ENDOCRINE UNIT

Prepared By Dr. Ahmed

ADRENAL GLAND (suprarenal gland)

5th Lecture

Adrenal glandLOCATION paired , retroperitoneal related to upper pole of kidney Yellowish in colour

SHAPE AND MEASUREMENTS Shape: Each gland is flattened A-P 1. RT. : pyramidal in shape2LT.: crescentric in shape like

Measurements:Length 50 mm.Breadth 30 mm.Thickness 10 mm.Weight= About 5 g.

At birth the gland is 1/3 of the size of kidney, in adults it is only 1/30th of the size of kidney

Adrenal glandLOCATION retroperitonealin the epigastric region of abdomen, anterosuperior to the upper part ofeach kidney yellowish in color

SHAPE AND MEASUREMENTS Shape: Each gland is flattened A-P 1. RT. : pyramidal in shape2. LT.: crescentric in shape

Measurements:Length 50 mm.Breadth 30 mm.Thickness 10 mm.Weight= About 5 g.

At birth the gland is 1/3 of the size of kidney, in adults it is only 1/30th of the size of kidney

Adrenal gland

Adrenal glandSheathsurrounded by two sheaths :

1. Surrounded by fat called perirenal fat.

2. Outer to this, renal fascia encloses the suprarenal gland together with the kidney

3. but the gland is separated from the kidney by a septum.

Adrenal glandARTERIAL SUPPLYEach gland is supplied by three arteries from three different sources :

1. Superior suprarenal artery: A branch of the inferior phrenic artery.

2. Middle suprarenal artery: A branch of the abdominal aorta.

3. Inferior suprarenal artery: A branch of the renal artery.

Adrenal glandVENOUS DRAINAGEEach gland is drained by only single vein which emerges from the hilus of the gland :1. Right suprarenal vein drains into the inferior vena cava.2. Left suprarenal vein drains into the left renal vein.

Adrenal glandPartsdivided into outer cortex 80% inner medulla 20%

outer cortex contains parenchymal cells synthesize & secrete but do not store various steroid hormones. Intracellular lipid droplets characteristic cytologic features

inner medulla contains two populations of parenchymal cells, called chromaffin cells which synthesize, store, and secretethe catecholamine

Adrenal glandEndocrine Cells are generally characterized

according to hormones they produce:1. Nitrogenous-hormone secreting cell:

RER.Golgi.Secretory granules.

2. Steroid-hormone secreting cell: SER. Lipid droplet: raw materials. Mitochondria: with tubular- vesicular cristae.

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Adrenal glandZona glomerulosaOccupy 15% of the cortex

Immediately beneath the capsule

cells arranged in closely packed, rounded cluster like glomeruli

cells are smaller , Columnar or pyramidal with dark stain cytoplasm

Adrenal glandZona Fasciculata Occupy 65% of the cortex

Intermediate zone

Arranged in one or two – cell thick straight cords(perpendicular to surface of the gland)

cells are Polyhedral, binucleated light staining ( a lot of lipid droplets in their cytoplasm)

Cells are also called spongyocytes (foamy cell) due to vacuolization

Adrenal glandZona Reticularisoccupy 7% of the cortex Innermost layer - lies between zona fasciculata and medulla Small cells arranged in irregular cords forming networkCells are darkly stained, characterize by presence of lipofuscin pigment granules ( with age)

Adrenal glandMedullaLies in the center of the adrenal glandClear line of demarcation

Composed of polyhedral cells arranged in clusters surrounded by an extensive capillary network& , supported by reticular fiber network

Composed of : Chromaffin cells of 2types A – CELLS N – CELLS

Adrenal gland

Adrenal glandMedullaA – CELLS Characterized by 80%containing small granules Store epinephrine

N – CELLS Characterized by 20%containing large dense granules Store Norepinephrine

Adrenal glandMedulla has a dual blood supply that arises from (1) medullary arterioles that bypass the adrenal cortex (2) capillary sinusoids that perfuse the adrenal cortex (adrenocortical sinusoids).

central adrenomedullary vein drains to IVC(Rt.) or Lt. renal V.(Lt.)

