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Endocrinology 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

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2
Q

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

A

The number of receptors

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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

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4
Q

A kinase…

A phosphatase…

A

attaches phosphate

removes phosphate

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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)

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6
Q

Name 4 things 2nd Messengers have effects on.

A

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

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7
Q

T/F

Steroid hormones cross membranes easily

A

True

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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

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9
Q

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

A

down-regulate

up-regulate

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10
Q

How is an imbalance in hormones usually assessed?

A

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

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11
Q

T/F

Endocrine issues are more common in women.

A

True

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12
Q

T/F

Endocrine issues are often auto-immune and run in families

A

True

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13
Q

What connects the pituitary gland to the hypothalamus?

A

Pituitary Stalk

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14
Q

Which lobe of the pituitary is larger?

A

Anterior

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15
Q

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

A

Posterior Pituitary

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16
Q

Where are the hormones in the Posterior Pituitary made?

A

Hypothalamic nuclei

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17
Q

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

A

Travel down axons

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18
Q

What are the 2 Posterior Pituitary hormone?

A

ADH (antidiuretic hormone)

Oxytocin

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19
Q

What is the function of ADH?

A

Concentrates urine

inhibits diuresis - urine output

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20
Q

What is the function of Oxytocin?

A

Controls uterine contractions and breast milk let down

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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

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22
Q

How are Anterior Pituitary hormones regulated?

A

through Hypothalamic hormones

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23
Q

What connects the hypothalamus to the Anterior Pituitary?

A

a Portal Venous system in the pituitary stalk

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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

