Intro to Endocrin Flashcards
1
Q
What is the study of hormones?
A
endocrinology
2
Q
Do endocrine glands have ducts?
A
no
3
Q
Where do endocrine glands secrete horomones?
A
into interstitutium to the circulation
4
Q
How does the endocrine system maintain homeostasis?
A
regulate salt/water balances blood volume/pressure regulate calcium and phosphate regulated response to stress regulation o reproduction, development and growth
5
Q
What does the hypothalamus reslease?
A
GHRH, CRH, TRH, GnRH
Some inhibitory: somatostatin, dopamine, vasopressin, oxytocin
6
Q
What do adrenal glands secrete?
A
cortisol, aldosterone, adrenal androgens, epinephrine, norepinephrine
7
Q
What does ovaries secrete?
A
estrogen and progesterone
8
Q
What does the pituitary glands secrete?
A
growth hormones, prolactin, ACTH, MSH,TSH, FSH, and LH
9
Q
What does the thyroid secrete?
A
T3, T4 and calcitonin
10
Q
What does the parathryoid gland secrete?
A
parathyroid hormone
11
Q
What does the pancreas secrete?
A
insulin, glucagon, somatostatin
12
Q
What does the testes secrete?
A
testosterone
13
Q
(blank) is a molecule functioning as a message to convey information.
A
hormone (steroids, amines, peptides)
14
Q
What does a target organ do?
A
responds to hormone
15
Q
What is an intracellular molecule that translates the message conveyed by hormones acting on the cell surface receptor?
A
second messenger
16
Q
When a hormone secretion has an action on a receptor in the same cell then what kind of secretion is this?
A
autocrine
ex. insulin inhibiting its own release
17
Q
When a hormone secretion has an action on a neighboring cell then what kind of secretion is this?
A
paracrine
ex. estrogen acting on the ovaries
18
Q
When a hormone secretion has an action outside the body and into ducts what kind of secretion is this?
A
An EXOCRINE
19
Q
When a hormone has an action at distant organs/tissues then what kind of secretion is this?
A
Endocrine secretion
20
Q
Explain the organization of the endocrine system
A
The hypothalamus releases hormones onto the pituitary which will release tropic hormones onto target organs , which will hit up effector hormones which will take action
21
Q
What all does the anterior pituitary gland secrete?
A
FLAT PIG
F- FSH
L- LH
A- ACTH
T- TSH
P- Prolactin
I - (ignore)
G- GH
22
Q
What does ACTH (adrenocorticotropic) secrete?
A
Coritosl
23
Q
What does GH do?
A
insulin-like growth factor
24
Q
What does TSH do?
A
releases thryoxine
25
What does FSH do?
ovulation and spermatogenesis
26
What does LH do?
releases estrogen, progesterone, and testosterone
| aids in ovulation and spermatogenesis
27
What does prolactin do?
helps with lactation in breasts
28
Are all hormones under direct regulation by the pituitary?
no
29
How do proteins (hydrophillic) hormones travel in the plasma?
freely
30
How do hydrophobic hormones travel through the plasma?
Must be bound to a plasma transport protein (globulins)
31
Why do hydrophobic hormones need to be bound to globulins?
protect the hormones from rapid degredation and clearance
32
What do bound hormones serve as?
serve as reserves, ensure easy distribution
33
Are hydrophobic bound proteins active?
no they are inactive, they become active once they become free
34
What is the relationship between free and bound horomone?
dynamic
35
What are the four hormone binding proteins?
coricosteroid binding globulin (CBG)
Thyrotropin binding globulin (TBG)
Sex Hormone binding globulin (SHBG)
Albumin (non specific)
36
(blank) is bound to TBG (thyrotropin binding globulin) and has a half life of up to 7 days.
Thryoxine (T4)
37
In hypothyroid patients what should they take?
thyroxine (T4)
| Can take doses to compensate for missed doses
38
Is PTH protein bound?
| What is its halflife?
no
| 2-4 minutes
39
What can PTH be measured for?
It can be measured during surgery to confirm removal of a hyperfunctioning parathyroid gland adenoma.
40
Explain how hormones act
- Hormones bind to receptor
- Creates allosteric change w/in receptor
- allosteric change translates the signal into biologic acitvity
41
Where are hormone receptors, within the cell or on the cell surface?
both
42
Where are cell surface receptors found?
located on target cell membrane
43
The cell suface receptors are integral proteins that penetrate through the membrane with (blank) domains
cytoplasmic effector domains (in cell) and ligand recognition domains (on surface)
44
When a hormone bonds to recognition domain on a cell surface receptor what happens?
