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Circulatory system - Weebly


  • pg 1
									S. MORRIS 2006
            What is the circulatory system?

Ø   The circulatory system carries blood and dissolved
    substances to and from different places in the body.

Ø   The Heart has the job of pumping these things around
    the body.

Ø   The Heart pumps blood and substances around the
    body in tubes called blood vessels.

Ø   The Heart and blood vessels together make up the
    Circulatory System.
               The Heart
• Very muscular, about the size of your fist
• Major portion of the heart known as
  MYOCARDIUM and composed of cardiac
• A PERICARDIAL SAC covers the heart,
  made from epithelial and fibrous tissue,
  that contains lubricating liquid
Our circulatory system is a double circulatory system.
              This means it has two parts parts.


the right side of                           the left side of
  the system                                  the system

   deals with                                 deals with

 deoxygenated                                oxygenated
                          Body cells

   The SEPTUM separates / divides the 2 sides
                 How does this system work?

pulmonary vein                 lungs            pulmonary artery

                           head & arms

                   main vein

                       Right             Left


                         digestive system



                      Circulatory System
                             The Heart

 This is a vein. It brings                  These are arteries.
 blood from the body,                       They carry blood
 except the lungs.                          away from the heart.

2 atria
                                             Coronary arteries,
                                             the hearts own
          2 ventricles                       blood supply

The heart has four chambers

                  now lets look inside the heart
                           The Heart

               Artery to Lungs    Artery to Head and Body

Vein from Head and Body
                                           Vein from Lungs

Right Atrium
                                                 Left Atrium

         valve                               valve

Right Ventricle                              Left Ventricle
               The Valves
• There are 4 valves in the heart:
  – 2 Atrioventricular Valves (AV Valves)
  – 2 Semi-Lunar valves (SL Valves)
               AV Valves
• Between the artia and ventricles
• Control the flow of blood between the
  chambers, and prevent backflow
  – TRICUSPID VALVE: between the right atrium
    and right ventricle. It has 3 flaps.
  – BICUSPID VALVE: between the left atrium
    and left ventricle. It has 2 flaps.
          Chordae Tendinae
• support the valves and prevent them from
  inverting. They are attached to muscles in the
  ventricular walls
            The SL Valves
• Between the ventricles and the attached
  blood vessels
• Blood flows through these valves as it
  leaves the heart
• Pulmonary SL Valve: right side, right
  ventricle pumps blood to lungs through the
  pulmonary artery
• Aortic SL Valve: left side, left ventricle
  pumps blood to body through the aorta
• Deoxygenated blood NEVER mixes with
  oxygenated blood.
• Remember too that both atria contract at
  the same time (simultaneously), and the
  ventricles both contract at the same time
                 How does the Heart work?


blood from the             blood from
body                       the lungs

                            The heart beat begins when the
                            heart muscles relax and blood
                            flows into the atria.
               How does the Heart work?


The atria then contract and
the valves open to allow blood
into the ventricles.
             How does the Heart work?


                    The valves close to stop blood
                    flowing backwards.

                    The ventricles contract forcing
                    the blood to leave the heart.

                    At the same time, the atria are
                    relaxing and once again filling with

