The Excretory System

What is Excretion? Excretion – the process of removing wastes from the body. – Can be in the form of a solid, liquid or gas. Wastes are useless to the body but if left to build up inside a person they could become poisonous and result in illness or death.

Types of Wastes Solid Wastes: – Indigestible material left after digestion and absorption – feces. Discussed during Digestive System Gaseous Wastes: – The carbon dioxide you exhale. Discussed during Respiratory System Liquid Wastes: – Excreted from the body as either urine or sweat. Both are more than 90% water. – Contains waste nitrogen and salts.

The Urinary System Kidneys Ureter Urinary Bladder Urethra

Organs of the Urinary System 1.The Kidneys We have two kidneys – Unfiltered blood enters through the renal artery off the aorta. – Filtered blood leaves through the renal vein. Function: – Filter blood – Remove water and salts. – Make urine for excretion. Renal Artery Renal Vein Ureter Urinary Bladder

Parts of the Kidney Nephrons – filter the blood to produce urine. – Approximately 1 million per kidney. – Located in the outer rim of the kidney. – Looks like a long coiled tube with a cup at one end. Each tiny tube extends into the center of the kidney. Nephron Artery Vein Ureter To the Urinary Bladder

Parts of the Kidney Glomerulus – A ball of capillaries surrounded by the nephrons. – Particles being filtered out; salts, amino acids, water, glucose and urea of the blood pass into the glomerulus. Harmful wastes continue down into the tubule. Beneficial products, water and some salts are reabsorbed. Glomerulus Tubule

Organs of the Urinary System 2. The Ureter Ducts that carry urine from the kidneys to the urinary bladder. 3. Urinary Bladder Stores the urine until it is released from the body. 4.Urethra Opening through which urine leaves the body. Renal Artery Renal Vein Ureter Urinary Bladder

Urine Yellowish in color – Dehydrated = darker yellow Less water and higher concentration of salts and metabolic wastes. Body purposely reabsorbs as much water as it can to keep functioning. – Hydrated = pale yellow to clear An excess of water that is not needed by the body and contains fewer metabolic wastes. Make-up: – 95% water – 5% dissolved particles (salts and metabolic wastes) Kidney StonesKidney Stones: 1:53min

Kidney Stones

Other Excretory Organs 1.The Liver Also filters the blood as it passes through it. – Absorbs drugs and other poisonous chemicals Changes their chemical structure. Excreted in the bile. Largest internal organ of the body! Gall Bladder Liver

Other Excretory Organs 2.The Skin The largest organ of the human body. Functions: – Excretion - water, salt, urea and uric acid are removed in sweat. – Waterproofing - oil glands prevent entry of water into, and loss of water out of the body. – Protection from Disease – Regulation of Body Temperature – Sensory Detection - heat, cold, touch, pressure and pain. Epidermis Dermis Fat Cells

Other Excretory Organs 2 layers: – Epidermis – outer layer Provides a waterproof, protective wrap over the body. Contains NO blood vessels. Epidermis Dermis Fat Cells

Other Excretory Organs – Dermis – inner layer Rich in blood vessels Also contains hair follicles, sweat glands, and oil glands. Epidermis Dermis Fat Cells Hair Follicle Oil Gland Sweat Gland

Sweating Also called Perspiration Primary means of temperature regulation: – sweat cools the body due to evaporation. Causes of sweating: – Too hot, stressed or nervous What is sweat? – Water, salts, urea. BrainPop – Excretory SystemExcretory System