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Transport in Animals
Large organisms have mass flow transport systems/ circulatory systems
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All circulatory systems have:
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A circulatory fluid; transport medium

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Vascular system; system of tubes which the transport medium flows through

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Force; circulates the transport medium

Animals have
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The blood vascular system (Cardiovascular) – in conjunction with respiratory
system

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The lymphatic system

The tissue fluid
Cells are surrounded by extracellular tissue fluid and exchange of materials occurs
via this fluid
...
They
have a heart, blood vessels and a series of open spaces (sinuses) which make up the
haemocoel
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Blood under low pressure moves slowly between the tissue percolating back into the
heart through valved openings (ostia)
...

Closed circulatory systems
These are present in annelids, molluscs (very active) and all vertebrates
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Only
entry and exit: through the walls of the blood vessels
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Made up of plasma and specialised cells (red and white blood cells and
platelets)
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Plasma
This is a straw-coloured liquid containing proteins, mineral ions, hormones,
nutrients, gases and wastes
...

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They lack a nuclei, ER and Golgi so more space is available for haemoglobin

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Circular and biconcave discs – increasing SA to uptake and release CO2 and
O2
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Production is controlled by
erythroprotein, they have a short life span (120 days)
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It is stored
in the liver and taken to the bone marrow to make new haemoglobin
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If O2 is low, more RBCs are produced
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White blood cells (Leucocytes)
They are larger than RBCs, and also made in the bone marrow
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The protect the body against foreign invaders and use circulatory system to travel
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Examples:
ü Basophil – produce heparin (prevents blood clotting in undamaged vessels by
preventing prothrombin into thrombin) and histamine (found in damaged
tissues)
ü Neurtophil – phagocytes (engulf and digest disease – causing bacteria)
ü Eosinophil – attack parasites and possess antihistamine properties
ü Monocyte – enter tissue and become macrophages, which engulf bacteria and
particles
ü Lymphocyte – B and T cells – produced in bone marrow but T cells mature in
the thymus gland
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Pinch off form larger cells in
bone marrow
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Damage to a blood vessel exposes collagen fibres
2
...
Platelets swell and irregularly shaped and release clotting factors
4
...
Clotting factors activate other platelets and converts prothrombin into
thrombine
6
...
Fibrin sticks to one another, forming a fibrals network sealing the vessel
8
...
Platelets contract, pulling the mesh tighter (scab)
If one fails to clot, excessive bleeding results to hepatitis
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Heparin prevents the clotting in undamaged sites and the prothrombin into
thrombin
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Transports products of digestion
2
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Transports soluble excretory materials
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4
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Transports O2 and CO2
6
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Defence against disease by clotting, phagocytosis and specific immune
response




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The vascular system
Vessels away from the heart – arteries (branch into arterioles -> capillaries)
Vessels towards the heart – veins (branch into venules)
Artery à arterioles à capillaries à venules à veins
Arteries and Arterioles
(Aorta à lungs, subclavian à arms, carotids à head)
Have thick walls containing smooth muscle and many collagen and elastic fibres
...

The elastic fibres stretch when the heart beats and absorb some of the pressure
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Small arteries possess more smooth muscle fibres; determine how blood is
distributed within the body
...
This increases the blood pressure, speed and ridirects blood to the
heart and muscle for vigorous action
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Therefore dissipate excess heat
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-

Form a vast network – all cells are close to them

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Narrow so that RBCs can pass through in a single file (all close to the wals
and slow flow)

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Thin, made up of 1 layer of endothelial cells

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Permissible to water and dissolved substances

The blood hydrostatic pressure squeezes water and solutes into the intercellular
spaces – tissue fluids
...

Formation and absorption of tissue-fluid:
The blood volume is maintained even though fluids are leaking out
...
Blood hydrostatic pressure (outward force) squeezes water and solutes out of
capillaries
2
...


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Total cross-sectional area increases with an increases in distance

Oedema – accumulation of water in the extracellular spaces causing tissue swelling
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The diameter of the lumen of veins is larger than that of
arteries to offer less resistance (very low pressure)
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Blood returns to the heart by the negative pressure (suction) in the chest and
contractions of the skeletal muscles
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If blood pressure falls the nervous system stimulates contractions of smooth muscles
in the veins, which decreases the volume and raises blood pressure
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muscle, collagen &

muscular & elastic fibres)

only squamous endothelium

elastic fibres)
No semilunar valves

tissue
Semilunar valves present

No semilunar valves

to prevent backflow
High pressure & pulsatile

Low pressure & no pulse

Low pressure & no pulse

Oxygenated blood

Deoxygenated blood

Mixed blood

(except in pulmonary

(Except in pulmonary

artery)

vein)

Blood flow rapid

Blood flow slow

Blood flow very slow

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The lymphatic system
This is a series of lymphatic capillaries forming lymphatic vessel, which end in two
lymphatic ducts that empty into two veins at the neck
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g
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Absorbs and transports fats from intestine through lacteal vessels
2
...
Combat infections
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Circulation
Vertebrates have a closed circulatory system and progressive separation
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Artrium – receives blood from the body and pumps it into the ventricle
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The aorta sends blood to the body
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Circulation of the lungs – pulmonary circuit
Circulation to the body – systematic circuit
Advantages of double over single
1
...
Pulmonary circuit operates at a low pressure to prevent damage to the
capillaries
3
...

