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119 Cards in this Set

  • Front
  • Back
Where does the thyroid gland reside?
over the trachea, below the larynx
Describe the lobes of the thyroid gland?
two lobes of endocrine tissue
What are the major secretory cells of the thyroid gland?
-the follicular cells
Describe the structure of the follicular cells in the thyroid?
-ring of follicular cells enclose inner lumen filled with colloid
The colloid that the follicular cells surround in the thyroid serves as what?
extracellular storage site of thyroid hormones
What is the main constituent of colloid?
Thyroglobulin (TGB) with thyroid hormones incorporated into the TGB
What do the follicular cells produce?
T4 and T3
-collectively called thyroid hormone
Another name for T4
-or thyroxine
Another name for T3
What does thyroid hormone regulate?
overall basal metabolic rate
Where are C cells located?
in the interstitial space between the follicular cells
What do C cells secrete? What does this play a role in?
-plays a role in calcium metabolism
What are the basic ingredients for thyroid hormone? (not looking for T4 and T3 as an answer)
Tyrosine and Iodine
Body needs tyrosine and iodine to produce TH. How does it attain them?
1. tyrosine is produced sufficiently in the body
2. iodine must be obtained from diet
Where does TH synthesis occur? (include molecules in answer)
Occurs on thyroglobulin molecules in the colloid
Kids need TH for what?
normal development
Some general TH effects?
1. metabolic rate
2. cardiovascular (mimics sns)
3. gastrointestinal (inc. secretions)
4. neuromuscular
What system regulates the secretion of TH?
hypothalamus-pituitary-thyroid axis
What stimulates the release of TRH from the hypothalamus?
-cold in infants
What is TRH aka?
thyrotropin-releasing hormone
What stim.s the release of TSH from the anterior pituitary?
TRH from the hypothal.
What stim.s the release of TH?
The TSH secreted from the anterior pituitary
Besides stimming the release of TH what else is TSH responsible for maintaining?
the structural integrity of the thyroid gland
How does increased TH feedback?
feeds back to anterior pit. to decrease TSH secretion
-neg. feedback
What is the only KNOWN factor to increase TRH secretion from the Hypoth.?
cold in infants
Abnormal thyroid function is among one of the most common what?
endocrine disorders
Two major categories of abnormal thyroid dysfunction?
1. hypothyroidism-deficient hormone
2. hyperthyroidism-excessive hormone
Imbalances in thyroid hormone causes changes in what?
Congenital hypothyroidism produces what?
-characterized by dwarfism and mental retardation
Some causes of congenital hypothyroidism? (3)
1. no thyroid gland
2. no TSH
3. dysfunctional thyroid gl.
Why are infants screened at birth for congenital hypothyroidism?
-1 in 5 infants inflicted
-it's preventable
-if deficient you just give exogenous thyroid hormone within 6 weeks of birth
Symptoms of congenital hypothyroidism? (2)
1. generally normal at birth b/c mother's TH (is lipophilic) crosses placenta
2. if untreated produces mental and growth retardation
How do you treat congenital hypothyroidism?
replacement therapy with exogenous TH
Transient congenital hypothyroidism will do what on it's own?
go away
Transient congenital hypothyroidism is characterized by what?
-high levels of TSH
-low thyroid hormone levels
What is transient congenital hypothyroidism caused by?
Increased maternal Iodine transiently suppresses infants thyroid function
Fetal and infant thyroid's are very sensitive to what?
to excess iodine
Treatment for transient congenital hypothyroidism?
TH for 6-12 months
-the longer the delay the poorer the psychomotor and mental development
Adult hypothyroidism produces what?
myxedema, an edematous cond. causing puffy appearance esp. noticeable in face
A lack of Iodine in diet could cause what?
Primary thyroid hormone?
Causes of adult hypothyroidism?
deficiency of TRH, TSH, T4
Primary cause of adult hypothyroidism?