Adrenal glandNerve supply of adrenal glandcortex is regulated by ACTH secreted by the anterior lobe of the pituitary gland

Medulla is regulated by sympathetic NS (myelinated preganglionic sympathetic fibers ) derived from splanchnic nerves & distributed to the chromaffin cells (modified postganglionic sympathetic neurons)

release of catecholamine from secretary granules stored in chromaffin cells by process called exocytosis

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Adrenal glandRadiology of Suprarenal Gland deeply located difficult to visualize on plain X-ray. CT scan of abdomen inverted Y shape with medial & lateral limbs

Adrenal gland Adrenalectomy ( removal of the adrenal glands)

Rt. suprarenal vein must be ligated before manipulating the gland 1. Short ,wide 2. To prevent surge of catecholamines to the circulation.

surgical removal of Lt. gland is easier because the identification & clamping of the left suprarenal vein is easy

Rt. gland is more difficult to approach than the left because part of it lies posterior to IVC

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Adrenal gland

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Adrenal glandConn’s disease HYPERALDOSTERONISM

usually caused by adrenal tumor

Na and water retentionK+ (hypokalemia)Hypertension

Adrenal glandCushing disease / syndrome

secretion of cortisol from Adrenal hyperplasia

4X more frequent in femalesPrimary-tumor on the adrenal cortexSecondary-tumor on the anterior pituitary gland

- truncal obesity- buffalo hump- “moon face”

Adrenal hyperplasia with excessive secretion of sex steroids leads to feminization of male and masculanization of female.

Adrenal glandCushing disease / syndrome

secretion of cortisol from Adrenal hyperplasia

4X more frequent in femalesPrimary-tumor on the adrenal cortexSecondary-tumor on the anterior pituitary gland

- truncal obesity- buffalo hump- “moon face”

Adrenal hyperplasia with excessive secretion of sex steroids leads to feminization of male and masculanization of female.

Adrenal gland

Adrenal glandAddison’s disease hypofunction of adrenal cortex

What hormones will you have too little of???

- glucocorticoids or _______ - mineralocorticoids or _______ - sex steroid or ____________

Adrenal glandAddison’s disease hypofunction of adrenal cortex

What hormones will you have too little of???

- glucocorticoids or _______ - mineralocorticoids or _______ - sex steroid or ____________

Adrenal glandPheochromocytomarare, benign tumor of the adrenal medullaHallmark is hypertension-200/150 or greater

Adrenal gland Embryologically : adrenal gland consists of two parts develops from two different sources at 5th week :

(a) a large outer part called cortex :is mesodermal in origin and develops from celomic epithelium

(b) a small inner part called medulla. develops from neural crest.

Adrenal glandA. Cortex1. forms from two episodes of mesoderm proliferation that occur between the root of the dorsal mesentery and the gonad. first episode forms the inner fetal cortex. second episode forms the outer adult cortex2. During the fetal period , the suprarenal glands are very large due to the size of the fetal cortex( 10–20 times larger than adult adrenal gland).

3. suprarenal glands become smaller as the fetal cortex involutes rapidly during the first 2 weeks after birth and continues to involute during the first year of life.4. zona glomerulosa and zona fasciculata of the adult cortex are present at birth, but the zona reticularis is not formed until age 3 years.

B. Medulla1. forms when neural crest cells aggregate at the medial aspect of the fetal cortex and become surrounded by the fetal and adult cortex.2. The neural crest cells differentiate into chromaffin cells

Adrenal glandCongenital anomalies

1. Ectopic adrenal tissue/adrenal gland: The adrenal tissue or complete adrenal gland may be found fused to kidney deepin its capsule or in the right lobe of the liver.

