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A-level
Transport in Mammals
The need for a transport system
in multicellular organisms
 As animal grew in size and complexity,
specific tissues and organs are developed.
 The system is needed to transport materials
such as food, oxygen to various organ.
 The waste such as carbon dioxide will be
removed.
The Composition of Blood
 Blood - cell particles 45%
– plasma 55%
 Plasma - water 92%
– plasma proteins 7%
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Fibrinogen
Prothrombin
Serum Globulins
Albumins
Cell particles
 erythrocytes
 leucocytes
 platelets
Transport functions of blood
 Oxygen is transported from lungs to tissues
 Carbon dioxide is transported from tissues to
lungs
 Organic digestive products and mineral salts will
be transported to various tissue
 Excretory products such as urea will be tranported
from liver to kidney
 Hormones such as insulin will be transported from
pancreas to liver.
 Heat is transported from liver and muscle to all
parts of the body to keep warm.
The role of haemoglobin in the transport
of oxygen and carbon dioxide
 Haemoglobin is a protein composed of four
polypeptide chains, two alpha and two beta
 Each chain will attached the atoms of iron
 The centre of the haemoglobin molecule is
HAEM which combines reversibly which oxygen
to form Oxy-haemoglobin.
Oxygen-dissociation curve
 The % of saturation of blood with oxygen is
plotted against the oxygen tension.
 S-shaped curve
 Haemoglobin absorbs oxygen rapidly at first and
progressively more slowly when the pigment
exposed to a gradual increase in oxygen tension.
 Partial pressure of oxygen in the lungs is usually
less than in the atmosphere because air in the
lungs includes the residual air from which some
oxygen has already been removed.
 The curve facilitates unloading
 Small drop in oxygen tension will bring a large
comparatively large fall in the % saturation of
blood and haemoglobin responds by giving up
more oxygen
 It takes up oxygen in the lungs and releasing it in
the tissue.
Bohr effect
 Increasing the carbon dioxide tension has the
effect of shifting the oxygen dissoication curve to
the right
 Heamoglobin must exposed to high oxygen
tension to become fully saturated
Comparison of oxygen dissociation curves for
fetal and maternal haemoglobin of humans
 The curve of fetal haemoglobin is to the left of the
mother's because fetus obtain oxygen through the
placenta. Thus, it must have a higher affinity for
oxygen than themother's haemoglobin
Myoglobin
 The myoglobin molecule is common is skeletal
muscle tissues of mammals and is responsible for
the colour of 'red muscle'
 It displays a greater affinity for oxygen and its
oxygen dissociation curve is displaced to the left
of haemoglobin.
 It acts as a storage of oxygen in resting muscle
 They release oxygen when supplies of
oxyhaemoglobin have been exhausted such as
severe muscular exercies.
Carriage of carbon dioxide
 Carbon dioxide is transported as
hydrogencarbonate ions
 Carbon dioxide combines with water to forem
carbonic acid which dissociates into hydrogen and
carbonate ions
The structure and function of blood
vessels
 Artery
– thick walll
– more elastic tissue
– the diameter of lumen is smaller
– no valves
– high pressure
– carries oxygenated blood except the pulmonary artery
 Vein
– thinner wall
– less elastic tissue
– the diameter of lumen is larger
– valves present
– low pressure
– carries deoxygenated blood except pulmonary vein
 Capillary
– thinest wall
– no elastic tissue
– the largest diameter of the lumen
– no valves
– carreis oxygenated and deoxygenated blood
– pressure lower than arteries but highter than veins
The diagram of the heart
The Structure of the heart
 The heart has 4 chambers (or spaces):
 Atria - receive blood
 Ventricles - pump blood away to organs
 The heart is divided in left and right sides.
 The right atrium receives blood from the entire
body except from lungs.
 The right ventricle pumps this blood to the lungs
 The left atrium receives blood from the lungs.
 The left ventricle pumps the blood to the all the
organs in the body.
The cardiac rhythm
 All vertebrate hearts are myogenic which the heart
beat is initiated wihtin the heart muscle itself
rather than by a nerve impulse form outside.
SA (Sinoatrial) Node
 Called "pacemaker" because it keeps the
heartbeat regular.
 Determine the basic rate of heart beat
 Found in the upper dorsal wall of the right atrium.
 Initiates the heartbeat by sending excitation
impulse every 0.85 seconds to cause the atria to
contract.
AV (Atrioventricular) Node
 Found at the base of the right atrium near the
septum.
 When receives stimulation from SA node, AV
node signals ventricles to contract by way of
Purkinje fibers.
Bundles of His and Purkinje Fibres
 Receive the signal from the purkinje fibres,
ventricles contract simultaneously
 Blood will be squeezed out towards to the
pulmonary arteries and aorta
Cardio-vascular Centres
 Present in the medulla oblongata of the brain
 Cardio-acceleratory centre is linked by the
sympathetic system to the SA node, cardic output
can be increased by stimulated this nerves
 Cardio-inhibitory centre is linked by the parasympathetic fibres within the vagus nerve, to the
SA node, AV node and bundle of His. They
decrease the cardiac output.
 Sympathetic nerves have more stimulation
-------------> faster heart beat
 Vagus nerve have more stimulation
-------------> slower heart beat
Nervous and hormonal control of the
heart beat
 I. Carbon dioxide
– 1.Carbon dioxide in blood is high
• pH of blood is low
• It will stimulates the chemo-receptors in the carotid
body and aortic arch
• They send nerve impulse along the afferent nerve to
the Cardio-acceleratory center
• Nerve impulses are sent along the sympathetic
nerves to the SA node to increase the rate of heart
beat
• Increase the rate for delivering carbon dioxide to the
lungs for removal
 2. Carbon dioxide in blood is low
– Fall in carbon dioxide
– pH of blood will rise
– It will stimulates carotid body to reducing the heart beat
through cardio-inhibitory centre.
II. Oxygen
 Oxygen tension in blood is low when the body is
active.
 It will stimulate the chemo-receptors in the carotid
bodies.
 The nerve impulse produced will be transmitted to
the cardio-acceleratory centre
 Heart beat will be increased
III. Hormones
 Thyroxine and adrenalin increase the heart beat
 Acetylcholine decrease heart beat
The diagram of lymph vessel
Lymph
 The tissue fluid drained into lymph capillaries is
known as lymph.
 Lymph system is closely associated with
cardiovascular system.
 Takes up excess tissue fluid and returns it to
bloodstream.
 Absorbs fats in intestinal villi and transports them
to bloodstream.
 Helps defend body against disease by producing
lymphocytes and anti-bodies to destroy the
bacteria.
Lymphatic Vessels Transport One Way
 Most body regions richly supplied with lymphatic
capillaries.
 Structure of larger lymph vessels similar to veins
including presence of valves.
 Movement of lymph depends upon skeletal muscle
contraction, similar to veins.
 Lymph capillaries take up unabsorbed tissue fluid.
 Once within lymph vessels, fluid is termed lymph.
Lymphatic capillaries join to form
two ducts:
 Right lymphatic duct serves right arm, right side
of head and neck, and right thoracic area.
 Larger thoracic duct serves left arm and thoracic
area, abdomen and lower body.
 Both ducts drain into the subclavian veins in the
thorax.