120. Adrenal Glands Flashcards
When is adrenalectomy indicated?
Functional tumors and characteristics of malignacy
Descibe the anatomy of the left adrenal gland in relation to the abdomen.
- Located in the retroperitoneal space
- Medial to the cranial pole of the left kidney and is loosely adhered to fa**scia of the psoas minor muscle **and transverse process of the second lumbar vertebra.
- Adjacent to the left side of the abdominal aorta medially
- Caudal aspect borders the left renal artery.
Descibe the anatomy of the right adrenal gland in relation to the abdomen.
- Located in the retroperitoneal space
- Further cranial than the left
- Ventral to the thirteenth thoracic vertebra
- Adhered to the right side of the vena cava
- Capsule is actually continuous with vascular adventitia
- Covered by the caudate process of the caudate liver lobe
Access can be complicated by hepatomegaly that accompanies hyperadrenocorticism.
The adrenal cortex is derived from a mass of which cells?
A. Endoderm
B. Ectoderm
C. Mesoderm
C. Mesodermal cells
cells arise near the genital ridges during embryonic development
Mesodermal cells differniate into which shapes?
Polygonal to columnar shapes with varying lipid content.
The cortex takes on a laminar architecture adapted to serve specific endocrine functions. Name two of these endocrine functions.
- Regulation of renal fluid and electrolyte balance (aldosterone synthesis)
- Chronic stress adaptation and carbohydrate metabolism (steroid hormone synthesis)
Embriologically, what forms the adrenal medulla?
Mesodermal mass is later invaded by neural crest ectoderm, which migrates to the center of the gland and forms the adrenal medulla.
The adrenal medulla is essentially a sympathetic ganglion, consisting of postsynaptic neurons that are modified to release their neurotransmitters (epinephrine and norepinephrine) into the systemic circulation through the adrenal gland’s rich vasculature
Name 2 neurotransmitters released from the adrenal medulla
- Epiniephrine
- Norepinephrine
Describe the aterial supply to the adrenal glands, include 2 vessels
- 20 to 30 small branches arising
1. Phrenicoabdominal
2. Renal
3. Cranial abdominal arteries
4. Adjacent aorta
These arteries form a plexus - sends penetrating branches into the cortex and medulla.
The plexus is visible through the thick adrenal capsule
Describe the venous drainage from an adrenal gland. Name the vein.
Collected in sinusoids and drains into a single adrenal vein.
Where does the right adrenal vein empty?
Directly into the** vena cava**
Where does the left adrenal vein empty?
Left renal vein
Name the 3 zones of the cortex
- Outer: Zona glomerulosa
- Central: Zona fasciculata
- Inner: Zona reticularis
GFR
What does the zona glomerulosa secrete?
Mineralocorticoids
What does the zona fasciculata secrete?
Glucocorticoids
What does the reticularis secrete?
Sex steroids
What are adrenal corticoids synthesised from?
Cholesterol
Enzymatic cleavage of a carbon side chain within mitochondria produces the C-21 steroid pregnenolone. Within cells of the zona fasciculata and zona reticularis, pregnenolone is hydroxylated at C-17 to form the glucocorticoid molecule.
What is the major difference between aldosterone and cortisol?
Absence of a hydroxyl group on C-17
Zona glomerulosa cells lack 17α-hydroxylase
Steroid hormones are lipids, transport through blood relies on what?
Binding to plasma proteins
Name two proteins with high affinity to cortisol?
- Corticosteroid binding globulin
- Transcortin