2. adrenal hyperplasia a) Congenital adrenal hyperplasia: It is most commonly caused by mutation of genes for enzymes involved in adrenocorticalsteroid biosynthesis (e.g., 21-hydroxylase deficiency),

b) Adrenogenital syndrome: It occurs due to congenital hyperplasia of the cells of the adrenal cortex, which secrete androgen. C/F differ in male and female :(a) In male: (adrenogenital syndrome) It leads to a very early development of secondary sexual characters.

(b) In female: (pseudohermaphroditism) female child may be mistaken as a male.

Abdominopelvic splanchnic nerves

Notes related to lecture

chromaffin cellscelomic epithelium

chromaffin cells

Neural Crest cells

Neural Crest cellsDerivatives of neural crest:1. C.T. and bones of the face and skull. 2. ganglia of the cranial nerves. 3. C-cells of the thyroid gland. 4. conotruncal septum of the heart. 5. odontoblast cells. 6. dermis of the face and neck. 7. spinal ganglia. 8. autonomic ganglia. 9. Chromaffin cells (adrenal medulla). 10. schwan cells. 11. glial cells of the brain. 12. melanocytes. 13. arachnoid and pia matter

Adrenal gland

Sites of chromaffin tissue :1. para-aortic bodies2. Along sympathetic chain near sympathetic ganglia3. Along sympathetic plexuses4. Near splanchnic nerves.

chromaffin tissue1. stain intensely with chromium salts yellow-brown .2. Neural crest derivatives Chromaffin cells can be found in extrasuprarenal sites at birth, but these sites normally regress completely by puberty.

In a normal adult, chromaffin cells are found only in the suprarenal medulla

Pheochromocytoma: tumor arising from chromaffin cells usually from extra-adrenal

celomic epithelium

• Formationintraembryonic celom

Abdominopelvic splanchnic nerves

Sympathetic Chain Extension:from the base of the skull to the coccyx.bears a number of ganglia along its lengthOn either side of V. column (paravertebral ganglion)Parts cervical, thoracic, lumbar and sacralGanglionCervical :3usually one ganglion less than the number of nerves: 11 thoracic; 4 lumbar; and 4 sacral

2 neurons (pre & postganglionic )Preganglionic N : T1- L2 in lat. horn

Communication with spinal nervesT1-L2 : by grey &white communicantsAbove & below this level: only grey communicants NO white communicants

Why?

Fate of preganglionic fibres preganglionic fibres arise from the lateral horns of spinal segments with ventral root 4 options

Sympathetic ganglion of sympathetic trunk (paravertebral ganglion

prevertebral ganglion

preganglionic fibres arise from the lateral horns of spinal segments with ventral root preganglionic fibres enter the sympathetic ganglion via white rami communicantes of the spinal nerve. Rely (synopsis) in the ganglionPostganglionic fibres from the ganglion re-enter the spinal nerve via grey rami communicantes supply the corresponding dermatome of the upper limb and the body wall.

BRANCHES of thoracic partVisceral & somatic Efferent Fibers divided into two groups: medial & lateral Medial branches(visceral)1) postganglionic fibres from 1st to 5th ganglia distributed to the heart, great vessels,

lungs, and esophagus through the following plexuses:

a) Pulmonary plexus bronchodilatationb) b) Cardiac plexus. vasoconstrictionc) Aortic plexus. Secretion d) Esophageal plexus HR & dilate coronary art.

2) preganglionic fibres 5th to 12th thoracic gangliaform three splanchnic nerves :a) Greater splanchnic nerve(5-9th)b) Lesser splanchnic nerve(10 &11th )c) Least (lowest) splanchnic nerve(12th (renal)

BRANCHES of thoracic part

Lateral branches(somatic) supply: • erector pili of hair follicle ( pilomotor)• Sweat gland (sudomotor)• Bl. V of the skin ( vasomotor) dilate Cutaneous Bl. V of limbs and body wall