Transcript Circulatory System

Unit 2 Notes
The Circulatory System
Overview of the Circulatory System
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Cells need oxygen and
nutrients in order to do
their work
They also need to get
rid of waste
The circulatory system
is what allows the cell
to exchange oxygen
and nutrients and
waste (it’s the body’s
transport system)
Overview cont.
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The circulatory system
is made up of: blood,
the heart, blood vessels
Blood carries
substances to all parts
of the body
The heart pumps blood
through a huge
network of tubes inside
your body called blood
vessels
Blood Vessels
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Think of blood vessels
like highways; they are
a network of channels
that circulate blood
through the entire body
and help keep the
blood flowing to and
from the heart
There are 3 different
kinds of blood vessels:
arteries, capilaries, and
veins (think – airplanes,
cars and vans)
Arteries
Arteries carry blood
AWAY from the heart
 They are strong, and
thick-walled so they
are capable of
withstanding high
pressures exerted by
blood as it’s pumped
by the heart
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Capillaries
Arteries branch into smaller
vessels called arterioles, which
become smaller in diameter as
they grow farther away from the
main vessel
 Capillaries are small blood vessels
where the exchange of important
substances and waste occurs
 They are very thin – only 1 cell
thick – so it’s easy to exchange
materials between the blood and
body cells through diffusion
 They’re so small that red blood
cells move single-file through
them, but they can expand if
needed (when exercising for
example)
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Veins
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After blood moves through the
capillaries, it enters larger
vessels called venules, and
then enters the largest blood
vessels called veins.
Veins carry oxygen-poor blood
(deoxygenated) back to the
heart (Your blood IS NOT
BLUE)
The walls of veins are thinner
than arteries because there’s
less pressure from the heart’s
original pushing force
*How can you tell if you’ve cut
a vein or an artery?
Brain Break
Draw the path that blood takes
going away from, and then back
into your heart, labeling each
blood vessel that it travels
through
The Heart
This is a muscular
organ that is about
the size of your fist.
It pumps blood
through your body
(pumps oxygenated
blood to the body,
and deoxygenated
blood to the lungs)
 It’s made of cardiac
muscle tissue
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The Heart cont.
It’s divided into four
compartments called
chambers
 The two on the top – left and
right atrium or atria – receive
blood that’s returning to the
heart. Below the atria are
the ventricles, which pump
blood away from the heart
 A strong muscular wall
separates the left and right
side of the heart
 Valves separate the atria
from the ventricles and keep
blood flowing in one
direction, and are also
located between each
ventricle and the large blood
vessels that carry blood away
from the heart
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Brain Break
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Draw and Label the
chambers of the heart
How the heart beats
The heart acts in two main
phases:
 1st, the atria fill with blood.
The atria contract, which
fills the ventricles with
blood
 2nd, the ventricles contract
to pump blood out of the
heart and into the lungs,
and forward into the body
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Heart beat cont.
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A group of cells in the right
atrium, called the pacemaker
(or sinoatrial- SA- node) send
out signals that tell the heart
muscle to contract. (each year
600,000 pacemakers are
implanted into people – the
battery usually lasts 5 to 8
years and needs to be
monitored frequently)
Your heart beats about 70
times a minute
To calculate your heart beat,
find your pulse on your wrist
below your thumb. Count the
number of beats you feel in 15
seconds, then multiply that
number by 4 (to get beats per
minute)
Blood Pressure
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Blood pressure is a measure of
how much pressure is exerted
against the vessel walls by the
blood and can give information
about the condition of the
arteries
The contraction of the heart
(systolic pressure) is when
your blood pressure is at its
highest point
The relaxation of the heart
(diastolic pressure) is the
lowest point
Anyone know ideal blood
pressure?
Blood flow in the body
Blood flows in 2 loops –
 First, the right side pumps
deoxygenated blood from the
heart to the lungs and then
back to the heart.
 Then, the left side pumps
oxygenated blood in another
loop from the heart through
the body and back.
