Week 3: Endocrine Flashcards
What do the endocrine glands do?
Regulate physiologic processes
Name the endocrine glands
- pituitary gland
- adrenal gland
- thyroid gland
- parathyroid gland
- islet cells of the pancreas
What do troPic hormones do?
stimulate the release of other hormones
What do troPHic hormones do?
promote the growth, development, and maintenance of tissues and organs
In which bone is the sella turcica found?
pituitary gland sits in the sella turcica
sphenoid
What structure sits above the pituitary gland?
optic chiasm
Which nerves are found in the cavernous sinus?
III, IV, V1, V2 and VI
What visual symptoms can occur if the pituitary gland is enlarged?
visual impairment, diplopia, horner’s syndrome
When tropic hormones are released from the hypothalamus, hormones are released from which gland?
anterior pituitary
These hormones act on the target gland via hormone receptors
what are the two categories of pituitary hormones?
polypeptide and glycoprotein
Which hormones are released by the posterior pituitary gland?
Antidiuretic hormone and oxytocin
What are the polypeptide hormones?
Growth hormone, adrenocorticotropic hormone, prolactin, antidiuretic hormone, oxytocin
Which hormones are the glycoprotein hormones?
thyroid stimulating hormone, luteinizing horone, follicle stimulating hormone, human chorionic gonadotropin
Is the cortex the inner or outer layers of the adrenal gland?
outer
What hormone regulates the adrenal cortex?
ACTH
Match the cell type with its hormone:
a) DHEA
b) Cortisol
c) aldosterone
1) zona fasiculata
2) Zona reticularis
3) zona glomerulosa
a2, b1, c3
zona reticularis: DHEA(S); zona fasiculata: cortisol; zona glomerulosa: aldosterone
What produces epinephrine and norepinephrine
adrenal medulla
3 conditions that are associated with adrenal gland dysfunction
- cushing disease
- addison disease
- pheochromocytoma
cushing: increased cortisol; addisons: decreased cortisol (and aldosterone); pheochromocytoma: von hippel-lindau disease, neurofibromatosis type 1
two unique characteristics of the adrenal medulla
function and regulation
functiosn separately from the adrenal cortex; not under pituitary control
What condition is associated with an increased risk of pheochromocytoma along with hemangioblastomas of the brain and spinal cord, renal cell cancer, pancreatic tumors and genital cystadenomas?
Von Hippel Lindau Disease
What condition is associated with retinal capillary hemangiomas?
Von Hippel Lindau Disease
60% of patients with VHL show retinal capillary hemangiomas and nearly all patients with multiple retinal capillary hemangiomas have VHL
What is an ancilary test that is recommended for patients with VHL?
neuroimaging
25% of patients with retinal findings d/t VHL also have hemangiomas of the CNS
What subtype of neurofibromatosis is the most common?
NF1
But NF2 does not have a risk of pheochromocytoma like NF1
What are the clinical ocular signs of neurofibromatosis?
- cutaneous neurofibromas (benign masses of nerve tissue)
- cafe au lait macules (6 or more)
- freckling in the regions of skin folds
- bilateral (or unilateral) optic nerve gliomas
- Lisch nodules of the iris: occur in 95% of pt with NF1
Which thyroid hormone is under hypothalamic control? Which is under pituitary control?
TRH: hypothalamus; TSH: pituitary
Which type of feedback does the thyroid gland provide in order to decrease stimulatory hormone release?
negative feedback
Which hormones are low in hypothyroid and hyperthyroid?
Hypothyroid: T3, T4
Hyperthyroid: TSH
Which hormones are elevated in hypothyroid? Hyperthyroid?
Hypothyroid: TSH
Hyperthyroid: T3/ T4
Along with high T3 and T4, what are other signs of Graves Disease?
presence of a goiter, thyroid eye disease
How long does the active phase of thyroid eye disease last for nonsmokers vs smokers?
nonsmokers: 1 year; smokers 2-3 years
When can surgical correction of residual eyelid misalignment or strabismus be pursued?
after 6 months of stability (Quiescent phase)
What is the first FDA approved pharmacologic immunotherapy for adults with TED?
Teprotumumab
Since parathyroid hormone does not have a tropic hormone to trigger its release, what is the stimulates the release of parathyroid hormone?
low blood calcium levels
What are the 3 functions of parathyroid hormone?
- increase calcium resorption from the bones
- stimulate renal tubular calcium resorption by kidneys
- stimulate renal hydroxylation of vitamin D: increase blood calcium levels
Ionized calcium is involved in what three physiologic processes?
muscle contraction (including the heart); neurological transmission, blood coagulation
What maintains calcium homeostasis?
PTH, calcitonin, Vitamin D
What are the functions of activated vitamin D?
increase calcium absorption from the intestines, regulate bone turnover; provide negative feedback tot the parathyroid glands to decrease PTH production
Which cells secrete calcitonin from the thyroid gland?
parafollicular cells
What are the 3 functions of calcitonin in the bones?
slows bone turnover, maintain calcium stores, slow bone loss
What ocular condition forms from calcium salt deposits across the interpalpebral cornea?
