Transcript human organs of excretion

EXCRETION
EXCRETION
 The
process by which wastes of cell
metabolism are removed from an
organism
 Review
: metabolism =
all of the chemical processes necessary to
keep an organism alive
Metabolic Activities and Wastes
Produced

Respiration


Carbon dioxide
and water
Metabolic Activities and Wastes
Produced

Dehydration
Synthesis
•Water
Metabolic Activities and Wastes
Produced

Protein Metabolism
(breakdown of amino
acids)

Nitrogenous Wastes
Metabolic Activities and Wastes
Produced

Other Metabolic
Activities

Mineral Salts (NaCl,
K2SO4)
Nitrogenous Wastes

Nitrogenous wastes
are produced from the
breakdown of amino
acids
Types of Nitrogenous Wastes
Ammonia
– highly toxic
Nitrogenous Wastes

Urea
 – slightly toxic,
formed in the liver
when nitrogenous
compounds are
broken down
 Urine contains urea
Nitrogenous Wastes
Uric Acidnon toxic
Found in bird,
insect and
reptile waste

Toxic wastes are
released in animals or
stored in plants

Nontoxic wastes may
be released, stored or
recycled for other
metabolic acitvities
plants produce oxygen during photosynthesis
which can be used during respiration
Example : Living things produce carbon
dioxide as a result of respiration which can
be used during photosynthesis
HUMAN ORGANS OF
EXCRETION
LUNGS

Excrete carbon
dioxide and water

These are the wastes
of cellular respiration
LIVER
Removes toxic
substances from the
blood
 Disposes of
Hemoglobin – old
RBC’s are broken
down in the liver and
hemoglobin is
released
 The liver converts the
hemoglobin to bile
pigments (waste
products) which are
eliminated in the
feces

LIVER

Disposal of
nitrogenous wastes



Breaks down excess
amino acids
(deamination)
The amino group is
converted to ammonia
and then to urea
Urea is transported to
the kidneys by the
blood
SKIN

The excretory
structures of the skin
are the sweat glands
 The sweat glands are
in contact with
capillaries
Water, salt and some
urea diffuse from the
blood into the sweat
gland and are
excreted as
perspiration
Perspiration acts to
regulate body
temperature by
removing excess
heat
URINARY SYSTEM

Includes kidneys,
ureters, urinary
bladder and urethra
URINARY SYSTEM
The kidneys (2) are
bean shaped
organs ,
approximately 10
cm long and are
located below the
diaphragm near the
back

Kidneys have 2 main
functions:
1. Remove wastes of
cellular metabolism
form the blood
2. They regulate the
concentrations of
substances found in
body fluids

Blood vessels carry
blood to the kidneys,
where wastes and
other dissolved
substances are
removed from the
blood

The wastes are
excreted from the
body and the useful
substances are
reabsorbed
Kidney Structure

Kidneys consist of
microscopic
structures called
NEPHRONS.
A NEPHRON is made of :
Glomerulus: a network of
capillaries
Bowman’s capsule: cuplike structure
surrounding the
glomerulus
A

nephron works in 2 stages:
Filtrations stage: water, minerals, salts, urea,
amino acids and glucose are filtered out of the
blood

Reabsorption stage:
 water, minerals,
amino acids and
glucose are
reabsorbed by active
transport from the
renal tubule into the
capillaries

The remaining
material is urine
which contains water,
salt and urea
URETERS

Tubes that carry urine
from the kidney to the
bladder
URINARY BLADDER

Stores urine
URETHRA

Tube that carries
urine from the bladder
to the outside of the
body
Malfunctions
 Kidney
Diseases:
 Include various conditions in which the
kidneys are unable to properly excrete
nitrogenous wastes
MALFUNCTIONS
 Kidney
stones:
 Substances crystalize out of the urine in the
urinary tract or in the kidney
 Some
pass out in the urine on their own
 Some can be shattered with lasers or sound
waves
 Some are surgically removed
Treatments

Dialysis – can some
times be used to treat
various kidney
diseases

Kidney transplants
are also successful