Unit 10 - Endocrine Flashcards
1
Q
negative feedback loop
A
The response is negative (opposite) the initiating stimulus, which returns the parameter to a set point to maintain stability (homeostasis).
2
Q
positive feedback loop
A
Provides an unstable cycle in which the system responds in a way that increases the magnitude of the response.
This results in the amplification of the original signal instead of stabilization
3
Q
what 2 major systems maintain homeostasis in the body
A
nervous system
endocrine system
4
Q
hormones released by the posterior pituitary
A
ADH
oxytocin
5
Q
hormones released by the anterior pituitary
A
Follicle-stimulating hormone
Luteinizing hormone
Adrenocorticotropic hormone
Thyroid-stimulating hormone
Prolactin
Growth hormone
“FLAT PiG”
i = ignore
6
Q
function of hypothalamus in the endocrine system
A
- monitors hormone concentrations in the systemic circulation
- instructs the pituitary to increase or decrease hormone release (usually through negative feedback)
7
Q
function of FSH
A
germ cell maturation
ovarian follicle growth (females)
8
Q
function of Luteinizing hormone
A
testosterone (males)
ovulation (females)
9
Q
function of ACTH
A
adrenal hormone release
10
Q
function of prolactin
A
lactation
11
Q
where are inhibiting and releasing hormones released from
A
hypothalamus into hypophysial portal vessels
12
Q
where is ADH primarily formed
A
in supraoptic nuclei of hypothalamus
13
Q
where is oxytocin primarily formed
A
paraventricular nuclei
14
Q
where does pituitary gland reside
A
sella turcica
15
Q
how is the pituitary connected to the hypothalamus
A
via pituitary stalk
16
Q
another name for anterior pituitary
A
adenohypophysis
17
Q
another name for posterior pituitary gland
A
neurohypophysis
18
Q
what results from FSH hyper hypo-secretion
A
hyper = early puberty
hypo = infertility
19
Q
what results from LH hyper and hypo-secretion
A
hypo = early puberty
hyper = infertility
20
Q
result of ACTH hyper and hypo-secretion
A
hyper = Cushing’s
hypo = Addison’s disease
21
Q
result of TSH hyper and hypo-secretion
A
hyper = hyperthyroidism
hypo = hypothyroidism, Cretinism
22
Q
result of prolactin hyper and hypo-secretion
A
hyper = infertility
hypo = menstrual dysfunctoin
23
Q
result of growth hormone hyper and hypo-secretion
A
hyper = acromegaly, gigantism
hypo = dwarfism
24
Q
result of ADH hyper and hypo-secretion
A
hyper = SIADH
hypo = diabetes insipidus
25
result of oxytocin hyposecretion
hypo = uterine atony
26
regulates TRH release
Triiodothyronine (T3)
27
regulates CRH release
cortisol
28
regulate LHRH release
testosterone
estrogen
progesterone
29
regulate GHRH and GHIG release
growth hormone
insulin growth factor-1
30
5 systemic hormones affected by negative feedback
1. TRH
2. CRH
3. LHRH
4. GHRH
5. GHIH
31
2 hormones not affected by negative feedback
oxytoxin
prolactin
32
hormone that is part of a positive feedback loop
oxytocin
33
how is oxytocin release stimulated
uterine contraction
34
how is prolactin release controlled
under neural control, where increased dopamine decreases prolactin release
35
why can metoclopramide caue hyperprolactinemia
increased dopamine decreases prolactin release
metoclopramide is a dopamine antagonist
36
conditions assoc. with SIADH
* TBI (most common)
* cancer (small-cell lung carcinoma)
* noncancerous lung disease
* carbamazepine
37
most common cause of SIADH
TBI
38
electrolyte abnormality with SIADH
hyponatremia
39
plasma volume, osmolarity, and sodium in SIADH
* Volume = euvolemic or hypervolemic
* Osmolarity = hypotonic (< 275 mOsm/L)
* Sodium = low (< 135 mEq/L)
40
urine volume, osmolarity, and sodium in SIADH
