The
Circulatory
System
Which activity caused the pulse
rate to increase the most?
The activity that was the most
rigorous.
What is the relationship
between physical activity and
pulse rate?
Increased physical activity
causes and increased pulse
rate.
Why do you think activity
caused the heart to pump
faster?
The muscles need more
oxygen and need to get rid of
waste faster. The heart
pumps faster to get more
blood to the muscles.
The Circulatory System
• Made up of (organs):
– heart
– blood vessels (veins
and arteries)
– blood
– smooth muscle
– cardiac muscle
Main Functions
• Moves needed materials around the
body
– glucose
– oxygen
– water
– lipids
• Carries waste away from the cells
– carbon dioxide
– lactic acid
– urea
• Contains disease fighters
The Heart
• Hollow, muscular organ that pumps
blood throughout the body
– size of your fist
– located in the center of the chest
Structure of the Heart
• The heart has two sides
• Each side has an upper chamber
– Atrium
• Each side has a lower chamber
– Ventricle
Structure of the Heart
• Blood enters the heart through the atria
– From the body – right atrium
– From the lungs – left atrium
• Blood leaves the heart through the
ventricles
– To the body – left ventricle
– To the lungs – right ventricle
How the Heart Works
How the Heart Works
• The heart’s action has two phases
– The heart relaxes and the atria fill with
blood
– The atria contract, blood is pumped into
the ventricles, then the ventricles contract
and send blood out of the heart
• Blood only travels in one direction, it
cannot flow backwards
Regulation of the Heartbeat
• The heart contains pacemaker cells
that tell the heart when to beat
– When you are exercising, excited, scared
etc…, your heart beats faster
– When you are relaxed, calm, asleep etc…,
your heart beats slower
Blood Vessels
• Blood vessels transport blood around
your body
• They run through all the tissue in your
body
• Some are as wide as your thumb
• Some are as small as a hair
Arteries
• Carries oxygen rich blood away from
the heart
• The ventricles of the heart pump into
the arteries to get blood to the rest of
your body
• As arteries get further from the heart,
they branch and get smaller and turn
into arterioles
• Artery walls are very thick, strong and
flexible
• They contain smooth muscle that
contracts or relaxes to let more or less
blood through
Arteries
Regulating Blood Flow
• The muscles in the middle layer are
involuntary smooth muscles
• When they contract, the artery
becomes smaller
• When they relax, the artery becomes
larger
Regulating Blood Flow
• When an organ needs more blood, the
arteries relax to let more flow in
• Food in your stomach triggers your
arteries going to the stomach to relax
so more blood is sent there
• During exercise, the arteries to your
stomach contract and the arteries to
your legs and arms relax
Capillaries
• Arterioles turn into capillaries
• Tiny blood vessels where material is
exchanged between the blood and the
body’s cells
• Oxygen and glucose rich blood from
the arteries goes into the capillaries
• From the capillaries needed materials
pass into the cells and waste material
is removed from the cells
Capillaries
Veins
• Capillaries then connect to venules
• Venules widen into veins
• The veins carry oxygen poor blood
back to the heart
• Blood with carbon dioxide and other
cellular wastes pass from the
capillaries into the veins
• Veins have 3 layers to their walls too
but the wall is much thinner
• Muscle contractions, breathing and
valves help move blood through veins
Veins
Oxygen rich blood
from an artery
Oxygen poor blood
from a vein
Red Blood Cells
• Contains hemoglobin that carries
oxygen
• disk shape helps them fit into
capillaries
• They have 4 month life span
• New red blood cells are produced
in bone marrow
Red Blood Cells
• there is a rare
condition where
hemoglobin is
replaced by
methemoglobin
• red blood cells can’t
carry much oxygen
• creates blue skin
White Blood Cells
• larger than rbc’s
• they can leave the blood stream
and enter into tissue
• 13-20 day lifespan
• they fight disease
•
Platelets
• irregularly shaped and colorless
• they help the blood form clots to
stop bleeding
• 5-10 day lifespan
Body systems that work with
the circulatory system;
• Depends on the muscular system
to pump the blood and move it
around the body, the respiratory
system to get oxygen to the blood,
the digestive system to supply
energy to the cells, and the skeletal
system to provide new red blood
cells