- >hormone binding
- >initiates an intracellular signaling cascade through 2nd messengers
- >specific biologic response
45
What are the three types of cell surface receptors?
G protein coupled transmembrane receptor
Receptor tyrosine kinase
ligand gated ion channel
46
Insulin phosphorylates SHC and IRS protein to do what?
```
effect:
cell growth
protein synthesis
glycogen synthesis
glucose transport
and stimulate P13 kinase
```
47
When insulin phosphorylates IRS protein to stimulate PI3 kinase, what happens?
Glut 4 is transported to cell surface to allow glucose to be transported into a cell and begin glucose breakdown
48
What does Insulin do to CBl and CAP?
stimulates it to translocate Glut 4 to cell surface
49
In pseudohypoparathyroidism, there is (blank) of PTH receptors to PTH from defect in the G-protein. PTH levels are elevated but patient presents with symptoms of hypoparathyroidism.
lack of response
50
How do you determine if someone has pseudohypoparathyrdoidism?
Measure cAMP in urine after admin of exogenous PTH (PTH decreases Calcium excretion)
51
What do intracellular (nuclear) receptors do>
- >mediate action of steroid hormones, vit D and thryoid homrone
- > communicate with surface recept. via 2nd messengers
- > transcription and gene expression
52
Binding a promoter area or transcription factors (HRE) of nuclear receptor by hormone (or 2nd messenger) result in (blank)
transcription and gene expression.
53
Explain how a steroid hormone works
steroid hormone enters cell, it binds to receptor and induces conformation change. Hormone receptor complex binds to DNA and starts transcription. mRNA are produced and amplify signal.
54
What kind of hormones bind to surface receptors?
peptide and amine
55
What kind of hormones bind to nuclear receptors?
steroid and thyroid
56
What is this:
Proteins synthesized through gene transcription.
Sythesized as pre-hormones and undergo post-translational processing.
peptide hormones
57
What is this:
Stored in secretory granules before release by exocytosis.
Travel free in plasma hence have short half lives (minutes).
peptide hormones
58
What is this:
Bind to surface receptor and act through 2nd messengers
Most hormones are in this class.
Examples: Insulin, Glucagon, ACTH, PTH, Glycoproteins(FSH, LH, TSH, HCG)
peptide hormones
59
What are amino acid derived hormones?
Synthesized from tyrosine
| Includes: Catecholamines and thyroid hormones.
60
What is this:
Synthesized from cholesterol in the adrenal cortex, gonads and placenta.
Lipid soluble and require binding to proteins to circulate in plasma to target organs.
Have longer half lives (hours – days).
Able to cross the cell membrane and act inside the cell.
Also includes Vitamin D.
steroid hormones
61
Where are steroid hormones synthesized?
from cholesterol in adrenal cortex, gonads and placenta
62
What are lipid soluble and require binding to proteins to circulate in plasma to target organs?
Steroid hormones
63
What have longer half lives, peptide hormones or steroid hormones?
steroid hormones
64
What are able to cross the cell membrane and act inside the cell?
steroid hormones
65
Is vit D a steroid hormone or peptide hormone?
steroid hormone
66
What are the three patterns of hormone secretion?
pulsatile
episodic
diurnal (daily)
67
What is this:
- >Hormone released in regular pulses varying in amplitude and frequency from minutes to hours.
- >several pulses= episodic variations (limits reliance on direct measurments of these hormones)
- >Continuous release can limit hormone action through desensitization.
pulsatile pattern
68
In pulsatile pattern
Several pulses results in (blank) variations in hormone level limiting reliance on the direct measurement of these hormones/
episodic
69
In pulsatile patterns,(blank) release of hormones can limit hormone action through desensitization.
continuos
70
What are some examples of pulsatile pattern?
Growth hormone (GH) and Gonadotropin releasing hormone (GnRH)
71
Explain why treatment of gonadotropin deficiency involves pulsatile admin of GnRH (gonadotropin) with a pulsing device.
cuz continuous admin would result in suppression of FSH and LH (infertility)
NOTE: remember with pulsatile flow patterns when hormone is continuously released, it will desensitize hormone action
72
Explain diurnal hormone variation
hormone secretion is determined by circadian rhythm (sleep-wake cycle) which is set by pacemaker in hypothalamus (SCN)
73
What is the pacemaker for diurnal hormone release?
hypothalamus
74
Explain how the levels rise and fall in diurnal hormone variation
Follows a 24 hour pattern,
hormones at night
peaks in waking hours
decline as day progresses
75
how will diurnal hormone release be affected?
by alterations in the sleep-wake cycle (shift work, jet lag)
76
Why do we wake up in the morning?
due to surge in hormones
77
In the dawn phenomenon (surge of hormones in the morning) what do these hormones result in?
an increase in blood glucose
78
In the dawn phenomenon, we have an increase in glucose due to a hormone surge, what happens next?
you will make a bunch of insulin
79
In diabetes,what can the dawn phenomenon manifest itself as?
elevated fasting blood glucose
80
Once hormones are released into circulation what 3 three ways can they go?
