The Circulatory System

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					The Circulatory System
                      February 3, 2009
•       Bell Ringer
    –      Complete the Bell Ringer Activity given to you when you entered the room
•     Objectives
    1. Explain the function of the circulatory system.
    2. Describe the parts of the circulatory system.
    3. Explain how the heart functions in the circulatory system.
•     Planner
    –    Skeletal System Test Retakes due Today!
    –    Bones Test Retakes due Friday February 6
    –    Muscular System Test Retakes due Monday February 9
    –    Path of Blood Flow Quiz Friday February 6
    –    Notebooks will be due on Monday February 9
             The Circulatory System
•    Also called the
     cardiovascular system
•    Is made of the heart, blood,
     and blood vessels
•    Allows blood to flow to all
     parts of your body
•    Has 3 main jobs:
    1.   Carries needed substances
         to cells
         –   Oxygen and glucose
    2.   Carries waste products
         away from cells
         –   Carbon dioxide
    3.   Contains cells that fight
The Heart
                      The Heart
• A hollow muscular organ
  that pumps blood
  throughout the body
• About the size of your fist
• Located in the center of
  the chest, beneath the
  sternum and inside the
• Made of cardiac muscle
   – Contracts over and over
     without tiring out
                         The Heart
• Acts as two pumps
   – Right side: pumps blood
     into the lungs where it
     picks up oxygen
   – Left side: pumps blood
     into the arteries where it is
     sent throughout the body
• The two sides are
  separated by a wall of
  tissue called the septum.
                   The Heart
• Each side has two
  – The upper chambers
    are called atria.
  – The lower chambers
    are called ventricles.
                    The Atria
• The upper chambers of
  the heart
• Job is to receive blood
  that comes into the heart
• The right atrium has a
  group of cells called the
  pacemaker (sinoatrial
  node) that sends signals
  to make the heart muscle
• Whenever someone
  has problems with an
  irregular heartbeat,
  doctors may give
  them an artificial
• This helps their heart
  maintain a normal
• The lower chambers
• Job is to pump blood
  out of the heart
  – Right ventricle
    pumps blood to the
  – Left ventricle pumps
    blood out of the heart
    and into the body
• The ventricles are
  separated from the
  atria by valves
  – Flaps of tissue that
    prevents blood from
    flowing backward
  – Also located between
    the ventricles and the
    large blood vessels
    that carry blood out of
    the heart
          How the Heart Works
•   Two phases
    1. Heart muscle relaxes and atria fill with blood
    2. Heart muscle contracts and blood pumps
      •   This closes the valves between the atria and the
          – Creates the lub sound
      •   The valves between the ventricles and the blood
          vessels snap shut
          – Creates the dup sound
                  Two Loops
• Overall pattern of blood flow in the body is like
  the figure eight.
• In the first loop, blood travels from the heart to
  the lungs and then back to the heart.
• In the second loop, blood is pumped from the
  heart throughout the body and then returns to
  the heart.
• Blood travels in only one direction.
• One drop of blood could make the journey
  through both loops in less than a minute.
      The Path of Blood Flow
1. Vena cava is a large vein that carries oxygen-
   poor blood to the heart
2. The right atrium receives the oxygen-poor
   blood from the vena cava.
3. Blood leaves the right atrium through the
   tricuspid valve and enters the right ventricle
4. From the right ventricle the blood passes
   through the pulmonary valve and enters the
   pulmonary artery, which sends the blood to
   the lungs
          The Path of Blood Flow
5. In the lungs, blood picks up oxygen; it then passes through the
    pulmonary veins.
6. From the pulmonary veins, oxygen-rich blood enters into the left
7. From the left atrium, the blood then passes through the mitral valve
    and empties into the left ventricle.
8. The blood leaves the left atrium through the aortic valve, and enters
    the aorta.
9. The aorta sends oxygen-rich blood to all parts of the body.
10. Once the body’s cells receive the blood, they exchange carbon
    dioxide for oxygen.
11. The oxygen-poor blood makes its way to the vena cava, where it
    can start its journey again.
Pumping Heart Video
               Blood Vessels
• There are three kinds of blood vessels
  – Arteries
     • Carry blood away from the heart
  – Veins
     • Carry blood to the heart
  – Capillaries
     • Exchange substances between the blood and body
                  February 4, 2009
•     Bell Ringer
•     Objectives:
         1. Describe the structures and the functions of the
      blood vessels.
          2. Describe the components of blood.
          3. Explain what determines the type of blood that a person
          can receive in a transfusion.
•     Planner:
    –     Skeletal System Test Retakes due Today!