T4 deficit
-destruction of thyroid gland
Secondary cause of adult hypothyroidism?
TSH deficit
-impaired pituitary function
Tertiary cause of adult hypothyroidism?
TRH deficit
-hypothalamic dysfunction
Signs and Symptoms of adult hypothyroidism? (5)
1. Goiter (may be 1st sign)
2. lowered basal metabolic rate
3. dry, rough skin, brittle hair, constipation, mental dullness
4. decreased reflexes
5. Puffy face
What is assoc. with lowered basal metabolic rate?
cold intolerance, weight gain, weakness, fatigue
Why would adult hypothyroidism cause decreased reflexes?
Because TH mimics SNS function
Tx for adult hypothyroidism?
either TH or Iodine (if thats what is needed)
Most common primary hypothyroidism? Why primary?
primary because it is an autoimmune disorder that causes the destruction of the thy. gl. itself
-Hashimoto's Thyroiditis
Hashimoto's thyroiditis affects more men or women?
women > men (5:1)
Diagnosis of Hashimoto's thyroiditis? (3)
1. low T4
2. high TSH
3. antibodies
Why would there be an increase in TSH in a person with Hashimoto's thyroiditis?
because there is no neg. feedback from T4 (TH)
Treatment for Hashimoto's thyroiditis?
replacement therapy with exogenous T3 or T4
Is myxedematous coma serious?
yes, life threatening, end-stage condition
Myxedematous coma is essentially what?
very severe hypothyroidism
5 Symptoms of Myxedematous coma?
1. coma
2. hypothermia (lowered HR)
3. cardiovascular collapse
4. hypoventilation
5. hypoglycemia (decreased glucose production)
Treatment for Myxedematous coma?
supportive (Oxygen, etc) and TH
Hyperthyroidism is aka?
4 causes of thyrotoxicosis (hyperthyroidism)?
1. Grave's disease (autoimmune)
2. multinodular goiter
3. adenoma of thy. gl.
4. ingestion of excess TH
What is the most common cause of hyperthyroidism?
Grave's disease (autoimmune)
If you stopped ingesting extra TH what would happen to your hyperthyroidism?
it would go away
Symptoms and signs of hyperthyroidism?
1. elevated metabolic rate
2. Increased HR, palpitations
3. irritablity, fatigue
What are some things associated with an elevated metabolic rate? (3)
1. excess perspiration
2. poor heat tolerance
3. decreased body wt despite increased appetite and consumption
What antibody is involved in Grave's disease?
TSI is aka?
thyroid stimulating immunoglobulin
In grave's disease what does TSI stimulate?
TSH receptors
Men or women are more affected by Grave's disease?
women (5:1)
Tx of grave's disease?
remove gland
Why do you get excess of TH with grave's disease?
Because TSI is not regulated by neg. feedback so it just continously stim. secretion of TH
Symptoms of Grave's disease?
1. elevated metabolic rate
2. increased HR, palpitations
3. irritability, fatigue
What is exophthalmos?
bulging eyes seen in grave's disease but not other forms of hyperthyroidism
Are thyroid storms seen frequently?
no, because we normally diagnose and treat hyperthyroidism early
What is a thyroid storm?
an extreme form of thyrotoxosis (hyperthyroidism) that is life threatening
-very high mortality rate
Signs and symptoms of a thyroid storm? (3)
1. fever, hyperthermia
2. tachycardia (congestive heart failure, angina)
3. agitation, delirium
Tx of thyroid storm?(3)
1. cooling blankets
2. protect heart w. beta blockers such as propranolol
3. antithyroid meds
What is a Goiter?
enlarged thy. gl
When does a goiter dev.?
when thy. gl. is overstimulated by either TSI or TSH
-can be caused by either hypothyroidism or hyperthyroidism
How does hypothyroidism cause goiter?
-it leads to high levels of TSH due to decreased neg. feedback.
-TSH acts on follicular cells to increase their size and number
How does hyperthyroidism cause goiter?
-ex. grave's disease
-TSI binds with TSH receptor, causing continual stimulation
How many adrenal glands do you have?
Where are the adrenal glands located?
embedded in a capsule of fat on top of each kidney
Describe inner and outer part of adrenal gland?
1. Outer = Steroid-secreting cortex