* Volume = low
* Osmolarity = higher than plasma
* Sodium = high
41
treatment of SIADH
* fluid restriction
* demeclocycline
* +/- treat hyponatremia
42
use of demeclocycline in SAIDH
decreases responsiveness to ADH
43
when should sodium be corrected in pt with SIADH
if pt is symptomatic or Na+ < 120 mEq/L, give hypertonic NS
## Footnote
Don’t correct hyponatremia > 1 mEq/L/hr
44
when should sodium be corrected in pt with SIADH
if pt is symptomatic or Na+ < 120 mEq/L, give hypertonic NS
## Footnote
Don’t correct hyponatremia > 1 mEq/L/hr
45
conditions assoc with DI
* pituitary surgery (most common)
* TBI
* subarachnoid hemorrhage
46
most common cause of DI
pituitary surgery
47
presentation of DI
polyuria
48
plasma volume, osmolariy, and sodium in DI
* Volume = euvolemic or hypovolemic
* Osmolarity = hypertonic (> 290 mOsm/L)
* Sodium = high (> 145 mEq/L)
49
urine volume, osmolarity, and sodium in DI
* Volume = high
* Osmolarity = lower than plasma
* Sodium = normal
50
DI treatment
supportive, DDAVP or vasopressin
51
what is acromegaly
Results from oversecretion of GH after adolescence
52
cause of nearly all cases of acromegaly
pituitary adenoma
53
what causes gigantism
increased GH output before puberty
54
why are pts with acromegaly at risk for difficult mask ventilation and DL
mask: distorted facial features, poor seal
DL: large tongue, teeth, and epiglottis
55
why should you use a smaller ETT in a pt with acromegaly
subglottic narrowing & vocal cord enlargement
56
why should nasal intubation be avoided in pts with acromegaly
risk epistaxis d/t turbinate enlargement
57
common comorbidities with acromegaly
* OSA
* HTN
* CAD
* rhythm disturbances
* glucose intolerance
* skeletal muscle weakness
* entrapment neuropathies
58
source of T4
Directly released from thyroid
59
source of T3
Mostly extrathyroid conversion of T4 to T3
Small amount released from thyroid
60
where is concentration of T4 the highest
In the blood
61
where is the concentrtion of T3 the highest
In the target cell
| T4 converted to T3
62
where is the concentrtion of T3 the highest
In the target cell
| T4 converted to T3
63
which is more protein bound - T4 or T3
T4
64
which is more potent - T4 or T3
T4
65
half-life of T3
1 day
66
half life of T4
7 days
67
TSH release from anterior pituitary affects the thyroid gland in 2 key ways:
**1)** Tells the thyroid gland to produce T3 & T4 (requires iodine)
**2)** Tells follicular tissue to produce thyroglobulin colloid (does not require iodine)
68
TSH release from anterior pituitary affects the thyroid gland in 2 key ways:
**1)** Tells the thyroid gland to produce T3 & T4 (requires iodine)
**2)** Tells follicular tissue to produce thyroglobulin colloid (does not require iodine)
69
substrate thyroid requires to synthesize T3 & T4
iodine
70
TSH in pt with hypoactive thyroid
chronically elevated
| there isn’t enough thyroid hormone to suppress TSH
71
TSH in pt with hypoactive thyroid
chronically elevated
| there isn’t enough thyroid hormone to suppress TSH
72
stimulates follicles to make thyroglobulin colloid
TSH
73
required for follicles to make thyroglobulin colloid
iodine
74
what causes goiter in hypoactive thyroid
Since TSH is chronically elevated, follicles continue to produce thyroglobulin colloid - causes thyroid gland to increase in size
75
3 hormones stored and released by the thyroid gland
1. **T4** = thyroxine
2. **T3** = Triiodothyronine
3. **calcitonin**
76
nerve at risk for injury in thyroid or parathyroid surgery
RLN
77
how does thyroid hormone affect VO2 & CO2 consumption
both increased
78
effects of increased thyroid hormone on ANS
* ↑ number & sensitivity of # receptors
