Day 9: The Circulatory System

Overview of the circulatory system 

 

       -Carries oxygen and food to the cells of the body 

       Carries carbon dioxide and other waste away from cells to excretory organs, kidney, lungs and skin 

      Aids in coagulation process

 

      Assists in defending body against disease 

 

      And in regulation of body temperature 

The circulatory system is a system of closed tubes. Circulation occurs in two large loops- the pulmonary circulation and the systemic circulation. The pulmonary circulation carries blood between the heart and the lungs for gas exchange, and the systemic circulation carries blood between the heart and the rest of the body's tissues. In both cases, arteries carry blood  from the heart to capillary beds, where exchange occurs. Veins return blood to the heart.

The Heart

     4 chambers 

    Atria, right and left 

    Ventricles, right and left 

Septa: partitions separating the right and left sides of the heart

Cardiac cycle 

          

              One complete contraction (systole ) and relaxation ( diastole ) of the heart 

             Last about 0.8 seconds 

Pulmonary circulation

     Carries blood from right ventricle of heart to lungs 

    

     Carbon dioxide is removed: oxygen is picked up 

      Oxygenated blood returns to the left atrium of the heart 

Systemic circulation 

         Carries oxygenated blood and nutrients from left ventricle to body cells

 

           Returns deoxygenated blood with carbon dioxide and wastes from cells to right atrium

-Origin of the heart sounds 

The first sound: “LUBB” (ventricles contract, AV valves close )

    

 The second sound: “DUPP” ( ventricles relax, semilunar valves close ) 

Heart rate: number of heartbeats per minute

Cardiac output: volume of blood pumped by the heart in one minute 

Pulse: palpable rhythmic dropping caused by alternating expansion and contraction of  an artery as blood passes through 

Blood pressure: force exerted by blood on the walls of vessels

Lumen: Internal space a blood vessel through which blood flows 

Valves: thin membrane leaflets in veins prevents back flow of blood

Coronary artery diseases (CAD): Illness where the arteries that supply the heart muscle become narrowed, thickened, and hardened by the buildup of fatty deposit called plaque.

The plaque damages the inner lining of the vessel and causes hardening and thickening of the vessel wall. The name of this condition is atherosclerosis.

The major cause of coronary artery diseases is atherosclerosis (is the build-up of fat in the wall of the arteries).

As coronary artery diseases progress, the damaged to the coronary arteries can cause increase in the blood pressure and decreases blood flow to the heart muscle.

In extreme cases, a total blockage of the artery can result in heart muscle death (Heart Attack or Myocardial Infarction, MI).

Arteriosclerosis can also affect other arteries, including those in the brain and those that supply the arms and legs.

Coronary artery diseases can also cause complications if plaque becomes dislodged from the artery wall or if damage in the artery results in the formation of a blood clot.

Thrombus: blood clot that stays in the wall of the blood vessels.

Embolus: is when this thrombus dislodged from the wall of the blood vessel and goes into the blood flow.

Ischemia and Myocardial Infarction

When an embolus (Blood Clot) blocks the coronary artery, the heart muscle supplies by that vessel does not get enough oxygen, creating a condition called ischemia

Ischemia: pain cause by a lack of oxygen and blood

If ischemia in not treated, it may results in myocardial infarction (MI).