Corneal band keratopathy
What systemic condition is associated with corneal band keratopathy?
sarcoidosis
What calcium related disorder is a cause of papilledema (especially chronic)
hypocalcemia
responsive to calcium supplementation
Does the pancreas have exocrine or endocrine functions?
both
What do beta cells of the pancreas secrete?
insulin
What do alpha cells of the pancreas secrete?
glucagon
What do delta cells of the pancreas secrete?
somatostatin
decreases smooth muscle contraction
What do gamma cells in the pancrease secrete?
pancreatic polypeptide
Which pancreatic cells secrete ghrelin, the hormone that stimulates hunger?
epsilon cells
What does the destruction of beta cells in type 1 diabetes lead to?
absolute insulin deficiency
What is the diagnostic criteria for fasting blood glucose and HbA1c?
FBG: > 126 mg/dL
HbA1c: >/=6.5%
What are the 3 mechanisms that cause damage to the retina in diabetic retinopathy?
microvascular injuries, inflammation and glutamate excitotoxicity
this damage exacerbates neuronal dysfunction, retinal hypoxia and increases VEGF
How does VEGF lead to angiogenesis?
by stimulating endothelial cell proliferation, migration and tube formation
True or False:
VEGF only released by the RPE
False
Other retinal cell types that produce and secrete VEGF are: Muller cells; astrocytes, ganglion cells and vascular endothelium
Which types of cells produce the greatest amount of VEGF under hypoxic conditions?
muller cells and astrocytes
What triggers muller cell proliferation and thus the production of VEGF?
High glucose levels
What is the pathway involved in the development in diabetic cataracts?
Sorbitol pathway
What converts glucose into sorbitol?
Aldose reductase
How does the lens swell in diabetes?
Sorbitol accumulates in the lens, increasing the osmolarity of the lens and drawing more water in
How can the swelling of the lens be reduced?
lowering glucose levels
All management for NPDR is observation, what is the follow up schedule?
- mild: 12 months
- moderate: 6 months
- Severe: 4 months
- Very severe: 2 months
All PRD management is specialty care by retina, when should patients be seen?
- early: 1 month: decide treatment vs observation
- High-risk: 24-48 hours: prompt treatment
- CSME (any stage): within 2 weeks: decide treatment vs observation
standard photo 2A is used to differentiate between which classifications of NPDR?
photo 2A is used for hemorrhages and microaneurysms
Mild, Moderate and Severe NPDR
Mild: < photo 2A
Moderate: > photo 2A in 1-3 quadrants
Severe: > photo 2A in all 4 quadrants
What is standard photo 6B used for?
Venous Beading
severe: venous beading in 2+ quadrants
What is standard photo 8A used for?
IRMA
the presence of IRMA in any quadrant is automatically severe NPDR
What is often found along with IRMA in severe NPDR
cotton wool spots
What is standard photo 10A used for?
neovascularization of the disk
neo > 10A is high risk PDR
What is the most common cause of diabetic retinopathy related vision loss?
diabetic macular edema
may be present with any level of retinopathy; can be focal or diffuse
What is the goal of panretinal photocoagulation?
lowering VEGF levels, vascular permeability, and angiogenesis
best when patient is between severe NPDR and early PDR
what is a benefit of pattern scan laser vs PRP?
shorter treatment time with reduced pain and less collateral damage
what are two laser treatments used for dme?
focal/grid laser and subthreshold diode micropulse laser photocoagulation
Which laser treatment can be combined with anti-VEGF therapy in severe DME?
subthreshold diode micropulse laser photocoagulation
When would we want to use an intravitreal steroid in DME treatment?
traimcinolone acetonide
diffuse edema throughout the macula
Which pathway is affected in horner syndrome?
oculosympathetic pathway
oculosympathetic pathway
what is the path of the first-order (central) neuron?
posterior hypothalamus
-> ciliospinal center of Budge
oculosympathetic pathway
What is the path of the second-order (preganglionic) neuron?
spinal cord -> stellate ganglion at pulmonary apex ->superior cervical ganglion (C3 to C4)
oculosympathetic pathway
What is the path of the 3rd order (postganglionic)?
superior cervical ganglion -> cavernous sinus -> superior orbital fissure
What is the relationship between axial length and the development of proliferative diabetic retinopathy?
Why is myopia believed to be protective against diabetic retinopathy?
increase axial length, decrease risk of diabetic retinopathy
Why is longer axial length associated with lower VEGF levels in the eye?
VEGF in the anterior chamber and in the vitreous cavity may be diluted due to the longer axial length leading to increased intraocular volume
Waht are 3 anatomical changes in myopia that are protective against diabetic retinopathy?
- longer axial length
- chorioretinal thinning
- altered blood flow
How is the chorioretinal thinning that happens as a result of myopia associated with lower VEGF production?
Thinning reduces metabolic demand and facilitates oxygen diffusion throught the retina via increased choroidal perfusion; this leads to decreased risk of retinal hypoxia
