when inhaling the intercostal contract causing the ribs to move up and out. at the same time the
diaphragm contracts causing a decrease in pressure in the lungs which means that air flows into the
lungs so the volume of air increases. When exhaling the intercostal muscles relax causing the lungs to
move in and down as the diaphragm relaxes causing pressure to increase and air is forced out of the
lungs which decreases the volume of air in the lungs.
tidal volume –
the volume of
air breathed in
or out in one
normal breath
vital capacity – the maximum
volume of air that can be
breathed out after breathing
in as much as you can
residual volume –
the volume of air
left in the lungs
after breathing out
as hard as you can
mucus -
dust sticks
to it
ciliated calls have
cilia which waft the
muscus out of
respiration system
polliution, dust particles, etc
pass through it. once it's in
there is way out. the cells are
thin and delecate
Methods of gaseous
exchange of amphibians and
fish restrict them to their
habitats i.e. amphibians need
moist habitats, fish gills only
work in water.
The permeable skin of amphibians
makes them susceptible to excessive
water loss
Fish gills work by forcing
water across the filaments.
Gaseous exchange occurs
within alveoli by diffusion
between air and blood.
Gaseous exchange surfaces are adapted for
efficient gaseous exchange in the following
ways: permeable, moist surface, large surface
area, good blood supply and thin lining (one cell
thick).
There are lung
diseases with
industrial causes (such
as asbestosis); with
genetic causes (such as
cystic fibrosis); caused
by life style (such as
lung cancer).
Asbestosis results in
inflammation and scarring
which limits gas exchange
Cystic fibrosis results
in too much mucus in
the bronchioles
Lung cancer is when cells
grow rapidly reducing surface
area in lungs.
The symptoms of asthma are:
difficulty breathing, wheezing,
tight chest and can be treated
with inhalers.
During an asthma attack: lining of airways becomes
inflamed, fluid builds up in airways, and muscles
around bronchioles contract constricting airways.
e
bile is stored in the gall
bladder. it neutralises material
in the stomatch to an optimum
ph. it helps break down fat
particles into ssmaller dorplets
by emulsifying.
smaller molecules have a
larger surface area than large
molecules. this means that
there is a faster rate of reaction
between the molecules and the
enzymes
small intestine is
adapted because...
large surface area
due to ridges called
villi
walls are only one cell
thick so food molecules
can easily diffuse
good blood supply so food molecules
are carried away and the diffusion
gradient increases
fat is separates from other food
molecules to avoid blockages as it is
carried off by the liphatic system
the ph of the stomach is very low. this is because
it maintains an optimum level for protease
enzymes to function. other enzymes work at a
different ph such as in the mouth and the small
intestine which have a ph close to neutral
The importance of
physical digestion is
so food can pass more
easily through the
digestive system and
to provide a larger
surface area.
Carbohydrates, proteins and
fats are digested by
specialised enzymes in the
mouth, stomach and small
intestine respectively:
carbohydrase breaks down
starch to sugar, protease
breaks down protein to
amino acids, and lipase
breaks down fat to fatty acids
and glycerol.
Stomach acid aids
protease function.
Breakdown of starch
is a two step process
involving the
breakdown of starch
into maltose and
maltose into glucose.
Small digested food
molecules are absorbed
into the blood plasma or
lymph in the small
intestine by diffusion.
f
if water concentration in blood
plasma is too high then the blood cells
absorbe the water through osmosis
and will explode (lysis) blood wouldn't
be able to flow and it would
agglutinate
low water consumption -
more urine less water - high
consentration
heat/excersize - less water, more
urine - high concentration
dialysis
‘Dirty’ blood (high in urea) is taken from a blood vessel in the
arm, mixed with blood thinners to prevent clotting, and pumped
into the machine. Inside the machine - separated by a partially
permeable membrane the blood flows in the opposite direction
to dialysis fluid, allowing exchange to occur between the two
where a concentration gradient exists.
Kidney failure has serious consequences as it means
that the water and ion balance cannot be regulated,
and the levels of toxic urea build up in the body. This
would ultimately be fatal if not treated.
carbon dioxide is removed from the body through respiration. when CO2 reacts
with water in blood plasma it created carbolic acid. carbolic acid lowers the ph of
the blood. the carotid arteries in the neck detect levels of CO2 in the body. the
carotid arteries send messages to the brain. then the brain send messages to
muscles such as the intercostal muscles, heart muscles and muscles in small
arteries telling them to contract.
The gross structure of a kidney and
associated blood vessels includes cortex,
medulla, ureter, renal artery and renal
vein.
Kidneys work by filtering blood
at high pressure, and
re-absorbing water and useful
substances.
Urea, is produced in the
liver (from excess amino
acids), and is removed from
the blood by the kidneys.
The structure of the kidney tubule (nephron) is related
to filtration of the blood and formation of urine. It
consists of: a filter unit of glomerulus and capsule, a
region for selective re-absorption, and a region for salt
and water regulation.
The concentration of urine is controlled by
the anti-diuretic hormone (ADH), released
by the pituitary gland.
ADH increases permeability
of kidney tubules so more
water is reabsorbed back into
the blood.
ADH production is controlled by a
negative feedback mechanism.
Increased carbon dioxide levels in the blood
are detected by the brain and the body
responds by increasing the rate of breathing.