The Urinary System

Waste ManagementThree major

areas of ridding the body of waste (not including digestive wastes)Exhalation

CO2

SweatingToxic metals

EliminationUrine

Designed to help keep body in homeostasis by removing and restoring selected amounts of solutes and water from blood.

Urinary System

6 Functio

ns of Urinary System

Kidneys filter large amts of fluid from bloodstream to eliminate Nitrogenous wastesDrugs, medications

and toxinsexcess water

1. Excretion

Kidneys maintain blood volume by regulating a balance between salts and waterAmt of urine producedConcentration of ions

SodiumChloridePotassiumCalciumPhosphate ions

2. Blood volume/concentration

Kidneys control balance of hydrogen ions

3. pH Regulation

Kidneys produce an

enzyme RENIN which helps adjust

filtration pressure.

4. Blood Pressure

Kidneys produce erythropoietin, a hormone that stimulates red blood cell production.

5. Erythrocyte Concentration

Kidneys convert vitamin D to calciferol, which enhances the uptake and absorption of calcium and other

6. Vitamin D Production

Kidney – paired organs located under diaphragm; creates urine

Ureter – duct from each kidney to bladder

Bladder – hollow muscular organ collect urine for excretion

Urethra – small tube leading from bladder to outside of body. Transports urine via peristalsis

Components of Urinary System

A lesson in Nephrology

The Kidneys

Renal Capsule – outmost covering of kidney

Cortex – outer area extending from capsule to pyramids

Medulla - inner area containing pyramids

Anatomy of the Kidney

Renal Pyramid – triangular structures inside medulla

Papillae – tips of pyramids

Anatomy of the Kidney

Anatomy of the Kidney

Nephron – the functional unit of the kidney

Medulla is composed of millions of these microscopic collecting tubules.

It is here that blood is passed through capillaries and filtered of toxins and excess water & ions

Anatomy of the Nephron

1. Blood vesselsFrom the renal

artery, blood enters afferent arterioles leading to Bowman’s Capsule

Inside this double-layered globe is the glomerulus, a tiny network of capillaries.

This is the site where water and solute filtration happens

The filtered fluid flows into the renal tubule

Pathway2. Bowman’s capsule

3. Renal Tubule Nutrients (salts,

vitamins, etc.) are moved out of the tubule through active transport.

Water follows the nutrients by osmosis.

Urine and other solutes continue on

Tissue around the Loop of Henle is salty, from active transport and diffusion of sodium chloride.

The salty conditions allow water to diffuse out of the loop.

Pathways

4. Loop of Henle

5. Distal tubuleActive transport is

used to move more nutrients out of the concentrated urine.

Some ions, drugs, and toxins are actively pumped into the tubule

More water leaves the tube by osmosis, since the tube is surrounded by salty tissue.

Some urea leaves by diffusion, and may be cycled through the system.

Pathways

6. Collecting Duct

The

Big

Pic

ture

Urine is a fluid that is composed of about 95% water. It also containsUrea (converted from ammonia)Uric acidAmino acids (few)Electrolytes

The average person makes between .6 and 2.5 liters a day!

Urine

Each collecting tubule leads ultimately through the calyces and to a ureter.

The ureter channels urine to the bladder.

The urine will then empty from the bladder via the urethra.

Urine