    –     Bones Test Retakes due Friday February 6
    –     Muscular System Test Retakes due Monday February 9
    –     Path of Blood Flow Quiz Friday February 6
    –     Notebooks will be due on Monday February 9
• Job is to carry blood
  away from the heart
• Each artery branches into
  smaller and smaller
   – Smallest branches are
     called arterioles.
      • Arterioles join to
• Aorta is the largest artery
  in the body
   – Has many branches
           Coronary Arteries
• The coronary
  arteries are the
  branches of the aorta
  that supply the heart
  muscle with blood
• Blockages of these
  arteries can lead to
  heart attacks
             Structure of an Artery
•    Have very thick walls made of three cell layers
    1. The innermost layer is smooth and is
         made of epithelial cells.
         • Lets blood flow freely
    2. The middle layer is made of muscle
         • Acts as a control gate, controlling how
             much blood enters the vessel
    3. The outer layer is made of flexible
         connective tissue
         • Allows the arteries to withstand the
             force of the blood being pushed
             through them.
•    Arteries are strong and flexible
•    Able to withstand much pressure
•    The pulse is caused by the alternating
     expansion and relaxation of the artery wall
• Veins carry blood to
  the heart.
• Veins branch into
  smaller and smaller
  – The smallest branches
    are called venules.
     • Venules are attached to
       the capillaries.
            Structure of the Veins
•   Veins are made of three
    layers, but are thinner than
•   Because the force of blood
    flow is not as strong when
    blood reaches the veins, the
    blood needs help moving.
       1.   Contractions of skeletal
            muscles helps to push
            blood through the veins.
       2.   Larger veins have valves in
            them to prevent blood from
            flowing backward.
       3.   Breathing movements help
            to force blood to the heart.
• In the capillaries, materials
  are exchanged between the
  blood and the body’s cells.
• The capillaries form a web
  between the arteries and the
• Capillary walls are made of
  epithelial tissue.
• Capillary walls are only one
  cell thick.
   – Materials pass easily through
     them using the process of
     diffusion, molecules moving
     from areas of high to low
• Blood is made of four
  components, or parts:
  – Plasma, red blood
    cells (RBCs), white
    blood cells (WBCs),
    and platelets
     • About 45% of the
       volume of blood is cells;
       the rest is plasma
• Most of the materials transported in the
  blood travel in the plasma.
• Plasma is the liquid part of blood.
  – 90% of plasma is water
  – 10% is dissolved materials, such as glucose,
    fats, vitamins, and minerals
     • Many waste products are carried away by the
•   Proteins give plasma
    its yellow color
    – Three groups of
      plasma proteins
      1. Helps regulate amount
         of water in blood
      2. Helps fight disease
      3. Interacts with platelets
         to form blood clots.
                  Red Blood Cells
• RBCs take up oxygen in
  the lungs and deliver it to
  cells throughout your
• Produced in the bone
  marrow (like other blood
• Look like doughnuts that
  someone forgot to cut out
  the hole
   – Because they are thin in
     the middle, they are able to
     bend and twist easily
       • Allows them to squeeze
         into tiny capillaries
• Made mostly of hemoglobin,
  an iron-containing protein that
  chemically binds to oxygen.
    – Hemoglobin is also able to
      pick up some carbon dioxide,
      but most is carried by the
    – When hemoglobin and oxygen
      join together, the cell becomes
      bright red; without oxygen, the
      cell is dark red
        • Arteries have blood that is
          bright red
        • Veins have blood that is dark
• Mature RBCs have no
  – Without a nucleus, it
    cannot reproduce or
    repair itself
     • Only are able to live
       120 days
         – Every second, about
           2 million RBCs die
             » Bone marrow
                makes new cells
                at the same rate
                 February 5, 2009
•     Bell Ringer
•     Objectives:
    1. Name the structures and functions of the lymphatic system.
    2. Identify some diseases of the cardiovascular system.
    3. Describe behaviors that can help maintain cardiovascular
•     Planner:
    –    Skeletal System Test Retakes due Today!
    –    Bones Test Retakes due Friday February 6
    –    Muscular System Test Retakes due Monday February 9
    –    Path of Blood Flow Quiz Friday February 6
    –    Notebooks will be due on Monday February 9
               White Blood Cells
• Produced in the bone
• WBCs are the body’s
  disease fighters.
  – Some recognize disease
    causing organisms and
    alert the body that it has
    been invaded
  – Others produce chemicals
    to fight the invaders
  – Others surround and kill
    the invaders
• There are fewer
  WBCs than RBCs.
