Basics of Nephrology

 

Kidneys are located retroperitoneally and receive 20 to 25% of cardiac output

The main blood supply of kidneys is through renal arteries

Where do renal arteries arise from?

Abdominal aorta

Each kidney has functional units called as nephrons

Each nephron has -

Glomerulus

Proximal convulated tubule

Loop of Henle

Distal convulated tubule

Glomerulus is responsible for ultrafiltration of blood

The glomerulus is made of a loop of capillaries.

The glomerulus is supplied by afferent arteriole and drained by efferent arteriole

What is Bowman capsule?

Bowman capsule is an extension of proximal tubule. Bowman capsule surrounds the glomerulus.

The filtration barrier is made up of

Endothelial cell

Glomerular basement membrane

Glomerular Epithelial cell (podocyte)

What is the role of mesangial cells?

They have contractile properties

They regulate the glomerular filtration rate(gfr)

Filtration pressure at the glomerulus is  maintained at a constant level, inspite of wide variations in systemic blood pressure and cardiac output. This is known as autoregulation.

How does the autoregulation take place? 

Reduced renal perfusion pressure

1. Increases production of prostaglandins

Prostaglandins cause vasodilatation of the afferent arteriole thus increasing the intraglomerular pressure

2. Renin is released by the juxtaglomerular 

apparatus 

Renin cleaves angiotensinogen to release angiotensin I, which is further cleaved by angiotensin-converting enzyme (ACE) to produce angiotensin II.

Angiotensin II causes vasoconstriction of efferent arteriole thus restoring the glomerular perfusion pressure

The proximal renal tubule, loop of Henle, distal renal tubule and collecting ducts play a role in reabsorption of water and electrolytes. They also regulate acid–base balance

The bladder stores and then releases urine during micturition

Which muscle is present in bladder?

Detrusor muscle

Where is the prostate gland located?

At the base of bladder

It surrounds the proximal urethra