2. Inner = Catecholamine secreting medulla
What are the catecholamines?
epinephrine and norepinephrine
How many different hormone secreting zones does the adrenal cortex have?
3 different zones
Each of the 3 different zones secretes what? (generally)
different families of hormones
Name the 3 different family of hormones secreted by the 3 different zones of the adrenal cortex?
1. Mineralocorticoids

2. Glucocorticoids

3. Sex Hormones
What do the mineralocorticoids secreted by the adrenal cortex do?
They influence mineral (electrolyte) balance
-retains Na
-increases BP
What do the glucocorticoids secreted by the adrenal cortex do?
They stimulate gluconeogenesis
-stress related
-brings glucose into blood
-increases [glucose] in blood
What do the sex hormones secreted by the adrenal cortex do?
Influence secondary sexual characterisics, female sex drive, growth spurt
-probably the least important of the 3 families of hormones released by the adrenal cortex
Give an example of a mineralocorticoid released by the adrenal cortex?
Give an example of a Glucocorticoid released by the adrenal cortex?
Give an example of a sex hormone released by the adrenal cortex?
3 mechanism action of cortisol (glucocorticoid) secretion?
1. Hypothalamus >>> CRH
2. Anterior Pit.>>> ACTH
3. Adrenal Cort.>>> Cortisol
Addison's disease is an example of what kind of insufficiency?
A primary adrenal insufficiency
-it's a particular type of adrenal dysfunction
In Addison's disease why can't you depend on the other adrenal gland?
Because it is an autoimmune disease so both would be affected
What does Addison disease do structurally speaking?
Destroys whole adrenal cortex, usually an autoimmune disease (Tb prior to 1950 in U.S., continues world)
What deficiencies are caused by Addison's disease?
Aldosterone and Cortisol are deficient (so is DHEA but doesn't really matter)
-Sooo all 3 families of hormones produced by adrenal cortex are deficient
What is increased in Addison's disease? Why does it happen and what does it cause?
-An increase in ACTH
-causes hyperpigmentation (bronze tan)
-happens because of continous stimulation of anterior pituitary
Some consequences of the mineralocorticoid deficiency caused by Addison's disease (primary adrenal insufficiency)?
Urinary Sodium >>>
Cl and H2O loss >>> hyperkalemia >>>
Dehydration >>>
Hypovolemic shock (decreased BV) >>>
Orthostatic hypotension
Consequences of the Glucocorticoid deficiency caused by Addison's disease (primary adrenal insufficiency)?
Hypoglycemia >>>
Lethargy >>>
Weakness >>>
Fatigue >>>
Anorexia >>>
Nausea >>>
Treatment for Primary adrenal insufficiency (Addison's disease)?
Replace Glucocorticoids and Mineralocorticoids, Hydrocortisone is the drug of choice
Cause of Secondary Adrenal insufficiency and Tertiary Adrenal insufficiency?
Abnormality of the pituitary (hypopituitarism) OR hypothalamus (tertiary adrenal insufficiency),
-with insufficient ACTH the result no matter which one is effected
Secondary Adrenal insufficiency causes insufficient ACTH. What does this cause? What does it not cause? Why?
Causes Cortisol deficiency
but it does not cause an Aldosterone deficiency because it is not dependent upon ACTH stimulation (only cortisol is affected by ACTH BUT cortisol is the more important one)
Rapid withdrawal of what kind of therapy is a common cause of 2ndary adrenal insufficiency? Why?
-Glucocorticoid tx
-Because if you don't ween off of tx the adrenal glands don't have time to repair
- Drugs suppress the HPA system, causing adrenal cortical atrophy and loss of cortisol
Acute adrenal crisis is what?
a deficiency
The onset of Acute adrenal crisis?
sudden or over a few days
Causes of acute adrenal crisis?
1. Addison's disease + exposure to illness or stress (or damage to adrenals)

2. Adrenal hemorrhage
What may be some causes of adrenal hemorrhage?
1. Trauma
2. Anticoagulants
3. Adrenal vein thrombosis
4. adrenal metastases
5. meningococcal septicemia
Acute adrenal crisis can cause what?
As a result of acute HTN it can cause Hypotension and Cardiovascular collapse (shock)
Tx for ACUTE adrenal crisis?
THE 5 S's
1. SALT replacement

2. SUGAR replacement

3. STEROID replacement

4. SUPPORT physiologic functioning

5. SEARCH and treat underlying cause
Give an example of Glucocorticoid excess?
Cushing's syndrome : hypercortisolism from any cause
What are some causes of Glucocorticoid excess (Cushing's syndrome)?
1. Tumor of Pituitary

2. Adrenal tumors

3. Ectopic ACTH-secreting tumors elsewhere

4. Iatrogenic : chronic steroid tx
Iatrogenic def.?
caused by physician
Ectopic def.?
abnormal area/region
What does a tumor of the pituitary gl. cause?
increased ACTH
What do adrenal tumors cause?
increased glucocorticoids
The main symptom of glucocorticoid excess (Cushing's syndrome)?
excessive gluconeogenesis, resulting from exaggerated effects of glucocorticoid
-poor wound healing
-look for [cortisol] in urine
Serum concentration in Hamburger thyrotoxicosis are in what?
excess (T4 and TSH)