* ↓ number of cardiac muscarinic receptors
79
CV effects of increased thyroid hormone
* Increased myocardial performance independent of the ANS
* ↑ chronotropy, contractility, lusitropy
* ↓ SVR
80
respiratory effects of increased thyroid hornone
↑ BMR = ↑ CO2 production = ↑ Vm (↑ Vt & RR)
81
increased thyroid hormone = increased O2 consumption in all tissues except:
CNS
82
how does thyroid hormone affect MAC
hyper- and hypothyroidism do NOT affect MAC
## Footnote
O2 consumption increased in all tissues except CNS
83
how does thyroid hormone affect MAC
hyper- and hypothyroidism do NOT affect MAC
## Footnote
O2 consumption increased in all tissues except CNS
84
GI effects of increased thyroid hormone
intestineal hypermotility, diarrhea
85
how does increased thyroid hormone affect fat
↑ utilization of fat stores = weight loss
86
how does increased thyroid hormone affect protein
↑ catabolism = skeletal muscle weakness
87
effect of thyroid hormone on carbohydrates
↑ gluconeogenesis, ↑ insulin release, ↑ glucose uptake
88
what causes tremors with increased thyroid hormone
↑ sensitivity of neuronal synapses in the spinal cord
89
etiologies of hyperthyroidism
* Grave's (autoimmune - most common)
* myasthenia gravis
* multimodal goiter
* carcinoma
* pregnancy
* pituitary adenoma
* amiodarone (less common)
90
TSH, T3, & T4 in hyperthyroidism
low TSH + high T3 & T4
91
CV s/s of hyperthyroidism
HTN
Tachyarrhythmias
Atrial fibrillation
92
pulmonary s/s hyperthyroidism
Increased minute ventilation
93
electrolyte imbalance associated with hyperthyroidism
hypercalcemia
94
medical management of hyperthyroidism
Thionamides
Beta blockers
potassium iodide
radioactive iodine
95
mechanism of thionamides
Inhibits thyroid synthesis by blocking iodine addition to tyrosine residues on thyroglobulin
96
meds that inhibit peripheral conversion of T4 to T3
PTU
Propranolol
glucocorticoids
thiopental
97
how long does it take to achieve a euthyroid state with thionamides
6-7 weeks
98
available routes of thionamides
Only available PO
99
serious side effects of thionamides
hepatitis
agranulocytosis
100
mechanism of potassium iodide in management of hyperthyroidism
Reduces thyroid hormone synthesis and release
101
when should potassium iodide be given in relation to surgery time
Administer 10 days before surgery
102
mechanism of radioactive iodine in hyperthyroidism
destroys thyroid tissue
103
surgical management of hyperthyroidism
subtotal or total thyroidectomy
104
complications of thyroidectomy
* hypothyroidism
* hemorrhage (tracheal compression)
* RLN injury
* hypocalcemia
105
etiologies of hypothyroidism
* Hashimoto’s thyroiditis (autoimmune – most common)
* iodine deficiency
* hypothalamic-pituitary dysfunction
* neck radiation
* thyroidectomy
* amiodarone (more common)
106
TSH, T3, & T4 in hypothyroidism
high TSH + low T3 & T4
107
CV s/s of hypothyroidism
Peripheral vasoconstriction
Decreased HR & contractility
Decreased CO
Heart failure
Pericardial effusion
108
pulmonary s/s hypothyroidism
Decreased minute ventilation
Reduced response to hypoxia
Reduced response to hypercarbia
Pleural effusion
109
GI effects of hypothyroidism
delayed gastric emptying, constipation
110
medical management of hypothyroidism
synthetic T4 (levothyroxine)
111
initial response to levothyroxine therapy
natriuresis & decreased TSH
112
complication of neonatal hypothyroidism that leads to limited physical and mental development
Cretinism
113
airway complications of hypothyroidism
Airway obstruction due to large tongue, swollen vocal cords, and/or goiter
| Goiter = awake intubation
114
how does hypothyroidism affect circulation
