Kidneys

Osmoregulation

Osmoregulation is the active regulation of osmotic concentration of an organism’s internal water levels within tissues and cells to maintain homeostasis and keep fluids from becoming too diluted or too concentrated.

Kidney

Kidneys are a pair of bean shaped organs below the ribs that function as a filtration system for the bloodstream. Blood enters kidneys via renal artery and exits via renal vein, blood is filtered by nephrons which produce urine that is then transported from kidneys to the bladder via ureter. Through excretion nitrogenous compounds like urea are removed from the body, and through osmoregulation internal water levels are regulated for suitable osmotic concentrations.

Kidney Components

Larger structures: Renal Cortex is the outer region containing nephrons. Renal Medulla is the inner region composed of cone-shaped structures that contain the loops of Henle and nephron collecting ducts. Renal Pelvis is a funnel shaped cavity that collects urine from the medulla and transports it to the bladder via ureter.

Nephrons are functional kidney units and each nephron consists of a Glomerulus which is a capillary network where blood is filtered and Bowman’s capsule collects filtered fluid, proximal convoluted tubule which is a folded structure where selective reabsorption of filtrate occurs, loop of Henle which is a selectively permeable u shaped loop that establishes a salt gradient, and a distal convoluted tubule another folder structure where further selective reabsorption of ions and water occurs.

Glomerulus, Bowman’s Capsule and Proximal Convoluted Tubule in Excretion

Ultrafiltration is the nonspecific filtration of blood under high pressure. Blood enters the glomerulus capillary network via afferent arterioles, the glomerulus has pores and is encapsulated by Bowman’s capsule which has narrow spaces between its lining, fluid moves freely from blood into nephron where basement membrane is the only filtration barrier.

Kidneys in Osmoregulation and Excretion

Loop of Henle

Osmoregulation by water reabsorption