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25
What type of hormones are made in the hypothalamus?
Peptide hormones
26
How are hypothalamic hormones secreted?
in pulses
27
What stimulates the release of hormones from the hypothalamus to the Anterior Pituitary?
higher brain centers *can be affected by stress
28
Are hypothalamic hormones measurable?
No. Too invasive.
29
What are the 4 Stimulatory hypothalamic hormones?
TRH - thyrotropin releasing hormone CRH - corticotropin releasing hormone GnRH - gonadotropin releasing hormone GHRH - growth hormone releasing hormone
30
What 2 substance inhibit hypothalamic hormones?
dopamine | somatostatin
31
What are the 5 cell types of the Anterior Pituitary and what Hormones do they produce?
thyrotrophs TSH - thyroid-stimulating hormone corticotrophs ACTH - adrenocorticotropic gonadotrophs LH and FSH somatotrophs GH - growth hormone lactotrophs prolactin
32
What 2 Pituitary hormones have both stiumulatory and inhibitory effectors?
Growth Hormone - stimulated by GHRH and inhibited by Somatostatin Prolactin - stimulated by TRH (thyrotropin releasing hormone) and inhibited by Dopamine
33
What two hormones does TRH (thyrotropin releasing hormone) stimulate?
TSH and Prolactin
34
Name 6 Anterior Pituitary Hormones and their targets.
``` TSH thyroid ACTH adrenal cortex FSH ovary or testis LH ovary or testis GH liver, all tissues Prolactin breast ```
35
Outline the Thyroid feedback loop.
TRH > TSH > T4, T3 (thyroxine, triiodothyronine) T4/T3 either provides feedback through TSH or directly onto TRH in hypothalamus
36
What is the main function of the thyroid hormones?
Energy expenditure
37
Outline the Adrenal feedback loop:
CRH > ACTH > Cortisol Cortisol either provides feedback through ACTH or CRH directly
38
Outline the Gonad Feedback loop:
GnRH > FSH/LH > Estrogen/Testosterone with feedback at either tertiary (hypothalamic) or secondary level *Kisspeptin starts this cascade
39
What effects GnRH directly and is regulated by higher brain centers?
Kisspeptin
40
What is Kisspeptin coded by and where is it made?
KISS1 gene | mainly hypothalamus
41
Outline the Growth feedback loop:
GHRH > GH > IGF-1 (insulin like growth factor1) feedback at secondary or tertiary (hypothalamic) level
42
What 3 hormones possibly effect the expression of Growth Hormone?
IGF-1 (through regulation feedback loop) GHRH (stimulation from hypothalamus) Somatostatin (inhibition)
43
Outline Prolactin feedback:
No suckling > Dopamine > Prolactin inhibited > no milk Suckling > inhibits dopamine > Prolactin > milk
44
What might cause a hormone deficiency? What might cause hormone excess?
Hypothalamic lesion Tumors
45
What are the 3 main questions to address with a pituitary tumor in making a diagnosis?
Tumor produce hormones? Pituitary mass effects? Other pituitary hormones affected?
46
What does excess GH cause?
acromegaly or gigantism
47
What does excess ACTH cause?
excess cortisol (Cushing disease)
48
What does excess TSH cause?
hyperthyroidism *very rare
49
In what 3 ways does excess Prolactin manifest?
breast milk, no menses, infertility
50
What does excess FSH/LH cause?
no disease
51
What are some pituitary tumor mass effects?
headache from stretched dura optic damage (peripheral) cranial nerve defects sinus invasion
52
What are the 3 main treatments for pituitary pathologies?
Tumor Mass - surgery/radiation Hormone excess - Antagonist Hormone deficiency - replacement of target hormone or pituitary hormone
53
Individual cell type failure in the pituitary or the failure of the entire gland (panhypopituitarism) can be caused by:
tumor infiltration (Fe deposits) infection (TB) auto-immune
54
What is the usual progression of loss in the pituitary when a mass is present?
GH, FSH, and LH first TSH and ACTH second
55
Why would a mass cause prolactin to increase?
Pressure on the pituitary stalk prevents dopamine inhibition from the hypothalamus
56
How would pituitary failure present at the target tissues?
*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
Name 6 causes of high prolactin:
``` Tumor Stalk damage Chest wall trauma Kidney failure Antipsychotics (suppress dopamine) Hypothyroidism (high TRH from hypothalamus) ``` *remember TRH affects both TSH and prolactin
58
What is an effective treatment for a pituitary tumor causing high prolactin output?
Dopamine or agonist this inhibits prolactin and causes tumor to shrink
59
What does high levels of prolactin suppress?
Kisspeptin - so bad for gonad function/fertility
60
What cause fits these metabolic conditions: increased FA mobilization Insulin resistance More protein synth
Tumor producing GH
61
What does too much GH cause if the onset is before/after puberty?
before - gigantism | after - Acromegaly
62
What is one of the first signs of excessive Growth Hormone?
enlarged sweat glands
63
What is a useful test for Acromegaly?
a GH increase after an oral glucose load | no one knows why this works
64
What is an appropriate treatment for Acromegaly?
Somatostatin (suppresses GH) GH antagonist *remember, goal is to suppress GH and get IGF-1 normal
65
What are 4 main tools to use in endocrinology?
Carbohydrate counting Growth charts DXA scan FRAX test
66
Describe the thyroid feedback system:
TRH > TSH > T4/T3
67
What do the thyroid hormones do?
Regulates energy expenditure, growth, etc
68
What are the hormones released from the thyroid?
T4 and T3 thyroxine and triiodothyronine *T3 is active form
69
What is unique about the thyroid hormones?
They contain iodine
70
What transports iodide from the blood into the thyroid cells?
sodium-iodide symporter
71
What enzyme oxidizes iodide to iodine to by used in T4/T3?
Thyroid peroxidase
72
How is iodine stored in the thyroid?
In thyroglobulin in colloid. Added to tyrosine and then makes T4/T3
73
What amounts of T4/T3 does the thyroid secrete?
85% T4 (inactive) | 15% T3 (active)
74
What is the blood carrier for T4/T3?
thyroid binding globulin
75
Does T3 act more like a peptide or steroid hormone?
Steroid. enters nucleus - changes DNA expression
76
What are some functions of T3?
Increase metabolic rate (oxygen, heat, protein, fat, cholesterol synth/degradation) *increases sympathetic nervous system tone
77
What is usually the most valuable test for the thyroid system?
TSH
78
What does TSI stand for?
Thyroid Stimulating Immunoglobulin
79
What can a radioactive iodine scan tell you?
Thyroid enlargment iodine distribution hot/cold nodules
80
Is Radioactive iodine useful for hypothyroidism?
no
81
What are the T4/T3 and TSH levels in Hyperthyroidism?
High T4/T3 Low TSH (high TSH may be present in very rare TSH producing pituitary tumor)
82
What condition entails lid lag and Proptosis?
Hyperthyroidism | Graves for Proptosis
83
What condition entails constipation?
Hypothyroidism
84
What condition entails slow relaxation of muscle on reflex test?
Hypothyroidism
85
What causes Graves disease?
TSI antibodies mimic TSH and overstimulate thyroid gland TSH low T4/T3 high
86
What is the difference between a multinodular goiter and a hot nodule?
Multi-nodular escapes TSH control Hot nodule has mutation in TSH receptor that kicks out more T4/T3.
87
What thyroid condition has a negative scan for iodine uptake and is often transient?
Thyroiditis *here, the inflamed gland releases stored hormone and causes a temporary hyperthyroidism
88
What might be the cause of hyperthyroidism with a negative iodine scan without any noticable inflammation of the gland?
Exogenous T4/T3
89
What does high levels of TSH suggest?
Tumor *very rare
90
What is a major cause of hyperthyroidism that is familial and 10x more common in women?
Graves disease *autoimmune (usually), TSI
91
What infiltrates the eye muscles in Graves disease?
mucopolysaccharides and lymphocytes *effects are worse in smokers
92
What usually happens after radio-active iodine treatment for hyperthyroidism?
Hypothyroidism
93
What are the 3 usual treatments for hyperthyroidism?
Radio-active iodine Anti-thyroid drugs Surgery
94
What are some causes of primary hypothyroidism?
Autoimmune destruction (Hashimoto thyroiditis) Congenital defects Radioactive iodine/surgery for hyperthyroidism Anti-thyroid drugs
95
What would the T4/T3 levels and TSH levels be in primary hypothyroidism?
Low T4,T3 High TSH
96
What would the thyroid hormone levels be in a secondary pathology?
low T4,T3 low TSH
97
What would the thyroid hormone levels be in a tertiary pathology?
low T4,T3 low TSH
98
In what ages are the effects of hypothyroidism reversible?
Childhood and Adult *dwarfism and low IQ from newborn/3rd trimester irreversible
99
Can a goiter be present in hypothyroidism?
yes. High TSH may cause this.
100
Why is Thyroxine (T4) increased slowly in dosage to treat hypothyroidism?
easier on the heart
101
What causes a goiter in hyperthyroidism? | Hypothyroidism?
Hyper - TSI (Grave's), multinodular (growth factor outside TSH control), inflammation (thyroiditis) Hypo - High TSH stimulates growth, but still low T4

Tim's Cards (140 decks)

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