Endocrine - Embryology and Anatomy

Question 1

Describe thyroid development

Answer 1

Thyroid diverticulum arises from floor of primitive pharynx, descends into the neck.

Question 2

How is thyroid diverticulum connected to the tongue?

Answer 2

Thyroglossal duct

Question 3

What is the pyramidal lobe of thyroid?

Answer 3

Persistent thyroglossal duct

Question 4

What is the foramen cecum of thyroid?

Answer 4

Normal remnant of thyroglossal duct

Question 5

Most common ectopic thyroid tissue site

Answer 5

Tongue

Question 6

Describe thyroglossal duct cyst

Answer 6

Anterior midline neck mass that moves with swallowing or pertrusion of the tongue

Question 7

How is thyroglossal duct cyst different from a brachial cleft cyst?

Answer 7

Brachial cleft cyst - persistent cervical sinus
Lateral neck (vs midline for thyroglossal duct cyst)

Question 8

Describe fetal adrenal gland

Answer 8

Consists of an outer adult zone and inner active fetal zone.

Adult zone is dormant during early fetal life but begins to secrete cortisol late in gestation.

Question 9

What controls cortisol secretion in the fetus?

Answer 9

ACTH and CRH from fetal pituitary and placenta

Question 10

Role of cortisol in the fetus

Answer 10

Fetal lung maturation and surfactant production

Question 11

What are the embryologic derivatives of the adrenal cortex and medulla?

Answer 11

Cortex - mesoderm

Medulla - neural crest

Question 12

What are the layers of adrenal gland?

Answer 12

Capsule
Zona glomerulosa
Zona fasciculata
Zona reticularis
Medulla (Chromaffin cells)

Question 13

Primary regulatory control and secretory products of: Zona glomerulosa

Answer 13

Regulation: Renin-Angiotensin-Aldosterone System

Secretion: Aldosterone

Question 14

Primary regulatory control and secretory products of: Zona fasciculata

Answer 14

Regulation: ACTH and CRH

Secretion: glucocorticoids (cortisol)

Question 15

Primary regulatory control and secretory products of: Zona reticularis

Answer 15

Regulation: ACTH and CRH

Secretion: sex steroids (androgens)

Question 16

Primary regulatory control and secretory products of: Adrenal medulla (Chromaffin cells)

Answer 16

Regulation: Pre-ganglionic sympathetic fibers (acetylcholine)

Secretion: Catecholamines (Epi, NE)

Question 17

What is the most common tumor of adrenal medulla in adults? And in children?

How are they different?

Answer 17

Adult: pheochromocytoma
Children: neuroblastoma

Pheochromocytoma causes episodic hypertension; Neuroblastoma does not

Question 18

Describe adrenal gland drainage

Answer 18

Left adrenal -> Left adrenal vein -> Left renal -> IVC

Right adrenal -> Right adrenal vein -> IVC

Same as left and right gonadal veins

Question 19

What are the embryologic derivatives of anterior and posterior pituitary?

Answer 19

Anterior pituitary (Adenohypophysis): oral ectoderm (Rathke’s pouch)

Posterior pituitary (neurohypophysis): neuroectoderm

Question 20

Function of posterior pituitary gland

Answer 20

Secretes vasopressin and oxytocin made in hypothalamus and shipped to posterior pituitary through neurophysins (carrier proteins)

Question 21

Function of anterior pituitary gland

Answer 21

Secretes FSH, LH, ACTH TSH, prolactin, GH, melanotropin (MSH)

Question 22

Describe structure of TSH, LH, FSH, hCG

Answer 22

Alpha and Beta subunit
Alpha: common to all
Beta: determines hormone specificity

Question 23

How do pituitary acidophils appear on histology and what do they make?

Answer 23

Pink

Prolactin, GH

Question 24

How do pituitary basophils appear on histology and what do they make?

Answer 24

Blue

FSH, LH, ACTH, TSH

Question 25

Describe organization of islets of langerhans

Answer 25

Alpha cells in periphery Beta cells central Delta cells interspersed

Question 26

What are the different cell types of islets of langerhans and what do they secrete?

Answer 26

Alpha: glucagon Beta: insulin Delta: somatostatin

Question 27

What does the islets of langerhans arise from?

Answer 27

Pancreatic buds

Question 28

Structure of insulin

Answer 28

Alpha and Beta chains connected by sulfur bonds

Question 29

Describe insulin secretion in the pancreatic beta-cell

Answer 29

1. Glucose enter cell 2. Glycolysis increases ATP/ADP ratio 3. ATP closes ATP-sensitive K+ channels 4. Depolarization of cell 5. Influx of Ca2+ through voltage-gated Ca2+ channels 6. Exocytosis of insulin granules into blood vessel

Question 30

Does insulin cross the placenta?

Answer 30

No

Question 31

What organs have insulin-independent glucose uptake? (6)

Answer 31

``` Brain RBC Intestine Cornea Kidney Liver ```

Question 32

What organs use: GLUT-1

Answer 32

RBCs, Brain | Insulin independent

Question 33

What organs use: GLUT-2

Answer 33

Beta islet cells, liver, kidney, intestines

Question 34

What organs use: GLUT-4

Answer 34

Adipose tissue, skeletal muscle | Insulin dependent

Question 35

Major functions of insulin (7)

Answer 35

1. Increase glucose transport into skeletal muscle/adipose 2. increase glycogen synthesis/storage 3. increase TG synthesis/storage 4. increase Na+ retention in kidneys 5. increase protein synthesis (muscles) 6. increase cellular uptake of K+ and AA 7. decrease glucagon release

Question 36

What upregulates insulin secretion? (3)

Answer 36

hyperglycemia GH Beta-2 antagonists

Question 37

What inhibits insulin secretion? (3)

Answer 37

hypoglycemia somatostatin alpha-2 agonists

Question 38

What pathway does insulin acts in cells?

Answer 38

RAS/MAP kinase -> cell growth/DNA synthesis | Phosphoinositide-3 kinase -> glycogen, lipid, protein synthesis; GLUT4 vesicles

Question 39

What does brain use in starvation?

Answer 39

Ketone bodies

Question 40

What does RBC use in starvation?

Answer 40

Always depend on glucose - no mitochondria for aerobic metabolism

Question 41

Major functions of glucagon

Answer 41

Catabolic effects Glycogenolysis, gluconeogenesis Lipolysis, ketone production

Question 42

What promotes (1) or inhibits (3) glucagon production?

Answer 42

Promoted by hypoglycemia Inhibited by insulin, hyperglycemia, somatostatin

Question 43

What is a lingual thyroid?

Answer 43

Persistence of thyroid tissue at base of tongue | Base of tongue mass