The Circulatory System

The Circulatory
System
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 The Circulatory System is responsible
for transporting materials throughout
the entire body.
 It transports nutrients, water, and
oxygen to your billions of body cells
and carries away wastes such as
carbon dioxide that body cells
produce.
 It is an amazing highway that travels
through your entire body connecting
all your body cells.
© iTutor. 2000-2013. All Rights Reserved

Components
 Heart
 Blood
 Vessels
 Arteries
 Veins
 Capillaries
Heart
Blood
ArteriesVeins

 Which gases are transported to and from the body’s
cells by the blood flowing in the circulatory system?
carbon
dioxide
oxygen
Oxygen is the gas needed for respiration and is
transported to the body’s cells.

 The circulatory system carries two types of blood
 Arrangement of the circulatory system means that these
two types of blood do not mix.
Oxygen-rich
blood
c
Oxygen-poor
blood
 Blood travelling
to the body cells
 High oxygen content
 Low carbon dioxide content
 Blood travelling
away from the body cells
 Low oxygen content
 High carbon dioxide content

 The heart is the organ at the centre of the circulatory
system. It pumps blood around the body.

 The inside of the heart is divided into two sections so
that the two types of blood (oxygen-rich and oxygen-
poor) are kept apart
Oxygen-poor
blood
Right side
of the heart
Oxygen-rich
blood
Left side
of the heart

 Heart coverings
 Pericardium
 Covers the heart and large blood vessels attached to
the heart
 Visceral pericardium
 Innermost layer
 Directly on the heart
 Parietal pericardium
 Layer on top of the visceral pericardium

 Pericardium
 Protective sac of
connective tissue
 Surrounds the heart
 Filled with fluid

 Heart walls:
 Epicardium
 Outermost layer
 Fat to cushion heart
 Myocardium
 Middle layer
 Primarily cardiac muscle
 Endocardium
 Innermost layer
 Thin and smooth
 Stretches as the heart pumps

 Myocardium
 The muscle of the heart
 Strong and thick
 Composed of spontaneously
contracting cardiac muscle
fibers
 Can conduct electricity like
nerves.
 It’s blood supply comes
from the coronary arteries.

 The right and left sides of the heart are separated by a
septum, or wall.
 The septum prevents the mixing of oxygen rich and
oxygen poor blood.
 On each side of the septum are two chambers.
 The upper chamber (receives blood) is the atrium.
 The lower chamber (pumps blood out of heart) is the
ventricle.

 Four chambers
 Two Atria
 Upper chambers
 Left and right
 Separated by interatrial
septum
 Two Ventricles
 Lower chambers
 Left and right
 Separated by interventricular
septum
Right Ventricle
Right Atrium
Left Ventricle
Left Atrium

 The chambers of the heart have different functions:
blood to
the body
blood from
the body
blood to
the lungs
blood from
the lungs
The Atria
collect blood
that enters the
heart.
The ventricles
pump blood
out of the
heart.

 The valves between the atria and ventricles are connected
to the inner walls of the heart by tough tendons.
valve open© iTutor. 2000-2013. All Rights Reserved

 The tendons allow the valves to close and hold the valve
flaps in place. They prevent the valves from flipping up
and turning inside out
valve open valve closed

 A valve acts like a door that only opens in one direction.
 If the door is held by someone at a fixed point, only the arm
moves as the door opens and closes.
 When the door is closed the arm is fully extended, so the
door can only be opened in one direction.

 A valve acts like a door that only opens in one direction.
 In the heart, the tendons holding the valve are like the
arm holding the door.
 One end of each tendon is fixed to the wall of the heart
and so the valve can only open in one direction.

 The heart can pump blood because it is made of muscle.
Muscle tissue works by contracting (squeezing) and
relaxing.

 All the parts of the heart on
either side, work together in a
repeated sequence.
 The two atria contract and
relax; then the two ventricles
contract and relax.
 This is how blood moves
through the heart and is
pumped to the lungs and the
body.
 One complete sequence of
contraction and relaxation is
called a heartbeat.

 As blood moves through the
circulatory system it moves
through 3 types of blood
vessels:
 Arteries: Carry blood away
from the heart .
 Capillaries: Link arterioles to
veins.
 Veins: Carry blood towards
the heart

Arteries
 Large vessels
 Carry blood from heart to tissues of body.
 Carry oxygen rich blood, with the exception of pulmonary
arteries.
 Thick walls-need to withstand pressure produced when heart
pushes blood into them.
 Smallest blood vessels
 Walls are only one cell thick and very narrow.
 Important for bringing nutrients and oxygen to tissues
and absorbing CO2 and other waste products.
Capillaries

 Once blood has passed through the capillary systems it
must be returned to the heart. Done by veins
 Walls contains connective tissue and smooth muscle.
 Largest veins contain one way valves that keep blood
flowing toward heart.
 Many found near skeletal muscles. When muscles
contract, blood is forced through veins.

 The heart produces pressure
 The force of blood on the wall of the arteries is
known as blood pressure.
 Blood pressure decreases as the heart relaxes,
but the rest of the circulatory system is still
under pressure.

 When blood pressure is taken, the cuff is wrapped
around the upper portion of the arm and pumped with
air until blood flow in the artery is blocked.
 As the pressure in the cuff is relaxed, 2 numbers are
recorded.
 Systolic pressure- the first number taken, is the force felt in the
arteries when the ventricles contract.
 Diastolic pressure- the second number taken, is the force of the
blood on the arteries when the ventricles relax.

Blood
 What percent of your body is blood?
 How much blood do we contain?
 On average 4-6 liters
 We contain about a pint of
blood for every 15 pounds
of body weight
 Composition of Blood:
 What percent of your blood is
cellular?
 What percent of your blood is
plasma?
8%
45%
55%

Blood
 Composed of plasma and blood cells
 Types of Cells are:
 Red Blood Cells
 White Blood Cells
 Platelets
 Plasma
 Straw colored
 90% water
 10% dissolved gases, salts, nutrients, enzymes,
hormones, wastes, and proteins.

Blood
 Plasma proteins
 3 Types: Albumins, globulins and fibrinogen.
 Albumins and Globulins- transport substances such as fatty
acids, hormones and vitamins.
 Fibrinogen- Responsible for blood’s ability to clot
 Red Blood Cells
 Most numerous type
 Transport oxygen
 Get color from hemoglobin
 Disk shaped
 Made in red bone marrow
 Circulate for 120 days

 White Blood Cells
 Guard against infection, fight parasites, and attack bacteria
 Number of WBC’s increases when body is fighting
 Lymphocytes produce antibodies which fight pathogens
and remember them
Blood
 Platelets
 Aid the body in clotting
 Small fragments
 Stick to edges of broken blood cell and secrete clotting
factor to help form clot.

Blood
Blood has 3 main
Functions
 Transport
 Protection
 Temperature
Regulation
Plasma
Red Blood
Cells
Platelets
White Blood
Cells

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The Circulatory System

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