        The cycle then repeats itself.
 Heartbeat: the sound you hear
  – first heart sound
  – Occurs when the A-V valves close due to
    ventricle contraction and is known as Systole
    (pressure in ventricle is higher than pressure
    in the atrium)
  – Louder and longer than the second heart
 – Sharp and short sound
 – Occurs when the S-L valves snap shut
 – Known as Diastole (when the ventricles relax)
• Systole: refers to CONTRACTION of the
  heart muscle
• Diastole: refers to RELAXATION of the
• Cardiac Cycle is another name for the
  heartbeat, it occurs on average 70 times
  per minute in an adult.
  What controls the heartbeat?
• 2 ways: Intrinsic (without the brain telling
  it) and Extrinsic (brain involved)
• Intrinsic: has special tissue called Nodal
  Tissue (has both nerve and muscle tissue)
  1. SA (sinoatrial) Node: located in the upper
     back wall of the right atrium (also called the
     Pacemaker of the heart)
     • Initiates the heartbeat by sending a signal every
       0.85 seconds to make the atria contract
2. AV (atrioventricular) Node: found at the
   base of the right atrium near the septum
• When pulse from the SA node reaches
   the AV node, the AV node sends out a
   signal to special fibers called Purkinjie
   Fibers to message the ventricles to
            Text page 245
• Intrinsic controls the steady beating of
  your heart, Extrinsic factors can control
  how fast your heat beats
• This involves Nervous Control, by a part of
  your brain called the Medulla Oblongata
• This part of your brain can sped up or slow
  down your heart rate depending on stimuli
  it receives from the Autonomic Nervous
  System (ie. Stress, oxygen levels, blood
           Blood Pressure
• Measured using a SPHYGMANOMETER
• 2 numbers:
 – First number (bigger number ALWAYS) is the
   highest arterial pressure reached during
   ejection of blood from ventricles of the heart
 – Second number (lower number ALWAYS) is
   the lowest arterial pressure while the
   ventricles are relaxing (DIASTOLIC)
• Blood pressure decreases with distance
  from the heart and as a result the velocity
  of blood also decreases gradually, which
  is very important because the slow
  movement going into capillaries allows for
  exchange of substances between blood in
  capillaries and surrounding tissues.
         blood from the heart gets around

          the body through blood vessels

There are 3 types of blood vessels

          a.     ARTERY

           b.    VEIN

           c.     CAPILLARY
                   The ARTERY
     Arteries carry blood away from the heart.

 the elastic fibres allow
  the artery to stretch
     under pressure

thick muscle and
                              the thick muscle can
elastic fibres
                              contract to push the
                                  blood along.
                    The VEIN
     Veins carry blood towards from the heart.

veins have valves
which act to stop the
blood from going in
the wrong direction.

thin muscle and
elastic fibres          body muscles surround the veins
                        so that when they contract to
                        move the body, they also squeeze
                        the veins and push the blood along
                        the vessel.
                 The CAPILLARY
          Capillaries link Arteries with Veins

  they exchange materials
  between the blood and
  other body cells.

the wall of a capillary
is only one cell thick      The exchange of materials
                            between the blood and the
                            body can only occur through
               The CAPILLARY
A collection of capillaries is known as a capillary bed.

 artery                                       vein

  body cell
                     what’s in
                     digested food
 red blood cells                     white blood cells

oxygen                                      waste (urea)

carbon dioxide                             platelets

                   plasma    hormones
                 The Blood

red blood cell                  white blood cell

platelets                    plasma
                     Red Blood Cells
                                        contain haemoglobin, a
a biconcave disc that is                molecule specially designed
round and flat without a                to hold oxygen and carry it
nucleus                                 to cells that need it.

                      can change shape to an
                      amazing extent, without
                      breaking, as it squeezes
                      single file through the
                 White Blood Cells

                            there are many different types and
                            all contain a big nucleus.

                            the two main ones are the
                            lymphocytes and the macrophages.

                            macrophages ‘eat’ and digest micro-
                            organisms .

some lymphocytes fight disease by making antibodies to destroy
invaders by dissolving them.
other lymphocytes make antitoxins to break down poisons.
Platelets are bits of cell
broken off larger cells.

Platelets produce
tiny fibrinogen
fibres to form a net.
This net traps other
blood cells to form a
blood clot.
                         It also contains useful
                         things like;

                         • carbon dioxide
A straw-                 • glucose
                         • amino acids
liquid that
carries the              • proteins
cells and the
                         • minerals
which help               • vitamins
blood clot.
                         • hormones
                         • waste materials
                           like urea.
copy and complete the following;

 Arteries take blood ______ from the heart. The walls of an artery
 are made up of thick _________ walls and elastic fibres. Veins carry
 blood ________ the heart and also have valves. The _________ link
 arteries and veins, and have a one cell thick wall. Blood is made up of
 four main things ______, the liquid part of the blood; Red Blood
 Cells to carry ______; White Blood cells to protect the body from
 disease and _________ to help blood clot.

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