Connections in series and parallel
Humans: parallel
Portal vessel – links two organs, neither of which is the heart
...
The liver monitors blood
passing through it and help to maintain a constant composition

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Hypothalamus and anterior pituitary are connected by a portal system

The heart
(Ventral side of the body)
It is surrounded by the pericardium (outer layer – inelastic white fibrous tissue and
inner made up of: inner membrane attached to the heart and outer membrane
attached to the pericardium fibrous tissue)
Pericardium fluid is secreted between the 2 membranes and reduces friction
...

Right side

Left side

Deoxygenated blood (dark red)

Oxygenated blood (bright red)

Blood from the body enters the RA

Blood from the lungs enter the LA

through the superior & inferior vena cava

through pulmonary veins

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RA to the RV (passive flow) – relaxation

LA to the LV (passive flow) – relaxation

of the heart

of the heart

Atrium contracts, to push any blood left

Atrium contracts, to push any blood left

there

there (thin walls)

RV contracts & sends blood to lungs via

Strong LV contractions (start at base) &

pulmonary artery (low pressure)

blood to body via aorta (high pressure)

The LV has high pressure since the wall of the LV is three times as thick and has to
pump blood all over the body
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Atrioventricular valves: separate atria from ventricles
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Left: mitral/bicuspid

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Right: tricuspid

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Chordate tendinae are attached to papillary muscles – contract preventing the valves
from being turned inside out
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The cardiac cycle
Contractions à systole
Relaxation à diastole


Right side

Left side

Atrial diastole
Both atria are relaxed (ventricles are also relaxed)
Atrioventricular valves are closed
Deoxygenated

blood

enters

the

RA Oxygenated blood enters the LA through

through the superior and inferior vena the pulmonary veins from the lungs at

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cava from the body at low pressure

low pressure

As the atria fill with blood, pressure in them rises until it becomes greater than that
in the ventricles
Tricuspid valve is pushed open and the The bicuspid valve is pushed open and
blood flow into the RV

the blood flows into the LV

Atrial Systole
Rings of muscle which surround the vena cava and pulmonary veins contract and
close off the veins
The atria contract and top up the volume of blood in the ventricles

Ventricular systole
Both ventricles contract (starting from base) and pressure rises
Tricuspid and bicuspid valves are closed preventing backflow, first sound is heard,
described as ‘lub’
The chordate tendinae contract on both sides preventing the valves from turning
inside out
Pressure

opens

semilunar

valves

of Pressure opens semilunar valves of aorta

pulmonary artery
Blood enters the pulmonary artery and Blood enters the aorta and flows to the
flows to the lungs

rest of the body

The RV pumps blood to the lungs at a lower pressure, not to damage the capillaries
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Ventricular diastole
Both ventricles relax
High pressures developed in pulmonary The semilunar valve of the aorta also
artery tend to force some blood back closes
towards the RV and this closes the
semilunar valve to prevent backflow
...

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Pressure in ventricle is greater than the pressure in the aorta, semilunar
valves open

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Pressure in the aorta is now higher than that in ventricle; semilunar valves
close to prevent backflow and ‘dub’ is heard

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First sound does not have ‘pressure’ in the atrium

Histology of heart muscle
Walls are made up of connective tissue, blood vessels and cardiac muscle fibres
which form a complex net-like arrangement
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Cardiac muscle fibres contain actin and myosin filament; bring about
contractions and are striped
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The heart gets oxygen through the coronary arteries and wastes leave by the
coronary veins
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Coordination and heart contractions
Contractions are initiated by a pacemaker: cells that can produce electrical signals
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Signals from the SA node spread through both the atria
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These are separated by an
unexcitable tissue; atrioventicular septum (no gap junctions) so the flow of ions is
interrupted except in the RA – atrioventicular node
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These run to the base of ventricles and spread into finer branches called Purkinje
fibres
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Hear rate: number of beats per minute
Cardiac output = stroke volume x heart rate
Heart rate is controlled by the nervous and endocrine control systems
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When a person runs, vena cava stretches
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Cardiac output and pressure increase if the heart rate increases
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Pressure depends on:
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Resistance of flow by vessels

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Cardiac output (depends on heart rate and stroke volume)
Parasympathetic
nerve
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Vasomolar centre in
medulla oblongata
Sympathetic
nerve

vasodilation - larger
diameter (decreases
pressure)
vasoconstriction smaller diameter
(increases pressure)

Chemical control of the vasomotor centre
Blood with a lot of CO2 arriving at carotid arteries stimulate chemoreceptors to
transmit impulses to the vasomotor centre, which sends impulses to the blood
vessels to vasoconstrict (increase blood pressure)
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