Suprarenal gland (Adrenal gland) Flashcards
Location of Suprarenal gland :
Each gland lies in the epigastric region, at the upper pole of the kidney, Infront of the crus of the diaphragm
It lies opposite the vertebral end of the 11th intercostal space and the 12th rib (T12)
Arterial supply of Suprarenal gland:
- Superior suprarenal artery: branch from the inferior phrenic artery
- Middle suprarenal artery: direct branch from the abdominal aorta
- Inferior suprarenal artery: branch from the renal artery
Venous drainage Suprarenal gland:
each gland is drained by one vein:
The right suprarenal vein drains into inferior vena cava
The left suprarenal vein opens into the left renal vein
Lymphatics from the suprarenal glands drain into:
the lateral aortic group of lymph nodes
Nerve supply of suprarenal gland:
-the medulla is supplied by the sympathetic fibres coming from the coeliac plexus conveying fibres from T8 to L1 segments of the spinal cord. These preganglionic fibres make synaptic connections with the chromaffin cells of the medulla which acts as post-ganglionic neurons.
-The activities of the cortex are mostly controlled by the ACTH of adenohypophysis
-Accessory suprarenal glands are small masses of cortical tissue often found around the main gland and sometimes in the spermatic cord, the epididymis, and broad ligament of the uterus
Development of the suprarenal gland:
The cortex develops from the mesoderm and the medulla from the neural crest cells (neuro-ectoderm)
Cortex: cells are arranged in three zones, named from outside inwards –
- Zona glomerulosa: consists of small polyhedral cells and the cells are arranged in arched columns or in irregular clusters.
- Zona fasciculata: thickest of the three zones and consists of polyhedral cells which are arranged in straight cords separated by blood capillaries and sinusoids. The cells also known as spongiocytes, which are rich in vitamin C, lipids and cholesterol.
- Zona reticularis: consists of irregularly arranged cell clusters separated by sinusoids and capillaries.
Function of Zona glomerulosa:
- This zone liberates mineralocorticoids (aldosterone) which regulate sodium and potassium balance of the body. The aldosterone helps in the absorption of Na+ from the distal convoluted tubules of nephrons in exchange of K+ in the tubular lumen.
- In deficiency of mineralocorticoids, such as in Addison’s disease, sodium is lost from the body via urine, and potassium is retained in the blood
- The activity of zona glomerulosa are mostly regulated by renin-angiotensin mechanism
Function of Zona fasciculata :
This zone liberates glucocorticoids (cortisol) which regulate carbohydrate and protein metabolism of the body. The cortisol helps in conversion of proteins to carbohydrates; so it is diabetogenic and is antagonised by insulin. Cortisol also diminishes the activities of fibrocytes and delays wound healing.
Function of Zona reticularis :
- This zone liberates sex steroids (androgen), which regulate the secondary sex characters. A few cells of this zone possess acidophilic cytoplasm and show signs of degeneration.
Medulla consists of which cells :
chromaffin cells
-secrete epinephrine and nor-epinephrine (catecholamines)
What is Addison’s disease :
Occurs due to chronic insufficiency of cortical secretion
Clinically it presents:
* Muscle weakness
* Weight loss
* Increased pigmentation of skin
* Low blood pressure
* Listlessness (little or no interest in anything) and tiredness
What is Conn’s syndrome :
- Results from adrenal hyperplasia with excessive mineralocorticoid (aldosterone) secretion
This condition is characterized by hypertension and hypokalaemia (low level of potassium (K+) in the blood serum).
what is Cushing’s syndrome :
- Results from adrenal hyperplasia with excessive secretion of glucocorticoids (cortisol)
This condition is manifested by: - Truncal obesity
- Hypertension
- Hirsutism (abnormal growth of hair on face and body) in females
This condition is most often due to a pituitary adenoma that results in excessive production of ACTH
What is Adreno-genital syndrome :
- Results from excessive secretion of adrenal androgens from the zona reticularis
This condition will results in: - Masculinization of females
- Precocious puberty in males
What is Pheochromocytoma :
A tumour of the adrenal medulla, produces paroxysmal (sudden attack) hypertension due to secretion of a large amount of catecholamine (epinephrine and nor-epinephrine )
Clinically it presents:
* Paroxysms of hypertension (is episodic and volatile high blood pressure)
* Palpitation (rapid, strong, or irregular heartbeat due to agitation, exertion, or illness)
* Headache
* Excessive sweating
* Pallor of the skin
What is Adrenalectomy :
- Bilateral removal (laparoscopically) of adrenal glands is done as a treatment of some advanced and inoperable cases of disseminated carcinoma of the breast and prostate which do not respond to radiotherapy and which are considered to be dependent on hormonal control.
- The right suprarenal gland is more difficult to approach than the left because part of it lies posterior to the inferior vena cava.
What is Endocrine pancreas [Islets of Langerhans] ?
- The pancreas lies obliquely on the posterior abdominal wall in the epigastric and left hypochondriac regions; opposite the level of T12 – L3 vertebrae
- The pancreatic juice helps in digestion of lipids, carbohydrates and proteins; whereas the pancreatic hormones maintain glucose homeostasis
Development of the pancreas
The pancreas develops from ventral and dorsal pancreatic bud
* The dorsal bud arises as a diverticulum from the dorsal wall of primitive duodenum slightly cephalic or cranial to the hepatic bud
-ventral bud arises from the junction of the fore gut and mid gut
-The whole of the neck, body and tail of the pancreas and upper half of the head are developed from the dorsal bud
-Lower part of the head and uncinate process develop from ventral bud
Four major types of cells are found in the islets:
- Alpha (α) cells – 20%: secrete glucagon; which is anti-diabetogenic
- Beta (β) cells – 68%: secrete insulin; which is diabetogenic
- Delta (δ) cells – 10%: secrete somatostatin; which inhibits the release of insulin & glucagon
- F or PP or gamma cells (γ) – 2%: secrete pancreatic polypeptide hormone; which stimulates the secretion of gastric and intestinal enzymes and inhibits intestinal motility
Clinical correlation of islets of Langerhans:
- Deficiency of insulin causes diabetes mellitus
- Carcinoma of pancreas is common in the head of pancreas
Endocrine part of the testis:
Functionally testis is concerned with the production of sperms and the endocrine part Interstitial cells of Leydig secretes the hormone testosterone
Function of testosterone :
the development of male secondary sexual characteristics.
-Contributes to sex drive, bone density, and muscle strength in women.
* Testosterone levels are controlled by the luteinizing hormone secreted by the pituitary gland (adenohypophysis).
Low level of testosterone or hypogonadism can lead to:
- Reduced sex drive
- Erectile dysfunction
- Low sperm count
- Enlarged or swollen breast tissue
These above symptoms in long run may result in:
Loss of body hair
Loss of muscle bulk
Loss of strength
Increased body fat