• Larger than RBCs
• Several different
  types of WBCs
• WBCs have nuclei
  – Can live for months or
    even years
• Platelets are cell
  fragments that play
  an important role in
  forming blood clots
                     Forming Clots
• When a vessel is cut,
  platelets collect and stick
  around the cut.
• Platelets release a
  chemical that leads to the
  production of a protein
  called fibrin.
   – Fibrin makes a net of fibers
     across the wound.
       • This net traps blood cells.
           – As more and more of the
             platelets and cells get
             caught in the fibrin net, a
             clot forms.
                » A scab is a dried
                   blood clot on the
                   skin’s surface
                Blood Types
• Four major blood
  types: A, B, AB, O
• Types are determined
  by the proteins known
  as marker molecules
  that are on RBCs
  – A has the A marker, B
    has the B marker, AB
    has both A and B, O
    has no markers on it
                Blood Types
• Plasma has proteins
  that recognize cells
  with foreign markers
  and they make those
  cells clump together
  – A has anti-B proteins
  – B has anti-A proteins
  – AB has no anti-
  – O has both anti-A and
    anti-B proteins
 Why is Blood Type Important?
• Your blood type
  determines what type of
  blood you can safely
  receive in a blood
   – If you are A, you can
     receive A and O blood
   – If you are B, you can
     receive B and O blood
   – If you are AB, you can
     receive, A, B, AB, and O
       • “Universal recipients”
   – If you are O, you can only
     receive O blood
       • “Universal donors”
                  Rh factor
• The Rh factor is
  another protein that is
  found in the blood.
• You are either Rh+ or
• Rh factor is named for
  the Rhesus monkey,
  which was the first
  organism recognized
  to have the Rh factor
        The Lymphatic System
• As blood travels through the circulatory system,
  some of the fluid leaks out.
   – The fluid moves through the walls of the capillaries
     and into the tissues.
      • The fluid carries materials the cells in the tissues need.
• After bathing the cells, the fluid moves into the
  body’s drainage system, the lymphatic
   – A network of vein-like vessels that returns the fluid to
     the bloodstream
• Once inside the lymphatic system, the fluid is
  called lymph.
• Lymph is made of water and dissolved materials;
  it also has some white blood cells in it.
• The lymphatic system has no pumps, so lymph
  moves very slowly.
• The lymphatic vessels connect to large veins in
  the chest.
  – Lymph empties into these veins and the fluid
    becomes part of the plasma again.
Lymph Nodes
• Lymph nodes are
  pieces of tissue that
  filter lymph, trapping
  bacteria and other
  microorganisms in the
               Lymph Nodes
• When the body is
  fighting infection, the
  lymph nodes enlarge.
• Sometimes referred
  to as “swollen
    Cardiovascular Diseases
• Cardiovascular disease is the leading
  cause of death in the U.S. today.
• Atherosclerosis is a
  condition in which an
  artery wall thickens as
  a result of the buildup
  of fatty materials such
  as cholesterol.
  – This reduces the
    flow of blood in the
    affected artery.
• When atherosclerosis develops in the
  coronary arteries, the heart muscle
  receives less blood (less oxygen), which
  can lead to a heart attack.
  – Heart attacks occur when the blood flow to
    part of the heart muscle is blocked.
     • Cells die in the part of the heart that does not
       receive blood and oxygen. This permanently
       damages the heart
         Treating Atherosclerosis
• Low-fat diet and exercise for
  mild cases.
• Some medications can be
• Severe cases may lead to
  angioplasty, where a small
  balloon is inserted into the
  blocked artery to help open it
• When arteries are completely
  blocked, a bypass operation
  may be performed.
    – In a bypass, a vein from the
      leg is used to create an
      alternate path for blood to flow
      into the heart muscle.
• Hypertension is high blood pressure.
• A person will have hypertension if their blood
  pressure is consistently greater than 140/90.
• High blood pressure makes the heart work
  harder to pump blood through the body, possibly
  damaging the walls of the blood vessel.
• Because most people have no obvious signs of
  the disease it is called the “silent killer”.
 Treating High Blood Pressure
• Closely related to atherosclerosis.
• As arteries narrow, the blood pressure
• Diet and exercise help
• Limit intake of salt
• Sometimes given medications that lower
  blood pressure
       Measuring Blood Pressure
•   Blood pressure is measured by a
    device called a
•   The first number in a blood
    pressure reading is the
    measurement of the blood
    pressure when the ventricles
•   The second number, which is
    lower, is the blood pressure when
    the ventricles relax.
•   The blood pressure is given as a
    fraction with the contraction
    pressure, or systolic, over the
    relaxation pressure, or diastolic.
     – A healthy blood pressure is
       120/80 or lower.

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