2. CIRCULATORY SYSTEMS
• Diffusion & osmosis are processes that allow
substances to be transported into and out of cells.
• Substances transported over SHORT distances
by diffusion & osmosis.
• In organisms (amoeba) substances enter and leave
across cell membrane.
• Bigger organisms have many layers of cells, thus
need special transport system called the:
• CIRCULATORY SYSTEM
3. THE HUMAN CIRCULATORY SYSTEM
• CIRCULATORY SYSTEMS in humans consists of
3 main parts:
– A fluid (blood), which transports substances in
the body
–Blood vessels, which carry the blood and
– A heart, which pumps the blood around the
body.
4. • Blood flows around and around in the
CIRCULATORY SYSTEM and never leaves the
blood vessels unless they are damaged:
– CLOSED CIRCULATION
– To keep blood flowing, it has to pass through the
heart, which pumps the blood through the blood
vessels.
5. BLOOD
• Is a mixture of RED BLOOD CELLS, WHITE
BLOOD CELLS & PLATELETS in a watery liquid
called PLASMA.
6. BLOOD
– Red blood cells contain HAEMOGLOBIN – a
protein transporting the oxygen.
– White blood cells destroy germs & produce
chemicals called ANTIBODIES (help fight disease).
– Plasma – mainly water with digested food, CO2,
hormones, salts.
– Platelets – fragments of blood cells – forms clot
when you cut yourself.
7. BLOOD VESSELS
• The heart pumps blood around the body through a
system of tubes:
– BLOOD VESSELS.
• There are 3 types of blood vessels:
–ARTERIES: pump blood AWAY from the heart to rest of
body,
– VEINS: carry blood TO the heart, they have one-way valves
to stop blood from flowing backwards.
– CAPILLARIES: a network of very tiny blood vessels that
connect the arteries & veins. They release substances into
the cells & carry waste substances away from the cells.
8.
9. THE HEART
• The heart consists of 2 SEPARATE PUMPS joined
together.
• One pump pushes DEOXYGENATED BLOOD into the
lungs
– In the lungs O2 diffuses into the blood through the thin
capillary walls and CO2 diffuses out of the blood
• The other pump takes the OXYGENATED BLOOD and
pumps it to the other parts of the body.
• The body cells use up all the OXYGEN.
• The system is called DOUBLE CIRCULATION.
11. STRUCTURE OF THE HEART
• Each side of the heart is divided into 2 CHAMBERS:
– Upper chamber called ATRIUM
– Lower chamber called VENTRICLE
• Blood enters the heart through the (Atriums) ATRIA,
• The atria contracts and pumps the blood into the
ventricles.
– the right ventricle has thinner walls than left because it
only pumps blood to the lungs.
– The left ventricle walls have thick muscles to pump blood
to rest of the body.
click4biology.info
12. HEART
• The ATRIA (2x Atriums) & VENTRICLES are
separated by VALVES.
– The valves prevent blood from flowing back into
the atria from the ventricles.
– The left & right side of the heart is separated by a
wall of muscles: SEPTUM
medindia.netactivity.ntsec.gov.tw
13. HEART BEAT AND PULSE
• Human heart beats 70 times per minute.
• Beats can be higher/lower depending on
person’s fitness & how active he/she has
been.
• Each time the heart beats, the heart muscle
contracts & relaxes.
• Doctor uses a STETHOSCOPE to listen to your
heart.
14. PULSE
• Your PULSE is the CONTRACTION & RELAXATION of
the ARTERIES each time your heart beats.
– Pulse is different to heart beat.
• Ventricles contract forcing blood into the arteries.
– Arteries expand when blood is pushed into them,
– Elastic walls of arteries contract.
– When you take your pulse, you feel the EXPANSION of the
artery wall followed by the CONTRACTION.
– Place to feel pulse – WRIST & NECK.
15. PRACTICAL
• PREPARE PRACTICAL 2
• See Learner Guide P 17
• All that will be completed in prac are
the results and discussion
