excretory ststem

kidney

-remove nitrogen waste from the blood

-humans have 2, can survive with 1

-if 2 kidneys damaged: kidney transplant or kidney dialysis

-paired organs in the lower back

ureter

-tube attached to each kidney that leads to urinary bladder

urinary bladder

-holding tank for urine to exit the body

secretion (urine formation)

-urine: material not reabsorbed

-concentrated (more water removed)

-enters collecting duct

-leaves kidneys through ureter to bladder

nephron

-kidneys contain thousands of nephrons

-functional units of the kidneys

-each has own blood supply to filter urine

-wastes leave nephrons and go into a collecting duct to leave the kidney

filtration

-1st part of blood purification

-happens in glomerulus

-blood going into the nephron contains blood cells, water, salts, proteins nutrients and urea

-the pressure of blood forces materials across the membrane of the capillaries (plasma proteins, platelets, & blood cells stay in the vessels)

glomerulus

-a capillary bed at the start of a nephron

-surrounded by the Bowman’s capsule

Bowman’s Capsule

-catches the product filtered out of the blood

reabsorption

-most of the substances filtered out, such as water, salt and nutrients are absorbed back into the blood

urethra

-tube connects to bladder for urine to exit body

nitrogenous waste

-when amino acids are used for energy the waste product is a toxic waste

-types: Ammonia (NH3) excreted by aquatic organisms needs lots of water to dilute it

-converted to a less toxic compound: urea

urea

-in humans, mammals some fish and amphibians NH3 is converted to a led toxic compound

-this happens in the liver, requires less water to dilute the toxin which prevents dehydration, travels in blood to kidneys, where it is filtered and excreted

Liver

-filter/breaks down, harmful poisons and chemicals that are either produced in the body or consumed

skin

-removes excess water and salt in sweat

explain how blood is filtered by the kidneys

-filter blood to remove nitrogen and other wastes from the body to regulate homeostasis, including water balance

-kidneys contain thousands of nephrons