excretory system

afferent arterioles bring blood to each nephron directly into the Bowman’s capsule. Filtrate (substances filtered from the blood) flows from the Bowman’s capsule into the proximal tubule then through the loop of Henle and into the distal tubule which finally empties into the collecting ducts

filters small solutes from the blood

reabsorbs ions, water and nutrients removes toxins and adjusts filtrate pH

aquaporins allow water to pass from the filtrate into the interstitial fluid

reabsorbs Na+ and Cl- from the filtrate into the interstitial fluid

selectively secretes and absorbs different ions to maintain blood pH and electrolyte balance

reabsorbs solutes and water from the filtrate

surrounds glomerulus and collects glomerular filtrate

• Primary function of the kidney is to remove metabolic wastes from the body and regulate fluid balance in the body. • Produces a hormone known as erythropoietin which stimulates erythropoiesis. • Provides the last step in the synthesis of Vitamin D. • Produces (renin) enzyme which plays a role in maintaining blood pressure. • Helps maintain acid-base balance in the body

glomerular filtration, tubular reabsorption and tubular secretion

the driving force for this process is blood pressure, afferent arterioles introduce blood into the Bowman’s capsule at a high pressure, the filtration membranes only allow water and solutes through and keeps blood cells, platelets and proteins in the blood.

ensures that useful filtered substances such as glucose, amino acids and electrolytes are returned to the peritubular capillaries and placed back into the bloodstream. Proximal tubules are where most reabsorption takes place.

this process removes unwanted substances and adds them to the forming urine in the nephron tubules. This process also carefully eliminated hydrogen ions, potassium ions and urea. This process plays a major role in maintaining acid/base balance.

• The kidneys concentrate urine before it reaches the bladder, this process regulates blood volume and blood pressure. • Salt and water are reabsorbed at the proximal tubule and loop of Henle, in order to prevent more loss than the body can afford, at the ascending limb and distal tubule, salt is reabsorbed but water cannot move it thus introducing dilute urine to the collecting ducts. • As water is reabsorbed the concentration of urea rises thus concentrating the filtrate. • Antidiuretic hormone (ADH) is released in the body when we are dehydrated and our salt concentration is high, this hormone acts on the distal and proximal tubule where it reabsorbs water into the bloodstream. This additional water balances the solute concentration in the blood, increases blood volume and thus blood pressure. • With regards to blood pressure, reduced blood volume introduced into the kidney by the afferent arteriole instigates the release of renin which converts angiotensin I to angiotensin II stimulating the secretion of aldosterone which induces sodium and water reabsorption at the distal tubules and collecting ducts.

The outer region of the kidney, (between the renal capsule and the renal medulla) that consists of a space that contains blood vessels that connect to the nephrons.

Innermost part of the kidney which is split into a number of sections called the renal pyramids

Chamber of the kidney through which urine passes. There are major and minor calyces. Two or three minor calyces make up one major calyces.

The point where the two or three major calyces join together.

thin membranous sheath that covers the outer surface of each kidney

The tube that carries urine from the kidney to the bladder

small blood vessels that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron

hormone that helps conserve the fluid volume of the body by reducing the amount of water passed out in the urine

hard deposits made of minerals and salt that form inside the kidneys.

condition which can be caused by infection in which the tissues in the kidney become inflamed and have problems filtering waste from the blood.