Hypodynamic circulation: ↓ HR, SV, contractility, CO, and baroreceptor responsiveness
115
best way to support hemodynamics in hypothyroidism
sympathomimetics that improve myocardial performance (not neo)
116
management of hypotension unresponsive to catecholamines in pts with hypothyroidism
corticosteroids
| Decreased adrenal function is common
117
management of hypotension unresponsive to catecholamines in pts with hypothyroidism
corticosteroids
| Decreased adrenal function is common
118
when is thyroid storm most likely to happen
6-18 hours after surgery
| Can occur in hyper- and euthyroid patients
119
when is thyroid storm most likely to happen
6-18 hours after surgery
| Can occur in hyper- and euthyroid patients
120
s/s thyroid storm
* fever
* tachycardia/tachyarrhythmias
* HTN
* CHF
* shock
* confusion & agitation
* N/V
121
4 B's of thyroid storm management
* Block synthesis
* Block release
* Block T4 to T3 conversion
* Block beta receptors
122
meds that block synthesis of thyroid hormone
* methimazole
* carbimazole
* PTU
* potassium iodide
123
meds that block release of thyroid hormone
* radioactive iodine
* potassium iodide
124
beta blockers used in treatment of thyroid storm
esmolol
propranolol
125
use of glucocorticoids in thyroid storm treatment
blocks conversion of T4 to T3 and supports stress response
hypermetabolism consumes endogenous steroids
126
why should aspirin be avoided in thyroid storm
can dislodge T4 from plasma proteins and ↑ free fraction of T4
127
preparing for a hyperthyroid patient needing emergency surgery
* administration of a beta-blocker, potassium iodide, and glucocorticoids
* PTU should be started
128
how long may medical management of hyperthyroidism take to be euthyroid
6-8 weeks
129
airway management in a patient with goiter
#1 - awake intubation
Next bet - technique that maintains spontaneous ventilation
130
meds to avoid in hyperthyroidism
* sympathomimetics
* anticholinergics
* ketamine
* pancuronium
131
why might pts with hyperthyroid be at higher risk for corneal abrasion
exopthalmos
132
why is positioning important with hyperthyroid pts
increased bone turnover increases risk of osteoporosis
133
s/s unilateral RLN injury
hoarseness
## Footnote
ipsilateral vocal cord is positioned midline on inspiration
134
s/s unilateral RLN injury
hoarseness
## Footnote
ipsilateral vocal cord is positioned midline on inspiration
135
s/s bilateral RLN injury
airway obstruction
## Footnote
both cords are positioned midline on inspiration
136
s/s bilateral RLN injury
airway obstruction
## Footnote
both cords are positioned midline on inspiration
137
cause of hypocalcemia after thyroid surgery
resection of parathyroid glands
138
how is thyroxine synthesized
from tyrosine
139
why should NMBs be used carefully in hyperthyroid pts
increased incidence of myasthenia gravis and myopathy
140
things thyroid storm can mimic under GA
1. MH
2. pheochromocytoma
3. neuroleptic malignant syndrome
4. light anesthesia
141
Chvostek’s sign
tapping on anlge of jaw (facial n./masseter muscle) = ipsilateral facial contraction
142
Trousseau’s sign
upper extremity BP cuff inflated above SBP for 3 min = dec blood flow accentuates neuromuscular irritability = **muscle spasm** of hand and forearm
143
2 CV side effects of hypocalcemia
hypotension
prolonged QT
144
when does hypocalcemia most commonly occur after thyroid surgery
24-48 hrs postop
## Footnote
If it happens to occur sooner, it's typically **no earlier** than 6- 12 hours after surgery
145
common electrolyte abnormality in a pt with myxedema
dilutional hyponatremia
146
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