Renal SystemRenal System

•Gross structure of the kidneys cortex, medulla (inner and outer zones of outer medulla and papilla or inner medulla), pyramids, renal calyxes and pelvis, ureter. •Gross size and weight (300~400 g) of kidneys (about 0.5% of body weight)• in humans

Anatomy of the KidneyAnatomy of the Kidney

The nephron is the basic unit of renal structure and functions.It has a malpigian corpuscle with a vascular

glomerulus within a matrix formed by mesangial cells and an epithelial Bowman’s capsule.

The capsule joins a series of tubules starting with the proximal tubule and followed by the loop of Henle the distal tubule.

Nephron

• Glomerulus• Bowman’s Capsule• Proximal Convoluted

Tubule• Loop of Henle

I. Proximal straight tubule ii. Descending Thin Limb iii. Ascending Thin Limb iv. Distal Straight Tubule

• Distal Convoluted Tubule

7

glomerulusbranch of renal artery

Bowman’s capsule

branch of renal vein

loop

DCT PCT

collecting duct

capillaries

8

glomerulusbranch of renal artery

Bowman’s capsule

branch of renal vein

loop

DCT PCT

collecting duct

capillaries

Anatomy of the KidneyAnatomy of the Kidney

Formation of UrineFormation of Urine

The initial step is the formation of a plasma ultrafiltrate (plasma without cells or proteins) at Bowman’s space through the action of hydrostatic pressure in the glomerular capillaries.

The ultrafiltrate flows along the tubules and is modified by reabsorption (sodium salts, glucose, amino acids) and most water from the when of the tubules back into the pennt? Capsule.

The luminal fluild is also modified by secretion of solutes from the peritubular (tubule cells) into the lumen.

Tubular Secretion and ReabsorptionTubular Secretion and Reabsorption

Function of Collecting ductsFunction of Collecting ducts

•The collecting ducts make the final fine adjustments in composition of the urine through anti-diuretic hormone stimulated water and urea reabsorption, and aldosterone stimulated Na, K and H transport.

Tubular ReabsorptionTubular Reabsorption Returns materials from

filtrate to blood 99% of filtrate reclaimed

– Lose 1.5 – 2 L/day as urine Mechanisms of

reabsorption:– Osmosis, Solvent drag,

Pinocytosis, Active transport & Diffusion

Amounts reabsorbed depends on:

– Need for substance & Concentration gradient

Proximal convoluted tubule

– Always permeable to water, reabsorbs 80% of water passing through

– Active Transport Ions-Na, Cl, K, HCO3

Nutrients– Passive Transport

Urea, Lipid-soluble solutes

Role of kidneyRole of kidney

Apart from urine formation

Blood pressure from Renin production

RBC production from Erythropoietin

Arteriole – Small artery Bowman capsule – A cup-shaped capsule surrounding each glomerulus Calyx – Cup-like collecting region of the renal pelvis Catheter – A tube for injecting or removing fluids Cortex – Outer region; the renal cortex is the outer region of the kidney Creatine – A waste product of muscle metabolism Electrolyte – A chemical that carries an electrical charge on solution Filtration – Process whereby some substances but not all, pass through a filter or other material Glomerulus – Tiny ball of capillaries in cortex of kidney

Kidney Structure

Hilum – Depression or pit in that part of an organ where blood vessels and nerves enter and leave

Kidney – One of two bean-shaped organs located behind the abdominal

cavity on either side of the backbone in the lumbar region

Meatus – opening or canal

Medulla – Inner region; the renal medulla is the inner region of the kidney

Nitrogenous wastes – Substances containing nitrogen and excreted

in urine

Renal artery – carries blood to the kidney

Kidney Structure

Renal pelvis - Central blood away from the kidney. Renal tubules - Microscopic tubes in the kidney Renal vein - Carries blood away from the kidney Rennin - A hormone synthesized, stored and secreted by the kidney Sodium (Na+) - A salt (electrolyte) regulated in the blood and urine by the kidneys Trigone - Triangular area in the bladder where the ureters enter and the urethra exits Urea - Major nitrogenous waste product excreted in urine Ureter - Tube leading from each kidney to the bladder Urethra - Tube leading from the bladder to the outside of the body Uric acid - Nitrogenous waste excreted in the urine Urinary bladder – Sac that holds urine Voiding – Expelling urine (micturation) Glomerulonephritis - Inflammation of the kidney glomerulus (Bright disease)

Kidney Structure

Interstitial nephritis - Inflammation of the renal interstitium Nephrolithiasis - Kidney stones (renal calculi) Nephrotic syndrome - A group of symptoms caused by excessive protein loss in the urine (also called nephrosis) Polycystic kidneys - Multiple fluid-filled sacs (cysts) within and upon the kidney Pyelonephritis - Inflammation of the renal pelvis and renal medulla Renal cell carcinoma - Cancerous tumor of the kidney in adulthood Renal failure - Failure of the kidney to excrete urine Renal hypertension - High blood pressure resulting from kidney disease Wilms tumor – Malignant tumor of the kidney occurring in childhood Diabetes insipidus - Inadequate secretion or resistance of the kidney to the

action of antidiuretic hormone (ADH) Diabetes mellitus - Inadequate secretion or improper utilization of insulin

Kidney Structure

Azot (nitrogenous) Dips Noct (night) Olig (few) Tripsy (crushing) BUN (blood urea nitrogen) IVP KUB (kidney, ureter, bladder) ADH (anti-diuretic hormone) UTI (urinary tract infection) CRF (chronic renal failure?, corticotropin releasing

factor?) ARF (acute renal failure?)