Anatomy of Adrenal Glands

Question 1

Describe the adrenal gland?

Answer 1

paired organs on the superior borders of kidneys embedded in fat against back muscles - pyramidal/triangular in shape and each consists of a cortex and medulla which function as separate glands

Question 2

What covers the adrenal gland?

Answer 2

connective tissue capsule which sends trabeculae into the parenchyma of the gland

Question 3

The adrenal gland is composed of which parts?

Answer 3

cortex + medulla

Question 4

Describe the adrenal cortex?

Answer 4

1. outer main part - 90% of gland 2. produces steroid hormones

Question 5

Describe the adrenal medulla?

Answer 5

1. inner 10% of adrenal gland 2. produces epinephrine + norepinephrine

Question 6

When do the adrenal glands begin to develop as well as end?

Answer 6

begins to develop in week 5 from 2 different origins & finishes at the end of 3rd year

Question 7

Cortical cells develop from?

Answer 7

originate from intermediate mesoderm - same region from where gonads develop

Question 8

Medulla (chromaffin) cells develop from?

Answer 8

originate from neural crest cells (neuroectoderm)

Question 9

Describe fetal adrenal glands?

Answer 9

1. larger than kidneys 2. larger than adult ones relative to body weight

Question 10

Describe the development of the adrenal gland?

Answer 10

there is migration of neural crest derivatives from nearby developing sympathetic ganglia into embryonic adrenal cortex

Question 11

Histologically the cortex is divided in which 3 zones?

Answer 11

1. zona glomerulosa (little ball) - outer zone about 15% of cortical thickness 2. zona fasciculata (band) - thick middle zone - about 75% 3. zona reticularis (network) - inner zone - 10%

Question 12

Describe the layers of the cortex developmentally?

Answer 12

1. Zona glomerulosa & fasciculata are present at birth 2. Reticularis not recognizable until end of 3rd year

Question 13

Describe the zona glomerulosa?

Answer 13

1. It lies under capsule 2. It represents 10-15% of the cortex 3. Cells arranged into glomerulus-like arrangement - cells organized into small rounded groups 4. Cells have moderate amount of lipid droplets in cytoplasm 5. Lacks enzyme 17α-hydroxylase, so cant produce sex steroids

Question 14

Describe the cells in the zona glomerulosa?

Answer 14

1. Cells smaller than in 2 other zones 2. Cells’ nuclei dark & round 3. Cytoplasm is light basophilic

Question 15

Describe the zona fasciculata?

Answer 15

1. consists of cell columns separated by fenestrated sinusoidal capillaries 2. Makes up 75% of cortex 3. Made up of cuboidal cells

Question 16

Describe the cells in the zona fasciculata?

Answer 16

1. Nucleus is typically centrally located 2. (H&E), Cytoplasm is light & often has a characteristic foamy or spongy appearance (called spongiocytes) - abundant lipid droplets containing steroid hormone precursor cholesterol 3. Mitochondria with tubular cristae have steroidogenic enzymes 4. Well developed smooth endoplasmic reticulum - with enzymes for synthesis of steroid hormones

Question 17

Describe the zona reticularis?

Answer 17

1. Formed by anastomosing cell cords separated by sinusoid spaces 2. Makes up 5-10% of cortex 3. Cells are typically smaller than in zona fasciculata

Question 18

Describe the cells in the zona reticularis?

Answer 18

1. Cytoplasm is eosinophilic & less spongy than that of other cells in cortex 2. Cells are acidophilic due to abundant lysosomes & lipofuscin granules + Fewer lipid droplets 3. Lipofuscin (brown pigment, lipid residue) accumulate in cells with age 4. mucleus is rather light and large

Question 19

What kind of hormones are produced in the cortex?

Answer 19

steroids - corticosteroids/corticoids

Question 20

Corticosteroids are subdivided into?

Answer 20

1. mineralocorticoids - aldosterone : regulate Na+ & K+ balance & control of blood pressure 2. glucocorticoids - cortisol : regulate metabolism of sugars & proteins (opposite of insulin) 3. Sex steroids - small amounts of androgens, estrogens & progesterones

Question 21

What kind of hormones are produced in the zona glomerulosa?

Answer 21

mineralocorticoids (aldesterone) - angiotensin II stimulates growth of zona glomerulosa & synthesis of aldosterone

Question 22

What kind of hormones are produced in the zona fascicularis?

Answer 22

1. glucocorticoids (cortisol) 2. sex hormones (androgens)

Question 23

What kind of hormones are produced in the zona reticularis?

Answer 23

1. glucocorticoids (cortisol) 2. sex hormones (androgens)

Question 24

Describe the cells of the medulla?

Answer 24

1. Stain yellow-brown with chromium 2. Large & pale-staining 3. Derived from neural crest cells 4. Are in clusters arranged around blood vessels 5. Have ganglion cells and nerves

Question 25

What kind of hormones do chromaffin cells secrete?

Answer 25

catecholamines

Question 26

Describe the hormones produced by chromaffin cells?

Answer 26

1. Adrenaline (epinephrine) - produced in 80% of cells and stored in granules 2. Noradrenaline (norepinephrine) - produced in 20% of cells and stored in smaller granules and occupy less dense central core 3. chromogranins - proteins helping to bind catecholamines

Question 27

Describe the arterial supply of the adrenal gland?

Answer 27

1. inferior phrenic artery gives rise to superior adrenal artery 2. aorta from which middle adrenal artery branches off 3. renal artery gives rise to inferior adrenal artery

Question 28

These vessels form a system that consists of?

Answer 28

1. capsular capillaries 2. fenestrated cortical sinusoidal capillaries 3. medullary arterioles 4. medullary capillaries

Question 29

Describe the venous drainage?

Answer 29

1. Right adrenal gland - through suprarenal vein into IVC 2. Left adrenal gland - through suprarenal vein into left renal vein

Question 30

Describe the nerve supply?

Answer 30

1. splanchnic nerves 2. fibers of celiac plexus 3. Chromaffin cells are innervated by preganglionic sympathetic fibres

Question 31

State other steroid secreting hormones?

Answer 31

1. ovaries - estrogen + progesterone 2. placenta - progesterone + estrogen 3. testes - androgen (testosterone) produced by Leydig cells

Question 32

What is a pheochromocytoma?

Answer 32

tumour in adrenal medulla - results in hypersecretion of medullary hormones causing hypertension

Question 33

Increased release of adrenocorticotropic hormone causes?

Answer 33

1. Congenital Adrenal Hyperplasia (CAH) or androgenic syndrome 2. Overproduction of androgens - masculinization of external genitalia & clitoris

Question 34

Name a consequence of congenital adrenal hyperplasia?

Answer 34

female pseudohermaphroditism (46 XX)

Question 35

What is pseudohermaphrodite?

Answer 35

genotypic sex is masked by phenotypic appearance that resembles the other sex

Question 36

Describe female pseudohermaphrodite?

Answer 36

excessive androgens musculinizes external genitalia caused by CAH which is due to an increase in ACTH