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exchange and transport systems - Coggle Diagram
exchange and transport systems
surface area: volume ratio
smaller organisms have a larger surface area: volume ratio
to work out volume =
L x W x H
to work out surface area =
L x W x amount of sides
exchange organs and mass transport systems
organisms need to supply every one of its cells with certain substances (like oxygen and glucose). It also need to be able to remove waste products from every cell to avoid damage.
SINGLE-CELLED ORGANISMS
single-celled organisms are able to diffuse these substances directly into/ out of the cell across the cell-surface membrane.
the diffusion rate is quick due to the short diffusion pathway.
MULTICELLULAR ORGANISMS
In multicellular organisms, the diffusion rate across the surface membrane is to slow because:
a. some cells are deep within the body so there is a larger diffusion pathway.
b. large animals have a small surface area: volume ratio. it is difficult to exchange enough substances to supply a large volume of animal through a small outer surface.
multicellular organisms use
exchange organs
(like lungs) to absorb and secrete substances
they also use
mass transport systems
to carry substances to and from cells.
HEAT EXCHANGE
depending on the
size of an organism
depends on how easily it is for it to maintain its body temperature. the larger the animal is the smaller the surface area so it is harder for the organism to lose heat.
the smaller an organism, the faster the metabolic rate
in order to generate enough heat to survive.
the
shape of an organism
also affect heat exchange. the more compact the organism is, the less heat is lost from their surface.
the less compact an organism is, the easy it is for it to
lose heat from it's surface.
animals adapt to their environments to increase survival.
BEHAVIORAL ANS PHYSIOLOGICAL ADAPTATIONS TO AID EXCHANGE
in cold climates, smaller animals may have thick layer of fur to contain and reduce heat loss or may hibernate. They also have to eat large amounts of food due to their high metabolism to keep warm.
in warm/hot climates, larger animals have adapted to keep themselves cool - this can be behavioral adaptations (eg: hippos spending most of the day in the water) and anatomical adaptations (elephants having large flat ears)
gas exchange
GAS EXCHANGE IN PLANTS
the main gas exchange surface in plants is the surface of the
mesophyll cells
in the
leaves
.
Gases move in and out of the epidermis through
stomata
which can open to allow the exchange of gases and close to prevent water loss .
guard cells
control the opening and closing of the stomata.
CONTROL OF WATER LOSS IN PLANTS
plants stomata are usually kept open during the day to allow gaseous exchange.
Water enters the guard cell to make it turgid and keep the pore open, yet if the plant becomes dehydrated, the guard cells become flaccid and the pore closes.
Xerophytes
are plants that are specially adapted to survive in warm, dry and windy environments where water loss is a problem.
some xerophytic adaptations are:
stomata sunk in pits
this is to trap water vapor and reduce evaporation from the leaf
layer of hairs on the epidermis
this is to trap water vapor around the epidermis.
curled leaves with the stomata inside
this protects the stomata from the wind reducing water loss
-
reduced stomata numbers
this is to reduce the amount of places water can be lost
-
thick waxy surfaces
this reduces evaporation rates
GAS EXCHANGE IN INSECTS
insects have microscopic air-filled pipes called
tracheae
which branch into smaller
tracheoles
which have thin permeable walls and go to individual cells. (this means oxygen diffuses directly into respiring cells)
air moves into the tracheae through tiny pores on their surface called
spiracles
.
oxygen travels down the concentration gradient towards the cells
CO2 moves down its own concentration gradient towards spiracles to be released into the atmosphere.
insects use
rhythmic abdominal movements
to move air out of the spiracles.
CONTROL OF WATER LOSS IN INSECTS
If insects are losing too much water, they will
close their spiracles
using muscles.
they also have a
waterproof, waxy cuticle
all over their body and have
tiny hairs around their spiracles
. both reduce evaporation.
GAS EXCHANGE IN FISH
there is a lower oxygen concentration in water than in air, therefore fish have adapted to ensure the cells are supplied enough.
gas exchange happens in the
gills
in fish
each gill is made of lots of thin plates called
gill filaments
which give a large surface area for gas exchange.
gill filaments are covered in lots of tiny structures called
lamellae
which further increase the surface area.
