Download Circulation and Gas Exchange

Circulation and Gas
Exchange
Intermediate 2 Biology
Unit 3
ANIMAL PHYSIOLOGY
Learning Objectives
Circulation
• Describe the structure of the heart in
relation to its function as a muscular
pump. (to include the four chambers,
valves, wall thickness and blood
supply)
• State that the heart receives its blood
supply from the coronary artery and
describe what affect a blockage in
this artery would have.
The Heart
• The function of the heart is to pump
blood round the body.
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The Heart
• The heart consists of four chambers.
– Atria – two upper chambers
– Ventricles – two lower chambers
The Heart
Right atrium
Right ventricle
Cardiac muscle
Left atrium
Left ventricle
The Heart
• The ventricles pump the blood
– Left Ventricle
• Round the body
– Right ventricle
• To the lungs
• The atria receive blood
• valves in the heart prevent the
backflow of blood
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The heart
semi-lunar valve
atrio-ventricular
valve
semi-lunar valve
atrio-ventricular
valve
The Heart
Pulmonary artery
Aorta
Vena cava
Pulmonary vein
The Heart
• All blood must pass through the heart
twice in each circulation.
• Deoxygenated blood from the body
enters the heart through the vena
cava into the right atrium.
• Complete the stages of circulation
until the blood is back in the vena
cava again.
The Heart
• Deoxygenated blood passes through
the right AV valve into the right
ventricle.
• Right ventricle contracts and blood is
pumped into the pulmonary arteries
through the semi-lunar valve
• In the lungs the blood loses its carbon
dioxide and gains fresh oxygen before
entering the pulmonary veins.
The Heart
• This oxygenated blood now returns to
the heart and enters the left atrium.
• Oxygenated blood moves through the
left AV valve into the left ventricle.
• The left ventricle then pumps the
blood through the SL valve into the
aorta which takes it around the body.
The Heart
• The wall of the left ventricle is very thick
since it has to pump blood all round the
body.
• The wall of the right ventricle is less thick
since it pumps blood only to the lungs.
The Heart
• The heart wall is made of cardiac
muscle and also requires its own blood
supply.
• The blood vessels which do this are
called the coronary arteries.
Coronary Arteries
Coronary artery
Coronary arteries
• Coronary arteries supply oxygen and
glucose to the cardiac muscle
• Coronary veins return the blood to the
vena cava.
• If the coronary arteries narrow or
become blocked in any way, this can
result in angina, a heart attack or in
severe cases heart failure.
Learning Objectives
Circulation
• Describe the path of blood flow
through the heart and its associated
vessels.
• Describe the functions of arteries,
capillaries and veins; give structural
adaptations of these blood vessels in
relation to their function.
Blood Vessels
• There are three main types of blood
vessel – arteries, veins and capillaries.
• Arteries carry blood away from the
heart.
• Veins carry blood back to the heart.
• Capillaries connect arteries to veins
and this is where the exchange of
essential materials takes place.
Arteries
• Arteries have thick muscular walls.
• This allows them to withstand the
pressure created by the heart.
Arteries
• Pulse
– Each time the heart beats, blood is forced
along the arteries
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Veins
• Veins have thinner walls than arteries
but a wider cavity.
• This is because the blood is now at a
much lower pressure.
Veins
• Veins contain valves
– prevent the backflow of blood.
Capillaries
• Capillaries are microscopic blood
vessels
Capillaries
• Walls are only one cell thick.
– allows for the exchange of materials
between the blood and body cells
– Examples - glucose, oxygen, carbon
dioxide
Learning Objectives
Circulation
• Give the names and positions of;
pulmonary artery and vein, aorta and
vena cava, hepatic artery, hepatic
vein, mesenteric artery, hepatic portal
vein, renal artery and renal vein.
• Colour in the key
and the diagram
using
– Blue
• deoxygenated blood
– Red
• Oxygenated blood
Circulatory System
Pulmonary artery
Vena cava
Hepatic vein
Hepatic portal vein
Renal vein
Pulmonary vein
Aorta
Hepatic artery
Mesenteric artery
Renal artery
Pulmonary artery
Vena cava
Pulmonary vein
Aorta
Hepatic vein
Hepatic artery
Hepatic portal vein
Mesenteric artery
Renal vein
Renal artery
In Summary – the bare minimum
• Blood leaves heart in arteries, flows through
capillaries and returns to heart in veins
• The pulse indicates that blood is pumped
through arteries;
• Structural adaptations of arteries, veins and
capillaries related to function.
• The heart obtains its blood supply from the
coronary arteries.
Learning Objectives
Gas Exchange
• Describe the internal structure of the
lungs (to include trachea, bronchi,
bronchioles, and alveoli).
• Describe the features of the alveoli which
allow efficient gas exchange
• Describe the role of diffusion in the
exchange of oxygen and carbon
dioxide.
• Describe the features of the capillary
network which allow efficient gas
exchange in tissues.
Gas Exchange
• Gas exchange occurs in the lungs.
• Stages
– Inhalation
– Gas Exchange
• oxygen from the air passes from the lungs into
the blood and carbon dioxide passes from the
blood into the lungs.
– Exhalation
Structure of the Lungs
• Air passes down the
– trachea (windpipe) which splits into 2 bronchi
– Bronchi split into smaller tubes called
bronchioles.
– bronchioles terminate in tiny air sacs called
alveoli.
• The trachea and bronchi are kept open
by rings of cartilage
– The cartilage stops the airways from
collapsing when the pressure changes
Alveoli
Bronchiole
Blood
Capillary
Alveolus
Gas Exchange
• Alveoli provide a large surface area for
the gas exchange
• The lining of each alveolus
– very thin
– Moist
– Surrounded by a capillary network
Gas Exchange
• Blood arriving in the lungs from the body is
deoxygenated.
• Oxygen diffuses through the thin lining of the
alveolus into the blood capillary
– Diffusion takes place because the concentration
of oxygen in the alveolus is higher than the
oxygen concentration in the blood.
Gas exchange
• Carbon dioxide diffuses in the opposite
direction.
– the concentration of CO2 in the blood
from the body is higher than the
concentration of CO2 in the alveoli.
• The blood now leaving the lungs is
oxygenated.
Features which make gas
exchange more efficient.
Feature
Function
Thin lining
To allow rapid diffusion
Lining moist
Allows oxygen to
dissolve
Large surface area
To absorb oxygen
Dense network of
capillaries
To absorb and
transport oxygen