Transport in Animals Detailed Summary

my transport in animals summary from last year, it's for the old spec but could help out this years AS students too // also those that are retaking!
made in pages so might look weird in word.

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  • Created by: amehlia
  • Created on: 10-04-16 12:19
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Amelia Kirk
Transport in Animals summary
Transport systems in animals
transport systems in large multicellular organisms are needed because of: size, SA:V ratio,
and level of activity
animals need oxygen & nutrients to survive & need to remove waste products
large layers of cells, cells on the inside will not receive enough nutrients/oxygen diffusing
through, cells deep inside the body will die
Surface-area-to-volume ratio
animals that grow to a large size need a range of tissues & structural support, volume
increases as body gets thicker but the surface area does not increase as much so SA:V ratio
is not large enough to supply all oxygen & nutrients needed by internal cells
Level of activity
more energy needed for animals like mammals that keep themselves warm and do lots of
things, more oxygen is needed to be supplied to the cells, efficient transport systems needed
Features of good transport system:
fluid to carry nutrients and oxygen around body (blood)
pump to create pressure to push fluid (heart)
exchange surfaces enabling oxygen and nutrients to enter blood and to leave it
tubes/vessels to carry blood
two circuits - one picking up oxygen & another delivering oxygen
Single & double circulatory systems
blood travels in a single circuit, e.g. fish- from heart, to gills, to tissues and back to heart
one system takes blood through lungs
(pulmonary circulation )
other circuit takes oxygenated blood to
tissues ( systemic circulation)
mammalian heart is adapted to form two
pumps for double circulation, blood
flows through heart twice for each
circulation of the body
single: blood pressure reduced as blood
passes through capillaries in gills, slows
flow, limited rate oxygen and nutrients
delivered to respiring tissues
double: heart can increase pressure of
blood after it has passed through the
lungs, blood flows more quickly to tissues,
systemic circulation can carry blood at
higher pressure than pulmonary
circulation, blood pressure cannot be too
high in pulmonary circulation otherwise
blood capillaries will be damaged
Structure of the mammalian heart

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The Cardiac Cycle
Diastole (filling phase):
atria and ventricles relaxing, internal volume increases & blood flows in heart from major veins
blood flows into atria then into ventricles through atrioventricular valves
Atrial systole (atrial contraction)
heart beat starts when atria contract (both right & left together)
small increase in pressure helps push blood into ventricles, once ventricles are full they begin
to contract
blood fills atrioventricular valve flaps causing them to snap shut & prevent back flow of blood
Ventricular systole (ventricular contraction)
short time…read more

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Control of the cardiac cycle
the heart is described as myogenic as it can initiate its own contraction, the muscle with
contract & relax rhythmically even if not in the body, and this property can cause fibrillation
(inefficient pumping)
I. heartbeat starts at the top of the right atrium, at the sinoatrial node (SAN), a small patch of
tissue generating a wave of depolarisation/electrical activity at regular intervals (SAN is also
known as the pacemaker)
II.…read more

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carry blood away from heart at high pressure
small lumen to maintain high pressure
thick wall containing collagen to give it strength to withstand pressure
elastic tissue in the wall allows it to stretch & recoil when the heart pumps (felt as a pulse)
recoil maintains high pressure
smooth muscle in wall can contract & constrict artery narrowing lumen (in arterioles this is
used to limit blood flow to certain organs & tissues & directly it elsewhere)
endothelium is folded & can unfold when…read more

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Carriage of oxygen
oxygen is transported in the erythrocytes which contain the protein haemoglobin (Hb)
this becomes oxyhaemoglobin
has 4 subunits consisting of a polypeptide chain & a haem (non-protein) group which
contains a single iron atom in the form Fe
the iron ion can attract & hold an oxygen molecule, haem group has an affinity for oxygen
each haemoglobin molecule can carry 4 oxygen molecules
oxygen diffuses into the blood plasma to be taken up by Hb, the oxygen is taken out of…read more

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CO2 + H2
O --> H2
carbonic acid dissociates to release hydrogen ions (H+ ) & hydrogen carbonate ions (HCO
hydrogencarbonate ions diffuse out of red blood cell into plasma
charge inside blood cell maintained by chloride shift, movement of chloride ions (Cl-
) from
plasma into red blood cell
hydrogen ions make contents of red blood cell acidic, to prevent this hydrogen ions are taken
up by haemoglobin: haemoglobinic acid (haemoglobin acts as buffer)
the hydrogen ions displace the oxygen from haemoglobin,…read more


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