Adrenal Glands Anatomy

Question 1

Adrenal glands aka

Answer 1

Suprarenal glands

Question 2

Where do the adrenal glands lie?

Answer 2

Lies superior medial aspect of the upper pole of each kidney

Question 3

Are the adrenal glands in the intraperitoneal or retroperitoneal space?

Answer 3

Retroperitoneal space

Question 4

Adrenal glands have what shape?

Answer 4

A flattened pyramidal shape

Question 5

In an adult, each adrenal gland is __-___cm in height, __-__cm in width, & a little less than ___cm thick. Also has a mass of __-__g, only half its size at birth.

Answer 5

3-5cm (height)
2-3cm (width)
1cm (thickness)
4-6g (mass)

Question 6

How are the adrenal glands similar to the pituitary?

Answer 6

They are derived from both neuronal tissue & epithelial (or epithelial-like) tissue.

Question 7

Adrenal glands consist of 2 parts:

Answer 7

1. Adrenal cortex
2. Adrenal medulla

Question 8

The cells of the cortex develop into what cells?

Answer 8

Steroidogenic cells

Question 9

Steroidogenic cells produce?
(3)

Answer 9

1. Mineralocorticoids
2. Glucocorticoids
3. Adrenal androgens

Question 10

Compare the left adrenal gland to the right one

Answer 10

The left adrenal is larger & flatter than the right adrenal gland.

Question 11

What separates the adrenals from other structures of the body?
- other structures = ribs, pleural reflection, subcostal, sacrospinalis, & latissimus dorsi muscles.

Answer 11

Gerota’s fascia & Pararenal fat

Question 12

Adrenal glands, like the thyroid gland, are…

Answer 12

highly vascularized.

Question 13

Adrenal Cortex - appearance & consistency

Answer 13

• Normal adrenal cortex is dark yellow
• Firm consistency & finely granular surface

Question 14

The Adrenal Cortex composes how much % of the volume of a normal adrenal gland?

Answer 14

80 - 90%

Question 15

Adrenal Cortex - develops from? forms?

Answer 15

• develops from mesodermal cells in the vicinity of the superior pole of the developing kidney.

Question 16

Adrenal Cortex is divided into 3 zones. Name the zones from outer to inner with the hormone that they secrete.

Answer 16

1. Zona glomerulosa (outer) = mineralocorticoids, mainly aldosterone.
2. Zona fasciculate (middle) = mainly glucocorticoids - primarily cortisol.
3. Zona reticularis (inner) = synthesizes small amounts of weak androgens.

Question 17

Zona glomerulosa

Answer 17

• outer zone
• just deep into the connective tissue capsule
• its cells are closely packed & arranged in spherical clusters & arched columns.
• secretes mineralocorticoids, mainly alosterone = affect mineral homeostasis.

Question 18

Zona Fasciculata

Answer 18

• middle zone
• widest of the 3 zones
• its cells are arranged in long, straight columns.
• secretes mainly glucocorticoids (primarily cortisol) = affects glucose homeostasis.

Question 19

Zona Reticularis

Answer 19

• inner zone
• arranged in branching cord
• synthesizes small amounts of weak androgens (steroid hormones that have a masculinizing effect).

Question 20

Adrenal Medulla - location & appearance

Answer 20

• small, centrally located that is enclosed completely by the adrenal cortex, except at the hilum.
• red-brown

Question 21

The Adrenal Medulla constitutes how much volume of a normal adrenal gland?

Answer 21

10 - 20%

Question 22

Adrenal Medulla - produces 3 catecholamine hormones:

Answer 22

1. Norepinephrine
2. Epinephrine
3. Small amount of Dopamine

Question 23

How are the chromaffin cells established in the adrenal medulla?

Answer 23

• Soon after the cortex forms, chromaffin cells (neural crest-derived cells associated with the sympathetic ganglia) migrate into the cortical cells & become encapsulated by them.
• Thus the chromaffin cells establish the inner portion of the adrenal gland = adrenal medulla.

Question 24

Chromaffin cells

Answer 24

• neural crest-derived cells associated with the sympathetic ganglia.
• stain with chromium stains.
• have the potential of developing into postganglionic sympathetic neurons.
• innervated by cholinergic preganglionic sympathetic neurons.
• can synthesize norepinephrine (catecholamine neurotransmitter) from tyrosine.

Question 25

Explain the potential of chromaffin cells developing into postganglionic sympathetic neurons.

Answer 25

Chromaffin cells of the adrenal medulla have the potential of developing into postganglionic sympathetic neurons, however, the cells are exposed to high local concentrations of cortisol from the cortex. Cortisol: - inhibits neuronal differentiation of the medullary cells so that they fail to form dendrites & axons. - induces the expression of an additional enzyme = phenylethanolamine-N-methyl transferase (PNMT), in the catecholamine biosynthetic pathway. - PNMT adds a methyl group to norepinephrine, producing epinephrine - primary hormonal product of the adrenal medulla.

Question 26

Adrenal gland - blood supply

Answer 26

- blood flow to the normal adrenal gland is approx. 10 mL/min. - blood supply to both the cortex & medulla increases during periods of stress. - Adrenocorticotropic hormone (ACTH) produces an immediate increase in blood flow to the adrenals.

Question 27

Adrenal gland - arterial supply from 3 main groups of inflow vessels:

Answer 27

1. Superior suprarenal arteries 2. Middle suprarenal artery 3. Inferior suprarenal arteries

Question 28

Superior suprarenal arteries

Answer 28

- derived from the inferior phrenic arteries - Inferior phrenic arteries: = pass just superior & medial to the adrenal glands = gives off a series of branches to the ipsilateral adrenal gland before it supplies the diaphragm.

Question 29

Middle suprarenal artery

Answer 29

derived from the aorta

Question 30

Inferior suprarenal arteries

Answer 30

derived from the adjacent renal artery

Question 31

Other adjacent vessels also may supply branches to the adrenal gland, these are:

Answer 31

Intercostal arteries, left ovarian artery, left internal spermatic arteries.

Question 32

Adrenal gland - venous drainage

Answer 32

- each adrenal gland has a single draining vein - left adrenal gland = left adrenal vein - right adrenal gland = right adrenal vein

Question 33

Vascular control of the left adrenal vein

Answer 33

Vascular control of the adrenal vein by the surgeon is easier on the left because the left adrenal vein is much longer than the right.

Question 34

Right adrenal vein

Answer 34

- emerges from the hilum - Is <1cm in length & empties directly into the posterior IVC, creating a risk for injury & hemorrhage during surgery. - often cant be exposed until the gland is circumferentially mobilized.