Transcript Diapositiva 1 - Cloudfront.net

Transport system
Mrs jackie
The transport systems
 Made of the heart, blood vessels and
blood.
 Circulation through the heart
 Deoxygenated blood arrives from
the lower and upper parts of the
body and pours into the right atrium
through the vena cava
Inferior vena
cava
Superior vena
cava
Circulation
 The right atrium contracts and blood
is pushed into the right ventricle
through the atrioventricular valve or
tricuspic valve
 The right ventricle contract increasing
the pressure inside it and so he
atrioventricular valve closes and the
semilunar valve open and blood is
pushed out of the heart through the
pulmonary artery
Pulmonary vein
Circulation
 Blood is carried in the pulmonary
artery to the lungs, where gaseous
exchange takes place and the blood
becomes oxygenated
 The pulmonary vein carries the
oxygenated blood into the left atrium,
which contracts and pushes the blood
into the into the left ventricle through
the atrioventricular valve(aortic valve)
Blood Circulation
 The left ventricle contract and the
pressure increases closing the
atrioventricular valve and opening the
Mitral valve
 Blood is pushed out the heart through the
mitral valve into the aorta that take it to
all pars of the body.
 The aorta branches into arteries that enter
all body organs
Circulation
 Inside the organs the artery branches into arterioles and the
arterioles into capillaries
 Capillaries are sites of exchange of substances.
 Capillaries merge into venules which merge into veins
 Veins merge into the vena cava that takes deoxygenated blood
back to the right atrium.
Important facts of the circulatory
system
 The left side of the heart is completely separated from the right
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side by a thick muscular wall called septum
The right side contain deoxygenated blood the left side
oxygenated blood
The atria received blood from the body and the lungs
The ventricles pump out blood to the body and lungs
The atria is connected to veins, the ventricles to arteries
Veins carry blood to the heart; arteries away from the heartç
Veins carry deoxygenated blood except the pulmonary vein which
takes oxygenated blood from the lungs to the left atrium
Arteries carry oxygenated blood except the pulmonary artery
which takes deoxygenated blood from the right ventricle to the
lungs.
Important facts of the circulatory
system
 Atria have very thin muscular walls because they need to
pump blood only a short distance, which is to the two
ventricles.
 Ventricles have thicker walls because they need to pump the
blood to a longer distance.
 The left ventricle has more thicker walls than the right
ventricle. This is because it send blood to the aorta
 The right ventricle has thinner walls because it sends blood only
to the lungs, which are to a shorter distance away from the
heart.
Important facts of the circulatory
system
 Inside the heart the blood only moves from atria to
ventricles. The atrioventricular valves prevent blood from
returning back to the atria
 When the ventricles contract the atrioventricular valves close
and blood is pushed into the main arteries; pulmonary
arteries and aorta and leaves back.
 Arteries have much thicker walls than veins, because they
carry blood pushed by the ventricles with a very large force
 The aorta has the thickest walls of all arteries because it
receives blood from the left ventricle which contracts with a
big force causing high pressure in the aorta.
Important facts of the circulatory
system
 Between the main arteries and the ventricles, there are valves
that prevent the blood from returning to the ventricles when
the ventricles relax.
 Veins contain valves art certain intervals in the whole
circulation, ensuring a one way traffic of blood.
 The coronary arteries branch from the aorta.
Initiation and regulation of heart
beat
 Heart is said to be myogenic
 It initiates its beat intrinsically, which means that it does need a
message from the brain to start its beat.
 If the heart is cut away from the body and immersed in the correct
solution containing oxygen and all the needed salts and nutrients, it
can keep beating for a very long time.
 This is because a tissue called sinoatrial node (SAN) or the
pacemaker which spontaneously produces electric impulses, which
spread into the two atria causing them to contract.
 The atrioventricular node (AVN) localized lower down in the wall
between the right atrium and right ventricle fires impulses that
travel through muscle fibers to the two ventricles causing
contraction
Initiation and regulation of heart
beat
Brain control of heart rate
 The pacemaker received two nerves from the brain
 Sympathetic nerve- release noradrenalin and causes an increase
in heart rate
 Parasympathetic nerve- releases acetylcholine and lowers heart
rate
Adrenaline
• The hormone adrenaline released by the adrenal gland
situated above each kidney also increases the heart rate.
• It is called the flight or fight hormone, because it
prepares the body for situations of stress by increasing
the heart and breathing rate, and blood sugar levels.