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What is the most common site of ectopic thyroid tissue?

The tongue

1

What does the thyroglossal duct become?
What if it persists?

Normally thyroglossal duct --> foramen cecum

If it persists --> thyroglossal duct cyst
(midline mass that moves with swallowing)

2

What adenohypophyseal hormones share a common subunit?

These all share the same alpha subunit (beta determines spec.)

TSH
LH
FSH
hCG

3

What do the basophil cells secrete in the anterior pituitary?

B-FLAT

Basophils:
FSH
LH
ACTH
TSH

4

What endocrine cell types are found in the pancreas?

Beta - Insulin
Alpha - Glucagon
Delta - Somatostatin
PP - Pancreatic polypeptide


This is the order of abundance

5

What tissues can take up glucose regardless of insulin status?

BRICK L

Brain
RBC's
Intestine
Cornea
Kidney
Liver

6

What are the glucose transporters and their locations?

GLUT1 (insulin-independent) --> RBC's & brain

GLUT2 (bidirectional) --> Beta cells, liver, kidney, small intestine

GLUT4 (insulin-dependent) --> Adipose tissue, skeletal muscle

7

What is insulin's effect on renal tubules?

Causes sodium retention

8

What 3 things cause release of insulin?
What 3 things inhibit it?

Release:
Hyperglycemia
GH (causes insulin resistance --> increased release)
Beta2 agonists

Inhibit:
Hypoglycemia
Somatostatin
Alpha2 agonists

9

What are the steps within beta cells leading to insulin release?

Glucose enters via GLUT2
Glycolysis --> ^ATP
ATP-sensitive K+ channels close --> Depolarization
Voltage-gated Ca2+ channels open
Exocytosis of insulin granules

10

What pathways are responsible for the intracellular effects of insulin?

Phosphoinositide-3 kinase pathway --> GLUT4 inserted into membrane & synthesis of glycogen, lipids, proteins

RAS/MAP kinase pathway --> Cell growth, DNA synthesis

11

What changes occur within target tissues that cause insulin resistance?

Serine kinase phosphorylation of signaling molecules. This causes inhibition of the Phosphoinositide-3 kinase pathway so that GLUT4 cannot be inserted into the membrane.

12

What is the regulation of prolactin?

TRH --> +Prolactin
Dopamine --> -Prolactin

13

What does CRH stimulate release of?

ACTH
Melanocyte-Stimulating Hormone (MSH)
Beta-endorphin

14

What is Somatostatin's effect in the pituitary?

Decreases GH & TSH release

15

What are the effects of growth hormone?

Stimulates linear growth & muscle mass (IGF-1 mediated)
Insulin resistance

16

What can stimulate GH secretion?
Inhibit?

Stimulated by:
Pulsatile GHRH
Sleep
Exercise

Inhibited by:
Glucose
Somatostatin

17

How does 17-alpha-hydroxylase deficiency present?

Cortisol & androgens cannot be produced:
Hypertension
Males - pseudohermaphroditism (ambiguous genitalia)
Females - normal anatomy, no secondary sex characteristics

18

How does 21-alpha hydroxylase deficiency present?

Most common form of congenital adrenal hyperplasia
^Androgens, deficient cortisol & mineralocorticoids

Hypotension
Hyperkalemia
Masculinization in females --> pseudohermaphroditism

19

How does 11-beta-hydroxylase deficiency present?

^Androgens, ^mineralocorticoids, deficient cortisol

Hypertension (11-deoxycorticosterone)
Hypokalemia
Masculinization of females

20

What is seen with congenital aromatase deficiency?

Increased Testosterone and decreased Estrogen levels
Maternal hirsutism while pregnant w/ affected fetus
Female pseudohermaphroditism

21

What are the actions of cortisol?

BBIIG:
Bones/BP
Immunosuppression/Insulin resistance
Glucose production

Decreases bone formation
Upregulates alpha1 receptors on arterioles (sensitizes)
Anti-inflammatory
Diabetogenic
Gluconeogenesis, lipolysis, proteolysis, inhibits fibroblasts

22

How can one differentiate primary adrenal insufficiency vs HPA axis dysregulation?

Metyrapone test

Metyapone inhibits 11-beta-hydroxylase --> should see compensatory rise in ACTH --> Increased cortisol precursors (urinary 17-hydroxy-corticosteroids or 11-deoxycortisol)

If ACTH^ but not the precursors --> adrenal problem
If no ACTH^ --> HP axis problem

23

How does cortisol affect blood pressure?

1) It upregulates Alpha1 adrenergic receptors on arterioles --> sensitizes them to catecholamines

2) It increases transcription of phenylethanolamine-N-Methyltransferase (NE-->EPI)

24

How does PTH stimulate osteoclastic activity?

Increases production of M-CSF & RANK-L in osteoBLASTS

25

How is PTH secretion regulated?

Decreased serum Ca2+ --> ^PTH
Decreased serum Mg2+ --> PTH
Very low serum Mg2+ --> Decreased PTH

Thus, if magnesium levels are very low, a patient may not respond well to Calcium supplementation (need Mg2+ as well).

26

What can cause hypomagnesemia?

Diarrhea
Aminoglycosides
Diuretics
Alcohol abuse

27

What form of Vit. D is active?
What forms are inactive?

Active = 1,25-Cholecalciferol = Calcitriol
Inactive = 25-OH-D3 & 24,25-OH-D3

28

How is Vit. D acquired?
Where is Vit. D activated?

D2 is dietary, D3 is synthesized in skin

Converted to 25-OH-D3 in liver
Converted to 1,25-OH-D3 in kidney PCT

29

What are the effects of Calcitriol?

^Bone resorption of calcium & phosphate
^GI absorption of calcium & phosphate