2.  Your heart is about the size of your fist.  It is made of muscle.  It is on the left side of your chest.  It is protected by the sternum and ribs.

3.  The heart has 4 chambers that beat in rhythm.  The rhythm is controlled by the pacemaker.  The chambers are separated by valves.

4.  It is split into two sides—the right and the left—separated by the septum.  The two sides are split into chambers.  The upper chambers are called right and left atrium.  The lower chambers are called right and left ventricles.

5.  The heart beats from the top to the bottom.  The atrium beats then the ventricle beats.  The heart beat is due to the closing of the valves.  The valves in the heart keep blood flowing in ONE direction.  No back flow!!

6.  The two sides of the heart have different jobs.  Right Side—receives blood from the body that is low in oxygen and pumps it to the lungs.  Left Side—pumps oxygen rich blood from the lungs to the rest of the body.

7.  SA Node—sinoatrial node is a group of cells in the heart that create electronic impulses that makes your heart beat.  What does the SA node in the heart do? - Sharecare What does the SA node in the heart do? - Sharecare

8. Normal Heart Sound - YouTube Shh!! Quiet please--we are listening to a normal heart beat.

9. Shh!! We are listening to the fetal heart around 16 weeks of pregnancy. http://www.youtube.c om/watch?v=jz5y- rKWkoE

10. This is a heart murmur. The sound is different from that of a normal heart beat. This sound occurs because the valves of the heart do not open/close properly.  http://www.youtube. com/watch?v=hYYQ dyDXaS8&feature=re lmfu http://www.youtube. com/watch?v=hYYQ dyDXaS8&feature=re lmfu

11.  There are 3 types of blood vessels: 1) Arteries 2) Veins 3) Capillaries http://www.youtube.c om/watch?v=CjNKb L_-cwA

12.  There are 3 types of blood vessels: 1) Arteries › Carry blood AWAY from the heart 2) Veins › Veins carry blood TOWARD the heart 3) Capillaries --Link the arteries to the veins and are the SMALLEST of the types.

13.  Carry blood AWAY from the heart.  Have thick muscles around them that SQUEEZE blood.  Are responsible for the PULSE you can feel.  Largest artery is the AORTA. › It has an inside diameter about the size of your thumb.

14.  Carry blood TOWARDS the heart  Do NOT have thick muscles.  Do HAVE valves which keeps blood flow moving and not backing up.  Largest vein is the VENA CAVA.  Veins are “sandwiched” between skeletal muscles. Flexing the muscles helps blood flow. This is why we stretch!

15.  Capillaries link the arteries and the veins.  They deliver oxygen and other nutrients to the cells.  They have very thin walls—about 1 cell thick.  This thinness allows material to transferred easily.  This thinness also allows them to be broken easily.  This is why we bruise—broken capillaries under the surface of the skin!!

16.  There are four components of the blood: 1) Plasma 2) Red blood cells 3) White blood cells 4) Platelets http://www.youtube.c om/watch?v=R- sKZWqsUpw

17. Plasma is the liquid part of the blood. It makes up 55% of blood volume.

18.  RBCs are disc shaped.  They do NOT have a nuclei.  RBCs have a life span of 120 days.  They are made in bone marrow of long bones.  They contain hemoglobin which carries oxygen and carbon dioxide. http://www.youtube.co m/watch?v=4HH3UXp dIFw

19.  WBCs fight viruses, bacteria, etc.  Their numbers increase when infection is present.  WBCs are bigger than RBCs but fewer in number.  WBCs have a much shorter life span than RBCs. http://www.youtube.c om/watch?v=JnlULO jUhSQ

20.  Platelets are irregularly shaped fragments.  They help to clot blood.  They live for 4 to 9 days. Clotting --Platelets produce a chemical called fibrin. --Fibrin helps make sticky “spider webs” to help blood clot. http://www.youtube.co m/watch?v=-- bZUeb83uU