- Bind to receptor in target organ
- transform in liver
- Undergo urinary excretion
81
What are the three ways you can regulate hormone release?
hormonally
nutrient/ion regulation
neurally
82
Hormonally how can you regulate hormone release?
- tropic hormones (hormones that target other endocrine glands)
- feedback loops
83
HOw do you regulate hormone release via nutrients/ions?
glucose and calcium
84
How do you regulate hormone release neurally?
via adrenal medulla releasing epinephrine
85
What is the purpose of feedback?
Is feedback usually postive or negative?
What does feedback require?
to maintain a steady state
negative
requires a closed loop system (product, effect and sensor)
86
What is this:
| reduction of an initial stimulus by the product of stimulation
negative feedback
87
What is the most common control of hormone release and protects against excess hormone production?
negative feedback
88
What is this:
| original stimulus results in an increased stimulation for hormone release.
positive feedback
89
What is an important positive feedback mechanism for childbirth and lactation?
oxytocin
| regulated by the presence or absence of the stimulation (fetal head, sucking
90
What is an open loop?
it means there is no feedback
| therefore closed loop means there is feedback
91
An open mainly refers to control of hormone secretion by (blank)
CNS stimulation
92
An (blank) is regulated by depletion of hormone in absence of further CNS stimulation.
What is an example of this?
Open loop
| epinephrine
93
In primary hypothyroidism, there is a failure of the thryoid gland to make (blank)
thyroxine
94
During treatment of hypothyroidism we rely on the (blank) level to determine the correct replacement dose of levothyroxine.
TSH
95
In a healthy pituitary what does TSH do?
it makes T4/T3
96
What does LT4 do?
Levothyroxine (LT4) is a synthetic version of T4/T3 and inhibits TSH via negative feedback loop
97
What is this:
Important in determining physiologic and pathologic function of endocrine organs.
Techniques involve direct measure of hormone level in plasma.
hormone measurment
98
If you cant measure hormones what can you measure as a surrogate?
products of hormone action :)
99
Can you test stimulation or suppression of hormone levels?
yes
100
Explain the ACTH stimulation test
Give exogenous ACTH->> stimulate cortisol production->>measure serum cortisol
101
What is the evaluation for cushings disease (excess cortisol)?
dexamethasone suppression test
102
How does the dexamethasone suppression test work?
give exogenous steroid (to suppress cortisol production), and measure serum cortisol
(i.e inhibit pituitary gland and check cortisol levels)
103
What does radioimmunoassay do?
uses immunoenicity to determine hormone levels in a solution (serum).
104
How does radioimmunoassy (RIA) work?
>>mix known amount of radio-labeled antigen (hormone) w/ antibody (they bind)
>> add patients serum containing hormone to compete with bound, radio labeled hormone
>>precipitate
>>measure
>>calculate (scatchard plot)
105
What is ELISA?
>>mix known antigen/hormone w/ antibody
>>add patients serum containing hormone to compete with bound, radio labeled hormone
>>precipitate
>>measure color change (bound to enzyme)
106
What is the problem with ELISA?
cross-reactivity of hormones binding to same antibody can result in errors (FSH, LH, HCG, TSH)
107
What is the hook effect?
Patient with very high hormone levels w/ clinical manifestation but assay shows normal or mildly elevated hormone levels.
108
What is the hook effect caused by?
| How do you fix this?
overwhelming of the antibody by very high levels of antigen preventing detection of actual concentration.
Dilute the sample
109
How are hormone levels interpreted?
based on populations and demographics, assumes normal distribution
110
2 SDs=(blank) percent of all numbers
95%
111
How should you interpret hormone levels?
Look at age and gender
remember patterns of hormone release, illness, nutrition
look at regulatory factors
interpret with clinical context
112
What are the three main categories of endocrine disorders?
Hormone deficiency
Hormone Resistance
Hormone excess
113
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What kind of endocrine disorder is this:
Autoimmune destruction (Type 1 DM)
Deficiency of precursor (Iodine/hypothyroidism)
```
Hormone deficiency
114
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What kind of endocrine disorder is this:
Receptor mutations (Psuedohypoparathyroidism)
Functional (Type 2 DM)
```
Hormone Resistance
115
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What kind of endocrine disorder is this:
Tumors/mutations (Acromegaly)
Autoimmune activation (Grave’s disease)
```
Hormone excess