THE COUNTER-CURRENT SYSTEM
oxygen flows in one way in the lamellae and the opposite in the water creating a
counter-current system
this maintains
a steep concentration gradient
gas exchange in humans
STRUCTURE OF THE GAS EXCHANGE SYSTEM
as you breathe in, air enter the
trachea
, it travels down the where the trachea splits into two
bronchi
. each bronchus leads to the lung and branches off into smaller tubes called
bronchioles
which end in small 'air-sacs' called
alveoli
.
at the alveoli is where gas exchange takes place.
there are also
intercostal muscles
that are found in-between the ribs
VENTILATION
ventilation consists of
inspiration
and
expiration
that are controlled by the movements of the
diaphragm
,
internal and external intercostal muscles
and the
ribcage
INSPIRATION
during inspiration, the external intercostal and diaphragm muscles
contract
. this causes the ribcage to
move upwards and outwards
and the diaphragm to
flatten
.
This
increases the volume of the thoracic cavity
and the
decreases the lung pressure
air will
always
flow from an area of high pressure to an area of low pressure.
inspiration is an
active process
- it requires energy
EXPIRATION
during inspiration, the external intercostal and diaphragm muscles
relax
. this causes the ribcage to
move downwards and inwards
and the diaphragm to
curve upwards
.
This
decreases the volume of the thoracic cavity
and the
increases the lung pressure
normal expiration is a
passive process
- it doesn't require energy
ALVEOLI AND GAS EXCHANGE
the lungs contain millions of microscopic 'air-sacs' where gas exchange occurs called
alveoli
the wall of each alveolus is made from a single layer of thin flat cells called
alveolar epithelium
. the alveoli are covered with
capillaries
(the walls of the capillaries are made of cells called capillary endothelium)
the walls if the alveoli contain a protein called
elastin
which helps the alveoli return to it's normal shape after inhaling and exhaling
THE MOVEMENT OF OXYGEN AND CO2 THROUGH THE GAS EXCHANGE SYSTEM
air moves down the trachea, bronchi and bronchioles into the alveoli,
down a pressure gradient
.
oxygen moves into the blood
where it can be transported around the body.
carbon dioxide moves down its own
diffusion and pressure gradients
but in the
opposite direction
to oxygen
oxygen diffuses out of the alveoli, across the alveolar epithelium and the capillary endothelium and into
hemoglobin
in the blood.
carbon dioxide diffuses across the same cells but in the opposite direction from the blood/capillary into the alveoli.
FACTORS AFFECTING THE RATE OF DIFFUSION
thin exchange surface
- the alveolar epithelium is only one cell thick meaning there is a quick rate of diffusion
large surface area
- there are millions of alveoli which means there is a large surface area for more efficient gas exchange.
steep concentration gradient
of oxygen and CO2 between the alveoli and the capillaries which increases the rate of diffusion.
lung disease
LUNG FUNCTION
lung disease affects how well the lungs function in terms of:
tidal volume
is the volume of air within each breath
ventilation rate
is the number of breaths per minute
forced expiratory volume (FEV1)
is the maximum volume of air that can be breathed out in 1 second
forced vital capacity FVC)
is the maximum volume of air it is possible to breathe forcefully out after a really deep breath.
TUBERCULOSIS
pulmonary tuberculosis (TB) is caused by bacteria.
when someone becomes infected the immune system builds a wall around the bacteria. this forms small, hard lumps called
tubercles
.
the infected tissues within the tubercles dies and therefore the gaseous exchange surface is damaged which decreases tidal volume.
TB also causes fibrosis.
symptoms of TB include:
persistent cough
coughing up blood and mucus
shortness of breath
fatigue
FIBROSIS
fibrosis is the formation of
scar tissue
in the lungs. this can be the result of infection or exposure to certain substances.
scar tissue is
thicker and less elastic
than normal lung tissue. this means the lungs are less able to expand and so can't hold as much air as normal.
because it is thicker it means there is a larger diffusion pathway making gaseous exchange harder.
symptoms of fibrosis include:
shortness of breath
dry cough
chest pain
fatigue and weakness
ASTHMA
asthma is a respiratory condition where the airways become inflamed and irritated. usually because of an allergic reaction but other factors can affect it.
during an asthma attack, the smooth muscle lining the bronchioles contracts and a large amount of mucus is produced. this causes
constriction of the airways
making it difficult for the sufferer to breathe.
symptoms of asthma include:
wheezing
tight chest
shortness of breath
symptoms can be relieved by drugs, often
inhalers
that cause the muscle in the bronchioles to relax
EMPHYSEMA
emphysema is caused by smoking or long term exposure to air pollution. this causes inflammation which attracts phagocytes to the area. the phagocytes produce
enzymes
that break down elastin.
therefore it causes the breakdown of the alveoli walls which decreases surface area and therefore rate of gaseous exchange decreases.
symptoms of emphysema include:
shortness of breath
wheezing