme oxidizes iodide to iodine to by used in T4/T3?

A

Thyroid peroxidase

72
Q

How is iodine stored in the thyroid?

A

In thyroglobulin in colloid. Added to tyrosine and then makes T4/T3

73
Q

What amounts of T4/T3 does the thyroid secrete?

A

85% T4 (inactive)

15% T3 (active)

74
Q

What is the blood carrier for T4/T3?

A

thyroid binding globulin

75
Q

Does T3 act more like a peptide or steroid hormone?

A

Steroid.

enters nucleus - changes DNA expression

76
Q

What are some functions of T3?

A

Increase metabolic rate (oxygen, heat, protein, fat, cholesterol synth/degradation)

*increases sympathetic nervous system tone

77
Q

What is usually the most valuable test for the thyroid system?

A

TSH

78
Q

What does TSI stand for?

A

Thyroid Stimulating Immunoglobulin

79
Q

What can a radioactive iodine scan tell you?

A

Thyroid enlargment
iodine distribution
hot/cold nodules

80
Q

Is Radioactive iodine useful for hypothyroidism?

A

no

81
Q

What are the T4/T3 and TSH levels in Hyperthyroidism?

A

High T4/T3
Low TSH

(high TSH may be present in very rare TSH producing pituitary tumor)

82
Q

What condition entails lid lag and Proptosis?

A

Hyperthyroidism

Graves for Proptosis

83
Q

What condition entails constipation?

A

Hypothyroidism

84
Q

What condition entails slow relaxation of muscle on reflex test?

A

Hypothyroidism

85
Q

What causes Graves disease?

A

TSI antibodies mimic TSH and overstimulate thyroid gland

TSH low
T4/T3 high

86
Q

What is the difference between a multinodular goiter and a hot nodule?

A

Multi-nodular escapes TSH control

Hot nodule has mutation in TSH receptor that kicks out more T4/T3.

87
Q

What thyroid condition has a negative scan for iodine uptake and is often transient?

A

Thyroiditis

*here, the inflamed gland releases stored hormone and causes a temporary hyperthyroidism

88
Q

What might be the cause of hyperthyroidism with a negative iodine scan without any noticable inflammation of the gland?

A

Exogenous T4/T3

89
Q

What does high levels of TSH suggest?

A

Tumor

*very rare

90
Q

What is a major cause of hyperthyroidism that is familial and 10x more common in women?

A

Graves disease

*autoimmune (usually), TSI

91
Q

What infiltrates the eye muscles in Graves disease?

A

mucopolysaccharides and lymphocytes

*effects are worse in smokers

92
Q

What usually happens after radio-active iodine treatment for hyperthyroidism?

A

Hypothyroidism

93
Q

What are the 3 usual treatments for hyperthyroidism?

A

Radio-active iodine
Anti-thyroid drugs
Surgery

94
Q

What are some causes of primary hypothyroidism?

A

Autoimmune destruction (Hashimoto thyroiditis)
Congenital defects
Radioactive iodine/surgery for hyperthyroidism
Anti-thyroid drugs

95
Q

What would the T4/T3 levels and TSH levels be in primary hypothyroidism?

A

Low T4,T3

High TSH

96
Q

What would the thyroid hormone levels be in a secondary pathology?

A

low T4,T3

low TSH

97
Q

What would the thyroid hormone levels be in a tertiary pathology?

A

low T4,T3

low TSH

98
Q

In what ages are the effects of hypothyroidism reversible?

A

Childhood and Adult

*dwarfism and low IQ from newborn/3rd trimester irreversible

99
Q

Can a goiter be present in hypothyroidism?

A

yes. High TSH may cause this.

100
Q

Why is Thyroxine (T4) increased slowly in dosage to treat hypothyroidism?

A

easier on the heart

101
Q

What causes a goiter in hyperthyroidism?

Hypothyroidism?

A

Hyper - TSI (Grave’s), multinodular (growth factor outside TSH control), inflammation (thyroiditis)

Hypo - High TSH stimulates growth, but still low T4

Decks in Tim's Cards Class (140):