 A detailed list of bloods path:
Superior and inferior vena cava –
right atrium – through the AV
(or tricuspid valve) -right
ventricle – through the
semilunar valve - pulmonary
arteries (away from heart) –
lungs – pulmonary veins
(returning to heart) – left
atrium – left AV valve - left
ventricle – aorta – body
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To the lungs and back
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When blood from the body flows into
the right atrium, it’s low on oxygen
and high in carbon dioxide (this blood
is not blue, it’s dark red)
The blood flows from the right atrium
into the right ventricle and is pumped
into the pulmonary arteries that lead
to the lungs
The blood flows into capillaries in the
lungs that are in close contact with the
air that enters the lungs
The air in the lungs has more oxygen
than the blood in the capillaries, so it
diffuses into the blood while carbon
dioxide diffuses in the opposite
direction, into the lungs.
The newly oxygenated blood goes to
the left atrium of the heart to be
pumped out to the body
To the body and back
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The left atrium fills with
oxygenated blood from the lungs,
which begins the second loop
The blood moves from the left
atrium into the left ventricle,
which pumps the blood into the
largest artery in the body called
the aorta
Blood flows into the capillaries
that branch throughout the body,
which are in close contact with
body cells
Oxygen is released from the blood
into the body cells by diffusion
and carbon dioxide moves from
the cells to the blood by diffusion
The deoxygenated blood then
flows back to the right atrium
through veins
Brain Break
Heart simulation activity AND
THEN drawing activity
Blood Components
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Blood is made of plasma, red
and white blood cells, and
platelets
Plasma is a clear, yellowish
fluid part of the blood (makes
up more than 50% of the
blood)
90% of plasma is water, and
the rest is dissolved material
Plasma carries glucose, fats,
vitamins, minerals, hormones,
and waste products
Plasma is made of proteins
(one of your macromolecules)
that help regulate water, fight
disease, and form blood clots
Blood components cont.
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Red blood cells carry
oxygen to all of the cells
in the body
Made in the bone marrow
They only live about 120
days
Made mostly of an ironcontaining protein called
hemoglobin (it’s what
gives blood its taste)
Platelets
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Platelets are cell fragments
that help form blood clots
If a blood vessel is cut, then
the platelets stick to the vessel
at the site of the wound then
release chemicals that produce
a protein called fibrin
Fibrin weaves fibers across the
cut
These fibers trap blood
platelets and red blood cells,
which forms a blood clot
White blood cells
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White blood cells are the
body’s disease fighters
Also made in the bone marrow
Some recognize diseasecausing organisms (like
bacteria) and alert the body,
while others surround and
fight them
There are fewer of these than
red blood cells – about one for
every 500 to 1000
They live longer then red blood
cells; they can live for many
months, or even years
Blood Groups
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There are marker
molecules attached to
red blood cells (called
blood groups); they
determine blood type
Blood groups cont.
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There are 4 types of blood – A,
B, AB, and O
If you ever need a blood
transfusion, you can only
receive certain blood types
because plasma contains
proteins called antibodies that
recognize red blood cells with
foreign markers and cause
those cells to clump together
Ex – if you have blood type B,
your blood contains antibodies
that cause cells with A marker
to clump; this can block blood
flow
O is the universal donor
AB is the universal receiver
Blood groups cont.
Rh factor is another marker found
on the surface of red blood cells
 If someone with Rh-negative
blood (no Rh factor) receives a
transfusion of Rh-positive blood
that has the Rh marker, it can
result in clumping of red blood
cells because of the antibodies
against Rh-positive cells
 It can cause complications during
some pregnancies (if the Rhpositive blood of a fetus mixes
with the mothers Rh-negative
blood, the mother will make antiRh antibodies. If the mother
becomes pregnant again, these
antibodies can cross the placenta
dn destroy red blood cells if the
fetus has Rh-positive blood)
 *may have been a problem for
Ann Boelyn
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Circulatory system disorders
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Atherosclerosis – blocked arteries
caused by blood clots or fat
deposits which reduce the flow of
oxygen and nutrient-rich blood
traveling through the arteries.
The heart has to work even
harder to pump blood and vessels
can burst
Can lead to a heart attack or
stroke
Heart attacks occur when blood
doesn’t reach the heart muscle
Strokes are caused when clots
form in the blood vessels that
supply oxygen to the brain, which
can lead to ruptured blood vessels
and internal bleeding (parts of the
brain die because brain cells are
deprived of oxygen)