20.1 Excretion

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Chapter 20

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8/3/2019 20.1 Excretion


Excretion is a process of removingunwanted substances from the body.

Unwanted substance are called excretory

products

The organs which removes theseexcretory products are called excretory

organs

Human excretory organs are SKIN,

LUNGS and KIDNEYS.

If excretory products are allowed to

accumulate in the body, it will become

harmful to health.

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Excretory Method

SWEATING1)The sweat glands

absorbs excretory

product from blood

capillaries around it.

2Sweat is eliminated

from the sweat gland

through sweat pores to

the surface of the skin.

3) Helps to control body

temperature

Excretory Products Water + Mineral Salts +

Urea Sweat

Sweat duct

Sweat

pores

Sweat

glands

Blood

capillaries

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Excretory Method exhalation

1)Carbon dioxide in theblood capillaries

diffuses into the

alveolus and is

eliminated from the

lungs when exhaling.

2)Water is eliminated

from the lungs in the

form of water vapour.Excretory Products Water and Carbon

dioxide

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Excretory Method URINATION.1)Excretory products are

carried by the blood to

the kidney and then

eliminated as urine.

**Kidney eliminated

many substances in large

quantities.

Excretory Products Water, Urea and excess

Mineral Salts.

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The urinary system has 4 big

components:

1. A pair of kidneys.

2. A urinary bladder.

3. A pair of ureters.

4. A urethra

The kidneys regulate the amount of

water, salts and other substances in

the blood.

The kidneys remove wastes (urine)

and excess salts from the blood.

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The ur eter s are tubes that carry

urine from the kidneys to the urinary

bladder.

The ur inar y bladder temporarily

stores urine until it is released from

the body.

The ur ethr a is the tube that carries

urine from the urinary bladder to the

outside of the body.

The outer end of the urethra is

controlled by a circular muscle called

a sphincter .

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The kidneys connected to renal artery and

renal vein that bring in /out blood

contains excess water, mineral, salts and

urea. This blood process in kidneys.

Each Kidney consists of

The cor tex is where the blood is

filtered.

The med ulla contains the collecting

ducts which carry filtrate (filtered

substances) to the pelvis.

The pelvis is a hollow cavity where

urine accumulates and drains into the

ureter.

CORTEXMEDULA

PELVIS

URETER

O2

CO2

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If kidneys do not function properly, toxic substances in the blood

will accumulate and this will lead to death.

The kidney will function properly if we :

a) Drink a lot of clean water.

b) Avoid drinking alcohol.

c) Reduce drinking gassy drinks.

d) Reduce eating food with high sugar content

Kidney failure is a condition in which kidney cannot carry out their

normal function.

Need to undergo DIALYSIS ,3 times per week if both kidneys do

not function.

Using machine to filter.

The kidney transplant must be compatible with the patient¶s,

otherwise it will be rejected by the patient body.

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PLANT

EXCREATION

Carbon dioxide,oxygen and

water

Leaf

Stomata

Water, ureaand mineral

salts

Tree

StemBark

Quinineand tannin

throughthrough through

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Plants performs excretion to remove excretory

products such as water, oxygen, carbon dioxide,

mineral salts and nitrogenous wastes.

Water-T ranspiration

Oxygen-Photosynthesis

Carbon Dioxide-transpiration.

Other excretory products of plants are found in the

form of secretions, alkaloids, oils and crystals.

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Plants do not have any special excretory system.

These excretory products are eliminated by:

1. Photosynthesis

2. Cellular respiration

3. Transpiration through stomata, lenticels and

cuticles at the stem and leaves.

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EXCRETORY

PRODUCT SOURCE USE

Latex Rubber tree To make vehicle tires

Resin

Certain tree stems like

the casuarina tree To make varnish

GumCertain tree stems like the acacia tree

To make cough medicine

Acid (tannic

acids or tannin)

Bar k of plants like the

tea, coffee and

mangrove tree To make ink

Quinine Bar k of cinchona tree to treat malaria

Oil

Flowers or leaves of

certain trees

To make perfume and

ointment for insect bites

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LATEX RESIN GUM

TANNIN QUINNIN OIL

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20.1 Excretion

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