Excretion in human

excretion the biological process

involved in the removal of harmful

metabolic wastes from the body is called

excretion as in other processes like

nutrition respiration transportation

different organisms use different

strategies to do excretion in case of

unicellular organisms wastes are removed

from body surface into the surrounding

water by the process called diffusion

but in case of multicellular organisms

specialized organs are evolved to

perform excretion excretion in human


the chief organ that is involved in

excretion is kidneys the excretory

system of human beings consists of one a

pair of kidneys right kidney and left

kidney - a pair of ureters right dorita

and left ureter 3 a urinary bladder for

a urethra kidneys are located in the

abdomen on either side of the backbone

kidney is a basic filtration unit it

consists of very thin wall blood

capillaries each capillary cluster is

associated with cup-shaped

end of a tube that collects filtered

urine each kidney has large number of

filtration units called nephrons pack

close together the waste products are

nitrogenous wastes that are collected

from the blood in the form of urine the

produced urine passes through ureters

into urinary bladder the urine is stored

in the urinary blood

and the urine is released to outside

through urethra now let us learn how

during is produced the process of urine

formation takes place in three steps one

filtration two reabsorption three

secretion filtration the nitrogenous

wastes such as urea uric acid are

removed from blood in the kidneys the

process of uric formation takes place in

nephron reabsorption some substances

like glucose amino acids salts and major

water which are filtered along with

nitrogenous wastes are reabsorbed the

amount of water reabsorbed depends on

excess water and dissolved wastes along

with wastes secretion reabsorbed

components of wastes are secreted into

the blood when the urine flows through

the tubular part of nephron in the

kidney mechanism of urination the urine

formed in kidney enters into a lung tube

called ureter the one end of the ureter

is connected to kidney and the other end

is connected to urinary bladder urine is

stored in the urinary bladder until the

pressure of urinary bladder leads to

urge to pass urine when it reaches the

pressure to urge to pass it urine passes

out through urethra how can we hold

urine until it reaches to the urge to

pass urine as urinary bladder is

muscular and it is under the control of

nervous system we can usually control


to urinate the process of passing up

urine is called as urination